Retinal ganglion cells are autonomous circadian oscillators synthesizing N-acetylserotonin during the day.

GARBARINO-PICO EDUARDO; CARPENTIERI AGATA RITA; CONTIN MARIA ANA; SARMIENTO MARIA INES; BROCCO MARCELA A; PANZETTA PEDRO; ROSENSTEIN RUTH; CAPUTTO BEATRIS; GUIDO MARIO EDUARDO

JOURNAL OF BIOLOGICAL CHEMISTRY

Año: 2004 vol. 279 p. 51172 - 51172

0021-9258

etinal ganglion cells send visual and circadian informationto the brain regarding the environmental lightdarkcycles. We investigated the capability of retinalganglion cells of synthesizing melatonin, a highly reliablecircadian marker that regulates retinal physiology,as well as the capacity of these cells to function as autonomouscircadian oscillators. Chick retinal ganglioncells presented higher levels of melatonin assessed byradioimmunoassay during both the subjective day inconstant darkness and the light phase of a light-darkcycle. Similar changes were observed in mRNA levelsand activity of arylalkylamine N-acetyltransferase, akey enzyme in melatonin biosynthesis, with the highestlevels of both parameters during the subjective day.These daily variations were preceded by the elevation ofcyclic-AMP content, the second messenger involved inthe regulation of melatonin biosynthesis. Moreover,