Альфа-меланоцитстимулирующий гормон как регулятор гипоталамо-гипофизарной оси

Abstract

Alpha-melanocyte-stimulating hormone (α-MSH) has a wide range of biological activities and is produced in the pituitary, hypothalamus, brain stem, hippocampus and periphery. α-MSH and its receptors are critically involved in the regulation of energy balance and body weight. At the functional and neuroanatomical levels, there is a very close overlap between the regulation of energy balance and neuroendocrine stress response. The review focuses on the involvement of α-MSH in the regulation of the hypothalamic-pituitary (HP) axis. The effects of centrally administered α-MSH and its analogues, and the data obtained from genetically altered animals indicate that α-MSH from the arcuate nucleus both directly and indirectly, via the medial amygdala, activates the HP axis. Since the amygdala plays a crucial role in the integration of behavioral and neuroendocrine responses to stress, it is obvious that α-MSH is an important participant in this process. The role of α-MSH in the regulation of the HP axis by other limbic structures, such as the hippocampus and prefrontal cortex, remains unexplored. The melanocortin MC4R receptor plays the main role in the activation of the HP axis. However, some data indicate the possible involvement of MC3R or MC5R receptors. The well-known anti-inflammatory effects of α-MSH are consistent with its ability to attenuate neuroinflammation-induced activation of the HP axis. Like adrenocorticotropic hormone (ACTH), pituitary α-MSH is secreted into the bloodstream during the stress response. However, unlike ACTH, α-MSH secretion is stimulated by epinephrine, and not inhibited by glucocorticoids. The role of circulating α-MSH in the stress response remains unclear, but may involve glucocorticoid-independent negative regulation of the HP axis.