Continuous intracerebroventricular administration of a corticotropin releasing hormone antagonist amplifies spontaneous growth hormone pulses in the rat.
Involvement of endogenous corticotropin releasing hormone (CRH) in the regulation of spontaneous growth hormone (GH) secretion was investigated. A CRH antagonist, alpha helical CRH 9-41, was intracerebroventricularly infused for 36 h at a rate of 1 microgram/0.5 microliter/h to freely moving, cannulated adult male rats. Serial blood samples were drawn every 20 min for the last 8 hours of alpha helical CRH 9-41 infusion. The treatment induced a marked increase in GH peak amplitude without affecting either trough levels or numbers of peaks. In parallel, levels of growth hormone releasing hormone (GHRH) mRNA in the arcuate nucleus, but not of somatotropin release inhibiting hormone (SRIH) mRNA in the periventricular and arcuate nuclei, were increased. These data suggest that, in addition to its action in the stress-induced inhibition of GH secretion through regulation of periventricular SRIH neurons, CRH can also act as a modulator of endogenous GH secretion through regulation of arcuate GHRH neurons. Whether the modulatory effects of CRH on GHRH neurons are direct or indirect remains to be established.
Mounier
F
F
Unité de Recherches de Dynamique des Systèmes Neuroendocriniens, U 159 INSERM, Paris, France.
Pellegrini
E
E
Kordon
C
C
Epelbaum
J
J
Bluet-Pajot
M T
MT
D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000378:metabolism*; D002552:Cerebral Ventricles; D003346:Corticotropin-Releasing Hormone / Q000008:administration & dosage* / Q000494:pharmacology; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000235:genetics*; D006727:Hormone Antagonists / Q000008:administration & dosage* / Q000494:pharmacology; D017403:In Situ Hybridization; D008297:Male; D010446:Peptide Fragments / Q000008:administration & dosage* / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism*; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D013004:Somatostatin / Q000235:genetics
D006727:Hormone Antagonists; D010446:Peptide Fragments; D012333:RNA, Messenger; D013004:Somatostatin; D000324:Adrenocorticotropic Hormone; D013006:Growth Hormone; D003346:Corticotropin-Releasing Hormone; D013007:Growth Hormone-Releasing Hormone; C045089:corticotropin releasing hormone (9-41)