Effect of dihydrotestosterone, 17-ß-estrogen, genistein and equol on remodeling and morphology of bone in osteoporotic male rats during bone healing.

INTRODUCTION: The aim of this study was to investigate the effect of dihydrotestosterone (DHT), 17-ß-estrogen (E2), genistein (GEN) and equol (EQ) on bone remodeling and bone morphology during healing of osteoporotic male rat tibiae. MATERIALS AND METHODS: 180 Sprague-Dawley male rats were divided in 5 groups of 36 animals. After orchidectomy (ORX) and development of osteoporosis, trepanation of the tibia was performed. Until the time of trepanation all groups received soya free food (SF), then food change occurred and treatment started. At day 95, 102 and 151, samples were taken and histomorphometry was performed to analyze changes in bone structure under treatment. At day 33 and 70 all animals received calcein respective alizarin for polychrome bone labeling. RESULTS: The cortical bone was particularly affected. Treatment with DHT and E2 led to a significant long-term expansion of the thickness of the diaphyseal cortical bone, while the phytoestrogens EQ and GEN only had a positive short-term effect in this area. Only E2 preserved the trabecular bone for a limited time. In all groups, periosteal and endosteal bone areas showed the highest bone formation activity. The osteoporotic male injured bone shows a shift in mineral apposition rate (MAR) from periosteal to endosteal bone in the SF, DHT and E2 groups but not in the GEN and EQ phytohormones groups. An MAR decrease in trabecular bone formation was observed at day 70 in all groups except the E2 group. CONCLUSION: We conclude from our results that healing of cortical bone defects in a rat model of male osteoporosis are mainly influenced by the estrogen pathway. Nevertheless, effects via purely androgenic mechanisms can also be demonstrated. The role of a phytohormone therapy is only marginal and if only useful for a short-term supportive approach. The role of the periosteal to endosteal shift during male osteoporotic bone healing needs to be further examined.

Effect of ovariectomy on proximal tibia metaphysis and lumbar vertebral body in common marmoset monkeys.

This study aimed to investigate the effect of estrogen withdrawal on bone tissue in adult female marmoset monkeys. In a 1-year follow-up study we used quantitative computer tomography to measure total bone mineral density (BMD) of the proximal tibia and the second-last lumbar vertebral body (L5/L6) before and 1, 3, 6, and 12 months after ovariectomy. Body mass did not significantly change during the 1-year observation period. However, a significant decline of total BMD after ovariectomy was observed in the proximal tibia but not in L5/L6. In addition, regression analysis showed a significant positive relationship between BMD and body mass in both tibia and L5/L6. The results of our study support the idea that ovariectomized marmoset monkeys may serve as a model to investigate bone loss related to decline of estrogen production.

Sex-specific effects of low-dose gestational estradiol-17ß exposure on bone development in porcine offspring.

Estrogens are important for the bone development and health. Exposure to endocrine disrupting chemicals during the early development has been shown to affect the bone phenotype later in life. Several studies have been performed in rodents, while in larger animals that are important to bridge the gap to humans there is a paucity of data. To this end, the pig as large animal model was used in the present study to assess the influence of gestational estradiol-17ß (E2) exposure on the bone development of the prepubertal and adult offspring. Two low doses (0.05 and 10µg E2/kg body weight) referring to the 'acceptable daily intake' (ADI) and the 'no observed effect level' (NOEL) as stated for humans, and a high-dose (1000µg E2/kg body weight), respectively, were fed to the sows every day from insemination until delivery. In the male prepubertal offspring, the ADI dose group had a lower strength strain index (p=0.002) at the proximal tibia compared to controls, which was determined by peripheral quantitative computed tomography. Prepubertal females were not significantly affected. However, there was a higher cortical cross-sectional area (CSA) (p=0.03) and total CSA (p=0.02) at the femur midpoint in the adult female offspring of the NOEL dose group as measured by computed tomography. These effects were independent from plasma hormone concentrations (leptin, IGF1, estrogens), which remained unaltered. Overall, sex-specific effects on bone development and non-monotonic dose responses were observed. These results substantiate the high sensitivity of developing organisms to exogenous estrogens.

