Effects of Estradiol Benzoate, Raloxifen and an Ethanolic Extract of Cimicifuga racemosa in Nonclassical Estrogen Regulated Organs of Ovariectomized Rats

Abstract

The special extract of Cimicifuga racemosa (CR) BNO 1055 was shown to have bone protective effects without exerting estrogenic effects in the uterus or mammary gland. Whether the effects of CR BNO 1055 would be exerted in other organs that also express estrogen receptors (ERs) but in which the effects of estrogens and of the selective estrogen receptor modulator raloxifen (Ral) were not thoroughly studied was therefore investigated in the present contribution. Rats were ovariectomized (ovx) and their food immediately substituted with estradiol benzoate (EB), Ral or 2 doses of CR BNO 1055 for 3 months. Expressions of estrogen receptor alpha (ERα), estrogen receptor beta (ERβ) and of insulin-like growth factor-1 (IGF-1) genes were determined in the vagina, liver, thyroid gland, lung, spleen, colon and kidney by means of quantitative RT-PCRs. Body weights in all treatment groups were significantly reduced and uterine weights in the EB treated animals were largely and in the Ral treated animals slightly but significantly increased. CR BNO 1055 was without effects in the uterus. We tested 3 genes: ERα gene expression was significantly reduced in the vagina, liver and kidney and remained unaffected in all other organs with the exception of the thyroid gland where ERα gene expression was stimulated by EB, Ral had – if any – similar effects in these organs. The CR extract BNO 1055 was devoid of any effect on ERα gene expression. ERβ gene expression was suppressed in the vagina and colon by EB and this effect was shared by Ral in the colon. In the thyroid, EB and Ral stimulated ERβ gene expression. Expression of IGF-1 gene was stimulated by EB and CR BNO 1055 in the vagina and kidney and inhibited by EB and Ral in the liver. No effects were observed by CR BNO 1055 in these organs. The effects of Ral, if occurring, were similar to those of EB while CR BNO 1055 was ineffective in all organs but the vagina. In the colon, reduced ERβ gene activity may augment ERα mediated effects. In all other organs the effects of ER await further investigation. The CR BNO 1055 did not show any activity pattern which would be similar to the pattern observed under EB or Ral. Therefore the observed effects of CR BNO 1055 in these organs are most likely not estrogenic in nature.

Key words

Cimicifuga racemosa - Ranunculaceae - estradiol - ovariectomy - rat - uterus - vagina

References

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