Corticotropin-releasing factor secretion increases in rat hypophysial portal blood during insulin-induced hypoglycemia.
To study the possible involvement of hypothalamic corticotropin-releasing factor (CRF) in the stimulation of adrenocorticotropic hormone (ACTH) release caused by insulin-induced hypoglycemia (IIH), we measured CRF secretion in hypophysial portal blood (HPB) in rats anesthetized with sodium thiopental after injection of insulin. Before treatment, systemic ACTH levels (952 +/- SE 143 pg/ml; n = 12) were well above normal values, probably reflecting the anesthetic and surgical stress consecutive to the preparation for portal blood collection. Insulin injection induced a significant increase of ACTH release within 15 min (1,588 +/- 168 vs. 741 +/- 144 pg/ml; n = 6, in vehicle-injected rats) which lasted for at least 1 h. CRF levels in HPB were 857 +/- SE 168 pg/ml (n = 13) during the first-hour pretreatment collection. Vehicle injection did not modify CRF secretion (759 +/- 142 pg/ml; n = 6). Insulin injection provoked a significant increase in CRF release (1,449 +/- 257 pg/ml; n = 7). These data suggest that an increased hypothalamic CRF secretion is responsible for the stimulation of pituitary ACTH release following IIH. The possible involvement of central neuromediators in the IIH-induced CRF production is discussed.
Guillaume
V
V
Laboratoire de Neuroendocrinologie Expérimentale, INSERM U 297, Faculté de Médecine Nord, Marseille, France.
Grino
M
M
Conte-Devolx
B
B
Boudouresque
F
F
Oliver
C
C
D000324:Adrenocorticotropic Hormone / Q000097:blood / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D003346:Corticotropin-Releasing Hormone / Q000097:blood* / Q000378:metabolism; D007003:Hypoglycemia / Q000097:blood* / Q000139:chemically induced; D007031:Hypothalamus / Q000098:blood supply* / Q000502:physiology; D007328:Insulin / Q000494:pharmacology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D001786:Blood Glucose; D007328:Insulin; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone