Melatonin secretion of the rat pineal gland in response to norepinephrine in different types of the anovulatory syndrome.

Earlier experimental results show the role of altered pineal function in the development of the constant estrous-anovulatory (CEA) state induced by neonatal androgen sterilization (NA) or in the spontaneously developed anovulatory syndrome in the aging rat (AG-CEA state). Since norepinephrinergic (NE) innervation of pineal gland represents the main stimulus for melatonin secretion in mammals, in the present experimental series, the reactivity of pineal tissue to NE was investigated in in vitro perifusion system in rats suffering from NA-CEA or AG-CEA state, using the model of pineal body deprived from neural inputs. The data indicate that the 'melatonin deficiency' observed in the 2 types of anovulatory syndrome (NA-CEA and AG-CEA states) is due to disturbance of norepinephrinergic innervation of the pineal gland rather than to deficient secretory capacity of pineal tissue.