Abstract
Dietary administration of Enovid (7.5 mg/kg of food) to female rats was accompanied by both an immediate reduction in their spontaneous runing activity and an abolition of its cyclic pattern. Escape from the effects of the drug occurred approximately 60 days after treatment began. It was characterized by a return of the cyclic pattern of activity although length of the activity cycle was increased above that observed prior to treatment. Ovariectomy greatly reduced activity level of control rats and abolished its cyclic pattern. Treatment with Enovid appeared to maintain activity of ovariectomized rats at a level considerably higher than that of controls but a cyclic pattern was not observed. Systolic blood pressure, measured at the end of the experiment, and heart, kidney, adrenal and uterine weights were all increased significantly by treatment. In addition, a striking appetite for either 0.15 or 0.25 M NaC1 solution was observed when the treated ovariectomized rats were given choice between either of them and distilled water to drink. These results suggest that administration of Enovid for nearly eight months at the dose used was accompanied not only by changes in spontaneous activity but by the development of hypertension as well. The mechanism of the escape of spontaneous activity from the effect of the drug remains to be elucidated.
Footnotes
- Received November 29, 1971.
- Accepted April 3, 1972.
- © 1972 by The Williams & Wilkins Co.
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