IOVS Physiological Genomics
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

(Investigative Ophthalmology and Visual Science. 2003;44:4968-4975.)
© 2003 by The Association for Research in Vision and Ophthalmology, Inc.
DOI:  10.1167/iovs.03-0140
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Li, F.
Right arrow Articles by Anderson, R. E.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Li, F.
Right arrow Articles by Anderson, R. E.

Alleviation of Constant-Light–Induced Photoreceptor Degeneration by Adaptation of Adult Albino Rat to Bright Cyclic Light

Feng Li,1,2 Wei Cao,1,2 and Robert E. Anderson1,2,3

1From the Departments of Ophthalmology and 2Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; and the 3Dean A. McGee Eye Institute, Oklahoma City, Oklahoma.


   Abstract
Top
 Abstract
Materials and Methods
 Results
 Discussion
 References
 
PURPOSE. To further test the hypothesis that light-adaptation–mediated photoreceptor protection works through inhibition of apoptosis by activation and/or upregulation of neuroprotective molecules.

METHODS. Albino rats were born and raised in 5-lux cyclic light (12 hours OFF and ON). At 8 weeks of age, animals were adapted to 400-lux cyclic light for different periods. Light damage was induced by exposure to constant light for 1 day at an illumination of 1700 lux. Animals were killed, and their eyes were removed for morphometric and biochemical analysis. TUNEL assay was used to evaluate photoreceptor cell apoptosis and Western blot analyses were used to determine the levels of basic fibroblast growth factor (bFGF), neuronal nitric oxide synthase (nNOS), and caspase-3.

RESULTS. Exposure of dim-reared rats to constant light for 1 day dramatically increased TUNEL-positive cells in the outer nuclear layer. Adaptation to 400-lux bright cyclic light for 4 days significantly reduced TUNEL-positive cells induced by exposure to constant light, which correlated with a significant increase in bFGF expression. Compared with control retinas, caspase-3 levels were not changed by exposure to constant light or after adaptation to 400 lux. There was a significant increase in nNOS level in the constant-light–exposed group, but not in the group adapted to 400-lux bright light before exposure to constant light.

CONCLUSIONS. The retina of the adult rat can rapidly upregulate neuroprotective mechanisms when switched from dim to bright cyclic light. Identification of the molecules involved in this process may allow rational development of therapeutic approaches to treat retinal degenerative diseases.

Light history has been shown to affect the susceptibility of the retina of the albino rat to light damage.1 2 3 Animals raised in relatively bright environments are protected against light-induced degeneration, compared with rats raised in dim cyclic light or darkness,1 2 4 5 6 suggesting that factors that determine the protection against light-induced apoptosis may be generated in response to light stress. This adaptability encompasses many aspects of retinal cell and molecular biology and physiology, one of which must be the up- or downregulation of retinal photoreceptor cell components. In this regard, several molecules and mechanisms have been found to change in animals raised from birth in bright cyclic light, compared with those raised in dim light, and in animals exposed acutely to damaging levels of light, compared with unexposed control animals. These include upregulation of antioxidant protective mechanisms,1 upregulation of cytokines,7 and other neuroprotective proteins, such as heat shock protein8 and heme oxygenase,9 up- or downregulation of visual transduction cascade components,10 and upregulation of transcription factor activator protein (AP)-1.11 12 It has been shown recently that hypoxia upregulates erythropoietin, which protects the retina from light damage.13 14 Hypoxia also induces the formation of bFGF and VEGF.15 16 17 18 19 20

It is now clear that apoptotic cell death occurs in virtually every cell type and that most pathologic insults can provoke apoptosis if delivered at a dose below that expected to cause acute, necrotic cell death. Apoptosis has been described in a wide variety of hereditary retinal degenerations,21 22 23 in light-induced damage,24 after retinal detachment,25 26 and in other types of retinal degeneration.27 Recent observations demonstrating the importance of mitochondrial function and the high metabolic demands of rods make it likely that loss of calcium homeostasis, free radical damage, and any other process leading to mitochondrial failure may also be of significance.28 29 30 We hypothesize that adaptive protection against light-induced apoptosis works through upregulation of neuroprotective molecules. To test this hypothesis, we examined the time course of activation of this adaptation system in adult rats born and raised in dim cyclic light (5 lux) and switched acutely to brighter cyclic light (400 lux). We also determined the levels of expression of bFGF, caspase-3, and neuronal nitric oxide synthase (nNOS) as a function of adaptation.


   Materials and Methods
Top
 Abstract
 Materials and Methods
Results
 Discussion
 References
 
Animals and Constant Light Exposure
Sprague-Dawley albino rats were born and raised in 5-lux cyclic light (12 hours ON and OFF). At 8 weeks of age, animals were adapted to 400-lux cyclic light for 1, 2, 3, 4, 6, or 9 days. Light damage was then induced by exposure to constant light for 24 hours at an illumination of 1700 lux. Except as noted, after exposure to 400-lux cyclic light, control animals were returned to 5-lux cyclic light for an additional 5 days before any measurements were made. After constant exposure to light, animals were placed in the dark for 24 hours and then returned to 5-lux cyclic light for an additional 4 days, except as noted. All experimental procedures adhered to the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research and the University of Oklahoma Faculty of Medicine Guidelines for Animals in Research. All research protocols were reviewed and approved by the Institutional Animal Care and Utilization Committees of the University of Oklahoma Health Sciences Center and the Dean A. McGee Eye Institute.

Functional Evaluation by Electroretinography
Animals were kept in total darkness overnight before electroretinograms (ERG) were recorded. Animals were anesthetized with ketamine (120 mg/kg body weight intramuscularly [IM]) and xylazine (6 mg/kg body weight IM). Pupils were dilated with 1.0% tropicamide and 2.5% phenylephrine HCl, and ERG responses were recorded with a gold electrode placed in the cornea with 1% tetracaine topical anesthesia. A reference electrode was positioned at the mouth and a ground electrode on one foot. The duration of white-light stimulation was 10 ms with a 60-second delay between flashes at seven light intensities presented in ascending order, beginning below threshold, to record the b-wave sensitivity curves and allow calculation of the saturated b-wave amplitude (Bmax).

