Cryopreservation Effect on Expression of Sex Steroid Receptors of Boar Spermatozoa

This study aimed to investigate the expressions of estrogen receptor (ER) alpha, ER beta, and progesterone receptor (PR) during semen cryopreservation, to evaluate the correlation among ER alpha, ER beta, PR, capacitation, acrosome reaction, and semen quality parameters, and to investigate the effect of different concentrations of L-cysteine on the expressions of ER alpha, ER beta, and PR. Semen samples were collected from 12 boars [Duroc (n = 4), Landrace (n=4), and Large white (n=4)]. The controlled rate-freezing method was used to cryopreserve the semen samples. The samples were collected at different times: fresh semen, after adding Modena (TM), after adding extender II (TE2), after adding extender III (TE3), and post-thaw (PT). For extender II and III, the samples were divided into 4 groups: negative control (group 1), 5 (group 2), 10 (group 3), and 15 (group 4) mM/100ml L-cysteine supplementation. Sperm parameters including motility, intact plasma membrane, acrosome integrity, non-capacitated sperm, ER alpha-, ER beta-, and PR-positive spermatozoa were evaluated. Correlations among all parameters were also investigated. Results demonstrated that the acrosome integrity of group 3 was higher than that of group 1 and 4. Moreover, the other parameters of group 3 tended to be higher than those of the other groups. Regarding time during cryopreservation, all parameters in TE2 and TE3 were higher than those in PT. The expression of sex steroid receptors (ER alpha, ER beta, and PR) positively correlated with motility, intact plasma membrane, acrosome integrity, and non-capacitated spermatozoa. In conclusion, cryopreservation and thawing resulted in decreased expressions of ER alpha, ER beta, PR, and sperm qualities. Moreover, L-cysteine supplementation in different concentrations did not affect the expressions of ER alpha, ER beta and PR.