Abstract
Hypercholesterolemia represents a high risk factor for frequent diseases and it has also been associated with poor semen quality that may lead to male infertility. The aim of this study was to analyze semen and sperm function in diet-induced hypercholesterolemic rabbits. Twelve adult White New Zealand male rabbits were fed ad libitum a control diet or a diet supplemented with 0.05% cholesterol. Rabbits under cholesterol-enriched diet significantly increased total cholesterol level in the serum. Semen examination revealed a significant reduction in semen volume and sperm motility in hypercholesterolemic rabbits (HCR). Sperm cell morphology was seriously affected, displaying primarily a “folded head”-head fold along the major axe-, and the presence of cytoplasmic droplet on sperm flagellum. Cholesterol was particularly increased in acrosomal region when detected by filipin probe. The rise in cholesterol concentration in sperm cells was determined quantitatively by Gas chromatographic-mass spectrometric analyses. We also found a reduction of protein tyrosine phosphorylation in sperm incubated under capacitating conditions from HCR. Interestingly, the addition of Protein Kinase A pathway activators -dibutyryl-cyclic AMP and iso-butylmethylxanthine- to the medium restored sperm capacitation. Finally, it was also reported a significant decrease in the percentage of reacted sperm in the presence of progesterone. In conclusion, our data showed that diet-induced hypercholesterolemia adversely affects semen quality and sperm motility, capacitation and acrosomal reaction in rabbits; probably due to an increase in cellular cholesterol content that alters membrane related events.
Highlights
Cholesterol is a steroid lipid found in the cell membranes and transported in the blood plasma of all animals
Body length was defined as the distance from the tip of the nose to the anus measured in m and body mass index (BMI) [17] correspond to weight in kg/square of the length expressed in m (BMI = body weight (BW)/BL2)
Sperm from hypercholesterolemic rabbits (HCR) showed increased number of morphological alterations compared to NCR
Summary
Cholesterol (chol) is a steroid lipid found in the cell membranes and transported in the blood plasma of all animals. Capacitation is defined as the time-dependent acquisition of fertilization competence [9], ability acquired by the sperm during its transit through the female tract. This process involves a PKAregulated increase in tyrosine phosphorylation (p-Y) of a subset of proteins [4,10,11], and is generally assessed as the ability of the acrosome-intact sperm to undergo AR in response to physiological inducers such as the zona pellucida or progesterone [10,12]
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