Arias Álvarez, MaríaGarcía García, Rosa MaríaTorres Rovira, L.González Bulnes, AntonioRebollar, P.G.Lorenzo González, Pedro Luis2024-04-082024-04-082010-03-011470–162610.1530/REP-09-0309https://hdl.handle.net/20.500.14352/102832Extreme body mass indexes may impair reproductive outcome in assisted reproductive technologies. Leptin reflects the amount of body fat and could act as a modulator of oocyte quality through activation of specific transcription factors. The aim of this work was to establish whether: 1) leptin influences meiotic and cytoplasmic oocyte maturation; 2) STAT3 and MAPK mediate the effects of leptin and 3) leptin modulates steroid secretion by cumulus-oocyte complexes (COC) during in vitro maturation (IVM). We confirmed immunolocalisation of leptin receptor in oocytes, cumulus/granulosa cells during the peri-ovulatory period. The confocal study showed that COC supplemented with 1, 10 and 100 ng/ml leptin had a significantly higher metaphase II (MII) percentage than those IVM without leptin (P < 0.05) and a similar MII index compared to the group supplemented with 10% FCS. Leptin did not increase the percentage of cytoplasmically matured oocytes in terms of cortical granule migration rate, whereas a significantly higher index was found in the FCS group (P < 0.001). Oestradiol concentrations in spent media were higher in the FCS group compared to other treatments (P < 0.001). Leptin-stimulated nuclear oocyte maturation was significantly impaired when leptin-induced JAK2/STAT3 and MEK 1/2 activation was suppressed by the inhibitors (P < 0.001). Steroid secretion of COC was not affected by leptin activation of JAK2/STAT3 or MEK 1/2 pathways. In conclusion, JAK2/STAT3 and MEK 1/2 pathways mediate the enhancement of nuclear oocyte maturation by leptin; however, neither cytoplasmic oocyte maturation nor steroidogenic response of COC were improved in the present rabbit model.engAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/journal article1741-7899https://rep.bioscientifica.com/view/journals/rep/139/3/523.xmlopen access636.09:615Growth factor IGranulosa cellsBovine oocytesProtein kinaseEstradiol 17 beta productionCytoplasmic maturationEstrous cycleCancer cellsRat ovaryFisiología veterinaria3109 Ciencias Veterinarias