Nicotine induces apoptosis in TM3 mouse Leydig cells

Objective: To investigate whether nicotine-induced testicular toxicity involves the induction of apoptosis in Leydig cells. Design: Cell study using cells of the TM3 cell line derived from mouse Leydig cells. Setting: Academic research laboratory. Intervention(s): Morphological and biochemical analyses for the detection of apoptosis. Main Outcome Measure(s): The effect of nicotine on the occurrence of apoptosis was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay, 4,6-diamidino-2-phenylindole staining, terminal deoxynuclotidyl transferase-mediated dUTP nick end labeling assay, DNA fragmentation assay, reverse transcription-polymerase chain reaction, caspase-3 enzyme assay, and Western blot analysis. Nicotine treatment exhibits several features of apoptosis in mouse Leydig cells. Result(s): TM3 cells treated with nicotine exhibit several features of apoptosis. It was also shown that nicotine increases the mRNA level of bax and decreases that of bcl-2. In addition, nicotine enhanced the expression of the activated form of caspase-3 and caspase-3 enzyme activity. Conclusion(s): Nicotine appears to activate specific intracellular death-related pathways, probably by bax-dependent activation of caspase-3, inducing apoptosis in Leydig cells. Thus, nicotine-induced apoptosis of Leydig cells might be one of the important mechanisms behind nicotine-related urogenital disorders in men.