Circumventricular Organs: Definition And Role In The Regulation Of Endocrine And Autonomic Function

• Published in: Clinical and experimental pharmacology & physiology Vol. 27; no. 5-6; pp. 422 - 427
• Main Author: Ganong, William F
• Format: Journal Article
• Language: English
• Published: Melbourne, Australia Blackwell Science Pty 01.05.2000
• Subjects: Adrenocorticotropic Hormone - blood; Adrenocorticotropic Hormone - drug effects; Angiotensin-Converting Enzyme Inhibitors - pharmacology; Animals; area postrema; blood-brain barrier; Blood-Brain Barrier - drug effects; Blood-Brain Barrier - physiology; Cholecystokinin - metabolism; circumventricular organs; Growth Hormone-Releasing Hormone - metabolism; Humans; Hypnotics and Sedatives - pharmacology; Hypothalamic Hormones - metabolism; Mammalia; median eminence; neuroendocrine control; neurohypophysis; organum vasculosum lamina terminalis; Pentobarbital - pharmacology; Pituitary Gland, Posterior - drug effects; Pituitary Gland, Posterior - physiology; Prolactin - metabolism; Saralasin - pharmacology; Subcommissural Organ - drug effects; Subcommissural Organ - physiology; subfornical organ; Subfornical Organ - drug effects; Subfornical Organ - physiology
• ISSN: 0305-1870; 1440-1681
• DOI: 10.1046/j.1440-1681.2000.03259.x

SUMMARY 1. The circumventricular organs (CVO) are structures that permit polypeptide hypothalamic hormones to leave the brain without disrupting the blood–brain barrier (BBB) and permit substances that do not cross the BBB to trigger changes in brain function. 2. In mammals, CVO include only the median eminence and adjacent neurohypophysis, organum vasculosum lamina terminalis, subfornical organ and the area postrema. 3. The CVO are characterized by their small size, high permeability and fenestrated capillaries. The subcommissural organ is not highly permeable and does not have fenestrated capillaries, but new evidence indicates that it may be involved in the hypertension produced by aldosterone acting on the brain. 4. Feedback control of corticotropin‐releasing hormone (CRH) secretion is exerted by free steroids diffusing into the brain, but substances such as cytokines and angiotensin II act on CVO to produce increases in CRH secretion. Gonadal steroids also diffuse into the brain to regulate gonadotrophin‐releasing hormone secretion. Thyrotropin‐releasing hormone secretion is regulated by thyroid hormones transported across cerebral capillaries. However, CVO may be involved in the negative feedback control of growth hormone and prolactin secretion.