Elsevier

Maturitas

Volume 44, Supplement, 14 March 2003, Pages S31-S38
Maturitas

In vitro effects of the Cimicifuga racemosa extract BNO 1055

https://doi.org/10.1016/S0378-5122(02)00346-8Get rights and content

Abstract

Objectives: Extracts of Black cohosh (Cimicifuga racemosa or CR) have been used for the treatment of climacteric complaints since decades. Efficacy, particularly concerning neurovegetative and psychic symptoms, has been proven in clinical trials. As active principle yet unknown substances with selective estrogen receptor modulator (SERM) activity are assumed. Recently, evidence arose that CR may also contain dopaminergic compounds, which may contribute to the therapeutic activity of the extract. Methods: Two subtypes of the estrogen receptor (ERα and ERβ) are known. To examine, whether active substances of CR extract BNO 1055 (which is contained in Klimadynon® and Menofem®) bind to either of the two estrogen receptors, subtype-specific estrogen receptor ligand-binding assays with recombinant ERα or ERβ were conducted. A ligand-binding assay with recombinant dopamine D2-receptor protein was employed to assess possible dopaminergic activity in the CR extract BNO 1055. Results: While a displacement of radiolabeled estradiol from binding sites of a cytosol preparation from procine and human endometrium by CR extract BNO 1055 was shown no such displacement was achieved when either ERα or ERβ protein was used as ligands for tracer. Dopaminergic activity in the CR extract BNO 1055 could be demonstrated with the D2-receptor assay. A countercurrent chromatography resulted in a separation of estrogenic and dopaminergic activity in two distinct fractions. Conclusions: It is suggested that not yet identified substances in the CR extract BNO 1055 bind to a yet unknown estrogen-binding site in the endometrium. Also, yet unknown dopaminergic compounds may contribute to the pharmacological profile of CR extract BNO 1055.

Introduction

The controversial discussion about adverse effects and increased risks of estrogen/progestin replacement therapy (HRT) and/or estrogen replacement therapy (ERT) has focussed the interest on alternative therapies like phytoestrogens [1]. Estrogen deficiency after menopause causes numerous changes in estrogen receptive tissues like the brain, the bone, the urogenital tract and the cardiovascular system, which affects quality of life and may result in diseases like osteoporosis [2], [3].

As an alternative treatment of climacteric symptoms, owing to estrogen deficiency, CR extracts have been used since decades. Efficacy of CR, particularly concerning neurovegetative and psychic symptoms, has been proven in clinical studies [4], [5], [6] (Wuttke et al., this volume). Hot flushes, the most prominent neurovegetative symptom, are closely linked to the occurrence of LH pulses, owing to estrogen deficiency in menopausal women or after ovariectomy [7]. In both situations, estrogen deficiency causes hyperactivity of neurons, which regulate the pulsatile release of GnRH from the hypothalamus. The GnRH pulses induce the episodic release of LH from the pituitary gland. The neuronal network in the hypothalamus, which causes rhythmic GnRH release, is called GnRH pulse generator [8]. The overactivation of the GnRH pulse generator in climacteric women additionally causes co-activation of other hypothalamic neurons, which regulate body temperature and thereby vasodilatation of skin vessels. This is experienced as hot flushes [9]. Estradiol diminishes the overactivity of the GnRH pulse generator and reduces hot flushes [10].

There is also evidence that hot flushes may be successfully treated with dopaminergic drugs [11]. This correlates with the observation that the activity of the GnRH pulse generator is also modulated by dopaminergic drugs [12]. Besides an effect on hot flushes, dopaminergic drugs reduce body temperature [13]. Recently, it was demonstrated that yet unknown compounds in CR extract reduced the number of hot flush equivalents in ovariectomized rats. This effect was inhibited by the co-administration of the dopamine receptor types 2 and 3 antagonist sulpiride [14]. Therefore, it is assumed that the neurovegetative symptoms in climacteric women are ameliorated by estrogenic compounds contained in CR extract, which may act via dopaminergic mechanisms. In addition, the extracts may contain substances which per se act on dopaminergic receptors.

Prerequisite of an estrogenic action is the binding of the ligand to the estrogen receptor (ER). Currently, two subtypes of the estrogen receptor ERα and ERβ, are known, which are encoded by two distinct genes. These receptors are transcription factors with distinct functional domains involved in DNA- and ligand-binding and transcriptional regulation [15]. While the endogenous ligand 17β-estradiol does not exert preferential binding to either subtype of ER, evidence accumulates that some phytoestrogens may have a higher binding affinity to the ERβ [16].

To examine whether compounds of CR extract BNO 1055 bind to either receptor, ER ligand-binding assays (ER-LBA) were performed with ER preparations obtained from uterine tissue or with human recombinant ERα and ERβ. To investigate whether CR extract BNO 1055 exerts dopaminergic activity, dopamine ligand-binding assays (DA-LBA) with human recombinant D2-receptors were conducted.

Section snippets

Chemicals

The tracers 125I-estradiol and 125I-sulpiride were supplied by NEN (Dreieich, Germany). Recombinant human ERα and ERβ were obtained from Panvera (Madison, USA), and recombinant human D2-receptors were obtained from Biotrend (Cologne, Germany). All other chemicals were purchased from Sigma (Deisenhofen, Germany).