Morphologic Evaluation by Quantitative Histology
After ERG testing, animals were killed by an overdose of carbon dioxide. The eyes were enucleated, fixed, and embedded in paraffin, and 5-µm-thick sections were taken along the vertical meridian, to allow comparison of all regions of the retina in the superior and inferior hemispheres. We used the method established by Rapp et al.31 and LaVail et al.32 to evaluate the morphologic changes quantitatively. In each of the hemispheres, outer nuclear layer (ONL) thickness was measured in nine defined areas, starting at the optic nerve head and extending along the vertical meridian toward the superior and inferior ora serrata. Measurements were made at 450-µm intervals. Mean ONL thickness was then calculated for the entire retinal section,32 as was ONL thickness of the superior region of retina, which is most sensitive to the damaging effects of light. In each experiment, a single section from the retinas of at least six eyes was measured.

Photoreceptor Cell Apoptosis Evaluation by TUNEL Assay
The TUNEL assay was used to study the effect of environmental light change on photoreceptor cell apoptosis and on the ability of the retina to adapt to 400-lux cyclic light. An apoptosis detection kit (ApopTag Peroxidase In Situ Apoptosis Detection; Intergen Co., Purchase, NY) was used in histochemical staining of the paraffin-embedded tissues to examine photoreceptor cell apoptosis through DNA fragmentation.

SDS-PAGE and Western Blot Analysis
Protein samples containing 50 to 100 µg of retinal protein were resolved by 7.5%, 10%, or 15% SDS-PAGE and transferred to nitrocellulose membranes. The blots were washed two times for 5 minutes each with TTBS (100 mM NaCl, 20 mM Tris-HCl [pH 7.4], and 0.1% Tween-20) and blocked with 10% nonfat dry milk in TTBS overnight at 4°C. The blots were then incubated with bFGF (1:500; Santa Cruz Biotechnology, Inc., Santa Cruz, CA), caspase-3 (1:500; Santa Cruz Biotechnology, Inc.), nNOS (1:2500; BD Biosciences, San Diego, CA), or rhodopsin (R1D4, 1:10,000) antibodies for 2 hours at room temperature. After primary antibody incubation, the blots were incubated with horseradish peroxidase (HRP)–linked secondary antibodies (anti-rabbit, anti-mouse, or anti-goat IgG) and developed by enhanced chemiluminescence (ECL), according to the manufacturer’s instructions.

Statistical Analysis
Results are expressed as the mean ± SD. Differences were assessed by ANOVA or t-test, depending on experimental design. P < 0.05 was considered significant.


   Results
Top
 Abstract
 Materials and Methods
 Results
Discussion
 References
 
Morphologic Evaluation of Photoreceptor Cell Protection
Morphologic evaluation of photoreceptor cell protection by adaptation to bright cyclic light was determined by quantitative histology. As mentioned earlier, after exposure to constant light for 24 hours or to 400-lux cyclic light, all animals were returned to 5-lux cyclic light for an additional 5 days before any measurement. Figure 1 shows the ONL thickness along the vertical meridian of the eye of rats maintained either in dim cyclic light (5 lux) or adapted to bright cyclic light (400 lux) for different periods ranging from 1 to 9 days, with or without exposure to constant light (1700 lux for 24 hours). Before adaptation, exposure to constant light caused a dramatic loss of photoreceptor cells, as evidenced by thinning of the ONL in both the superior and inferior hemispheres (Fig. 1A) . The average ONL thickness of constant-light–stressed rats was 15% of that in the nonstressed control animals (Fig. 1H) . Adaptation to 400-lux cyclic light had two measurable effects. First, there was a modest but significant time-dependent loss of photoreceptor cells due to the adaptive process, such that after 9 days of cyclic 400-lux light, the ONL thickness was reduced to 65% of control thickness (Fig. 1H) . The greatest loss occurred in the superior retina and was evident from the second day of exposure. Second, there was a significant, time-dependent increase in survival of photoreceptors after adaptation to 400-lux cyclic light. After 9 days, 78% of the photoreceptor cells survived the constant-light challenge.



View larger version (38K):
[in this window]
[in a new window]
  		FIGURE 1. Quantification of morphologic changes. Measurements of ONL thickness along the vertical meridian of the eye in albino rats maintained in dim cyclic light (5 lux) or adapted to bright cyclic light (400 lux) for 0 to 9 days, either with (CL) or without (control) exposure for 1 day to constant light (1700 lux). (A–G) Average of six retinas of animals adapted for 0, 1, 2, 3, 4, 6, and 9 days. (H) Histogram of the average ONL thickness with or without constant light exposure. ¶P < 0.05 vs. day 0 non-light-damage groups. *P < 0.05 vs. day 0 light damage groups.

 
Functional Evaluation of Photoreceptor Cell Protection
The effect of adaptation on retinal function was determined by electroretinography 5 days after exposure to constant light. Figure 2 shows the b-wave amplitudes of rats adapted to 1, 2, 3, 4, 6, or 9 days of cyclic 400-lux light, before and after constant-light challenge. Histograms of Bmax values are presented in Figure 2H . As expected, exposure of nonadapted animals to constant light for 24 hours almost completely abolished the ERG response. Adaptation to 400-lux bright cyclic light gradually reduced the b-wave amplitudes in nonexposed animals, evidenced by the decline of the sensitivity curves (Figs. 2B 2C 2D 2E 2F 2G) and in Bmax values (Fig. 2H) . Bmax was significantly reduced to 68% or 60% of the time 0 control after 6 (P < 0.03) or 9 (P < 0.009) days of adaptation, respectively (Fig. 2H) . Significant protection of function was first noted at 3 days of light adaptation (P < 0.05). Bmax increased from 0 µV in nonadapted rats to 285 µV in animals adapted for 3 days and increased to 434 µV and 493 µV after 6 and 9 days of adaptation, respectively. Thus, although there was some loss of function as a result of the adaptation, exposure to 400-lux cyclic light significantly preserved function when the animals were challenged by 24 hours of constant illumination.



