Isopropanolic extract of black cohosh stimulates osteoprotegerin production by human osteoblasts.
ABSTRACT An isopropanolic extract (iCR) from the rhizomes of Cimicifuga racemosa (black cohosh) is used an alternative in the treatment of menopausal symptoms, and animal studies suggest positive skeletal effects. iCR stimulated osteoblastic OPG protein secretion by 3- to 5-fold as early as 12 h without affecting RANKL expression. The iCR effect, abrogated by the pure estrogen receptor antagonist ICI 182,780, also enhanced ALP activity (4-fold) and osteocalcin expression (3-fold), possibly contributing to the skeletal effects of black cohosh.
Despite its positive effects on the skeleton, estrogen replacement therapy is no longer recommended as first-line therapy for the prevention and treatment of postmenopausal osteoporosis because it increases cardiovascular, thromboembolic, and breast cancer risk. Recently, herbal therapeutics such as an isopropanolic extract (iCR) from the rhizomes of Cimicifuga (=Actaea) racemosa (black cohosh) are gaining interest as an alternative in the treatment of menopausal symptoms. Whereas animal studies in rats suggest positive skeletal effects, the mechanism of its actions on bone cells remain unclear. RANKL is essential for osteoclast formation and activation, while osteoprotegerin (OPG) neutralizes RANKL.
In this study, we assessed the effects of iCR on OPG and RANKL mRNA steady-state levels by semiquantitative RT-PCR and on protein production by an ELISA system in human osteoblasts (hOBs).
Under serum-free conditions, treatment with iCR increased OPG mRNA levels and protein secretion of hOBs by 2- to 3-fold in a dose-dependent manner, with a maximum effect at a 10(6)-fold dilution of iCR (p < 0.001) after 24-48 h. Time-course experiments indicated a stimulatory effect of iCR on osteoblastic OPG protein secretion by 3- to 5-fold (p < 0.001) as early as 12 h, whereas RANKL expression was very low and was not found to be modulated by iCR. Of note, the stimulatory effect of iCR on OPG production was abrogated by the pure estrogen receptor antagonist ICI 182,780. Moreover, iCR enhanced two osteoblastic differentiation markers, bone-specific alkaline phosphatase activity and osteocalcin expression, by up to 4- and 3-fold, respectively (p < 0.001).
Our data suggest that iCR enhances differentiation and increases the OPG-to-RANKL ratio of normal human osteoblasts. These effects may contribute to the positive skeletal effects of black cohosh.
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ABSTRACT: We previously reported that the antiproliferative effect of an isopropanolic-aqueous extract of black cohosh (iCR) on MCF-7 estrogen-responsive breast cancer cell line was due to the induction of apoptosis. Here we address the question to what extent apoptosis induction can be ascribed to one of the two major fractions of iCR, the triterpene glycosides (TTG) or the cinnamic acid esters (CAE). Furthermore, as black cohosh is routinely administered orally, we studied whether its pharmacological effects would withstand simulated liver metabolism. The antiproliferative activity of TTG and CAE as well as of rat liver microsomal S9 fraction-pretreated iCR on MCF-7 cells were investigated by WST-1 assay. The features of cell death induced were tested for apoptosis by flow cytometry (light scatter characteristics, Annexin V binding). Irrespective of S9-pretreatment, 72 h iCR treatment induced a dose-dependent down regulation of cell proliferation with the same IC50 of 55.3 microg/ml dry residue which corresponds to 19.3 microg/ml TTG and 2.7 microg/ml CAE. The degree of apoptotic MCF-7 cells was also comparable. Both, isolated TTG and CAE fractions inhibited cell growth, the IC50 being 59.3 microg/ml and 26.1 microg/ml, respectively. Interestingly, whereas IC50 and apoptosis induction correspond well for the whole extract, TTG and CAE fractions induced apoptosis at concentrations (25 and 5 microg/ml) well below those required for significant growth inhibition. Observation of this study firstly showed that the cell death induced by iCR withstood a metabolic activation system. In addition, TTG and CAE compounds significantly contributed to its apoptotic effect, CAE being the more potent inhibitor of proliferation and apoptosis inducer.Biological & Pharmaceutical Bulletin 01/2005; 27(12):1970-5. · 1.85 Impact Factor
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ABSTRACT: Estrogen deficiency in the postmenopausal woman results in numerous symptomatic and asymptomatic manifestations, including vasomotor symptoms, osteoporosis, heart disease, bladder and vaginal symptoms, and cardiovascular disease. Estrogen replacement therapy is associated with amelioration of these problems but has attendant risks. A newer class of drugs, the selective estrogen receptor modulators, provides both estrogen agonist and antagonist properties, depending on the target tissue. This article discusses the mechanism by which selective estrogen receptor modulators may vary in their end-organ effects and reviews the clinical studies associated with these compounds. Phytoestrogens are widely used in the United States, but little information is available regarding their potential long-term effects.Mayo Clinic Proceedings 07/1999; 74(6):601-7. · 5.79 Impact Factor
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ABSTRACT: Estrogen therapy prevents bone loss in postmenopausal women who take it early in the postmenopausal period. The risk of fracture is highest much later in life, however. We studied whether bone mass in elderly women was affected by earlier estrogen use and how long women needed to take estrogen for it to have a beneficial effect on bone density later in life. In 1988 and 1989, we measured bone mineral density at the femur, spine, shaft of the radius, and ultradistal radius in 670 white women in the Framingham Study cohort (mean age, 76 years; range, 68 to 96). These women had been followed prospectively through menopause and had been asked repeatedly about estrogen therapy. After excluding women who began taking estrogen after a fracture, we investigated whether postmenopausal estrogen therapy affected bone density; in these analyses we adjusted for age, weight, height, cigarette smoking, physical activity, and age at menopause. A total of 212 women (31.6 percent) had received estrogen therapy (mean estimated duration of treatment, 5 years). Only women who had taken estrogen for 7 to 9 years or for 10 or more years had significantly higher bone mineral density than women who had not taken estrogen (7 to 9 years of treatment, P < 0.05 at sites in the femur and the spine; > or = 10 years, P < 0.05 at all sites except the spine). In the women less than 75 years of age who had taken estrogen for seven or more years, the bone density was, averaging all sites, 11.2 percent greater than in women who had never received estrogen. Among women 75 years of age and older in whom the duration of therapy was comparable, bone density was only 3.2 percent higher than in women who had never taken estrogen. For long-term preservation of bone mineral density, women should take estrogen for at least seven years after menopause. Even this duration of therapy may have little residual effect on bone density among women 75 years of age and older, who have the highest risk of fracture.New England Journal of Medicine 10/1993; 329(16):1141-6. · 51.66 Impact Factor