Corticosterone modulation of ACTH secretogogue gene expression in the paraventricular nucleus

This review will describe effects of corticosterone on the temporal dynamic s of components within the hypothalamo-pituitary-adrenal (HPA) axis in resp onse to sustained hypovolemia. The characterization of the synthetic and se cretory profiles of HPA elements in these rat models reveals the complexiti es of steroid-mediated regulation of neuroendocrine: and corticotrope funct ion during a sustained stress event. Collectively, our data suggest activat ion of gene transcription and secretion are independently controlled, and t hat corticosterone affects adrenocorticotropin hormone (ACTH) gene expressi on in the parvicellular neuroendocrine part of the hypothalamic paraventric ular nucleus using two mechanisms: first, an inhibition which contributes t o classic negative feedback. and secund, a facilitation, which is seen at l ow plasma concentrations.