View larger version (26K):
[in this window]
[in a new window]
  		FIGURE 2. Functional protection by retinal adaptation to bright cyclic light. Measurements of electroretinogram (ERG) b-wave amplitudes in albino rats maintained in dim cyclic light (5 lux) or adapted to bright cyclic light (400 lux) for 0 to 9 days, either with (CL) or without (control) exposure for 1 day to constant light (1700 lux). (A–G) are the average b-wave amplitudes of six retinas of animals adapted for 0, 1, 2, 3, 4, 6, and 9 days. (H) Average Bmax values with or without constant light exposure. ¶P < 0.05 vs. day 0 non-light-damage groups. *P < 0.05 vs. day 0 light damage groups.

 
Protection through Inhibition of Apoptosis
We used the TUNEL assay to examine the possibility that the protection provided by retinal adaptation to bright cyclic light works through inhibition of apoptosis. In these studies, animals were killed immediately after bright-light adaptation and/or exposure to constant light, and sections were taken between 0.5 and 1 mm from the optic nerve head along the superior meridian. Control retinas from animals born and raised in 5-lux cyclic light environment have no TUNEL-positive cells (Fig. 3A) . However, constant exposure to light for 24 hours induced extensive photoreceptor cell apoptosis, as indicated by TUNEL-positive staining in the ONL (Fig. 3B) . In comparison with control retinas (Fig. 3A) , there was a significant increase in TUNEL-positive cells in the ONL after adaptation to 400-lux bright cyclic light for 4 days (Fig. 3C) . However, when challenged with constant light, retinas from these animals showed a significant reduction in TUNEL-positive cells (Fig. 3D) compared with control animals (Fig. 3B) .



View larger version (106K):
[in this window]
[in a new window]
  		FIGURE 3. Inhibition of light-induced apoptosis by retinal adaptation to bright cyclic light. The ability of retinal adaptation in the inhibition of photoreceptor cell apoptosis was measured by TUNEL assay. (A) Control rat born and raised in 5-lux cyclic light. (B) Rat born and raised in 5-lux cyclic light and exposed to 1700-lux constant light for 1 day. (C) Rat born and raised in 5-lux cyclic light and adapted to 400-lux cyclic light for 4 days. (D). Rat born and raised in 5-lux cyclic light, adapted to 400-lux cyclic light for 4 days, and exposed to 1700-lux constant light for 1 day. These are representative micrographs from four animals per experimental group.

 
Increased bFGF Expression after Adaptation to Bright Cyclic Light
Because bFGF has been shown to protect photoreceptor cells and to inhibit photoreceptor apoptosis induced by damage from constant light,32 33 34 35 we investigated whether adaptation to bright cyclic light could increase bFGF expression in the retina in a time frame contemporaneous with adaptive neuroprotection. Animals born and raised in 5-lux cyclic light environment were adapted to bright cyclic light (400 lux) for 1, 2, 3, 4, 6, or 9 days before retinas were collected. Animals not adapted to bright cyclic light served as the control. Western blot analysis of bFGF showed an increase after 2 days of adaptation (Fig. 4A) . Scanning of the blots of four independent experiments showed a significant increase in bFGF expression after 4 days of adaptation (Fig. 4B) . This increase was maintained after 6 and 9 days of adaptation, the longest examined time point in this study. As a loading control, we also ran a parallel blot to detect rhodopsin expression. Although a slight but not statistically significant decrease in rhodopsin expression was seen after 4 or 6 days of adaptation, a significant decrease in rhodopsin expression was seen after 9 days’ adaptation to bright cyclic light (Fig. 4A) . This probably reflects the loss of photoreceptor cells during adaptation, as well as the shortening of outer segments1 2 3 and reduction in rhodopsin packing density6 36 in animals raised in bright cyclic light.



View larger version (32K):
[in this window]
[in a new window]
  		FIGURE 4. Western blot analysis of bFGF and rhodopsin as a function of time of adaptation to 400-lux cyclic light. (A) bFGF was detected as a 17-kDa protein with anti-bFGF antibody. Rhodopsin, a 40-kDa protein, was detected with anti-rhodopsin antibody in a parallel blot. (B) Quantitation of relative bFGF levels. Results from four independent experiments were averaged and presented relative to control levels (no adaptation). Each gel contained 50 µg of retinal protein.

 
Western Blot Analysis of Caspase-3 and nNOS
Because it has been reported that the expression of caspase-3 is increased in the retina of transgenic rats with the S334ter rhodopsin mutation,37 we determined whether there was an effect of adaptation for 4 days to bright cyclic light on retinal caspase-3 levels. Western blot analysis of retinal extracts of four independent experiments (Fig. 5A) probed with anti-caspase-3 antibodies did not show any effect of adaptation or of exposure to 24 hours of constant illumination. However, nNOS, which has been shown to be increased in mice exposed to 6 hours of very bright light (6000 lux),38 was significantly increased in the retinas of both groups of rats exposed to constant light, although there was no difference in nNOS expression in control animals and rats adapted to bright cyclic light for 4 days (Fig. 5) .



View larger version (38K):
[in this window]
[in a new window]
  		FIGURE 5. Western blot analysis of caspase-3 and nNOS expression after retinal adaptation to 400-lux cyclic light for 4 days. (A) Caspase-3 was detected as a 32-kDa protein with anti-caspase-3 antibody. nNOS is a 155-kDa protein detected with anti-nNOS antibody in a parallel blot. (B) Quantitation of relative nNOS levels. Data from three independent experiments were averaged and presented relative to control levels.

 

   Discussion
Top
 Abstract
 Materials and Methods
 Results
 Discussion
References
 
It is now well known that rats raised in dim cyclic light or darkness are more susceptible to light damage than animals raised in bright cyclic light.1 2 10 39 A number of biochemical and morphologic differences have been described in rats raised under these two conditions. Morphologically, bright cyclic light rearing leads to shortened and more disorganized rod outer segments than dim cyclic light rearing.1 Biochemically, three types of changes occur: (1) a change in components of the visual cascade pathway to reduce the efficiency of photon capture and transduction, which includes reduced rhodopsin-packing density in ROS,6 36 reduced rhodopsin protein and opsin mRNA,10 40 reduced transducin protein and mRNA,10 40 and increased arrestin protein and mRNA10 40 ; (2) an enhancement of mechanisms that protect against lipid peroxidation, including increases in enzymatic activities of glutathione enzymes,1 decreased levels of polyunsaturated fatty acid substrates of lipid peroxidation,36 and increased levels of the antioxidants vitamin E and ascorbic acid1 ; (3) an upregulation of neuroprotective cytokines such as bFGF and CNTF.41 Many of these changes and others occur during acute light damage, in which case it is difficult to differentiate between the neuroprotective effects and a response to an acute insult.

In an earlier study,39 adult rats switched from a cyclic light environment of less than 250 to 800 lux for 1 week were protected against constant light damage to photoreceptor cells. In the present study, the time course of adaptation was determined for rats born and raised in 5-lux cyclic light and moved at age 8 weeks into a cyclic light environment of 400 lux. This intensity has been shown to be sufficient to upregulate neuroprotection against light damage.1 We used this level in an attempt to reduce light damage, which occurs when adult rats are brought from a dim to bright cyclic light environment.39 We confirmed our earlier work showing that the adult albino rat retina has a remarkable ability for rapidly upregulation of neuroprotective mechanisms that prevent retinal damage due to intense constant illumination.39 Only one 12-hour exposure to 400-lux light was sufficient to provide some protection of retinal function (Figs. 1 2) . Significant protection of retinal structure was evident after two 12-hour exposures to 400-lux light. Under our experimental conditions, there was a 65% loss of photoreceptor cells in rats adapted for 9 days to 400-lux cyclic light, indicating a competition between the adaptive and degenerative processes. However, of the cells that adapted to the acute 400-lux cyclic light challenge, 78% survived an acute 1700-lux exposure for 24 hours, compared with only 15% in nonadapted control cells (Fig. 1) .

An interesting finding in this study was that the reduction in function (Bmax) over the 9-day adaptive period was greater than the reduction in ONL thickness. This could reflect an adaptive change in the components of the visual cascade, mentioned earlier. However, the ERG measurements of animals that were not exposed to 1700 lux for 24 hours were made 5 days after the animals were returned to 5-lux cyclic light, which should have been sufficient time for some recovery of function. Also, after acute exposure, the relative loss of Bmax in adapted animals at all time points was greater than the relative loss of ONL thickness. Thus, it may be possible that adaptation preserves retinal structure to a greater extent than it preserves function. This is not a new idea, as it has been reported that retinal structure in transgenic rats containing rhodopsin mutations is better preserved than function in animals treated with neuroprotective cytokines42 43 (Steinberg RH, et al. IOVS 1997;38:ARVO Abstract 1069).

Apoptosis is the mode of photoreceptor cell death in inherited and light-induced retinal degeneration.21 22 23 24 In this study, we demonstrated that the protection provided by retinal adaptation to bright cyclic light works through inhibition of apoptosis, although the molecular basis for this protection has yet to be elucidated. Nevertheless, a diverse range of agents has been used to prevent photoreceptor apoptosis in this model.35 44 45 46 These include survival factors such as bFGF,33 47 48 implicating a role for growth-promoting factors in the inhibition of photoreceptor apoptosis. It has also been demonstrated that bFGF promotes photoreceptor survival in RCS rats,49 which have a defect in phagocytosis of rod outer segments by RPE cells due to a mutation in the receptor tyrosine kinase gene Mertk.50 In albino rats, bFGF also protects photoreceptors from the damaging effects of constant light.33 35 We have shown in this study that adaptation to bright cyclic light increases bFGF expression in the retina in a time frame contemporaneous with that of development of neuroprotection, suggesting that upregulation of bFGF expression may play a role in photoreceptor cell protection by adaptation to bright cyclic light.41 It has been demonstrated in differentiated pheochromocytoma (PC12) cells that bFGF rapidly inhibits whole-cell sodium channels, which are fundamental for the regulation of electrical excitability in neuronal cells. This inhibition is coincident with a hyperpolarizing shift in the voltage dependence of inactivation.51 However, the relation between such inhibition and bFGF induced by light adaptation in the photoreceptor protection in this study remains unknown. We have also studied the FGFR-1 protein level in the retina in response to light adaptation from 1 to 9 days. No difference between control and light-adapted groups was observed at any time point. Caspase-3 is recognized as one of the key executioners in apoptosis. The role of caspase-3 in photoreceptor degeneration has been examined in a line of transgenic rats that carry a rhodopsin mutation S334ter, and an increase in caspase-3–like activity was noted,37 suggesting the involvement of caspase-3 in hereditary photoreceptor cell death. Donovan et al.38 examined the activation status of caspase-3 during photoreceptor apoptosis in a mouse model and found that light-induced photoreceptor degeneration occurs independent of caspase-3. In three independent experiments, we found no obvious changes in retinal caspase-3 expression after adaptation, constant light exposure, or adaptation plus constant light exposure. The slight increase in caspase-3 level in the retinas of rats treated for 4 days with bright light shown in Figure 5A is probably due to the slight relative decrease in rhodopsin in total retinal proteins that occurs when photoreceptor cells are lost. Our Western blot analyses are similar to those presented by Donovan et al.38 in mice and quite different from the Western blots and enzyme activities reported by Liu et al.52 in rats with a mutant rhodopsin (S334ter). This suggests that the mechanisms involved in photoreceptor cell death by light damage, which are likely to involve oxidative damage, are different from those that occur in cell death due to mutations in photoreceptor-specific genes.

