Differential regulation of corticotropin-releasing hormone and vasopressingene transcription in the hypothalamus by norepinephrine

All stress-related inputs are conveyed to the hypothalamus via several brai n areas and integrated in the parvocellular division of the paraventricular nucleus (PVN) where corticotropin-releasing hormone (CRH) is synthesized. Arginine vasopressin (AVP) is present in both magnocellular and parvocellul ar divisions of the PVN, and the latter population of AVP is colocalized wi th CRH. CRH and AVP are co-secreted in the face of certain stressful stimul i, and synthesis of both peptides is suppressed by glucocorticoid. CRH and AVP stimulate corticotropin (ACTH) secretion synergistically, but the physi ological relevance of the dual corticotroph regulation is not understood. N orepinephrine (NE) is a well known neurotransmitter that regulates CRH neur ons in the PVN. We explored the mode of action of NE on CRH and AVP gene tr anscription in the PVN to examine the effect of the neurotransmitter on mul tiple genes that are responsible for a common physiological function, After NE injection into the PVN of conscious rats, CRH heteronuclear (hn) RNA in creased rapidly and markedly in the parvocellular division of the PVN, AVP hnRNA did not change significantly in either the parvocellular or magnocell ular division of the PVN after NE injection, The present results show that the transcription of CRH and AVP genes is differentially regulated by NE, i ndicating the complexity of neurotransmitter regulation of multiple releasi ng hormone genes in a discrete hypothalamic neuronal population.