CIRCADIAN-RHYTHM IN THE QUAIL ELECTRORETINOGRAM (ERG) - POSSIBLE RELATION TO RETINAL INDOLEAMINES (SEROTONIN AND MELATONIN) ACTIVITY

The effects of intravitreal injections of indoleamines or their inhibi tors on the quail ERG were investigated. The ratio of b- to a-wave in amplitudes showed daily fluctuations in the control eyes. Repeated inj ections of para-chlorophenylalanine (PCPA), an indoleamines synthesis inhibitor, reduced the ratio to the nocturnal levels. And the level wa s restored by serotonin injection during the daytime but not during th e night. Melatonin application into the diurnal eye slightly but signi ficantly reduced the ratio. Furthermore, 5,7-dihydroxytryptamine (5,7D HT) which destroyed the indoleamine-accumulating amacrine cells had a similar effect. These results suggest that the activity of the retinal indoleamines serotonin and melatonin may be involved in circadian cha nges of the quail ERG.