Effect of amino acids and dipeptides on the acrosome reaction and accumulation of ammonia in porcine spermatozoa.

Aim :  The present study was designed to investigate the effect of amino acids and their dipeptides in the medium related to the urea cycle on the motility, viability, acrosome reaction (AR) and accumulation of ammonia in the medium over different incubation periods in porcine spermatozoa and to assess the utilization of glucose. Methods :  Porcine spermatozoa were washed, swim-up and incubated at 37°C for 0-4 h in mTALP medium supplemented with 75-600 µmol/L ammonia. Amino acids (1.0 mmol) or their dipeptides (2.0 mmol) were added individually to the mTALP medium containing either no ammonia or 300 µmol/L of ammonia. The viability and AR of porcine spermatozoa were assessed using the triple-staining technique and the accumulation of ammonia in the medium was measured using the indophenol method. Results :  The motility, viability and AR were adversely affected ( P  < 0.05) by concentrations of ammonia ≥300 µmol/L compared with the control. Supplementation of l-alanyl-l-glutamine (AlaGln), l-glycyl-l-glutamine (GlyGln) and AlaGln + GlyGln in the presence of 300 µmol/L ammonia significantly increase ( P  < 0.05) the rate of motility, viability, AR, incorporation, accumulation of ammonia and oxidation of ¹⁴ C(U)-glucose compared with the ammonia supplement control. Conclusion :  AlaGln and GlyGln in mTALP medium were more stable and effective than the individual amino acids in reducing the accumulation of ammonia, and subsequently increasing the rate of AR and the utilization of glucose in porcine spermatozoa. (Reprod Med Biol 2008; 7 : 123-131).