20-OH-ecdysone prevents hot flushes in ovariectomized rats

Hot flushes are due to the lack of estrogens and are the most characteristic climacteric complaints. Hormone replacement therapy was the standard treatment but now its use is limited because of side effects. Need therefore arises to search for non-estrogenic alternatives. The molting hormone 20-beta-hydroxyecdysone (Ecd) is produced by several plants including spinach and has no estrogenic or androgenic properties but enhances GABAergic effects in neurons. Since GABAergic compounds can ameliorate hot flushes, we investigated the effects of Ecd on subcutaneous body temperature of intact and ovariectomized (ovx) rats. The subcutaneous body temperature was recorded at 5-min intervals over a period of 3 hours. Rats were then ovx, and skin temperatures were recorded after an acute intravenous (5 mg) and during subchronic and chronic oral application of Ecd (73 mg/animal/day). For additional control purposes, a group of ovx rats received food containing estradiol-17 β (E2). Skin temperature in individual ovx animals fluctuated largely with peaks (hot flushes) occurring every 20-40 minutes. Following the i.v. treatment with Ecd, skin temperature dropped by more than 1 °C, an effect much larger than in the controls. One and two weeks later, hot flushes were only seen in ovx controls but not in intact, E2-, or Ecd-treated animals. As a consequence, E2 and Ecd intake significantly (p < 0.05) reduced the mean temperature in ovx rats during the various time points of the study. These results suggest that Ecd is efficient to prevent hot flushes in ovx rats.