Effects of perinatal Kepone exposure on sexual differentiation of the rat brain.

Timed-pregnant Sprague-Dawley rats were injected intraperitonealy with Kepone dissolved in sesame oil on alternate days beginning on day 18 of gestation and extending through day 7 of lactation with doses of 10 or 5 mg/kg. At 7 days of age the neurologic development of the pups was assessed using the following tests: day of eye opening, occurrence of auditory startle, righting response, reflex suspension, tactile forelimb-placing response, negative geotaxis, and open-field activity. At 70 days of age, vaginal washes from female offspring were examined microscopically for evidence of cyclic activity. At 120 days of age, animals were sacrificed and the brains were examined histologically and the volume of the medial preoptic nucleus was determined. The results indicated that exposure of rat pups to Kepone via either placental and/or milk transfer can result in an acute, or transient, impairment of neurologic development and a possible permanent neuroendocrine impairment. The permanent neuroendocrine dysfunction may be similar to the androgenization phenomenon (i.e., female pups exposed to sex steroids during development) and thus may be related to the reported estrogenic properties of Kepone.