Effects of black cohosh and estrogen on the hypothalamic nuclei of ovariectomized rats at different temperatures

Transfer of preclinical study data on the influence of cimicifuga racemosaon functional changes in the hippocampus during menopause

Menopausal transition in women involves complex neurobiochemical changes linked to ovarian dysfunction, resulting in symptoms like vasomotor symptoms (VMS), sleep disturbances, anxiety, and cognitive impairments. Hormone replacement therapy is the first-line treatment. However, many women are reluctant to use HRT or have contraindications toward HRT and seek for alternatives. Non-hormonal therapies with extracts of Cimicifuga racemosa rhizomes like the isopropanolic extract (iCR, black cohosh) offer a promising alternative. A preclinical pilot study exploring iCR's effects on gene expression in the hippocampus and hypothalamus of ovarectomized (OVX) rats mimicking menopausal conditions identified important signaling pathways and CNS-based contributions to the multitargeted modes of action of iCR. Especially in the hippocampus, iCR compensated effects of OVX on gene expression profiles. These changes are reflected by the genes AVPR1A, GAL, CALCA, HCRT, PNOC, ESR1, ESR2 and TAC3 contributing to the formation of hot flushes or thermoregulation as well as to secondary effects such as blood pressure, metabolism, hormonal regulation, homeostasis, mood regulation, neuroendocrine modulation, regulation of sleep and arousal, and in learning, memory and cognition. To understand the mechanisms in the brain of estrogen-depressed animals (OVX) and subsequent iCR treatment we combined the results of the pilot study with those of up-to-date literature and tried to transfer the current knowledge to humans during menopausal transition and adaptation. Focus was laid on changes in the hippocampal function, that is disturbed by hormonal fluctuations, but can also be brought back into balance by iCR.

The influence of Black Cohosh on hippocampal and hypothalamic gene expression profiles in ovariectomized rats and its potential to treat menopausal decrease in smell discrimination

PURPOSE

Menopause is associated with a decrease in smell discrimination ability. This study assessed the impact of black cohosh on hippocampal (HC) and hypothalamic (HT) gene expression profiles in rats, to understand, if herbal treatment has an impact on neurologic changes due to menopause and whether this could address a decrease in smell discrimination.

METHODS

HC and HT tissues from female Sprague Dawley rats (total n = 19) were analyzed at three different life stages: intact tissues of the HC (n = 4) and the HT (n = 4), oophorectomized tissues 3 months after oophorectomy (OVX) of the HC (n = 4) and the HT (n = 3), and tissues after treatment with an isopropanolic extract (iCR) from the rhizomes of black cohosh (60 mg/kg) for 3 months after OVX of the HC (n = 2) and the HT (n = 2).

MAIN OUTCOME MEASURES

To reveal underlying biological processes a gene set enrichment analysis (GSEA) was performed.

RESULTS

The GSEA revealed gene ontology terms that were significantly enriched, including several genes associated with the olfactory system, indicating biological processes regulated by treatment with iCR. Six olfactory receptor genes were further analyzed by another GSEA, demonstrating the possibility of iCR treatment to compensate for oophorectomy-induced changes.

CONCLUSION

Findings suggest that herbal treatment, such as iCR, has an esteeming impact on HC and HT genes that are changed through menopause. Further studies are needed to suggest black cohosh as a treatment option for decreased smell discrimination.

Neural substrates underlying rhythmic coupling of female reproductive and thermoregulatory circuits

Coordinated fluctuations in female reproductive physiology and thermoregulatory output have been reported for over a century. These changes occur rhythmically at the hourly (ultradian), daily (circadian), and multi-day (ovulatory) timescales, are critical for reproductive function, and have led to the use of temperature patterns as a proxy for female reproductive state. The mechanisms underlying coupling between reproductive and thermoregulatory systems are not fully established, hindering the expansion of inferences that body temperature can provide about female reproductive status. At present, numerous digital tools rely on temperature to infer the timing of ovulation and additional applications (e.g., monitoring ovulatory irregularities and progression of puberty, pregnancy, and menopause are developed based on the assumption that reproductive-thermoregulatory coupling occurs across timescales and life stages. However, without clear understanding of the mechanisms and degree of coupling among the neural substrates regulating temperature and the reproductive axis, whether such approaches will bear fruit in particular domains is uncertain. In this overview, we present evidence supporting broad coupling among the central circuits governing reproduction, thermoregulation, and broader systemic physiology, focusing on timing at ultradian frequencies. Future work characterizing the dynamics of reproductive-thermoregulatory coupling across the lifespan, and of conditions that may decouple these circuits (e.g., circadian disruption, metabolic disease) and compromise female reproductive health, will aid in the development of strategies for early detection of reproductive irregularities and monitoring the efficacy of fertility treatments.

