Exogenous melatonin induced disparate changes in pineal karyomorphology and thyroid cytophysiology and T4 levels in chick (Gallus domesticus)

Abstract

A composite study including pineal and thyroid cell morphology, hormonal analysis and function in response to exogenous melatonin administration awaits in depth investigation in any bird. To investigate the pineal and thyroid responsiveness to exogenous melatonin from combined morphological and hormonal studies in neonatal chicks – two groups, each with eleven chicks were used as control (C) and treated with melatonin (M) at a dose of 100 μg.100 g body weight for fifteen consecutive days. The treatment with melatonin induced stimulation of pineal karyomorphology as evidenced from significantly increased nuclear diameter in the melatonin treated group. On the contrary, melatonin used inhibition of thyroidal activity as evidenced by significantly decreased values of thyroid nuclear diameter, thyrofollicular epithelial height, diameter and D/N activity associated with significantly decreased T4 values in neonatal male chicks. Our study thus shows that exogenous melatonin induced disparate changes in pineal and thyroid gland activity in these neonatal chicks, whereas pineal gland showed an overall stimulation; in contrast, melatonin induced thorough inhibition of thyroid cytophysiomorphology and hormonal milieu compared to control group of neonatal chick (Gallus domesticus)