Submitted to: Domestic Animal Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 15, 2005
Publication Date: August 20, 2005
Citation: Barb, C.R., Barrett, J.B. 2005. Neuropeptide Y modulates growth hormone secretion but not luteinizing hormone secretion from prepuberal gilt anterior pituitary cells in culture. Domestic Animal Endocrinology. 29:548-555. Interpretive Summary: Inadequate nutrition is characterized by low blood levels of pituitary hormones, such as luteinizing hormone (LH), necessary for stimulation of the reproductive system and growth hormone (GH), necessary for growth. A lack of these hormones results in delayed puberty, irregular heat cycles and failure of animals to breed and poor growth. The brain peptide, neuropeptide Y (NPY), produced by the brain in response to changes in body weight or energy, stimulates GH and suppresses LH secretion in rodents. NPY may serve as a signal linking the body's energy regulating system with the reproductive and growth system. This is the first report to demonstrate that administration of NPY stimulated GH secretion, and suppressed GH response to GH releasing hormone (GHRH, brain hormone that stimulates GH secretion) but did affect LH secretion from pig pituitary cells in culture. Therefore, understanding the NPY- LH and GH interactions is necessary in order to develop new methods to improve reproductive efficiency and growth in the pig.
Technical Abstract: To test the hypothesis that neuropeptide Y (NPY) acts directly on the anterior pituitary to regulate LH and growth hormone (GH) secretion, anterior pituitary cells from prepuberal gilts were studied in primary culture. On day 4 of culture cells were challenged with 1 nM, 10 nM, or 100 nM, gonadotropin releasing hormone (GnRH), 100 pm, 10 nM or1 uM growth hormone releasing hormone (GHRH) or 1 nM, 10 nM, 100 nM, or 1 uM, NPY individually or in combinations with 1nM and 10 nM GnRH or 10nM and 1 uM GHRH. LH and GH were measured at 4 h. 1 uM and 100 nM NPY increased basal GH secretion. Addition of 1, 10 and 100nM NPY in combination with 10 nM GHRH suppressed GHRH-stimulated GH secretion. NPY failed to effect LH secretion. These results demonstrate that NPY directly modulats GH secretion from the pituitary gland.