Cimicifuga racemosa extract BNO 1055

The CR extract BNO 1055 was used to determine the binding of its compounds to ERs, in either porcine or uterine human endometrial cytosol or to recombinant human ERα, ERβ or human

Results

In the initial step of the investigations, the binding of compounds of the CR extract BNO 1055 to a cytosolic ER preparation, prepared from porcine uteri, was examined. As shown in Fig. 1, there is a clear competition of the radioactive-labeled estradiol with compounds of the CR extract BNO 1055, which shows that this extract contains phytoestrogens. The porcine cytosol preparation was also used for monitoring of chromatographic separation of the extract (see below).

The available data, which

Discussion

Previous investigations with an ethanolic CR extract in ovariectomized rats revealed an estrogenic effect in the hypothalamo/pituitary unit. A suppression of pituitary LH secretion has been shown. No increase of uterine weight was observed [19]. This effect was attributed to unknown phytoestrogens of the CR extract. In accordance with this assumption are the results of the present in vitro investigations. The displacement of estradiol from binding sites in human endometrium cytosol preparation

Acknowledgements

This work is in part funded by an EU grant ((E)UROESTROGEN(E)ES #QLK-6-CT-2000-00565).

References (31)

  • E. Lehmann-Willenbrock et al.

    Klinische und endokrinologische Untersuchungen zur Therapie ovarieller Ausfallserscheinungen nach Hysterektomie unter Belassung der Adnexe

    Zentralblatt. Gynäkol.

    (1988)
  • I.V. Tataryn et al.

    LH, FSH and skin temperature during the menopausal hot flash

    J. Clin. Endocrinol. Metab.

    (1979)
  • J. Ginsburg et al.

    Cardiovascular responses during the menopausal hot flush

    Br. J. Obstet. Gynaecol.

    (1981)
  • J.M. Kaufman et al.

    Electrophysiological manifestation of luteinizing hormone-releasing hormone pulse generator activity in the rhesus monkey: influence of alpha-adrenergic and dopaminergic blocking agents

    Endocrinology

    (1985)
  • M.R. Zarindast et al.

    Bromocryptine-indiced hypothermia: D-2 receptor involvement

    Arch. Int. Pharmacodyn. Ther.

    (1989)
  • Cited by (102)

    • Treat more than heat—New therapeutic implications of Cimicifuga racemosa through AMPK-dependent metabolic effects

      2022, Phytomedicine
      Citation Excerpt :

      Therefore, the question is of high relevance, as to whether CREs have also estrogenic effects and carry the same risk of tumor induction. In early studies, binding of different CREs or their components to cytosolic estrogen binding site was reported (Düker et al., 1991; Jarry et al., 1985, 2003). In OVX rats, binding of CRE BNO 1055 showed different estrogenic effects in the brain, uterus and bone, and since tissue pharmacological profile could not be explained by an estrogenic action of CRE a selective estrogen receptor modulator (SERM) mechanism of action was postulated (Jarry et al., 1999, 2002; Liu et al., 2001b; Seidlová-Wuttke et al., 2003; Wuttke et al., 2003a, 2000).

    • The non-estrogenic alternative for the treatment of climacteric complaints: Black cohosh (Cimicifuga or Actaea racemosa)

      2014, Journal of Steroid Biochemistry and Molecular Biology
      Citation Excerpt :

      In Germany and in many East European countries CR extracts are medicines sold exclusively in pharmacies whereas in Anglo-American countries such extracts are sold as food supplements. There is ample evidence that extracts of C. racemosa do not contain estrogenic compounds as they bind neither to ERα nor to ERβ (Fig. 1a and b) [18,19]. This does not exclude estrogenic effects which could be exerted via non genomic mechanisms.

    • An ethanolic extract of black cohosh causes hematological changes but not estrogenic effects in female rodents

      2012, Toxicology and Applied Pharmacology
      Citation Excerpt :

      BCE appears to reduce luteinizing hormone secretion in ovariectomized rats but not in perimenopausal women (Chung et al., 2007; Jacobson et al., 2001; Jarry and Harnischfeger, 1985; Nappi et al., 2005; Rachon et al., 2008; Reame et al., 2008; Seidlova-Wuttke et al., 2003); demonstrations of estrogenic/anti-estrogenic activity of black cohosh are inconclusive (Jarry and Harnischfeger, 1985; Jarry et al., 2003). However, neurotransmitter activities that can modify activity of the hypothalamic-pituitary-gonadal (HPG) axis at the CNS level (reviewed by Rivier and Rivest, 1991), including dopaminergic, serotonergic, and opioid activity, have been observed in vitro (Jarry et al., 2003; Powell et al., 2008; Rhyu et al., 2006). Given the scientific literature to date, NTP designed studies focused on subchronic toxicity of BCE with special emphasis on possible toxic effects in the liver and reproductive systems.

    • Black cohosh (Cimicifuga racemosa) relaxes the isolated rat thoracic aorta through endothelium-dependent and -independent mechanisms

      2011, Journal of Ethnopharmacology
      Citation Excerpt :

      Although the estrogenic effects of black cohosh are still controversial, numerous studies have investigated this plant; these studies include phytochemical studies, bioassay, and clinical trials (Jacobson et al., 2001). Recently, the effect of black cohosh in menopause-related symptoms has been presumed to involve the central nervous system (CNS) through CNS receptors such as dopamine, serotonin, and human opiate receptors (Burdette et al., 2003; Jarry et al., 2003; Rhyu et al., 2006). It is well known that there are significant correlations between estrogen-deficient symptoms and the CNS as well as a tight connection between sex hormones and CNS receptors (Stomati et al., 1999; Weiss et al., 2004).

    View all citing articles on Scopus
    View full text