Because the free radical NO appears to play a role in light-induced retinal degeneration,38 53 54 55 we examined the effect of 400-lux cyclic light adaptation on the expression of nNOS. Our results showed that nNOS expression was increased in the retinas exposed to constant light, but that adaptation to 400-lux cyclic light did not change nNOS expression. Inhibition of nNOS by NG-nitro-L-arginine methyl ester (L-NAME) is sufficient to prevent light-induced photoreceptor degeneration in mice38 and rats.53 54 55 Therefore, the protection by adaptation to 400-lux cyclic light observed in this study is not through reduction in nNOS expression, but probably involves some other pathways.

The greater sensitivity of the superior retina to light-induced apoptosis is a well-known phenomenon,56 and selective loss of rod photoreceptor cells in this region of the retina has been reported in numerous studies in which the entire retinal expanse was examined.46 57 In our present study, the regional difference is not due to regional differences in light exposure, because our light box was designed to provide uniform exposure. In the studies of Vaughan et al.,57 S334ter and P23H rhodopsin mutant rats in green Plexiglas chambers4 were placed inside a circular fluorescent light to guarantee uniform exposure, and there was a selective loss of superior photoreceptor cells in both mutant groups. Early studies suggested a diurnal susceptibility to light damage.58 59 Organisciak et al.60 used short-term light exposures at different times of the light cycle and found that albino rats exposed at 1 AM were four times more susceptible to light damage than those exposed at 5 PM. They suggested, "The expression profile of an intrinsic retinal factor(s) at the onset of light exposure appears to be important in determining light damage susceptibility". Because studies have shown a genetic predisposition to light damage among different albino rat61 and mice62 strains, and because we1 2 and others7 8 10 60 have reported the capacity of the retina to alter protein expression in response to environmental light changes, we suggest that the susceptibility of the superior region of the rat retina is due to differential expression of neuroprotective factors.


   Acknowledgements
 
The authors thank Isabelle Ranchon for helpful advice and Mark Dittmar, Mark McClellan, Kathleen Alvarez, and Sherry Chen for technical support.


   Footnotes
 
Supported by Grants EY00871, EY04149, EY06973, EY12190, from the National Eye Institute; and Grant RR17703 from the Division of Research Resources, National Institutes of Health; Research to Prevent Blindness, Inc., New York, New York; The Foundation Fighting Blindness; and Presbyterian Health Foundation, Oklahoma City, Oklahoma.

Submitted for publication February 7, 2003; revised March 26, 2003; accepted April 2, 2003.

Disclosure: F. Li, None; W. Cao, None; R.E. Anderson, None

The publication costs of this article were defrayed in part by page charge payment. This article must therefore be marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Corresponding author: Robert E. Anderson, Department of Ophthalmology, University of Oklahoma Health Science Center, 608 Stanton L. Young Boulevard, Oklahoma City, OK 73104; robert-anderson{at}ouhsc.edu.


