neurosekretorische

Neurosekretorische, or neurosecretory, refers to the cells and processes by which certain neurons release hormones into the bloodstream rather than at synapses. This mechanism links the nervous and endocrine systems and enables long-range regulation of physiology.

In vertebrates, the hypothalamus is the central hub of neurosecretory activity. Hypothalamic neurosecretory neurons synthesize neurohormones and transport them along their axons to release sites. The posterior pituitary (neurohypophysis) stores and releases hormones such as vasopressin and oxytocin that originate in the hypothalamus and enter the blood stream upon neuronal activation. A parallel pathway involves the hypothalamic-pituitary portal system, in which hypothalamic neurons secrete releasing and inhibiting hormones into portal veins that perfuse the anterior pituitary (adenohypophysis). There, these neurohormones regulate the secretion of pituitary hormones such as TSH, ACTH, growth hormone, prolactin, and the gonadotropins (LH and FSH).

Storage and release of neurohormones typically depend on secretory granules within the axon terminals and Ca2+-triggered exocytosis into capillary networks. Neurohormones act on distant target organs, producing broad physiological effects, from metabolism and growth to reproduction and water balance. Dopamine exemplifies a hypothalamic neurohormone that inhibits prolactin release via the portal system.

In invertebrates, neurosecretory cells similarly release hormones into the circulatory system, regulating development, metabolism, and behavior through neurohormonal signaling, illustrating the conserved role of neurosecretory systems across animal groups.