MELATONIN ACTIVITY RHYTHMS IN EYES AND CEREBRAL GANGLIA OF APLYSIA-CALIFORNICA

In this study, we used a sensitive and specific radioimmunoassay to de tect a substance which appears to be melatonin, an acetylation and met hylation product of serotonin, in the eyes and central nervous system of the opisthobranch mollusc Aplysia californica. This identification was confirmed in the eyes by HPLC with fluorimetric detection. Melaton in activity was high in the eyes during the day and in the cerebral ga nglia during the night. Only small amounts of melatonin were present a t midday or midnight in the pedal ganglia. A single 1-hr exposure to l ight in the middle of the dark phase resulted in a sharp increase of m elatonin in the eyes, whereas no such activity was detectable in cereb ral and pedal ganglia. Eyes maintained in culture exhibited a diurnal rhythm of released melatonin activity over a 3-day period. These resul ts suggest that melatonin is produced in A. californica in a rhythmic pattern different from that associated with pineal melatonin productio n in vertebrates, (C) 1994 Academic Press, Inc.