The effects of maternal care on the development of individual differences in behavioral and HPA responses to stress in the rat are mediated by alterations of the neural systems that regulate central CRF systems furnishing the critical signal for the activation of behavioral, emotional, autonomic, and endocrine responses to stressors. There are two major CRF pathways. First, a CRF pathway from the parvocellular regions of the paraventricular nucleus of the hypothalamus (PVNh) to the portal system of the anterior pituitary, which serves as the principal mechanism for the transduction of a neural signal into a pituitary-adrenal response.43-45 In responses to stressors, CRF is released from PVNh neurons into the portal blood supply of the anterior pituitary and stimulates the synthesis and release of adrenocorticotropin hormone (ACTH). Pituitary ACTH, in turn, causes the release of glucocorticoids from the adrenal gland. CRF synthesis and release are inhibited through a glucocorticoid negative-feedback system mediated by both mineralocorticoid and glucocorticoid receptors (GRs) in a number of brain regions including, and perhaps especially in, the hippocampus.46,47 CRF neurons in the amygdala project directly to the