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

In postmenopausal women estrogens in combination with progestins have beneficial effects on climacteric complaints and on osteoporosis but this hormone replacement therapy (HRT) bears the risk of increased mammary carcinomas and cardiovascular diseases. Phytoestrogens at low doses have little or no effects on climacteric complaints, at high doses they mimic the effects of estrogens. Therefore other plant derived substances are currently intensively investigated. Extracts of the rhizome of black cohosh (Cimicifuga racemosa=CR) did not bind to estrogen receptors and were shown to be devoid of estrogenic effects on mammary cancer cells in vitro and on mammary gland and uterine histology in ovariectomized rats. In addition in this rat model the special extract CR BNO 1055 inhibited the occurrence of hot flushes and development of osteoporosis. In postmenopausal women CR BNO 1055 reduced major climacteric complaints as effectively as conjugated estrogens and significantly more than placebo. Similar data were published for other European CR preparations whereas 2 US American preparations were ineffective. This was most likely due to the too high doses or due to the adulteration with Asian Cimicifuga preparations. In all European studies neither effects in the uterus nor in mammary glands were observed. The effective compounds in CR are most likely neurotransmitter-mimetic in nature: dopaminergic, noradrenergic, serotoninergic and GABAergic effects were demonstrated and some have been structurally identified. We conclude that CR extracts at low doses are effective to ameliorate climacteric complaints but are devoid of adverse estrogenic effects. These finding strengthens the role of CR extracts as substitutes for HRT. This article is part of a special issue entitled: Special Issue on Phytoestrogens.

Estrogen receptor alpha augments changes in hemostatic gene expression in HepG2 cells treated with estradiol and phytoestrogens.

Phytoestrogens are popular alternatives to estrogen therapy however their effects on hemostasis in post-menopausal women are unknown. The aim of this study was to determine the effect of the phytoestrogens, genistein, daidzein and equol on the expression of key genes from the hemostatic system in human hepatocyte cell models and to determine the role of estrogen receptors in mediating any response seen. HepG2 cells and Hep89 cells (expressing estrogen receptor alpha (ERα)) were incubated for 24 h with 50 nM 17ß-estradiol, genistein, daidzein or equol. Tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), Factor VII, fibrinogen γ, protein C and protein S mRNA expression were determined using TaqMan PCR. Genistein and equol increased tPA and PAI-1 expression in Hep89 cells with fold changes greater than those observed for estradiol. In HepG2 cells (which do not express ERα), PAI-1 and tPA expression were unchanged. Increased expression of Factor VII was observed in phytoestrogen treated Hep89 cells but not in similarly treated HepG2s. Prothrombin gene expression was increased in equol and daidzein treated HepG2 cells in the absence of the classical estrogen receptors. These data suggest that phytoestrogens can regulate the expression of coagulation and fibrinolytic genes in a human hepatocyte cell line; an effect which is augmented by ERα.

Phytoestrogens selective for the estrogen receptor beta exert anti-androgenic effects in castration resistant prostate cancer.

Prostate cancer is the leading cause of cancer death in men of the Western world. A castration-resistant prostate cancer (CRPC) eventually will arise when a local restricted prostate carcinoma was not cured duly by radical prostatectomy or radiation therapy. Although androgen ablation therapies are considered the gold standard for treatments of advanced prostate cancer there is no curative therapy available at present. In previous pre-clinical and clinical trials several phytoestrogens were investigated for their anticancer potential in various models for prostate cancer. Phytoestrogens feature tumour preventive characteristics and most probably are involved in the low incidence rate of hormone related cancers in Asian countries. Phytoestrogens such as isoflavones can have a marked impact on the most essential therapy target of CRPC i.e. the androgen receptor. Furthermore, functional analyses solidified the notion of such drugs as androgen antagonistic. Phytoestrogens commonly feature low toxicity combined with a potential of targeted therapy. Thus, these drugs qualify for conceivable implementation in prostate cancer patients under active surveillance. In addition, relapse prevention with these drugs after radical prostatectomy or radiation therapy might be considered. This article is part of a Special Issue entitled 'Phytoestrogens'.

Plant derived alternatives for hormone replacement therapy (HRT).

Abstract Hormone replacement therapy (HRT) has undisputable positive effects on climacteric complaints, in the bone and on body weight but also several undesired side effects. Therefore, plant-derived alternatives are currently promoted. Phytoestrogens - primarily the isoflavones genistein, daidzein and coumestrol, stemming from soy (Glycine max) or red clover (Trifolium pratense) - were suggested to have the desired but not the undesired effects of estrogens. Most recently published placebo-controlled studies question the beneficial effects. When taken at the time of puberty however, phytoestrogens appear to protect against mammary cancer later in life. Extracts from the rhizome of Cimicifuga racemosa (black cohosh) have no estrogenic effects. In a narrow dose range they have beneficial effects on climacteric complaints, which are due to several compounds with dopaminergic, noradrenergic, serotoninergic and GABAergic actions that act together in the hypothalamus. Ecdysone is produced by several plants, including spinach (Spinacia oleracea) and was very early on shown to increase muscle mass. Later it became apparent that spinach extracts containing ecdysone decreased body fat load, thereby reducing secretion of proinflammatory cytokines by visceral adipocytes and oxidative stress. This had beneficial effects on body weight and serum lipids not only in obese postmenopausal but also in premenopausal women and in men. For the above-described plant extracts, solid placebo-controlled clinical trials are available. For other plant extracts claiming beneficial effects on climacteric complaints or postmenopausal diseases, no solid data are available.

