Supplementation with specific branched-chain amino acids (BCAAs) affects mouse sperm parameters and testicular apoptotic gene expression

Summary In Western diets, high consumption of meat and dairy products, known to be rich in branched-chain amino acids (BCAAs), including leucine (Leu), isoleucine (Ile), and valine (Val), as well as BCAAs supplementation itself, may have unforeseen consequences on sperm quality. In addition, bodybuilders are increasingly resorting to BCAA supplementation to build-up their muscle mass. This study aimed to assess the effect of dietary BCAAs, provided alone or in combination, on semen parameters, apoptotic gene expression, and blood amino acid (AA) profiles. To address this question and determine whether these different BCAAs have a distinct impact on sperm quality and testicular homeostasis, fifty NMRI mature male mice were exposed or not to BCAAs supplementations (control diet: CTR; CTR + Leu supplementation; CTR + Ile supplementation; CTR + Val supplementation; CTR + all three BCAA supplementation). Only valine supplementation resulted in a significant decrease in sperm concentration and viability. In addition, only valine supplementation was associated with a dramatic increase in sperm immotility. The Bax/Bcl2 ratio, an indicator of apoptosis, was found to be significantly higher in the testes of BCAA-supplemented animals when compared with the other groups. Caspase3 expression was also significantly higher in the testes of BCAA-supplemented and Val-supplemented animals. There were no significant differences in plasma AA profiles between groups. Thus, amongst BCAAs, valine supplementation appears to carry the greatest effect on sperm functional parameters and testicular apoptotic status.