Characterization of aromatase in testes and potential functional analysis with letrozole administration in male Chinese soft-shelled turtle (Pelodiscus sinensis)

Abstract Aromatase, encoded by Cyp19a1, is essential in estrogen biosynthesis and crucial in sex differentiation and ovary development. Although aromatase regulates the proliferation, development, maturation and functional maintenance of male germ cells during mammalian spermatogenesis, its role in nonmammalian vertebrates is unclear. In the current study, a polyclonal antibody was prepared and the function of aromatase in testes was determined by administering letrozole. With ELISA detection, the titer of the antibody prepared in this study was more than 1:30000. Western blot analysis showed that the antibody could bind with cyp19a1 specifically. Aromatase was detected in Leydig cells and spermatogonia by immunohistochemistry. Thirty turtles were randomly assigned into three groups and received either letrozole treatment at 0 mg/kg (in control) body weight (BW), 5 mg/kg BW, or 10 mg/kg BW each day for 8 weeks. Histological analysis demonstrated that sperm count decreased in testis after letrozole treatment, and increasing levels of apoptosis were revealed by TUNEL staining. Quantitative real time PCR showed that Esr1, Esr2, and Gper exhibited different expression patterns after letrozole treatment. Dvl2, Cdc20, Dmc1, Sycp3, and Casp3 expression was significantly upregulated with the 10 mg/kg treatment (P