Diestrous treatment with lindane disrupts the female rat reproductive cycle

Regularly cycling, adult female rats were treated during diestrus with 10, 25, 33 or 50 mg/kg lindane or with 2.5 mg/kg picrotoxin. The effects of the treatments on estrous cyclicity and on sexual behavior were examined. Doses of lindane greater than or equal to 25 mg/kg significantly increased the length of the vaginal cycle. Sexual receptivity was reduced by doses greater than or equal to 33 mg/kg, but reduction of sexual receptivity appeared to be secondary to the elongation of the estrous cycle. Most females treated with 50 mg/kg lindane failed to exhibit vaginal proestus during the duration of the experiment (6-8 d following treatment). For the lower doses, vaginal proestrus occurred later than was predicted from the cyclic history but was usually accompanied by sexual receptivity. Although lindane is reported to inhibit the GABAergic system, its reproductive effects were not mimicked by diestrous treatment with picrotoxin.