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 locus ceruleus and increase the firing rate of locus ceruleus neurons, resulting in increased noradrenaline release in the vast terminal fields of this ascending noradrenergic system. Thus, intracerebroventricular (ICV) infusion of CRF increases extracellular noradrenaline levels.48-52 The amygdaloid CRF projection to the locus ceruleus52-56 is also critical for the expression of behavioral responses to stress.57-64 Hence, the CRF neurons in the PVNh and amygdala serve as important mediators of both behavioral and endocrine responses to stress.