Black cohosh efficacy and safety for menopausal symptoms. The Spanish Menopause Society statement

OBJECTIVE

The increasing interest in Western countries regarding phytotherapy use to treat menopause-related symptoms has led the Spanish Menopause Society (AEEM) to update its position statement performed in 2009 on the role of black cohosh (Cimicifuga racemosa) for the treatment of menopausal symptoms.

MATERIAL AND METHODS

A panel of experts from both clinical and research backgrounds were assembled to investigate the best available evidence. Selected studies were obtained by an electronic search, including the Internet search engines MEDLINE-Pubmed (1997-December 2021) and the Cochrane Controlled Trials Register.

RESULTS

Most of the well-designed studies published in recent years have been conducted with the isopropanolic extract of black cohosh/C. racemosa. The most common dose is 40 mg/day capable of achieving a significant reduction in hot flushes (particularly in women with intense hot flushes) and an improvement in mood. Used at the recommended doses, C. racemose produces no significant adverse reactions.

CONCLUSION

Black cohosh is an effective and safe treatment option for the relieving of vasomotor symptoms. Finally, further clinical trials with sufficient patient enrollment and longer study follow-up are needed.

Benefits of Black Cohosh (Cimicifuga racemosa) for Women Health: An Up-Close and In-Depth Review

Women’s health is an imminent concern worldwide, but it remains an ignored segment of research in most developing countries, and is yet to take the center stage in even developed nations. Some exclusive female health concerns revolve around both pathological and physiological aspects. These gender-specific maladies include breast, cervical, and ovarian cancers, and physiological concerns such as menopause and osteoporosis, which are often coexistent. Recently, women’s health issues, including postmenopausal syndrome, have attracted the attention of researchers and practitioners alike, opening newer pharmaceutical research and clinical avenues. Although not counted as a disease, postmenopausal syndrome (PMS) is a female health phenomenon underpinned by hormonal depletion. Enhanced life expectancy in women has added to their suffering, and pharmacological interventions are needed. Amongst the available treatment modalities, the use of numerous botanicals has emerged as an efficient health management tool for women. Cimicifuga racemosa (CR or Black Cohosh) is a plant/herb which has been traditionally exploited and extensively used by women. This review is an attempt to compile and provide a summary of the importance of CR in complementary and alternative therapies for the improvement of various disorders related to women, such as menopausal syndrome, mammary cancer, and osteoporosis. It aims to systematically highlight the bioactive constituents, pharmacology, pharmacokinetics, therapeutic potentials, quality control processes, chromatographic techniques, and possible mechanisms of action of clinically effective phytomedicine for women’s health. Various clinical trials and patents relating to CR and women’s health have been collated. Furthermore, the plant and its related products have been considered from a regulatory perspective to reveal its commercial feasibility. The present review summarizes the existing data on CR focusing on women’s health, which can help to introduce this traditional phytomedicine to the world and provide some reference for future drug development.

Gene expression analyses on multi-target mode of action of black cohosh in menopausal complaints - a pilot study in rodents

PURPOSE

This study aimed at assessing gene expression profiles in hippocampus and hypothalamus of ovariectomized (OVX) rats with or without treatment with an isopropanolic extract of Cimicifuga racemosa rhizomes (iCR) in comparison to intact rats.

METHODS

Exploration of hippocampal (Hi) and hypothalamic (Hy) tissue from Sprague Dawley rats: without OVX (NHi = NHy = 4), tissues 3 months after OVX (NHi = 4, NHy = 3), or tissues of rats after their treatment with iCR for 3 months after OVX (NHi = NHy = 2). Gene expression profiles in these tissues were investigated by RNA-microarray-analysis and subsequent verification by qPCR.

