CORTICOTROPIN-RELEASING FACTOR MESSENGER-RNA EXPRESSION IN THE HYPOTHALAMIC PARAVENTRICULAR NUCLEUS AND THE CENTRAL NUCLEUS OF THE AMYGDALAIS MODULATED BY REPEATED ACUTE STRESS IN THE IMMATURE RAT

Age-appropriate acute stress, such as cold exposure, provokes the secr etion of corticotropin releasing factor (CRF) from the hypothalamus, l eading to a robust increase of plasma corticosterone in the immature r at. This activation of the hypothalamic-pituitary-adrenal system is ac companied by a stress-induced increase of steady-state CRF-mRNA expres sion in the hypothalamic paraventricular nucleus (PVN), In the current study, we analysed changes in CRF-mRNA expression in the PVN and the central nucleus of the amygdala (ACe) in the immature rat in response to a single episode of cold stress and three repeated exposures to thi s same stressor. CRF-mRNA expression in the PVN increased after a sing le, but not repeated exposures to cold stress, while repeated acute st ress increased the content of the CRF peptide in the anterior hypothal amus, In the ACe, repeated episodes of cold stress resulted in increas ed expression of CRF-mRNA, These findings indicate a differential regu lation of CRF gene expression in the PVN and ACe of the immature rat b y single and repeated acute stress.