Abstract
Summary
Rats with DMBA-induced mammary tumors were given an implant of EB or cholesterol in the ME, or an implant of EB in the cerebral cortex or under the skin. At 25-28 days after implantation, serum prolactin levels in rats with an EB implant in the ME were significantly higher than in the other groups. There were no significant differences among groups in pituitary prolactin concentration, but pituitary prolactin content in rats with an EB implant in the ME was significantly higher than in the other groups. Whereas an implant of EB in the ME resulted in continuous diestrus within a few days, the same dose of EB implanted elsewhere did not disrupt regular estrous cycles. These results indicate that an estrogen implant in the ME can promote pituitary prolactin secretion by direct stimulation of the hypothalamus, pituitary, or both.
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