Pathophysiology of Hypothalamic-Pituitary-Adrenal Axis

Child Health And Human Development

Investigators

Linked publications & trials

Abstract

We seek to advance the understanding of the physiology and pathophysiology of the hypothalamic-pituitary-adrenal and -gonadal axes. The roles of the stress-related hormones corticotropin-releasing hormone (CRH) and glucocorticoids in normal and disease states are being examined, and clinical applications for these hormones and their antagonists are sought. We have demonstrated that several human states are characterized by hyperactivity or hypoactivity of the central stress system, which explains not only mood changes but also the propensity of patients with such disorders to develop developmental, metabolic cardiovascular or autoimmune complications. We are currently performing preclinical studies with the newly discovered nonpeptide, oral, CRH type 1 receptor antagonist, antalarmin, which show that such an antagonist may be useful in a large number of states characterized by hyperactivity of the stress system, such as depression, anorexia nervosa and idiopathic insomnia. At the level of the stress system target tissues, we have elucidated the molecular pathophysiology of sporadic and familial glucocorticoid resistance by defining mutations and/or deletions of the glucocorticoid receptor gene leading to abnormally functioning or decreased receptors. In the same area, we have found abnormal expression of the beta dominant negative isoform of the glucocorticoid receptor in patients with glucocorticoid resistant asthma, and have described inflammation-induced glucocorticoid resistance in the acute respiratory distress syndrome. Finally, we have determined that Vpr and Tat, two small HIV-1 accessory proteins, are potent coactivators of the glucocorticoid receptor, causing marked target tissue glucocorticoid hypersensitivity, the presence of which may explain some of the clinical features and pathogenesis of AIDS. Also, we have made advances in understanding the pathophysiology and treatment of congenital adrenal hyperplasia, by demonstrating that these patients have epinephrine deficiency and insulin resistance, which leads to ovarian dysfunction and metabolic abnormalities, while we have shown that treatment with androgen antagonists combined with aromatase inhibitors decreases their need for glucocorticoid therapy resulting in a better height outcome.