   References
Top
 Abstract
 Materials and Methods
 Results
 Discussion
 References
 

  1. Penn, JS, Naash, MI, Anderson, RE. (1987) Effect of light history on retinal antioxidants and light damage susceptibility in the rat Exp Eye Res 44,779-788[CrossRef][Medline][Order article via Infotrieve]
  2. Penn, JS, Anderson, RE. (1992) Effects of light history on the rat retina Osborne, N Chader, G eds. Progress in Retinal Research ,75-98 Pergamon Press New York.
  3. Penn, JS, Tolman, BL, Thum, LA, Koutz, CA. (1992) Effect of light history on the rat retina: time course of morphologic adaptation and readaptation Neurochem Res 17,91-99[CrossRef][Medline][Order article via Infotrieve]
  4. Noell, WK, Walker, VS, Kang, BS, Bergman, S. (1966) Retinal damage by light in rats Invest Ophthalmol 5,450-473[Abstract/Free Full Text]
  5. Noell, WK, Albrecht, R. (1971) Irreversible effects of visible light on the retina: role of vitamin A Science 172,76-80[Abstract/Free Full Text]
  6. Organisciak, DT, Noell, WK. (1977) The rod outer segment phospholipid/opsin ratio of rats maintained in darkness or cyclic light Invest Ophthalmol Vis Sci 16,188-190[Abstract]
  7. Liu, C, Peng, M, Laties, AM, Wen, R. (1998) Preconditioning with bright light evokes a protective response against light damage in the rat retina J Neurosci 18,1337-1344[Abstract/Free Full Text]
  8. Yu, Q, Kent, CR, Tytell, M. (2001) Retinal uptake of intravitreally injected Hsc/Hsp70 and its effect on susceptibility to light damage Mol Vis 7,48-56[Medline][Order article via Infotrieve]
  9. Kutty, RK, Kutty, G, Wiggert, B, Chader, GJ, Darrow, RM. (1995) Induction of heme oxygenase 1 in the retina by intense visible light: suppression by the antioxidant dimethylthiourea Proc Natl Acad Sci USA 92,1177-1181[Abstract/Free Full Text]
  10. Organisciak, DT, Xie, A, Wang, HM, Jiang, YL, Darrow, RM, Donoso, LA. (1991) Adaptive changes in visual cell transduction protein levels: effect of light Exp Eye Res 53,773-779[CrossRef][Medline][Order article via Infotrieve]
  11. Hafezi, F, Marti, A, Grimm, C, Wenzel, A, Remé, CE. (1999) Differential DNA binding activities of the transcription factors AP-1 and Oct-1 during light-induced apoptosis of photoreceptors Vision Res 39,2511-2518[CrossRef][Medline][Order article via Infotrieve]
  12. Wenzel, A, Remé, CE, Williams, TP, Hafezi, F, Grimm, C. (2001) The Rpe65 Leu450Met variation increases retinal resistance against light-induced degeneration by slowing rhodopsin regeneration J Neurosci 21,53-58[Abstract/Free Full Text]
  13. Grimm, C, Wenzel, A, Groszer, M, et al (2002) HIF-1-induced erythropoietin in the hypoxic retina protects against light-induced retinal degeneration Nat Med 8,718-724[CrossRef][Medline][Order article via Infotrieve]
  14. Junk, AK, Mammis, A, Savitz, SI, et al (2002) Erythropoietin administration protects retinal neurons from acute ischemia-reperfusion injury Proc Natl Acad Sci USA 99,10659-10664[Abstract/Free Full Text]
  15. Hata, Y, Nakagawa, K, Ishibashi, T, Inomata, H, Ueno, H, Sueishi, K. (1995) Hypoxia-induced expression of vascular endothelial growth factor by retinal glial cells promotes in vitro angiogenesis Virchows Arch 426,479-486[Medline][Order article via Infotrieve]
  16. Shima, DT, Adamis, AP, Ferrara, N, et al (1995) Hypoxic induction of endothelial cell growth factors in retinal cells: identification and characterization of vascular endothelial growth factor (VEGF) as the mitogen Mol Med 1,182-193[Medline][Order article via Infotrieve]
  17. Favard, C, Ortega, N, Bayard, F, Plouet, J. (1996) Vascular endothelial growth factor and retinal neovascularization: a new therapeutic approach for diabetic retinopathy Diabetes Metab 22,268-273[Medline][Order article via Infotrieve]
  18. Frank, RN, Amin, RH, Eliott, D, Puklin, JE, Abrams, GW. (1996) Basic fibroblast growth factor and vascular endothelial growth factor are present in epiretinal and choroidal neovascular membranes Am J Ophthalmol 122,393-403[Medline][Order article via Infotrieve]
  19. Yan, Q, Li, Y, Hendrickson, A, Sage, EH. (2001) Regulation of retinal capillary cells by basic fibroblast growth factor, vascular endothelial growth factor, and hypoxia In Vitro Cell Dev Biol Anim 37,45-49[CrossRef][Medline][Order article via Infotrieve]
  20. Böcker-Meffert, S, Rosenstiel, P, Röhl, C, et al (2002) Erythropoietin and VEGF promote neural outgrowth from retinal explants in postnatal rats Invest Ophthalmol Vis Sci 43,2021-2026[Abstract/Free Full Text]
  21. Portera-Cailliau, C, Sung, CH, Nathans, J, Adler, R. (1994) Apoptotic photoreceptor cell death in mouse models of retinitis pigmentosa Proc Nat Acad Sci USA 91,974-978[Abstract/Free Full Text]
  22. Tso, MO, Zhang, C, Abler, AS, et al (1994) Apoptosis leads to photoreceptor degeneration in inherited retinal dystrophy of RCS rats Invest Ophthalmol Vis Sci 35,2693-2699[Abstract/Free Full Text]
  23. Gregory, CY, Bird, AC. (1995) Cell loss in retinal dystrophies by apoptosis: death by informed consent! Br J Ophthalmol 79,186-190[Free Full Text]
  24. Hafezi, F, Steinbach, JP, Marti, A, et al (1997) The absence of c-fos prevents light-induced apoptotic cell death of photoreceptors in retinal degeneration in vivo Nat Med 3,346-349[CrossRef][Medline][Order article via Infotrieve]
  25. Chang, CJ, Lai, WW, Edward, DP, Tso, MO. (1995) Apoptotic photoreceptor cell death after traumatic retinal detachment in humans Arch Ophthalmol 113,880-886[Abstract]
  26. Cook, B, Lewis, GP, Fisher, SK, Adler, R. (1995) Apoptotic photoreceptor degeneration in experimental retinal detachment Invest Ophthalmol Vis Sci 36,990-996[Abstract/Free Full Text]
  27. Xu, GZ, Li, WW, Tso, MO. (1996) Apoptosis in human retinal degenerations Trans Am Ophthalmol Soc 94,411-430discussion 430–431[Medline][Order article via Infotrieve]
  28. Carmody, RJ, McGowan, AJ, Cotter, TG. (1999) Reactive oxygen species as mediators of photoreceptor apoptosis in vitro Exp Cell Res 248,520-530[CrossRef][Medline][Order article via Infotrieve]
  29. Missiaen, L, Robberecht, W, van den Bosch, L, et al (2000) Abnormal intracellular Ca2+ homeostasis and disease Cell Calcium 28,1-21[CrossRef][Medline][Order article via Infotrieve]
  30. Barron, MJ, Johnson, MA, Andrews, RM, et al (2001) Mitochondrial abnormalities in ageing macular photoreceptors Invest Ophthalmol Vis Sci 42,3016-3022[Abstract/Free Full Text]
  31. Rapp, LM, Naash, MI, Wiegand, RD, Joel, CD, Nielsen, JC, Anderson, RE. (1985) Morphological and biochemical comparison between retinal regions having differing susceptibility to photoreceptor degeneration LaVail, MM Hollyfield, JG Anderson, RE eds. Retinal Degeneration: Experimental and Clinical Studies ,421-437 Alan R. Liss New York.
