Independent and overlapping effects of corticosterone and testosterone on corticotropin-releasing hormone and arginine vasopressin mRNA expression in the paraventricular nucleus of the hypothalamus and stress-induced adrenocorticotropic hormone release.
Adrenocorticotropin (ACTH) release is regulated by both glucocorticoids and androgens; however, the precise interactions are unclear. We have controlled circulating corticosterone (B) and testosterone (T) by adrenalectomy (ADX) +/- B replacement and gonadectomy (GDX) +/- T replacement, comparing these to sham-operated groups. We hoped to reveal how and where these neuroendocrine systems interact to affect resting and stress-induced ACTH secretion. ADX responses. In gonadal-intact rats, ADX increased corticotropin-releasing factor (CRH) and vasopressin (AVP) mRNA in hypothalamic parvocellular paraventricular nuclei (PVN) and ACTH in pituitary and plasma. B restored these toward normal. GDX blocked the increase in AVP but not CRH mRNA and reduced plasma, but not pituitary ACTH in ADX rats. GDX+T restored increased AVP mRNA in ADX rats, although plasma ACTH remained decreased. Stress responses. Restraint-induced ACTH responses were elevated in ADX gonadally intact rats, and B reduced these toward normal. GDX in adrenal-intact and ADX+B rats increased ACTH responses. Without B, T did not affect ACTH; together with B, T restored ACTH responses to normal. The magnitude of ACTH responses to stress was paralleled by similar effects on the number of c-fos staining neurons in the hypophysiotropic PVN. We conclude that gonadal regulation of ACTH responses to ADX is determined by T dependent effects on AVP biosynthesis, whereas CRH biosynthesis is B-dependent. Stress-induced ACTH release is not explained by B and T interactions at the PVN, but is determined by B- and T-dependent changes in drive to PVN motorneurons.
Viau
V
V
Department of Physiology, University of California at San Francisco, San Francisco, California 94143, USA.
Chu
A
A
Soriano
L
L
Dallman
M F
MF
D000315:Adrenalectomy; D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000818:Animals; D001127:Arginine Vasopressin / Q000235:genetics / Q000378:metabolism*; D003345:Corticosterone / Q000097:blood / Q000494:pharmacology*; D003346:Corticotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism*; D008297:Male; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012149:Restraint, Physical; D013312:Stress, Physiological / Q000378:metabolism*; D013739:Testosterone / Q000494:pharmacology*
D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D001127:Arginine Vasopressin; D013739:Testosterone; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D003345:Corticosterone