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.