Central administration of neuropeptide B, but not prolactin-releasing peptide, stimulates cortisol secretion in sheep.
Two neuropeptides, neuropeptide B (NPB) and prolactin-releasing peptide (PrRP), have been suggested to play important roles in control of the hypothalamic-pituitary-adrenal (HPA) axis in rodents. The aim of the present study was to clarify the central actions of NPB or PrRP in sheep. Ovariectomized ewes were surgically implanted with a cannula directed to the lateral ventricle. They received intracerebroventricular (icv) administration of 400 mul of artificial cerebrospinal fluid, NPB (0.05, 0.5 or 5 nmol), PrRP (0.5, 5 or 50 nmol) or corticotropin-releasing hormone (CRH, 0.5 or 5 nmol) through the cannula, and blood samples were taken 30 and 0 min prior to and 15, 30, 60 and 90 min after the injection. Cortisol concentrations in plasma were determined by enzyme immunoassay. Administration of 0.5 nmol NPB resulted in a significant increase in the cortisol concentration compared with the vehicle control, whereas the cortisol concentration after lower or higher doses of NPB did not differ from the control value. Thus, an icv injection of NPB produced a bell-shaped dose-response of cortisol concentration. Administration of PrRP had no significant effect on the cortisol concentrations at any dose examined. Icv injection of CRH dose-dependently increased plasma cortisol concentrations. These results demonstrate that central NPB stimulates cortisol secretion, suggesting that this neuropeptide plays some roles in control of the HPA axis in sheep. On the other hand, unlike its role in rodents, PrRP is unlikely to be involved in control of the HPA axis in this species.
Mogi
Kazutaka
K
Laboratory of Neurobiology, National Institute of Agrobiological Sciences, Tsukuba, Japan.
Ito
Shuichi
S
Matsuyama
Shuichi
S
Ohara
Hiromi
H
Sakumoto
Ryosuke
R
Yayou
Kenichi
K
Ohkura
Satoshi
S
Sutoh
Madoka
M
Mori
Yuji
Y
Okamura
Hiroaki
H
D000818:Animals; D019540:Area Under Curve; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D005786:Gene Expression Regulation; D006854:Hydrocortisone / Q000097:blood / Q000378:metabolism; D007028:Hypothalamic Hormones / Q000008:administration & dosage* / Q000494:pharmacology; D007030:Hypothalamo-Hypophyseal System; D007276:Injections, Intraventricular; D008954:Models, Biological; D009479:Neuropeptides / Q000008:administration & dosage* / Q000494:pharmacology; D010913:Pituitary-Adrenal System; D056690:Prolactin-Releasing Hormone; D012756:Sheep; D013997:Time Factors
D007028:Hypothalamic Hormones; D009479:Neuropeptides; D056690:Prolactin-Releasing Hormone; C495188:neuropeptide B; D003346:Corticotropin-Releasing Hormone; D006854:Hydrocortisone