<i style="">In vitro</i> effects of 5-hydroxytryptophan, indoleamines and leptin on arylalkylamine N-acetyltransferase (AA-NAT) activity in pineal organ of the fish, <i style="">Clarias gariepinus</i> (Burchell, 1822) during different phases of the breeding cycle

Abstract

Arylalkylamine N-acetyltransferase (AA-NAT) is the rate-limiting enzyme of melatonin biosynthetic pathway. <i style="">In vitro</i> effects of 5-hydroxytryptophan (5-HTP) and indoleamines (serotonin, N-acetylserotonin and melatonin) were studied on AA-NAT activity in the pineal organ of the fish, <i style="">C. gariepinus</i> during different phases of its annual breeding cycle. Further, <i style="">in vitro e</i>ffects of leptin on AA-NAT activity in the pineal organ were studied in fed and fasted fishes during summer and winter seasons. Treatments with 5-HTP and indoleamines invariably stimulated pineal AA-NAT activity in a dose-dependent manner during all the phases. However, leptin increased AA-NAT activity in a dose-dependent manner only in the pineal organ of the fed fishes, but not of the fasted fishes irrespective of the seasons