Immunohistochemical study of Ki‐67 protein, androgen receptor, and estrogen receptor beta in testicular tissues of male pigs immunocastrated with different times of GnRH vaccination

Abstract

This study aimed to investigate the immunoexpression of Ki-67 protein, androgen receptor (AR), and estrogen receptor beta (ERβ) in testicular tissues of male pigs immunocastrated using GnRH vaccine (Improvac™, Zoetis Co., Ltd., Thailand) with different times. Totally, 30 male pigs were classified by castration protocol into three groups: T1 (n = 10) consisted of pigs immunocastrated at 14 and 18 weeks of age, T2 (n = 10) included pigs immunocastrated at 9 and 19 weeks of age, and C (n = 10) contained intact pigs. The results revealed that testicular length of pigs in C was longer than that of both T1 (8.1 ± 0.76 vs 6.5 ± 0.5 cm, p < 0.001) and T2 (8.1 ± 0.76 vs 6.9 ± 1.0, p = 0.007). Spearman correlation coefficients showed negative correlation between testicular length and H-score of AR (r = -0.38, p = 0.037), as well as positive correlation between testicular length and Ki-67 index (r = 0.602, p < 0.001). Generally, mean Ki-67 index and mean H-scores of AR and ERβ of pigs in T1 were not different from those in T2 (p > 0.05). However, mean Ki-67 index and mean AR H-scores of T1 and T2 were significantly different from C group (p < 0.05). In summary, the immunocastration significantly affected testicular length, including expressions of Ki-67, AR, and ERβ in pig testes. Moreover, the duration between two shots of GnRH vaccine could be extended from 4 to 10 weeks without difference in Ki-67 protein, AR, and ERβ immunoexpressions.

Estrogen receptor alpha expression in fattening pig’s testes by the timing of the first injection for immunocastration

“…In this study, immunohistochemical reaction of ERα was detected both in the seminiferous tubules and interstitial areas. Likewise, our earlier study reported that ERβ is also localized both in Leydig cells and seminiferous tubules of the male fattening pigs (Srisuwatanasagul et al, 2018). This was because estrogen is an indispensable hormone for regulating Sertoli cell development and spermatogenesis within the seminiferous tubules (At-Taras et al, 2006), as well as the development of Leydig cells in the interstitial areas (Abney, 1999).…”

“…Apart from histology, certain studies investigating the testicular gross morphology have reported that the testicles of immunocastrated pigs are smaller and lighter than those of the intact pigs (Zamaratskaia et al, 2008;Brunius et al, 2011;Einarsson et al, 2011;Kubale et al, 2013). Moreover, our previous study demonstrated that testicular length, measured between both apexes, of the intact pigs is more than that of the immunocastrated pigs (Srisuwatanasagul et al, 2018). As for the timing of immunocastration, our earlier study confirmed that the first GnRH vaccine administration either at 9 or 15 weeks of age contributes to comparable testicular length and histomorphometric parameters, including the height of spermatogenic epithelia, the diameter of seminiferous tubules, and the number of seminiferous tubules (Srisuwatanasagul et al, 2021).…”