LINDANE DOES NOT ALTER THE ESTROGEN-RECEPTOR OR THE ESTROGEN-DEPENDENT INDUCTION OF PROGESTERONE RECEPTORS IN SEXUALLY IMMATURE OR OVARIECTOMIZED ADULT-RATS

Lindane, gamma-1,2,3,4,5,6-hexachlorocyclohexane (gamma-HCH), has been shown to disrupt reproductive function in mammals. Many of these adve rse effects on female reproduction such as alterations in sexual recep tivity, disrupted ovarian cyclicity, reduction in uterine weight and t ermination of pregnancy are thought to be due to altered ovarian hormo ne secretions and/or an impaired response to circulating. estrogen. It has been suggested that gamma-HCH may block the response of estrogen- dependent tissues to estradiol via an interaction with the estrogen re ceptor. To test this hypothesis, estrogen (ER) and progesterone (PR) r eceptor affinity and number were evaluated in sexually immature, 17 be ta-estradiol-3-benzoate (EB)-primed Long Evans female rats following e xposure to vehicle or gamma-HCH (40 mg/kg) for 7 days (Study 1) and in adult, ovariectomized EB-primed Long-Evans rats following gavage with vehicle or gamma-HCH (0, 10, 20, or 40 mg/kg) for 5 days (Study 2). C hlordecone (kepone 40 mg/kg; i.p.) was used in Study 2 as a positive c ontrol for the alteration of the estrogen-induction of PR in the pitui tary. Neither gamma-HCH nor chlordecone altered serum estradiol concen trations. gamma-HCH did not change the ER number (1, 24, or 30 h after EB) or the estrogen-dependent induction of PR (24 or 48 h after EB) i n the hypothalamus (HYP), pituitary, or uterus. These data indicate th at the effects of gamma-HCH on the female reproductive system do not i nvolve an alteration in the ER and that heterogeneity exists between t arget tissues in their response to xenobiotics.