Neuropeptide Y induces gonadotropin-releasing hormone gene expression directly and through conditioned medium from mHypoE-38 NPY neurons.
Neuropeptide Y (NPY) regulates reproductive function at the level of the hypothalamus through control of GnRH secretion. However, the direct control of GnRH gene expression by NPY has not yet been studied. GT1-7 neurons were treated with 100 nM of NPY over a 36 h time course. GnRH mRNA levels were significantly increased by NPY up to 12 h. We determined that GT1-7 neurons expressed Y1, Y2, and Y4 NPY receptors, but not Y5. Functional analysis of NPY receptor activation indicated that the Y1/Y4/Y5 receptor agonist [Leu31, Pro34] significantly induced cAMP accumulation in the GT1-7 neurons. Western blot studies demonstrated changes in the phosphorylation status of AKT, ERK1/2, CREB and ATF-1 after NPY exposure. Pharmacological inhibitors of the MAPK and PKA signal transduction pathways attenuated the NPY-mediated increase in GnRH transcription. This NPY-mediated increase in GnRH mRNA was also inhibited with the Y1-receptor specific antagonist BIBP-3226. The mHypoE-38 neurons secrete detectable levels of NPY and can be used as an endogenous source of NPY. Conditioned medium from mHypoE-38 neurons induced an increase in GnRH mRNA, which was inhibited by the Y1 receptor antagonist BIBP-3226. Together, these studies strengthen the evidence for the importance of NPY in the regulation of reproductive function.
Department of Physiology, University of Toronto, Medical Sciences Building 3247A, 1 Kings College Circle, Toronto, ON, Canada M5S 1A8.
Sandeep S
SS
Dhillon
Sarah
S
Gingerich
Denise D
DD
Belsham
D051697:Activating Transcription Factor 1 / Q000378:metabolism; D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D015153:Blotting, Western; D002460:Cell Line; D017077:Culture Media, Conditioned; D000242:Cyclic AMP / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D009478:Neuropeptide Y / Q000378:metabolism / Q000494:pharmacology*; D010766:Phosphorylation; D011863:Radioimmunoassay; D017476:Receptors, Neuropeptide Y / Q000819:agonists / Q000037:antagonists & inhibitors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects
D051697:Activating Transcription Factor 1; D014151:Anti-Anxiety Agents; C092926:BIBP 3226; D017077:Culture Media, Conditioned; D017362:Cyclic AMP Response Element-Binding Protein; D009478:Neuropeptide Y; D017476:Receptors, Neuropeptide Y; D007987:Gonadotropin-Releasing Hormone; D001120:Arginine; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases