RESUMEN
The aim of this work was to determine the relationship of intracellular reactive oxygen species (ROS) and the disulphide bonds established between sperm proteins with the achievement of capacitation in boar spermatozoa. With this purpose, spermatozoa were incubated in a specifically designed in vitro capacitation medium (CM) in the presence or absence of reduced glutathione (GSH). Incubation of boar spermatozoa in CM for 4 h significantly (p < 0.05) increased free cysteine residues, which is a marker of disrupted disulphide bonds, and also intracellular ROS levels. The addition of GSH to the medium prevented most capacitation-like changes in sperm motility, membrane lipid disorder, mitochondrial membrane potential, intracellular calcium levels and localization of tyrosine-phosphorylated proteins (pTyr), but not in tyrosine phosphorylation of P32. These effects were accompanied by the inhibition of the ability of sperm cells to trigger the acrosome exocytosis in response to progesterone. When GSH was added together with progesterone after 4 h of incubation, acrosome exocytosis was not altered, but the subsequent decrease in intracellular calcium observed in controls cells was inhibited. Furthermore, co-incubation of oocytes with spermatozoa previously incubated in CM in the presence of GSH for 4 h significantly (p < 0.05) increased the number of spermatozoa attached to the oocyte surface but decreased normal fertilization rates. Our results suggest that boar sperm capacitation is related to an increase in disrupted disulphide bonds and intracellular ROS levels and that both events are related to the regulation of hyperactivated motility, intracellular calcium dynamics, sperm binding ability to the oocyte and achievement of proper nuclear decondensation upon oocyte penetration.
Asunto(s)
Disulfuros/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Capacitación Espermática , Espermatozoides/metabolismo , Reacción Acrosómica , Animales , Calcio/metabolismo , Cisteína/metabolismo , Fragmentación del ADN/efectos de los fármacos , Exocitosis , Femenino , Fertilización In Vitro , Glutatión/farmacología , Masculino , Lípidos de la Membrana/metabolismo , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Peróxidos/metabolismo , Fosforilación , Capacitación Espermática/efectos de los fármacos , Motilidad Espermática/efectos de los fármacos , Espermatozoides/efectos de los fármacos , Superóxidos/metabolismo , Porcinos , Tirosina/metabolismoRESUMEN
This experiment was conducted to evaluate the effects of sex and uterus position on swine foetal myogenesis at different gestational ages. Fifteen primiparous sows were divided into three groups according to gestational age: 50, 80, and 106 days. The experiment was a block randomized factorial design with two sexes (male and female) and three uterine regions (apex, middle, and base). After slaughter, each uterus horn was divided into three segments of equal length: apex region near the ovary; base region near the uterine body; and the middle region, lying between the apex and base regions. The foetuses were weighed, identified, and longitudinally opened to harvest the semitendinosus muscle for later morphological analysis. After 50 days of pregnancy, male foetuses had greater (p < .05) weight than females. The number of primary fibres at 50 days of gestation was negatively correlated (r = -.29, p = .04) with the number of foetuses in utero. After 80 days, foetuses in the base region had less (p < .05) secondary area of muscle fibres compared to the apex region, which was accompanied by differences in the weight of the foetuses, the lowest weight were for foetuses located in the base region (p < .05). In the same period, the ratio of secondary to primary fibres had a positive correlation with weight. In conclusion, sex did not influence myogenesis in the gestational ages studied and the development of secondary muscle fibres of the foetuses at 80 days of gestation was affected by their uterine position with foetuses at the base of the uterine horn being less developed.