Effects of Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) and Vasoactive Intestinal Polypeptide (VIP) on Prolactin, Luteinizing Hormone and Growth Hormone Secretion in the Ewe
| Autor: | K Sawangjaroen, J. D. Curlewis |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
endocrine system
medicine.medical_specialty Endocrinology Diabetes and Metabolism Vasoactive intestinal peptide Luteal phase Cellular and Molecular Neuroscience Endocrinology Internal medicine medicine Animals Infusions Intra-Arterial Injections Intraventricular Estrous cycle Sheep Endocrine and Autonomic Systems Chemistry Neuropeptides Luteinizing Hormone Growth hormone secretion Prolactin Carotid Arteries Growth Hormone Ovariectomized rat Pituitary Adenylate Cyclase-Activating Polypeptide Female Luteinizing hormone hormones hormone substitutes and hormone antagonists Vasoactive Intestinal Peptide Hormone |
| Zdroj: | Journal of Neuroendocrinology. 6:549-555 |
| ISSN: | 1365-2826 0953-8194 |
| DOI: | 10.1111/j.1365-2826.1994.tb00618.x |
| Popis: | This study was undertaken to investigate the roles of PACAP and VIP in the control of pituitary hormone secretion in the ewe. The first experiment was designed to identify any direct effects at the level of the pituitary and was conducted during the luteal phase of a prostaglandin-synchronized oestrous cycle. PACAP (0.008, 0.04, 0.2 and 1.0 nmol/min) or VIP (0.06, 0.2, 0.6 and 1.8 nmol/min) was infused into the carotid artery over a 10 min period. Blood samples were taken before and after the infusions so that plasma PRL, LH and GH concentrations could be measured. Blood pressure was also monitored to determine if the doses used were biologically active. In no case was an effect on hormone secretion observed. In contrast, the highest dose of each peptide induced an increase in heart rate to almost three-fold the resting value. Although both peptides are active in vivo, this result suggests that neither peptide has a direct effect on hormone release from the pituitary of prostaglandin-synchronized ewes. In a second experiment, we investigated whether the peptides had central effects on hormone secretion. Intracerebroventricular (ICV) injection of PACAP or VIP at the dose 10 nmol was tested in ovariectomized ewes. After injection, PACAP suppressed PRL and GH secretion so that plasma hormone concentrations from 1-3 h after injection were significantly different from the control (P < 0.05 for PRL, P < 0.01 for GH). In addition, PACAP significantly reduced mean LH concentration (P < 0.05) and LH pulse frequency (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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