| Affiliation: | (1) Department of General Zoology and Neurobiology, University of Pécs, 7601 Pécs, u. 6. Ifjúság, Hungary;(2) MTA-PTE Adaptational Biology Research Group, University of Pécs, 7601 Pécs, u. 6. Ifjúság, Hungary;(3) Department of Psychology, Barnard College, New York, NY 10027, USA;(4) Uniformed Services, University of Health Sciences, Department of Surgery, Center for Prostate Diseases Research, Bethesda, MD 20814, USA;(5) Department of Psychology, Columbia University, New York, NY 10027, USA;(6) Department of Ophthalmology, New York University School of Medicine, 550 First Ave., New York, NY 10016, USA;(7) Department of Physiology and Neuroscience, New York University School of Medicine, 550 First Ave., New York, NY 10016, USA |
| Abstract: | We investigated parvalbumin immunoreactivity (PA-IR) in the retinas of rats maintained on a 12:12 h light:dark cycle, or after being placed in constant darkness for 24–72 h. Retinas were harvested at zeitgeber and circadian times 02:00, 06:00, 10:00, 14:00, 18:00 and 22:00 h. PA-IR was found primarily in retinal amacrine cells of the AII subtype. In a light/dark cycle, PA-IR showed a clear rhythm, with a low near zeitgeber time (ZT) 10:00 h and a peak near ZT 18:00 h. The ratio of immunofluorescence intensities at these timepoints was >15-fold. When animals were kept in complete darkness for 1–3 days, the rhythm of PA-IR was still preserved, but was progressively reduced in amplitude. The rhythm of PA-IR inferred from immunohistochemical data was confirmed by Western blots. We conclude that PA-IR in the rat retina shows an underlying circadian rhythm that is enhanced by cyclic light. The regulation may involve translocation of the protein between cell compartments and/or new protein synthesis.This study was supported by an OTKA grant (T 34160), NIH grants NS 37919 (R.S.) and ET 03570, NSF grant IBN-96418886 (R.S.), and grants from the Helen Hoffritz Charitable Trust and Research to Prevent Blindness, Inc. R.G. was also in receipt of a János Bolyai fellowship |
