title: Gonadotropin-inhibitory hormone (GnIH) receptor gene is expressed in the chicken ovary: potential role of GnIH in follicular maturation.
abstract: Gonadotropin-inhibitory hormone (GnIH), an RFamide peptide, has been found to inhibit pituitary LH secretion in avian and mammalian species. The gene encoding a putative receptor for GnIH (GnIHR) was recently identified in the chicken and Japanese quail brain and pituitary gland. GnIHR appears to be a seven-transmembrane protein belonging to a family of G-protein-coupled receptors. In the present study, we have characterized the expression of GnIHR mRNA in the chicken ovary and demonstrate that GnIHR may exert an inhibitory effect on ovarian follicular development. By RT-PCR, we detected GnIHR mRNA in the chicken testis and in the ovary, specifically both thecal and granulosa cell layers. Real-time quantitative PCR analysis revealed greater GnIHR mRNA quantity in theca cells of prehierarchial follicles compared with that of preovulatory follicles. GnIHR mRNA quantity was significantly decreased in sexually mature chicken ovaries versus ovaries of sexually immature chickens. Estradiol (E(2)) and/or progesterone (P(4)) treatment of sexually immature chickens significantly decreased ovarian GnIHR mRNA abundance. Treatment of prehierarchial follicular granulosa cells in vitro with chicken GnIH peptide significantly decreased basal but not FSH-stimulated cellular viability. Collectively, our results indicate that the ovarian GnIHR is likely to be involved in ovarian follicular development. A decrease in ovarian GnIHR mRNA abundance due to sexual maturation or by E(2) and/or P(4) treatment would implicate an inhibitory role for GnIHR in ovarian follicular development. Furthermore, GnIH may affect follicular maturation by decreasing the viability of prehierarchial follicular granulosa cells through binding to GnIHR.
authors.affiliation: Department of Poultry Science, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Sreenivasa R
authors.initials: SR
authors.lastname: Maddineni
authors.forename: Olga M
authors.initials: OM
authors.lastname: Ocón-Grove
authors.forename: Susan M
authors.initials: SM
authors.lastname: Krzysik-Walker
authors.forename: Gilbert L
authors.initials: GL
authors.lastname: Hendricks
authors.forename: Ramesh
authors.initials: R
authors.lastname: Ramachandran
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000235:genetics*; D002470:Cell Survival / Q000187:drug effects; D002645:Chickens / Q000235:genetics / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006107:Granulosa Cells / Q000187:drug effects; D007028:Hypothalamic Hormones / Q000235:genetics*; D008297:Male; D006080:Ovarian Follicle / Q000187:drug effects / Q000378:metabolism*; D011374:Progesterone / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012741:Sexual Maturation; D013737:Testis / Q000378:metabolism
chemical_list: D030161:Avian Proteins; D007028:Hypothalamic Hormones; D012333:RNA, Messenger; D011374:Progesterone; D004958:Estradiol; D005640:Follicle Stimulating Hormone