|Dyer, C - UNIVERSITY OF MISSOURI|
|Keisler, D - UNIVERSITY OF MISSOURI|
Submitted to: Society for the Study of Reproduction Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 27, 1996
Publication Date: N/A
Technical Abstract: Neuropeptide Y (NPY) has been shown to exert effects upon the hypothalamic- pituitary-gonadal axis, but the mechanisms through which this peptide acts remain unclear. NPY is highly expressed during times of undernutrition, and has been shown to have inhibitory actions on LH release during such times, presumably through affecting the release of LHRH. Recently it was shown that NPY synthesis is regulated by energy balance through the hormon leptin (the OB gene product produced by adipocytes), which is in turn regulated by insulin. Although several subtypes of NPY receptors exist, there is evidence that the effects of NPY on reproductive function are mediated by the Y1 subtype. To being to determine the possible role of this receptor, ovariectomized ewe hypothalamic RNA was used in RT-PCR with primers derived from the published human and rat Y1 sequences to amplify a 350 base pair cDNA. Cloning and sequencing revealed a >85% homology to the ecorresponding human sequence. Expression of Y1 mRNA in hypothalamus and pituitary was consistently detected in as low as 5 ug total cellular (tc) RNA; expression in adipose was detectable in 15 ug tc RNA. The observed expression of Y1 mRNA in adipose may be indicative of a feedback regulatory mechanism by which NPY can directly influence production of leptin in adipocytes. in situ hybridization of hypothalamic sections showed high levels of Y1 mRNA expression within specific clusters of cells within the arcuate nucleus. The detection of Y1 mRNA expression in the pituitary may indicate a possible mechanism for a direct effect of NPY on cells of the pituitary, as has been implicated in several previous studies. These findings suggest that the Y1 NPY receptor may be involved in mediating the effects of undernutrition on reproductive function at several levels.