RESULTS

4812 genes were differentially regulated when comparing the three groups in hippocampus and hypothalamus. iCR compensated the effects of OVX in 518 genes. This compensatory effect was most prominent in hippocampal signalling pathways, thereof genes (GAL, CALCA, HCRT, AVPR1A, PNOC, etc.) involved in thermoregulation, regulation of sleep and arousal, blood pressure regulation, metabolism, nociception, hormonal regulation, homeostasis, learning and cognition, mood regulation, neuroendocrine modulation, etc.. In the hypothalamus, iCR compensated OVX-effects at TAC3 and OPRM1 but not at KISS1. These genes are involved in the pathophysiology of hot flashes.

CONCLUSIONS

Our pilot study findings support a multifaceted mode of action of iCR in menopausal complaints on a tissue-specific brain gene expression level.

Cimicifuga racemosa isopropanolic extract for menopausal symptoms: an observational prospective case-control study

OBJECTIVE

We aimed to investigate the effectiveness of isopropanolic extract of Cimicifuga Racemosa (iCR) on reducing menopausal symptoms.

MATERIALS AND METHODS

A single-center observational prospective case-control study was performed to assess the improvement of menopausal symptoms in menopausal women undergone iCR administration (cases) or no treatment (controls). Menopausal symptoms were assessed through a modified version of the Menopause Rating Scale questionnaire (mMRS) at T₀ (baseline), T₁ (1-month follow-up), and T₂ (3 months follow-up). Univariate comparisons between cases and controls were performed by using the unpaired T test for two-tailed P value with α = 0.05 significance level.

RESULTS

A total of 163 women (83 cases and 80 controls) were enrolled in the study. The difference in menopausal symptoms between cases and controls from T₀ to T₂, and from T₀ to T₁, was found significant for all analyses. In particular, the difference in all menopausal symptoms was 20.56 ± 0.90 points (95%CI: 18.77-22.33, p < .001) from T₀ to T₂, and 10.69 ± 0.6 (95%CI: 9.49-11.88, p < .001) from T₀ to T₁.

CONCLUSION

iCR may be effective in reducing menopausal symptoms, both after 1 month and after 3 months of treatment. The improvement was higher in vasomotor symptoms, sleep problems, and irritability.

Changes in skin temperature of ovariectomized rats under different incubation temperatures

AIM

This study aimed to investigate changes in skin temperature in the main body regions of ovariectomized rats under different incubation temperatures to identify regions that are similar to hot flashes experienced by menopausal women.

METHODS

A total of 96 adult female Sprague-Dawley rats were randomly divided into sham, ovariectomized and ovariectomized with estrogen treatment groups, with treatment lasting for 4 weeks. After 3 weeks of treatment, each group was randomly divided into five subgroups and placed in separate incubators set at 4, 15, 25, and 37°C. Changes in the skin temperature in seven main regions (head, neck, chest, abdomen, back, tail, and paws) for four time intervals (0-3 min, 3-5 min, 5-10 min and 10-15 min) were monitored using infrared thermography.

RESULTS

All rats showed rapid changes in skin temperature followed by a gradual slowdown under different incubation temperatures. However, changes in ovariectomized rats were significantly different from that in normal rats, and changes on the back, tail and paws were more rapid and lasted longer. Estrogen treatment effectively controlled these abnormalities of ovariectomized rats.

CONCLUSIONS

Temperature responses in the back, tail and paws in ovariectomized rats might be similar to the face, neck and upper chest in menopausal women, where the symptoms of hot flashes are most obvious, which suggests that the back, tail and paws could be regarded as the focus of research on hot flashes, and offer theoretical foundations for mechanisms behind the occurrence of hot flashes in specific regions. Geriatr Gerontol Int 2020; ••: ••-••.

The Effects and Action Mechanisms of Phytoestrogens on Vasomotor Symptoms During Menopausal Transition: Thermoregulatory Mechanism

Background:

Phytoestrogens have recently been claimed to positively influence menopausal discomforts, including hot flashes. However, little is known about the influence of phytoestrogens on core body temperature during oestrogen fluctuation at menopause.

