title: The effect of oxytocin on progesterone secretion, phosphoinositide hydrolysis and intracellular mobilisation of Ca2+ in porcine luteal cells.
abstract: Oxytocin (OT) is involved in the regulation of steroid secretion by the corpus luteum (CL) in pigs, but OT signal transduction in the porcine CL has not been identified. In this study, the effects of OT on in vitro progesterone (P4) secretion, phosphoinositide (PI) hydrolysis and intracellular mobilisation of Ca2+ ([Ca2+]i) were investigated in porcine luteal cells during the early (days 3-5), mid(days 8-10) and late luteal phases (days 12-14) of the oestrous cycle. Basal concentrations of P4 and accumulation of inositol phosphates (IPs) were higher (P < 0.05) on days 3-5 and 8-10 of the oestrous cycle than on days 12-14. Basal [Ca2+]i mobilisation did not differ among studied periods of the oestrous cycle. Oxytocin (10(-7) M) enhanced P4 secretion and PI hydrolysis (P < 0.05) by luteal cells harvested on days 8-10 of the oestrous cycle. Moreover, OT started to increase mobilisation of [Ca2+]i at the 15th (days 3-5 and 8-10) or 30th second (days 12-14) in porcine luteal cells. It was concluded that in pigs OT acts as a regulator of steroidogenesis, stimulating P4 secretion in mature CL. This OT action may be mediated by changes in PI hydrolysis and [Ca2+]i mobilisation.
authors.affiliation: Department of Animal Physiology, Faculty of Biology, University of Warmia and Mazury in Olsztyn, Oczapowski Str. 1A, 10-718 Olsztyn, Poland. anitaf@uwm.edu.pl
authors.forename: Anita
authors.initials: A
authors.lastname: Franczak
authors.forename: Beata
authors.initials: B
authors.lastname: Kurowicka
authors.forename: Magdalena
authors.initials: M
authors.lastname: Kowalik
authors.forename: Renata Elzbieta
authors.initials: RE
authors.lastname: Ciereszko
authors.forename: Genowefa
authors.initials: G
authors.lastname: Kotwica
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003338:Corpus Luteum / Q000166:cytology / Q000187:drug effects*; D030762:Estrous Cycle / Q000187:drug effects* / Q000502:physiology; D005260:Female; D008184:Luteal Cells / Q000187:drug effects* / Q000378:metabolism; D010121:Oxytocin / Q000494:pharmacology*; D010716:Phosphatidylinositols / Q000378:metabolism*; D011374:Progesterone / Q000032:analysis / Q000378:metabolism*; D013552:Swine / Q000378:metabolism / Q000502:physiology*
chemical_list: D010716:Phosphatidylinositols; D011374:Progesterone; D010121:Oxytocin; D002118:Calcium