All amacrine neurons of the rat retina show diurnal and circadian rhythms of parvalbumin immunoreactivity

Robert Gábriel*, Joseph Lesauter, Tamás Bánvölgyi, György Petrovics, Rae Silver, Paul Witkovsky

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


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.

Original languageEnglish
Pages (from-to)181-186
Number of pages6
JournalCell and Tissue Research
Issue number2
StatePublished - Feb 2004


  • Calcium-binding proteins
  • Immunocytochemistry
  • Inner plexiform layer
  • Rat
  • Western blots


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