Adição de fator de crescimento semelhante à insulina tipo I (IGF-I) e glutationa reduzida (GSH) ao sêmen suíno criopreservado

Abstract

The objective of this study was to evaluate the influence of the addition of GSH to the freezing medium of swine semen, added or not of IGF-I or anti-IGF-I, on the quality of frozen swine semen. Eight ejaculates from eight Boars of the Duroc and Large White breeds were used. The experimental design was a randomized block design (ejaculate) with six treatments and eight replications. The treatments were: T1: control (diluted semen); T2: control + IGF-I; T3: control + anti-IGF-I antibody; T4: control + GSH; T5: Control + GSH + IGF-I and T6: Control + GSH + anti-IGF-I antibody. IGF-I (30 ng / ml semen) or its antibody (60 ng / ml) were added shortly after the dilution of fresh semen and GSH (5 mM) to the freezing medium. Samples of semen were evaluated before and after 24 hours of cooling, and also soon after thawing. For this, the samples were incubated at 37oC in a water bath and evaluated after 10 and 120 minutes of incubation. Addition of IGF-I and its antibody increased (P <0.05) the osmotic resistance and acrossomal integrity of fresh swine semen incubated for 120 minutes. After 24 hours of cooling, these substances increased (P <0.05) the percentage of cells with higher mitochondrial activity and reduced the percentage of cells with high superoxide levels after 120 minutes of incubation. However, anti-IGF-I reduced (P <0.05) the percentage of viable spermatozoa and both IGF-I and anti-IGF-I decreased (P <0.05) the intensity of cells with high mitochondrial membrane potential relative to the control at 10 minutes incubation. After thawing and at 10 minutes incubation, GSH associated or not with IGF-I or anti-IGF-I decreased (P <0.01) the acrosome integrity in relation to the control. When associated, GSH decreased (P <0.05) the osmotic resistance and the percentage of spermatozoa with high mitochondrial activity. Lower values of peroxides and intracellular superoxides were observed (P <0.01) when GSH was associated with IGF-I or anti-IGF-I. At 120 minutes incubation, GSH associated or not reduced (P <0.01) the percentage of spermatozoa with intact acrosome, the intensity of cells with a high superoxide content and the percentage of spermatozoa with high peroxide content. It is concluded that the effects of the addition of GSH to the freezing media of the porcine semen seem to be related to the presence of this hormone in the ejaculate. Greater antioxidant potential of GSH to thawed swine semen can be observed when a blockade of the IGF-I semen system occurs. The addition of IGF-I or its antibody improves the quality of diluted fresh semen and increases the antioxidant potential of both cooled semen and thawed semen.