Effects of black cohosh extract on body weight gain, intra-abdominal fat accumulation, plasma lipids and glucose tolerance in ovariectomized Sprague–Dawley rats

Abstract 

Extracts of the black cohosh (Actaea/Cimicifuga racemosa (CR)) have long been used to treat estrogen deficiency symptoms in women after menopause. Recent data from randomized controlled studies have shown that CR consumption alleviates “hot flushes” and due to the lack of uterotropic effects can be a safe alternative to estrogen replacement therapy. Objective: To evaluate the effects of dietary CR extract consumption on body weight (BW) gain, intra-abdominal fat (IAF) accumulation, plasma leptin, lipids and glucose tolerance in ovariectomized rats and to compare them with the effects of 17β-estradiol. Design: Twenty-seven female Sprague–Dawley rats were ovariectomized and fed soy-free chow with the addition of estradiol-3 benzoate (E2B) (10mg/kg, n=10) or CR BNO 1055 extract (6.67g/kg, n=9). The control group (n=8) received soy-free chow only. Weight and food intake were recorded once a week. After 6 weeks, intra-abdominal fat was measured using computer tomography and the intraperitoneal glucose tolerance test was performed. In the seventh week of the experiment animals were sacrificed, blood was collected for plasma and uteri were removed. Results: Dietary CR BNO 1055 extract had no effects on uterine mass but significantly reduced serum lutenizing hormone (LH) levels (P<0.05). Although, the average weekly food consumption throughout the experiment (calculated in g/kg of BW) did not differ between our studied groups, E2B or CR BNO 1055 treated animals gained less weight and had significantly less IAF accumulation compared to control animals (P<0.05). E2B treatment also decreased plasma total (T-,) high-density lipoprotein (HDL-) and low-density lipoprotein (LDL)-cholesterol (P<0.05). Plasma T-Ch levels in CR BNO 1055 treated animals did not differ from the controls whereas LDL-Ch levels were significantly higher and plasma triglycerides (TG) significantly lower (P<0.05). In the glucose tolerance test, the area under the curve (AUC) was significantly smaller in the E2B treated animals compared to controls (P<0.05). AUC in CR BNO 1055 treated animals did not differ significantly from the controls (P>0.05). Nevertheless, fasting plasma insulin (FPI) levels were significantly lower in E2B and CR BNO 1055 treated animals (P<0.05). Conclusions: In OVX rats, CR BNO 1055 extract consumption decreases enhanced pituitary LH secretion, attenuates body weight gain and IAF accumulation, lowers FPI and has no effects on uterine mass. The effects on plasma lipids seem to be more complex and are characterized by an increase of LDL-Ch and decrease of TG levels which is in contrast to the effects of estrogen.

Keywords: Cimicifuga racemosa, Menopause, Metabolic syndrome, Intra-abdominal fat, Dyslipidemia, Glucose tolerance, Ovariectomized rats