title: Diurnal regulation of hypothalamic kisspeptin is disrupted during mouse pregnancy.
abstract: Kisspeptin, the neuropeptide product of the Kiss1 gene, is critical in driving the hypothalamic-pituitary-gonadal (HPG) axis. Kisspeptin neurons in the anteroventral periventricular nucleus (AVPV) and arcuate nucleus (Arc) of the hypothalamus mediate differential effects, with the Arc regulating negative feedback of sex steroids and the AVPV regulating positive feedback, vital for the preovulatory surge and gated under circadian control. We aimed to characterize hypothalamic Kiss1 and Kiss1r mRNA expression in nonpregnant and pregnant mice, and investigate potential circadian regulation. Anterior and posterior hypothalami were collected from C57BL/6J mice at diestrus, proestrus, and days 6, 10, 14, and 18 of pregnancy, at six time points across 24h, for real-time PCR analysis of gene expression. Analysis confirmed that Kiss1 mRNA expression in the AVPV increased at ZT13 during proestrus, with a luteinizing hormone surge observed thereafter. No diurnal regulation was seen at diestrus or at any stage of pregnancy. Anterior hypothalamic Avp mRNA expression exhibited no diurnal variation, but Avpr1a peaked at 12:00h during proestrus, possibly reflecting the circadian input from the suprachiasmatic nucleus to AVPV Kiss1 neurons. Rfrp (Npvf) expression in the posterior hypothalamus did not demonstrate diurnal variation at any stage. Clock genes Bmal1 and Rev-erbα were strongly diurnal, but there was little change between diestrus/proestrus and pregnancy. Our data indicate the absence of the circadian input to Kiss1 in pregnancy, despite high gestational estradiol levels and normal clock gene expression, and may suggest a disruption of a kisspeptin-specific diurnal rhythm that operates in the nonpregnant state.
authors.affiliation: School of AnatomyPhysiology and Human Biology, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Cassandra C
authors.initials: CC
authors.lastname: Yap
authors.affiliation: School of AnatomyPhysiology and Human Biology, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Michaela D
authors.initials: MD
authors.lastname: Wharfe
authors.affiliation: School of AnatomyPhysiology and Human Biology, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Mark
authors.affiliation: School of AnatomyPhysiology and Human Biology, The University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: Waddell
authors.affiliation: School of AnatomyPhysiology and Human Biology, The University of Western Australia, Perth, Western Australia, Australia jeremy.smith@uwa.edu.au.
authors.forename: Jeremy T
authors.initials: JT
authors.lastname: Smith
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000235:genetics; D002940:Circadian Rhythm / Q000235:genetics / Q000502:physiology*; D005260:Female; D015870:Gene Expression; D006728:Hormones / Q000097:blood; D007031:Hypothalamus / Q000502:physiology*; D059648:Kisspeptins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000235:genetics / Q000502:physiology*; D011359:Proestrus / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017483:Receptors, Vasopressin / Q000235:genetics
chemical_list: C000600609:AVPR1a receptor, mouse; D006728:Hormones; C491407:Kiss1 protein, mouse; D059648:Kisspeptins; D012333:RNA, Messenger; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin
keywords: circadian; hypothalamus; kisspeptin; mouse; pregnancy