Objective:

Previously published findings showed that phytoestrogens could relieve menopausal complaints, thus, the present review was aimed at assessing the effects of phytoestrogens on thermoregulatory mechanism during menopausal transition.

Results:

The molecular mechanisms underlying hot flashes are complex. Oestrogen fluctuations cause hypothalamic thermoregulatory centre dysfunction, which leads to hot flashes during menopause. The phytoestrogens of interest, in relation to human health, include isoflavones, lignans, coumestans, and stilbenes, which are widely distributed in nature. The phytoestrogens are capable of reducing hot flashes via their oestrogen-like hormone actions. The potential effects of phytoestrogens on hot flashes and their molecular mechanisms of action on thermoregulatory centre are discussed in this review.

Conclusion:

The effects of phytoestrogens on these mechanisms may help explain their beneficial effects in alleviating hot flashes and other menopausal discomforts.

Effects of black cohosh and estrogen on core body and tail-skin temperatures in ovariectomized rats by telemetric monitoring with dual thermistor probes

OBJECTIVES

To investigate the effects of black cohosh and estrogen on the temperature in ovariectomized rats, the core body temperature (CBT) and tail-skin temperature (TST) were simultaneously monitored and the relationship between these two temperatures was explored.

METHODS

Twenty-four female Sprague-Dawley rats aged 8 weeks were randomly divided into four groups: sham-operated (SHAM), ovariectomized (OVX), OVX treated with estradiol valerate (OVX + E), and OVX treated with isopropanolic black cohosh extract (OVX + ICR). Rats were sham-operated or ovariectomized and were implanted with telemetry transmitters with dual thermistor probes. Two weeks after surgery, the animals were treated with drugs for 4 weeks. During the last week of the treatments, the dynamic temperature profiles of the CBT and TST were collected.

RESULTS

The average CBT and TST, TST fluctuation frequency, and the average amplitude fluctuation were significantly higher in OVX than in SHAM rats. In addition, dramatic fluctuations of TST in OVX rats occurred at the time points of the day when the CBTs were lower in OVX rats than in SHAM rats. Treatment of OVX rats with estradiol valerate or isopropanolic black cohosh extract markedly decreased the average CBT and TST, TST fluctuation frequency, and the average amplitude fluctuation. Moreover, CBT was found to be significantly higher, while TST was lower in OVX + E than in OVX + ICR rats.

CONCLUSIONS

Both black cohosh and estradiol treatments ameliorated the abnormal thermoregulation in OVX rats. In particular, black cohosh reduced CBT better than estradiol and estradiol reduced TST better than black cohosh.

Traditional uses, phytochemistry, pharmacology and toxicology of the genus Cimicifuga: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Plants of the genus Cimicifuga have long been used as an ethnomedicine in China, Europe, and North America for its high medicinal value and health benefits. Their dried rhizomes are widely used for treating wind-heat headache, toothache, aphtha, sore throat, measles, spot poison, archoptosis, and uterine prolapse. In addition, it is used as a dietary supplement for preventing women menopausal symptoms and osteoporosis.

AIM OF THE REVIEW

This paper aims to provide up-to-date information on the genus Cimicifuga, including botanical characterization, medicinal resources, traditional medicinal uses, phytochemistry, quality control, pharmacological research as well as the toxicology. The possible structural-activity relationships and molecular mechanisms of the bioactive constituents are discussed in ways that contribute to the structural optimization and preclinical safety assessment for further drug design.

MATERIALS AND METHODS

The relevant information on Cimicifuga was collected from scientific databases (such as Google Scholar, PubMed, SciFinder Scholar, Science Direct, CNKI, Baidu Scholar, Web of Science, China Knowledge Resource Integrated Database), Chinese herbal classics, ethnobotanical books, PhD and MSc dissertations, Chinese Pharmacopoeia, published articles in peer-reviewed journals, local magazines, and unpublished materials. In addition, the Plant List (TPL, www.theplantlist.org) was also used to validate the scientific names and synonyms of this plant. The literature cited in this review dated from 1953 to 2017.

