Objective] This study aimed to investigate the effects of glycidamide （GA） on growth and progesterone biosynthesis of rat R2C Leydig cel s cultured in vitro. [Method] The R2C Leydig cel s were treated with GA with concentrations of 0.25, 0.5, 0.75, 1, 2, 4 and 6 mmol/L respectively for 48 h. The IC25, IC50 and IC75 values of GA were al detected by MTT assay. The Leydig cel s were treated with GA at concentrations of IC25, IC50 and IC75 respectively for 48 h, and then the morphology of Leydig cel s was observed. After the Leydig cel s were treated with GA for 4 h, the cel ular DNA damage was measured by the comet assay technique; and after the Leydig cel s were with treated with GA for 24 h, the progesterone biosynthesis amount was detected by radioimmunoassay （RIA）. [Result] GA could inhibit the via-bility of R2C Leydig cel s, and its IC25, IC50 and IC75 were 0.635, 0.872 and 1.198 mmol/L, respectively. The GA at concentrations of IC25, IC50 and IC75 affected the growth and morphology of rat R2C Leydig cel s in varying degrees. The 4-h treat-ment of GA could significantly damage the DNA of R2C Leydig cel s, and the 24-h treatment of GA at concentrations of IC25, IC50 and IC75 al reduced the progesterone biosynthesis amount. [Conclusion] GA could inhibit the growth and progesterone biosynthesis of rat R2C Leydig cel s.
