Molecular Aspects of Neurohypophysial Hormone Release

• Published in: Proceedings of the Royal Society of London. Series B, Biological sciences Biological sciences, 1968-05, Vol.170 (1018), p.27-36
• Main Author: Ginsburg, M.
• Format: Article
• Language: English
• Subjects: Animals; Calcium - pharmacology; Cattle; Dialysis; Hormones; Kidneys; Models, Biological; Nerves; Neurons; Neurophysins; Neurosecretion - drug effects; Neurosecretory cells; Pituitary Hormones, Posterior - metabolism; Posterior pituitary; Posterior Pituitary Hormones and Neurophysiology; Potassium - pharmacology; Swine; Ungulates; Uterus
• ISSN: 0962-8452; 0080-4649; 0950-1193; 1471-2954; 2053-9193
• DOI: 10.1098/rspb.1968.0021

The secretion of hormone from the nerve terminals in the infundibular process of the neurohypophysis is mediated by the arrival of impulses generated in cell bodies of neurons in the anterior hypothalamus and propagated along the fibres of the hypothalamo-hypophysial tract. Influx of Ca$^{2+}$ into the secretory cells is believed to play a part in hormone release. It has been proposed that Ca$^{2+}$ may act either by causing dissociation of the hormones from complexes formed with the protein neurophysin, or by promoting extracellular extrusion of the contents of the neurosecretory particles (exocytosis). Evidence is presented that allosteric transitions are involved in the interaction between neurophysin and neurohypophysial hormone and the possibility that these might determine some of the changes in the ultrastructure of nerve terminals in stimulated neurohypophyses is discussed. The occurrence of neurophysin-like proteins in extracts from porcine kidney, mammary gland, uterus and serum has been demonstrated and must be considered when critical experimental tests for the exocytosis theory are evaluated.