Seasonal changes in in vivo cortisol response to ACTH and in plasma and pituitary concentrations of ACTH in a desert rodent, the sand rat (Psammomys obesus).
1. During spring, decreased sensitivity of the adrenal cortex to adrenocorticotrophic hormone (ACTH) in the sand rat inhabiting the Béni-Abbès area (Algeria), results in a reduction in the production of cortisol. Thus the secretion of ACTH is enhanced, becoming maximal in June and presumably also during the following weeks. 2. Increase in ACTH secretion, together with a slightly increased adrenal sensitivity, is likely to stimulate corticosteroidogenesis throughout the summer. 3. In autumn, as levels of cortisol are high, the negative feedback increases leading to a reduction in ACTH production. 4. An increase in the adrenocortical sensitivity to ACTH allows a high production of cortisol until February.
Amirat
Z
Z
Laboratoire d'Endocrinologie et Ecophysiologie Animale, URZA, Alger Gare, Algeria.
Brudieux
R
R
D000311:Adrenal Glands / Q000187:drug effects / Q000502:physiology; D000324:Adrenocorticotropic Hormone / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D003345:Corticosterone / Q000097:blood; D004334:Drug Administration Schedule; D005849:Gerbillinae / Q000502:physiology*; D006854:Hydrocortisone / Q000097:blood*; D008297:Male; D009929:Organ Size / Q000187:drug effects; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012621:Seasons
D000324:Adrenocorticotropic Hormone; D003345:Corticosterone; D006854:Hydrocortisone