title: Biosynthesis of gonadotropin-releasing hormone (GnRH) and GnRH receptor (GnRHR) in hypothalamic-pituitary unit of anoestrous and cyclic ewes.
abstract: This study was performed to explain how the molecular processes governing the biosynthesis of gonadotropin-releasing hormone (GnRH) and GnRH receptor (GnRHR) in the hypothalamic-pituitary unit are reflected by luteinizing hormone (LH) secretion in sheep during anoestrous period and during luteal and follicular phases of the oestrous cycle. Using an enzyme-linked immunosorbent assay (ELISA), we analyzed the levels of GnRH and GnRHR in preoptic area (POA), anterior (AH) and ventromedial hypothalamus (VM), stalk-median eminence (SME), and GnRHR in the anterior pituitary gland (AP). Radioimmunoassay has also been used to define changes in plasma LH concentrations. The study provides evidence that the levels of GnRH in the whole hypothalamus of anoestrous ewes were lower than that in sheep during the follicular phase of the oestrous cycle (POA: p < 0.001, AH: p < 0.001, VM: p < 0.01, SME: p < 0.001) and not always than in luteal phase animals (POA: p < 0.05, SME: p < 0.05). It has also been demonstrated that the GnRHR amount in the hypothalamus-anterior pituitary unit, as well as LH level, in the blood in anoestrous ewes were significantly lower than those detected in animals of both cyclic groups. Our data suggest that decrease in LH secretion during the long photoperiod in sheep may be due to low translational activity of genes encoding both GnRH and GnRHR.
authors.affiliation: a The General Karol Kaczkowski Military Institute of Hygiene and Epidemiology, Department of Pharmacology and Toxicology, Kozielska 4, 01-163 Warsaw, Poland.
authors.forename: M O
authors.initials: MO
authors.lastname: Ciechanowska
authors.affiliation: a The General Karol Kaczkowski Military Institute of Hygiene and Epidemiology, Department of Pharmacology and Toxicology, Kozielska 4, 01-163 Warsaw, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Łapot
authors.affiliation: a The General Karol Kaczkowski Military Institute of Hygiene and Epidemiology, Department of Pharmacology and Toxicology, Kozielska 4, 01-163 Warsaw, Poland.
authors.forename: K
authors.initials: K
authors.lastname: Mateusiak
authors.affiliation: a The General Karol Kaczkowski Military Institute of Hygiene and Epidemiology, Department of Pharmacology and Toxicology, Kozielska 4, 01-163 Warsaw, Poland.
authors.forename: E
authors.initials: E
authors.lastname: Paruszewska
authors.affiliation: b The Museum and Institute of Zoology, Polish Academy of Sciences, Wilcza 64, 00-679 Warsaw, Poland.
authors.forename: T
authors.initials: T
authors.lastname: Malewski
authors.affiliation: c The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Department of Neuroendocrinology, Instytucka 3, 05-110 Jabłonna, Poland.
authors.forename: F
authors.initials: F
authors.lastname: Przekop
mesh_terms: D000780:Anestrus / Q000097:blood / Q000378:metabolism*; D000818:Animals; D007025:Anterior Hypothalamic Nucleus / Q000378:metabolism; D030762:Estrous Cycle / Q000097:blood / Q000378:metabolism*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000096:biosynthesis*; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000097:blood; D008473:Median Eminence / Q000378:metabolism; D010902:Pituitary Gland / Q000378:metabolism; D011301:Preoptic Area / Q000378:metabolism; D011966:Receptors, LHRH / Q000096:biosynthesis*; D012756:Sheep; D014697:Ventromedial Hypothalamic Nucleus / Q000378:metabolism
chemical_list: D011966:Receptors, LHRH; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone
keywords: GnRH; GnRHR; LH; R-GnRH; brebis; ewe; hypophyse; hypothalamus; pituitary; saisonnalité; seasonality