  32. LaVail, MM, Unoki, K, Yasumura, D, Matthes, MT, Yancopoulos, GD, Steinberg, RH. (1992) Multiple growth factors, cytokines and neurotrophins, rescue photoreceptors from the damaging effects of constant light Proc Natl Acad Sci USA 89,11249-11253[Abstract/Free Full Text]
  33. Faktorovich, EG, Steinberg, RH, Yasumura, D, Matthes, MT, LaVail, MM. (1992) Basic fibroblast growth factor and local injury protect photoreceptors from light damage in the rat J Neurosci 12,3554-3567[Abstract]
  34. Miho, Y, Kouroku, Y, Fujita, E, et al (1999) bFGF inhibits the activation of caspase-3 and apoptosis of P19 embryonal carcinoma cells during neuronal differentiation Cell Death Diff 6,463-470[CrossRef][Medline][Order article via Infotrieve]
  35. Cao, W, Tombran-Tink, J, Elias, R, Sezate, S, Mrazek, D, McGinnis, JF. (2001) In vivo protection of photoreceptors from light damage by pigment epithelium-derived factor Invest Ophthalmol Vis Sci 42,1646-1652[Abstract/Free Full Text]
  36. Penn, JS, Anderson, RE. (1987) Effects of light history on rod outer segment membrane composition in the rat retina Exp Eye Res 44,767-778[CrossRef][Medline][Order article via Infotrieve]
  37. Liu, C, Li, Y, Peng, M, Laties, AM, Wen, R. (1999) Activation of caspase-3 in the retina of transgenic rats with the rhodopsin mutation S334ter during photoreceptor degeneration J Neurosci 19,4778-4785[Abstract/Free Full Text]
  38. Donovan, M, Carmody, RJ, Cotter, TG. (2001) Light-induced photoreceptor apoptosis in vivo requires neuronal nitric-oxide synthase and guanylate cyclase activity and is caspase-3-independent J Biol Chem 276,23000-23008[Abstract/Free Full Text]
  39. Li, F, Cao, W, Anderson, RE. (2001) Protection of photoreceptor cells in adult rats from light-induced degeneration by adaptation to bright cyclic light Exp Eye Res 73,569-577[CrossRef][Medline][Order article via Infotrieve]
  40. Farber, DB, Danciger, JS, Organisciak, DT. (1991) Levels of mRNA encoding proteins of the cGMP cascade as a function of light environment Exp Eye Res 53,781-786[CrossRef][Medline][Order article via Infotrieve]
  41. Liu, C, Peng, M, Laties, AM, Wen, R. (1998) Preconditioning with bright light evokes a protective response against light damage in the rat retina J Neurosci 18,1337-1344
  42. Lewin, AS, Drenser, KA, Hauswirth, WW, et al (1998) Ribozyme rescue of photoreceptor cells in a transgenic rat model of autosomal dominant retinitis pigmentosa Nat Med 4,967-971[CrossRef][Medline][Order article via Infotrieve]
  43. Lau, D, McGee, LH, Zhou, S, et al (2000) Retinal degeneration is slowed in transgenic rats by AAV-mediated delivery of FGF-2 Invest Ophthalmol Vis Sci 41,3622-3633[Abstract/Free Full Text]
  44. Steinberg, RH. (1994) Survival factors in retinal degenerations Curr Opin in Neurobiol 4,515-524[CrossRef][Medline][Order article via Infotrieve]
  45. Organisciak, DT, Darrow, RA, Barsalou, L, Darrow, RM, Lininger, LA. (1999) Light-induced damage in the retina: differential effects of dimethylthiourea on photoreceptor survival, apoptosis and DNA oxidation Photochem Photobiol 70,261-268[CrossRef][Medline][Order article via Infotrieve]
  46. Ranchon, I, Chen, S, Alvarez, K, Anderson, RE. (2001) Systemic administration of phenyl-N-tert-butylnitrone protects the retina from light damage Invest Ophthalmol Vis Sci 42,1375-1379[Abstract/Free Full Text]
  47. Gargini, C, Belfiore, MS, Bisti, S, Cervetto, L, Valter, K, Stone, J. (1999) The impact of basic fibroblast growth factor on photoreceptor function and morphology Invest Ophthalmol Vis Sci 40,2088-2099[Abstract/Free Full Text]
  48. Bowers, F, Valter, K, Chan, S, Walsh, N, Maslim, J, Stone, J. (2001) Effects of oxygen and bFGF on the vulnerability of photoreceptors to light damage Invest Ophthalmol Vis Sci 42,804-815[Abstract/Free Full Text]
  49. Faktorovich, EG, Steinberg, RH, Yasumura, D, Matthes, MT, LaVail, MM. (1990) Photoreceptor degeneration in inherited retinal dystrophy delayed by basic fibroblast growth factor Nature 6,83-86347
  50. D’Cruz, PM, Yasumura, D, Weir, J, et al (2000) Mutation of the receptor tyrosine kinase gene Mertk in the retinal dystrophic RCS rat Hum Mol Genet 9,645-651[Abstract/Free Full Text]
  51. Hilborn, MD, Vaillancourt, RR, Rane, SG. (1998) Growth factor receptor tyrosine kinases acutely regulate neuronal sodium channels through the src signaling pathway J Neurosci 15,590-60018
  52. Liu, C, Li, Y, Peng, M, Laties, AM, Wen, R. (1999) Activation of caspase-3 in the retina of transgenic rats with the rhodopsin mutation s334ter during photoreceptor degeneration J Neurosci 19,4778-4785
  53. Goureau, O, Jeanny, JC, Becquet, F, Hartmann, MP, Courtois, Y. (1993) Protection against light-induced retinal degeneration by an inhibitor of NO synthase Neuroreport 5,233-236[Medline][Order article via Infotrieve]
  54. Káldi, I, Dittmar, M, Pierce, P, Anderson, RE. (2003) L-NAME protects against acute light damage in albino rats, but not against retinal degeneration in P23H and S334ter transgenic rats Exp Eye Res 76,453-461[CrossRef][Medline][Order article via Infotrieve]
  55. Goureau, O, Becquet, F, Courtois, Y. (1995) Nitric oxide in the retina: potential involvement in retinal degeneration and its control by grow factors and cytokines Anderson, RE LaVail, MM Hollyfield, JG eds. Degenerative Diseases of the Retina ,61-68 Plenum Press New York.
  56. Rapp, LM, Williams, TP. (1980) The role of ocular pigmentation in protecting against retinal light damage Vision Res 20,1127-1131[CrossRef][Medline][Order article via Infotrieve]
  57. Vaughan, DK, Coulibaly, SF, Darrow, RM, Organisciak, DT. (2003) A morphometric study of light-induced damage in transgenic rat models of retinitis pigmentosa Invest Ophthalmol Vis Sci 44,848-855[Abstract/Free Full Text]
  58. Duncan, TE, O’Steen, WK. (1985) The diurnal susceptibility of rat retinal photoreceptors to light-induced damage Exp Eye Res 41,497-507[CrossRef][Medline][Order article via Infotrieve]
  59. White, MP, Fisher, LJ. (1987) Degree of light damage to the retina varies with time of day of bright light exposure Physiol Behav 39,607-613[CrossRef][Medline][Order article via Infotrieve]
  60. Organisciak, DT, Darrow, RM, Barsalou, L, Kutty, RK, Wiggert, B. (2000) Circadian-dependent retinal light damage in rats Invest Ophthalmol Vis Sci 41,3694-3701[Abstract/Free Full Text]
  61. LaVail, MM, Gorrin, GM, Repaci, MA, Thomas, LA, Ginsberg, HM. (1987) Genetic regulation of light damage to photoreceptors Invest Ophthalmol Vis Sci 28,1043-1048[Abstract/Free Full Text]
  62. LaVail, MM, Gorrin, GM, Repaci, MA. (1987) Strain differences in sensitivity to light-induced photoreceptor degeneration in albino mice Curr Eye Res 6,825-834[Medline][Order article via Infotrieve]



This article has been cited by other articles:


Home page
 J. Neurosci.Home page
A. Rattner, L. Toulabi, J. Williams, H. Yu, and J. Nathans
The Genomic Response of the Retinal Pigment Epithelium to Light Damage and Retinal Detachment
J. Neurosci., September 24, 2008; 28(39): 9880 - 9889.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
R. Maccarone, S. Di Marco, and S. Bisti
Saffron Supplement Maintains Morphology and Function after Exposure to Damaging Light in Mammalian Retina
Invest. Ophthalmol. Vis. Sci., March 1, 2008; 49(3): 1254 - 1261.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
O. Perche, M. Doly, and I. Ranchon-Cole
Caspase-Dependent Apoptosis in Light-Induced Retinal Degeneration
Invest. Ophthalmol. Vis. Sci., June 1, 2007; 48(6): 2753 - 2759.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
S. Joly, V. Pernet, S. Chemtob, A. Di Polo, and P. Lachapelle
Neuroprotection in the Juvenile Rat Model of Light-Induced Retinopathy: Evidence Suggesting a Role for FGF-2 and CNTF
Invest. Ophthalmol. Vis. Sci., May 1, 2007; 48(5): 2311 - 2320.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
A. Rajala, R. E. Anderson, J.-X. Ma, J. Lem, M. R. Al-Ubaidi, and R. V. S. Rajala
G-protein-coupled Receptor Rhodopsin Regulates the Phosphorylation of Retinal Insulin Receptor
J. Biol. Chem., March 30, 2007; 282(13): 9865 - 9873.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurosci.Home page
G. Li, R. E. Anderson, H. Tomita, R. Adler, X. Liu, D. J. Zack, and R. V. S. Rajala
Nonredundant Role of Akt2 for Neuroprotection of Rod Photoreceptor Cells from Light-Induced Cell Death
J. Neurosci., January 3, 2007; 27(1): 203 - 211.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
S. Joly, V. Pernet, A. L. Dorfman, S. Chemtob, and P. Lachapelle
Light-induced retinopathy: comparing adult and juvenile rats.
Invest. Ophthalmol. Vis. Sci., July 1, 2006; 47(7): 3202 - 3212.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurosci.Home page
A. Rattner and J. Nathans
The Genomic Response to Retinal Disease and Injury: Evidence for Endothelin Signaling from Photoreceptors to Glia
J. Neurosci., May 4, 2005; 25(18): 4540 - 4549.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
R. Grewal, J. Stepczynski, R. Kelln, T. Erickson, R. Darrow, L. Barsalou, M. Patterson, D. T. Organisciak, and P. Wong
Coordinated Changes in Classes of Ribosomal Protein Gene Expression Is Associated with Light-Induced Retinal Degeneration
Invest. Ophthalmol. Vis. Sci., November 1, 2004; 45(11): 3885 - 3895.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
H. Huang, F. Li, R. A. Alvarez, J. D. Ash, and R. E. Anderson
Downregulation of ATP Synthase Subunit-6, Cytochrome c Oxidase-III, and NADH Dehydrogenase-3 by Bright Cyclic Light in the Rat Retina
Invest. Ophthalmol. Vis. Sci., August 1, 2004; 45(8): 2489 - 2496.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
C. Zhang, B. Lei, T. T. Lam, F. Yang, D. Sinha, and M. O. M. Tso
Neuroprotection of Photoreceptors by Minocycline in Light-Induced Retinal Degeneration
Invest. Ophthalmol. Vis. Sci., August 1, 2004; 45(8): 2753 - 2759.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Li, F.
Right arrow Articles by Anderson, R. E.
Right arrow Search for Related Content