Hypothalamic regulatory hormones: a review

Abstract

There is little doubt that the hypothalamic pituitary target organ system provides a sophisticated amplifier, whereby the brain can cause a tiny amount of hypothalamic hormone to be released which in turn activates the pituitary and causes large amounts of target gland hormones to be secreted. These can not only profoundly alter the subject's physical and behavioural functioning, but also, by influencing his reactivity with his surroundings, alter his environment. By sensing the circulating hormone levels as well as the physical and environmental changes, the brain modulates the secretion of its own hormones and the system as a whole. The isolation and synthesis of various hypothalamic regulatory hormones has revolutionized the field of endocrinology and led to a greater understanding of the pathophysiology of many disease processes. The feedback mechanisms operating between the hypothalamus, pituitary, and target organ secretions which have been revealed already will no doubt be further clarified when sensitive assays for the regulatory hormones themselves are developed. Meanwhile recent experience with these biologically active polypeptides has provided encouraging opportunities in both diagnosis and treatment of endocrine disorders. The discovery and synthesis of further regulatory hormones and their application in clinical medicine is therefore eagerly awaited.