Mechanisms responsible for autocrine regulation of the epiphysis function

Abstract

The effect of injection of exogenous melatonin on formation of the nocturnal peak of the melatonin concentration and intrapineal hormonogenesis was studied on mature male rats. It was shown that 3H-melatonin is selectively uptaken by pinealocytes, and the uptake intensity depends on the degree of saturation of an organism with exogenous melatonin. Exogenous melatonin exerts an inhibitory influence on the hormone self-production, at the same time apparently stimulating synthesis of epiphyseal peptides. The results can be considered an indication of the existence of an ultra-short connection between the mechanisms of production of epiphyseal indoles and peptides, which apparently plays an important role in autocrine regulation of the epiphyseal functions.

Biocycles of kidney excretory function in hypothyroid patients

“…In this connection of particular interest are the disturbances of the pituitary-thyroid relations occurring in hypothyrosis. It was shown that hypothyrosis causes a drastic decrease in melatonin concentration [6,9].…”

Role of Melatonin in the Mechanisms Underlying Neuroendocrine Control of the Hypothalamo-Hypophyseal-Thyroid Axis

“…The data on the effect of the parafollicular apparatus on the processes of synthesis of methoxyindoles in the brain epiphysis indicate that thyrocalcitonin, as compared with Т 3 and Т 4 , suppresses the production of melatonin and 5-methoxytryptamine in pinealocytes [91]. Such oppositely directed effects were observed not only in intact animals but also in animals preliminarily injected with Т 4 [92].…”

“…According to the existing concepts, biologically active substances of epiphyseal nature are also directly involved, together with TRH and TTH, in the mechanisms underlying central neuroendocrine regulation of morphofunctional activity of the thyroid gland [9,32,[34][35][36][37][38][39].…”