Reduced beta adrenergic responsiveness in rats treated with estrogenic agents

Chronic treatment with ethynyl estradiol alone (48-50 mug/kg/day) and in combination with several doses of norethynodrel either attenuated or prevented the increase in tail skin temperature accompanying sC. administration of isoproterenol (200 mug/kg b.wt.) to male and female rats. Dietary administration of an oral contraceptive containing norethynodrel and mestranol (7.5 mg/kg of food) was also accompanied by an attenuated response to isoproterenol. Attenuation of the tail skin temperature response was present in all groups after 3 to 5 weeks of treatment but was detectable in the oral contraceptive-treated group after 1 week of treatment. All steroids and combinations, except norethynodrel administered alone (154 mug/kg/day), reduced body weight gain.