123. THE EFFECT OF PATERNAL DIET INDUCED OBESITY ON SPERM CAPACITATION, ACROSOME REACTION, BINDING AND FERTILISATION IN MOUSE MODEL

Abstract

While the effects of obesity on male fertility are emerging, the direct effects on sperm function are less clear. The aim of this study was to determine the effects of diet-induced obesity on sperm capacitation, acrosome reaction, oocyte binding and fertilisation. C57/Bl6 male mice (n = 12) were randomly allocated to two groups; group 1 received a control diet (6% fat) while group 2 received a high fat diet (HFD, 22% fat) for up to 14 weeks. Mice were sacrificed and spermatozoa obtained. Capacitation and acrosome reaction were measured using Arachis hypogaea (peanut) agglutinin. Sperm binding to oocytes was assessed by co-incubation of sperm with superovulated cumulus-enclosed oocytes for 4 hrs. Fertilisation rates were expressed as the percentage of oocytes with 2 pronuclei from the total number inseminated 6 hrs post insemination. The percentage of non-capacitated sperm in males fed a high fat diet was significantly lower compared to males fed a control diet (12.3% vs 21.1%; P < 0.01). The percentage of acrosome reacted sperm did not differ between the groups. Following 4 hrs of co-incubation with cumulus-enclosed oocytes, the number of sperm bound to each oocyte was significantly lower in the HFD group compared to controls (41.14±2.5 vs 58.39±2.4; P < 0.01). Moreover, the percentage of fertilized oocytes was significantly lower in the HFD group compared to controls (25.9% vs 43.9; P < 0.01). This study demonstrates that males fed a HFD to induce obesity have impaired spermatozoa as evidenced by lower levels of capacitation and reduced ability to bind and fertilise an oocyte. These data therefore provide direct evidence that the metabolic health of the male can have a significant impact on sperm function parameters that are associated with infertility.