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Alteration of androgen receptor expression, apoptosis and cell proliferation in cryptorchid suckling, nursery and growing-finishing pigs

Yimpring, Nathamon, Teankum, Komkrich, Srisuwatanasagul, Sayamon, Kunnasut, Nanthida, Am-in, Nutthee, Suriyaphol, Gunnaporn
Theriogenology 2019 v.127 pp. 49-55
androgen receptors, apoptosis, cell proliferation, congenital abnormalities, cryptorchidism, genes, immunohistochemistry, piglets, protein synthesis, stem cells, suckling, swine diseases, testes
Cryptorchidism, a condition of one or two undescended testicles, is a common congenital disease in pigs, causing loss in the pig industry. One of the major factors affecting testicular descent is the androgen receptor (AR), which binds to androgen and then regulates the expression of androgen-responsive genes in the inguinoscrotal phase of testicular descent. AR expression has been reported to regulate apoptosis in testicular stem cells. The present study aimed to immunohistochemically examine AR and Ki-67 protein expression and apoptosis detection in unilateral undescended testicles (UDT) and descended testicles in cryptorchid pigs (DT) of suckling (aged 1–2 weeks), nursery (aged 6 weeks) and growing-finishing pigs (aged 12, 15 and 20 weeks) and in normal testicles (NT) at 1–2 and 12 weeks of age. At 1–2 weeks, decreased expression of AR was observed in UDT and DT compared with NT and was lower than that at 6–20 weeks. The expression of Ki-67, a marker of cell proliferation, in UDT and DT at 12 weeks was lower than that in NT at the same age. In addition, Ki-67 expression in UDT at 6 and 12 weeks was lower than that in UDT at 1–2 and 15–20 weeks. More testicular apoptosis was revealed in UDT at 1–2 weeks than in DT and NT at the same age. At 15–20 weeks, more apoptosis was detected in UDT than in DT. Positive correlation of AR expression in DT at 6 and 12 weeks was also noted, in addition to the association of the expression of AR and Ki-67 in NT at 12 weeks. Taken together, this study unveiled the low expression of AR and high apoptosis detection in UDT, whereas low expression of AR and low apoptosis detection were noted in DT in suckling piglets. Diminished cell proliferation was shown in UDT at 6–12 weeks, whereas high apoptosis was observed in UDT at 15–20 weeks. High expression of AR was shown only in nursery pigs. Distinct expression of AR in DT and NT at 1–2 and 12 weeks indicated that both conditions were not interchangeable.