Corticosterone modulation of ACTH secretogogue gene expression in the paraventricular nucleus.

This review will describe effects of corticosterone on the temporal dynamics of components within the hypothalamo-pituitary-adrenal (HPA) axis in response to sustained hypovolemia. The characterization of the synthetic and secretory profiles of HPA elements in these rat models reveals the complexities of steroid-mediated regulation of neuroendocrine and corticotrope function during a sustained stress event. Collectively, our data suggest activation of gene transcription and secretion are independently controlled, and that corticosterone affects adrenocorticotropin hormone (ACTH) gene expression in the parvicellular neuroendocrine part of the hypothalamic paraventricular nucleus using two mechanisms: first, an inhibition which contributes to classic negative feedback, and second, a facilitation, which is seen at low plasma concentrations.