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Galanin-Like Peptide Elicits a Robust Discharge of Growth Hormone in the Rhesus Monkey (Macaca mulatta)
- Source :
- Neuroendocrinology. 81:254-258
- Publication Year :
- 2005
- Publisher :
- S. Karger AG, 2005.
-
Abstract
- Galanin-like peptide (GALP) stimulates the release of gonadotropin-releasing hormone in rodent and primate species. The widespread distribution of GALP fibers in the hypothalamus suggests that this neuropeptide may influence hypophysiotropic factors that control other aspects of adenohypophysial function. Here we studied the effects of intracerebroventricular administration of GALP on serum levels of growth hormone (GH) and prolactin (PRL) in adult male monkeys. The animals (n = 5) were orchidectomized and implanted with testosterone-containing Silastic capsules to maintain the circulating testosterone levels (∼9 ng/ml) within the physiological range. The animals were implanted with an intracerebroventricular cannula and venous catheter for continuous access to the cerebroventricular and the venous circulation, respectively. GALP (500 µg), or vehicle alone, was administered as a bolus intracerebroventricular injection, and sequential blood samples were collected at 20-min intervals for 3 h before and after the injections. Within 20 min following GALP injection, the GH concentrations increased 3.5-fold, and a peak level (12.9 ± 2.7 ng/ml) was observed 40 min after injection. The GH levels remained elevated until 60 min after injection and thereafter declined to values similar to those observed at 0 min. The GH concentrations were not changed by vehicle alone. A decline in PRL levels was observed following GALP administration, with significantly reduced concentrations occurring between 60 and120 min following the injection of the neuropeptide. We conclude that in the monkey GALP is a potent secretagogue for GH and an inhibitor of PRL secretion and that GALP may, therefore, interact with the hypothalamic circuitry involved in the regulation of these pituitary hormones.
- Subjects :
- medicine.medical_specialty
biology
Endocrine and Autonomic Systems
GalP
Endocrinology, Diabetes and Metabolism
digestive, oral, and skin physiology
Neuropeptide
Prolactin
Cellular and Molecular Neuroscience
chemistry.chemical_compound
Endocrinology
chemistry
Hypothalamus
Internal medicine
Galanin-like peptide
medicine
biology.protein
Secretagogue
Galanin
Hormone
Subjects
Details
- ISSN :
- 14230194 and 00283835
- Volume :
- 81
- Database :
- OpenAIRE
- Journal :
- Neuroendocrinology
- Accession number :
- edsair.doi...........e412355477534f307d35f8d5d68ba46c