Estrogenic effects of an antiestrogen, MER-25, on eating and body weight in rats
Roy, E.J.; Uade, G.N.
Journal of Comparative and Physiological Psychology 90(2): 156-166
1976
ISSN/ISBN: 0021-9940 PMID: 942584 DOI: 10.1037/h0077203Document Number: 428912
Effects of ethamoxytriphetol (MER-25) and oestradiol benzoate (EB) on eating and regulation of bodyweight in rats and the ability of MER-25 to antagonise the actions of EB were investigated in 5 trials with 162 ovariectomized and 8 castrated rats. MER-25 produced a transient depression of food intake, more pronounced in females than in males, and a permanent reduction in bodyweight. Effects of MER-25 and EB were reversed by progesterone, especially in recently ovariectomized rats, but were not due to production of a general malaise or to subclinical toxicity, since a high dose, 10 times the amount required to induce a reduction in food intake and bodyweight gain, failed to induce an aversion to the novel flavour of saccharin, although this could be achieved by injection with lithium chloride in a paired response test. Similar effects are caused by EB, which produces similar reductions in food intake (for up to 30 days) accompanied by a reduction in bodyweight. Results suggest that MER-25 exerts its effects as an oestrogen on food intake and growth, while other oestrogen-induced effects involving sexual behaviour after treatment with EB showed inhibition by MER-25 with little or no oestrogenic effect due to MER-25 alone. It is concluded that systems mediating the effects of oestrogens on bodyweight and eating behaviour differ biochemically from other oestrogen-sensitive systems involving sexual behaviour.