title: Downregulation of LH receptor mRNA in the rat uterus.
abstract: We detected luteinizing hormone receptor (LHR) mRNA in the immature rat uterus by northern blotting and downregulation of this receptor mRNA after pregnant mare serum gonadotropin (PMSG)-human chorionic gonadotropin (hCG) treatment. After administration of hCG, the mRNA levels in the rat uterus declined to an extremely low level from Days 1 to 3 and then rebounded and reached higher than pretreatment values at Day 4. At Day 5 the levels were 3-fold higher than the control levels. The cultured uterus displayed an hCG concentration-dependent increase in cAMP production in the medium. Immunohistochemical experiments showed that these receptor proteins were expressed in the epithelial cells of the endometrium. These results suggest that functional LHRs are present in the immature rat uterus and are downregulated by signals resulting from hCG treatment. These data may support the idea that LH acts on the uterus to inhibit contraction at ovulation. Although the precise role of the LHR in the uterus remains unknown, this study may provide a model with which to investigate the regulation of LHR.
authors.affiliation: Department of Obstetrics and Gynecology, Gunma University Graduate                     School of Medicine, Maebashi, Gunma 371-8511, Japan.
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Kasahara
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Kitahara
authors.forename: Kazuto
authors.initials: K
authors.lastname: Nakamura
authors.forename: Takashi
authors.initials: T
authors.lastname: Minegishi
mesh_terms: D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects*; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology*; D006801:Humans; D010060:Ovulation / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017208:Rats, Wistar; D011974:Receptors, LH / Q000096:biosynthesis*; D013997:Time Factors; D014590:Uterine Contraction / Q000187:drug effects / Q000502:physiology; D014599:Uterus / Q000378:metabolism*
chemical_list: D006063:Chorionic Gonadotropin; D006064:Gonadotropins, Equine; D012333:RNA, Messenger; D011974:Receptors, LH; D000242:Cyclic AMP