Antioxidants prevent gamma-hexachlorocyclohexane-induced inhibition of ratmyometrial gap junctions and contractions

Lindane (gamma -hexachlorocyclohexane) is a commonly used pesticide that bi oaccumulates in mammalian adipose tissue. Lindane inhibits gap junctional i ntercellular communication and oscillatory contractions of pregnant rat myo metrium in vitro. The present study investigated the role of oxidative stre ss in lindane's inhibition of myometrial function in mid-gestation pregnant rat uteri. Lucifer yellow dye was microinjected into cultured myocytes to assess gap junctional intercellular communication. Lindane exposure (100 mu M) resulted in a time-dependent, biphasic inhibition of dye transfer. This pattern of inhibition was also seen upon cell exposure to the pro-oxidant, tert-butyl hydroperoxide (100 muM). Lindane's initial and secondary-onset d ye transfer inhibitions were reversed by cotreatment and pretreatment with the antioxidants, alpha -tocopherol (25-100 muM), diphenyl-1,4-phenylene di amine (10-30 muM), and superoxide dismutase (100-400 U/ml). D-mannitol (100 -300 mM) also reversed lindane's initial dye transfer inhibition. Nitro blu e tetrazolium reduction to formazan (measured spectrophotometrically) was e levated upon exposure of cultured cells to lindane or tert-butyl hydroperox ide, indicating the presence of reducing agents. Lipid peroxidation, assess ed as thiobarbituric acid-reactive substances, was also elevated in lindane -exposed cell cultures. alpha -Tocopherol reversed this elevation. Finally, uterine contractility was assessed by measuring isometric contractions of uterine strips hung in standard muscle baths. Pretreatment with or-tocopher ol prevented lindane's abolishment of uterine contractions in vitro. These data support the hypothesis that lindane inhibits uterine contractility and myometrial gap junctions by establishing an oxidative stress environment.