International Science Community Association International Research Journal of Biological Sciences 2278 - 3202 5 12 2016 12 10 An in vitro study on the role of protein kinase C, phosphodiesterase and Ser/Thr phosphatases in adrenergic stimulation of arylalkylamine-N-acetyltransferase (AA-NAT) activity in the pineal gland of Clariasgariepinus 18 23 EN N.M. Aka 1 Oceanological Research Center (Abidjan, Côte d’Ivoire), BPV 18, Abidjan R.N. Etilé 2 Hydrobiology Laboratory, UFR Biosciences, University Félix HOUPHOUËT-BOIGNY (Côte d’Ivoire), 22 BP 582 Abidjan, Côte d’Ivoire F.K. Konan 3 Department of Environment, University Jean Lorougnon Guédé, BP 150 Daloa, Côte d’Ivoire Y.K. Bony 4 Department of Environment, University Jean Lorougnon Guédé, BP 150 Daloa, Côte d’Ivoire Melaku Yadessa 1 Program of Chemistry, Adama Science and Technology University, Adama, Ethiopia Duguma Tolessa 2 Program of Chemistry, Adama Science and Technology University, Adama, Ethiopia Khamtilin Kharshiing 1 Department of Zoology, Lady Keane College, Shillong-793 001, India Gupta B.B.P. 2 Environmental Endocrinology Laboratory, Department of Zoology, North-Eastern Hill University, Shillong – 793 022, India > Research Paper 2016 10 31 2016 12 10 The effects of inhibitors of PKC, PDE and ser/thr phosphatase 1, 2A and 2B on the activity of arylalklyamine N-acetyltransferase (AA-NAT) was studied in vitro in the pineal glands of the catfish, Clariasgariepinus.Pineals were pre-treated with specific inhibitors prior induction by norepinephrine then maintained in organ culture for 7 hr. In vitro treatment of the fish pineal organ with chelerythrine (PKC inhibitor) significantly decreased AA-NAT activity as compared to that of the control group. Theophylline (PDE inhibitor) treated at different incubation periods significantly increased AA-NAT activity. Okadaic acid (inhibitor of ser/thr phosphatase 1) and calyculin A (inhibitor of ser/thr phosphatase 2A) significantly inhibited basal AA-NAT activity. Cypermethrin (inhibitor of ser/thr phosphatase 1) show no significant effect neither on basal AA-NAT activity nor on NE-induced increased in the enzyme activity. These results suggest that PKC does not seem to be involved in adrenergic stimulation but necessary for maintaining basal activity of the enzyme. PDE also crucially regulate the activity of the AA-NAT enzyme. The normal as well as the adrenergic stimulation of AA-NAT by Ser/Thr phosphatase 1 and 2A are essential, but, Ser/Thr phosphatases 2B do not play any major part in adrenergic signal transduction in the fish pinealocytes. Copyright@ International Science Community Association