RESULTS

The majority of chemical constituents of this plant include triterpenoid glycosides, phenylpropanoids, nitrogenous compounds, chromones, flavonoids and 4α-methyl steroid. Among them, the primary bioactive constituents are believed to be present in the triterpene glycoside fraction. To date, investigation of seven Cimicifuga spp. plants led to the identification of more than 457 compounds. Years of pharmacological research proved that the crude extracts and certain pure compounds obtained from Cimicifuga exhibited menopausal syndrome-treatment, anti-osteoporosis, antiviral, antitumor, antioxidant and antiangiogenic activities. On the other hand, Cimicifuga plant-induced toxicities of liver, cardiovascular, central and peripheral nervous systems have also been reported. Therefore, safety consideration should be placed into a high priority for herbal medicine Cimicifuga therapy in the early stages of development and clinical trials.

CONCLUSIONS

This review presents information on botany, medicinal resources, and traditional medicinal history of some Cimicifuga plants. Modern pharmacology researchers have validated many traditional uses of Cimicifuga species. As the quality control and safety assessment of Cimicifuga plants is still incomplete, only a small part of the plant is permitted to be used as medicines. Expansion of medicinal resources in Cimicifuga is urgently needed to enable its full use. Currently research primarily focuses on the triterpenoid glycosides but there are many other types of compounds which may possess new biological activities however the systematic studies of these compounds are lacking. Extensive study is required on Cimicifuga plant before it can be fully used in clinics as a potent drug candidate.

Mechanisms underlying alterations in norepinephrine levels in the locus coeruleus of ovariectomized rats: Modulation by estradiol valerate and black cohosh

Hot flushes are common in menopause. Norepinephrine (NE), primarily synthesized in the locus coeruleus (LC), plays a major role in central thermoregulation. Furthermore, we previously observed decreased dopamine beta hydroxylase (DβH), a key enzyme in NE synthesis, in LC neurons following ovariectomy. In this study, we explore the mechanisms underlying decreased NE levels in the LC (LC-NE) in ovariectomized (OVX) rats, and the modulating effects of estradiol valerate (E2) and black cohosh (ICR). We used high-performance liquid chromatography to detect LC-NE in SHAM, OVX, OVX-E2, and OVX-ICR groups. Western blotting and immunohistochemistry were performed to investigate the expression of NE metabolic enzymes, the NE reuptake transporter (NET), and estrogen receptors (ERs) in the LC. We observed significant LC-NE decreases in the OVX group. E2 and ICR enhanced LC-NE but did not restore them to SHAM levels. Ovariectomy affected NE synthesis, degradation, and reuptake. Levels of NE catabolic enzymes monoamine oxidase A (MAOA) and catechol-O-methyltransferase (COMT) decreased, while NET expression increased. E2 restored MAOA and COMT to SHAM levels but had no effect on NET. ICR restored COMT and NET to SHAM levels but had no effect on MAOA. Moreover, the OVX group also exhibited decreased expression of ERα and ERβ. E2 enhanced the expression of ERα and ERβ, while ICR only enhanced ERβexpression. Taken together, reduced NE in OVX rats resulted from reduced synthesis and increased degradation and reuptake. E2 and ICR may regulate these processes in different ways through various ERs.

60 years of Cimicifuga racemosa medicinal products : Clinical research milestones, current study findings and current development

Cimicifuga racemosa (CR) extracts are important worldwide as therapy for menopausal symptoms. The first medicinal product from CR has been available since 1956 (Germany, Remifemin® [Schaper & Brümmer, Salzgitter, Germany], isopropanolic extract iCR). This review describes how CR developed, via clinical studies on safety (breast, breast cancer, endometrium, liver) and efficacy, into a successful and safe medicinal product in Germany, Europe and the world. In line with developing legal frameworks for medicinal products in Germany and Europe, clinical studies on CR were observational during the 50s and 70s, and controlled studies since the 80s. The first placebo-controlled study emerged 1986. From 2000 to 2015, a total of 28 clinical studies in Europe, America and Asia were published on the efficacy of CR. In these studies, 11,073 patients received a CR-based medicinal product, 93% thereof iCR. A meta-analysis of all nine placebo-controlled studies published until 2013 confirmed the reliable efficacy of CR-based medicinal products for menopausal symptoms.

