Effects of the antiestrogens, MER-25 and CI 628, on rat and hamster lordosis
Morin, L.P.; Powers, J.B.; White, M.
Hormones and Behavior 7(3): 283-291
1976
ISSN/ISBN: 0018-506X PMID: 992584 DOI: 10.1016/0018-506x(76)90034-9Document Number: 429690
Anti-oestrogens were used to test the hypothesis that oestrogen exerts a "maintenance" as well as a "priming" effect on rat and hamster sexual receptivity, as it apparently does for guinea pigs. MER-25 (75 or 150 mg/kg) significantly reduced rat lordosis responses when given 2 h before or 8 h after oestradiol benzoate (EB) injection. MER-25 given 34 h after EB (2 hr prior to progestogen) failed to diminish lordosis responses. With hamsters, MER-25 in large doses (750 mg/kg) given either at 2 h before or 34 h after EB reduced lordosis duration to 40% of that of controls, but this effect was confounded by severe illness among the MER-25 injected animals. Lower doses failed to block lordosis behaviour. CI 628 (50 mg/kg) greatly reduced hamster lordosis duration and increased lordosis latency when given 0 h, but not 34 h, after EB. The results are consistent with similar previous work on rats and do not support the concept of oestrogen "maintenance" in either rats or hamsters.
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