RESUMEN
VISFATIN is a novel adipokine, also known as a nicotinamide phosphorybosyltransferase (NAMPT), that is able to modulate different processes, including lipid and glucose metabolism, oxidative stress, inflammation, and insulin resistance. Recent data suggest that it also plays a role in reproductive function in rats, humans, and chickens. Here we identified VISFATIN in the bovine ovary and investigated the in vitro effects of this hormone on granulosa cell steroidogenesis and proliferation and oocyte maturation. By RT-PCR, immunoblotting, and immunohistochemistry, we found VISFATIN in various ovarian cells, including granulosa and theca cells, corpus luteum, and oocytes. In cultured bovine granulosa cells, we showed that IGF1 (10(-8) M) and VISFATIN (10 and 100 ng/ml) but not FSH (10(-8) M) increased mRNA expression levels of NAMPT after 48 h of stimulation. Moreover, we observed that human recombinant VISFATIN (hVisf, 10 ng/ml, 48 h) increased the release of progesterone and estradiol secretion, and this was associated with an increase in the protein level of STAR, the HSD3B activity, and the phosphorylation levels of IGF1R and MAPK ERK1/2 in the presence or absence of IGF1 (10(-8) M). All these effects were abolished when NAMPT was knocked down and when the sirtuin pharmacological inhibitors CHIC-35 (60 nM) and EX-527 (0.5 µM) were preincubated in bovine granulosa cells. Thus, in cultured bovine granulosa cells, VISFATIN improves basal and IGF1-induced steroidogenesis and IGF1 receptor signaling through SIRT1.
Asunto(s)
Factor I del Crecimiento Similar a la Insulina/farmacología , Nicotinamida Fosforribosiltransferasa/farmacología , Receptores de Somatomedina/metabolismo , Transducción de Señal/fisiología , Sirtuina 1/metabolismo , Esteroides/biosíntesis , Animales , Bovinos , Estradiol/biosíntesis , Femenino , Hormona Folículo Estimulante/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/fisiología , Células de la Granulosa/efectos de los fármacos , Células de la Granulosa/fisiología , Humanos , Nicotinamida Fosforribosiltransferasa/genética , Nicotinamida Fosforribosiltransferasa/metabolismo , Progesterona/biosíntesis , ARN Mensajero/genética , ARN Mensajero/metabolismo , Proteínas Recombinantes/farmacología , Sirtuina 1/genéticaRESUMEN
Combinations of genetic, environmental, and management factors are suspected to explain the loss in fertility observed for over 20 years in dairy cows. In some cases, IVF is used. When compared with in vivo embryo production, IVF resulted in low success rates until the FSH coasting process (FSH starvation after superstimulation) was introduced in 2002. Increased competence associated with FSH withdrawal of aspirated oocyte for in vitro maturation and IVF has not been optimized nor explained yet. The goal here was to determine and characterize the optimal oocyte competence acquisition window during the coasting period by determining blastocyst rates and follicular cohort development. Commercial milking cycling cows (n=6) were stimulated with 3 days of FSH (6×40âmg NIH Folltropin-V given at 12âh intervals) followed by a coasting period of 20, 44, 68, or 92âh. Each animal was exposed to the four conditions and served as its own control. At the scheduled time, transvaginal aspirations of immature oocytes were performed followed by IVF of half the oocytes. The outcomes were as follows: i) FSH coasting was optimal at a defined period: between 44 and 68âh of coasting; ii) The best estimated coasting duration was â¼54±7âh; iii) Under these conditions, the best statistical blastocyst rate estimation was â¼70%; iv) Between 44 and 68âh of coasting, follicle size group proportions were similar; v) Follicle diameter was not linearly associated with competence. In conclusion, coasting duration is critical to harvest the oocytes at the right moment of follicular differentiation.