Estradiol Valerate and Remifemin ameliorate ovariectomy-induced decrease in a serotonin dorsal raphe-preoptic hypothalamus pathway in rats

Perimenopausal syndromes begin as ovarian function ceases and the most common symptoms are hot flushes. Data indicate that the projections of serotonin to hypothalamus may be involved in the mechanism of hot flushes. Therefore, the aim of this study is to investigate the potential role of the serotonin dorsal raphe-preoptic hypothalamus pathway for hot flushes in an animal model of menopause. We determined the changes in serotonin expression in the dorsal raphe (DR) and preoptic anterior hypothalamus (POAH) in ovariectomized rats. We also explored the therapeutical effects of estradiol valerate and Remifemin in this model. Eighty female Sprague-Dawley rats were randomly assigned to sham-operated (SHAM) group, ovariectomy (OVX) group with vehicle, ovariectomy with estradiol valerate treatment (OVX+E) group and ovariectomy with Remifemin (OVX+ICR) group. Serotonin expression was evaluated in the DR and POAH using immunofluorescence and quantified in the DR using an enzyme-linked immunosorbent assay (ELISA). Apoptosis was analyzed in the DR by TUNEL assay. The number of serotonin immunoreactive neurons and the level of serotonin expression in the DR decreased significantly following OVX compared to the SHAM group. No TUNEL-positive cells were detected in the DR in any group. In addition, following OVX, the number of serotonin-positive fibers decreased significantly in the ventromedial preoptic nucleus (VMPO), especially in the ventrolateral preoptic nucleus (VLPO). Treatment with either estradiol or Remifemin for 4 weeks countered the OVX-induced decreases in serotonin levels in both the DR and the hypothalamus, with levels in the treated rats similar to those in the SHAM group. A fluorescently labeled retrograde tracer was injected into the VLPO at the 4-week time point. A significantly lower percentage of serotonin with CTB double-labeled neurons in CTB-labeled neurons was demonstrated after ovariectomy, and both estradiol and Remifemin countered this OVX-induced decrease. We conclude that serotonin pathway is changed after ovariectomy, including the serotonin synthesis in DR and serotonin fibers in PO/AH, both E and Remifemin have an equivalent therapeutic effect on it.

Effects of estradiol valerate and remifemin on norepinephrine signaling in the brain of ovariectomized rats

AIMS

We investigated the norepinephrine pathway changes from the locus coeruleus (LC) to the preoptic area of the hypothalamus (POAH) in the brain of ovariectomized rats under low estrogen levels and explored the therapeutic effects of estradiol valerate (E2) and Remifemin (ICR) on these changes.

METHODS

40 female Sprague-Dawley rats were randomly divided into the following groups: surgery with vehicle (SHAM), ovariectomy surgery with vehicle (OVX), ovariectomy with E2 treatment (OVX + E2), and ovariectomy with Remifemin (OVX + ICR). After 4 weeks of treatment, we observed the changes by immunohistochemistry.

RESULTS

(1) The average optical density of DBH-ir fibers and the number of α1-adrenoreceptor- and estrogen receptor (ER)α-positive neurons in the main nuclei of POAH were all reduced in OVX rats compared with the SHAM group. The above changes were normalized in all nuclei of the POAH in the E2 group, while they were normalized in some nuclei in the ICR group. Coexpression of ERα and α1-adrenoreceptor was observed in the POAH. (2) The number of DBH- and ERα-positive neurons in the LC decreased in the OVX group compared with the SHAM group and increased after treatment with E2 and ICR. Coexpression of ERα and DBH was observed in the LC.

CONCLUSION

Low estrogen (OVX) altered norepinephrine synthesis in the LC, the projection of norepinephrine fibers and α1-adrenoreceptor expression in the POAH. Both E2 and ICR normalized the norepinephrine pathway, but E2 achieved greater effects than ICR. ICR had different effects in different nuclei in the POAH and its therapeutic effect was better in the LC.