Methoxychlor induces apoptosis via mitochondria- and FasL-mediated pathways in adult rat testis

Abstract

In the past few years, there has been much concern about the adverse health effects of environmental contaminants in general and organochlorine in particular. Studies have shown the repro-toxic effects of long-term exposure to methoxychlor, a member of the organochlorine family. However, the insight into the mechanisms of gonadal toxicity induced by methoxychlor is not well known. In the present study we sought to elucidate the mechanism(s) underpinning the gonadal effects within hours of exposure to methoxychlor. Experimental rats were divided into six groups of four each. Animals were orally administered with a single dose of methoxychlor (50 mg/kg body weight) and killed at 0, 3, 6, 12, 24, and 72 h post-treatment. The levels and time-course of induction of apoptosis-related proteins like cytochorome C, caspase 3 and procaspase 9, Fas–FasL and NF-κB were determined to assess sequential induction of apoptosis in the rat testis. DNA damage was assessed by TUNEL assay and flowcytometry. Administration of methoxychlor resulted in a significant increase in the levels of cytosolic cytochrome c and procaspase 9 as early as 6 h following exposure. Time-dependent elevations in the levels of Fas, FasL, pro- and cleaved caspase 3 were observed. The DNA damage was measured and showed time-dependent increase in the TUNEL positive cells, and also by flowcytometry of testicular cells. The study demonstrates induction of testicular apoptosis in adult rats following exposure to a single dose of methoxychlor.