Capacitation-like changes in sex-sorted boar spermatozoa

Sex-sorting process induces several changes in sperm cell functionality which are defined as capacitation-like modifications. The aim of the present study was to evaluate protein tyrosine phosphorylation (TP) status and Chlortetracycline (CTC) staining pattern in boar spermatozoa after sex-sorting procedure and to compare these parameters with those of freshly ejaculated, capacitated and acrosome reacted cells. TP status was evaluated by immunofluorescence and three different patterns were recognized; each of them was considered to be typical of fresh (F), capacitated (C) and acrosome reacted(AR) cells. In sorted spermatozoa the most expressed pattern was F (80.2 ± 6.6% Mean ± SD), while C and AR patterns were 8.5 ± 5.9% and 11.3 ± 5.6%, respectively. These pattern distribution is similar to that observed in freshly ejaculated sperm cells (F 87.5 ± 7.3%; C 9.9 ± 6.1%; AR 2.6 ± 2%). CTC positivity was assayed in that it is considered a sensitive capacitation index. Sex sorted cells presented the following pattern distribution: F 68.4 ± 5.2%; C 26.3 ± 4.3%; AR 5.3 ± 0.9%, which are very similar to the those observed in capacitated spermatozoa (F 67.8 ± 6.1%; C 25.2 ± 2.5%; AR 7 ± 4.3%). These results suggest that sex sorting procedure induces a capacitation-like switch in sperm subpopulations of boar ejaculates, as registered with CTC technique. As for protein TP immunoreactivity, it evidences a fresh-like subpopulation trend, with an increase of AR pattern, probably due to mechanical damage. Further studies would be necessary to better define the pathways involved in sex sortinginduced modifications.