Comparison of MMP‐2 and TIMP‐2 expressions in yak testes at different ages

Abstract

AbstractThis study aimed to investigate the distribution and expression of matrix metalloproteinase‐2 (MMP‐2) and tissue inhibitor of matrix metalloproteinase‐2 (TIMP‐2) in yak testes. The testes of healthy yaks at different ages: newborn [3 days], young [1 year], adult [4 years], and old [9 years] were collected for microscopic analyses using hematoxylin and eosin staining, immunohistochemistry and immunofluorescence, as well as western blot to compare the expression of MMP‐2 and TIMP‐2. Furthermore, the levels of MMP‐2mRNA and TIMP‐2mRNA was detected by real‐time quantitative polymerase chain reaction (qPCR). The results of immunohistochemistry and immunofluorescence demonstrated that MMP‐2 and TIMP‐2 were mainly located in gonocytes of newborn, Sertoli cells of young, spermatozoa of adult and Leydig cells of old. The protein levels of MMP‐2 and TIMP‐2 exhibited a downward from newborn to adult, but increased again in old yaks. The analysis of qPCR showed that MMP‐2 was higher in young compared with newborn or adult(**p < .01), but a lower expression was detected in adult compared with old yak testicular tissues (*p < .05). Compared with adults, TIMP‐2 was significantly higher in newborn and young yaks (**p < .01), and slightly higher in old yaks (*p < .05). Hence, The location of MMP‐2 and TIMP‐2 in gonocytes were associated with the development of newborn yak testes. The expression of MMP‐2 and TIMP‐2 in Sertoli cells at young and adult yaks suggested that they provided a clue for the regulation of spermatogenesis. The positive labeling of MMP‐2 and TIMP‐2 in Leydig cells in old yaks suggested that both may be involved in the interstitial metabolism of the testes during this period. This study revealed the possible role of MMP‐2 and TIMP‐2 in testicular functionality of yaks at different ages.