Osteoprotective effects of Cimicifuga racemosa and its triterpene-saponins are responsible for reduction of bone marrow fat.

PURPOSE: Elderly people often develop visceral obesity accompanied by osteoporosis. Visceral adipocytes secrete a number of adipokines and cytokines which augment the development of arteriosclerosis and type 2 diabetes. Bone marrow fat cells also secrete these pro-inflammatory cytokines which stimulate osteoclast and inhibit osteoblast activity. Ovariectomized (ovx) rats also develop general and bone marrow obesity and osteoporosis both of which can be partially prevented by estradiol (E2) and the special extract of Cimicifuga racemosa (CR) BNO 1055. Whether this extract or the thereof isolated triterpene-saponins or polar substances can also prevent bone marrow obesity and thereby the development of osteoporosis was compared with the effects of estradiol (E2). METHODS: Rats were ovx and fed with food containing either CR BNO 1055 or its triterpene-saponin or polar constituents or with E2 for 4 weeks. Histomorphometry and STRUT analyses were applied to histological preparations to determine the amount of trabecles, hematopoietic and fat tissue in the bone marrow. RESULTS: Ovx rats lost significant amounts of trabecular BMD, surface and nodes while the number of free trabecular ends and fat load in the marrow increased. This was totally prevented by E2 and partially by CR BNO 1055 and the triterpene-saponin but not by the polar fraction. High serum osteocalcin and CrossLaps levels were reduced by E2 and the S-fraction. CONCLUSIONS: It is well established that E2 prevents osteoporosis. It is also known that CR BNO 1055 does not contain estrogenic substances. CR BNO 1055 and the triterpene-saponin-fraction reduced the development of osteoporosis most likely by a reduction of the bone marrow fat load and possibly by reducing the secretion of pro-inflammatory cytokines. Hence, the triterpene-saponin-fraction may serve as a basis for a new osteoporosis preventing preparation also in human patients.

Cimicifuga racemosa and its triterpene-saponins prevent the Metabolic Syndrome and deterioration of cartilage in the knee joint of ovariectomized rats by similar mechanisms.

PURPOSE: An unphysiologic accumulation of fat cells in many parts of the body including abdomen and joints results in increased production of pro-inflammatory cytokines which have adverse effects on serum lipids, glucose and on joint cartilage. The special extract of Cimicifuga racemosa CR BNO 1055 was shown to reduce the size of the abdominal fat depot. It was therefore tempting to test whether this extract, its saponin and its unpolar and polar fractions S- and R-fraction respectively (no quotation) also reduce fat depots and fat cell accumulation in a fat depot located in the lower hind leg (called paratibial fat depot = PFD), in joint fat pads (in the knee joint this is called Hoffa's fat pad) that occur in response to ovariectomy and whether this was accompanied by reduced serum lipids, glucose and improved cartilage features in the knee joint. METHODS: Rats (n = 10/group) were ovariectomized (ovx) and fed with CR BNO 1055, S- or R-fraction containing food (average intake 8.2, or 2.05 or 7.07 mg/day/animal) for 4 weeks. Ovx rats kept under no additive-containing food served as controls. The sizes of the PFD, of Hoffa's fat pad and of the cartilage thickness of the knee joints were determined by quantitative computer tomography and histomorphometrically. In the serum cholesterol, leptin and glucose levels were measured. RESULTS: High load with fat tissue in the PFD and in the knee joints was present in the ovx rats. Treatment with CR BNO 1055 and its S-fraction reduced fat load of both, Hoffa's fat pad and of the PFD significantly and this resulted in reduced body weight which was significant under CR BNO 1055. Fat load in the PFD correlated significantly with the height of serum leptin and cholesterol. The fat load in the knee joint correlated inversely with the size of knee cartilage tissue. CONCLUSIONS: High fat load of the body increases following ovx and this causes increased serum leptin, cholesterol and glucose levels. Following ovx the size of Hoffa's fat pad increases also significantly and this has adverse effects on knee cartilage tissue. Therefore, increased fat tissue in joints appears to belong to the Metabolic Syndrome. This effect can be largely prevented by CR BNO 1005 and its S- but not by its R-fraction. Hence, the saponins in CR BNO 1055 may be useful in preventing the Metabolic Syndrome and osteoarthritis.

Long-term effects of ovariectomy on osteoporosis and obesity in estrogen-receptor-ß-deleted mice.

Untreated BERKO mice demonstrate few abnormalities in bone phenotype and recent ovariectomy has few effects on various bone characteristics in these mice. Long-term studies on the bone phenotype of intact and ovariectomized mice are unavailable. Using quantitative computed tomography (qCT), we determined various parameters of the metaphysis of the tibia in sham-ovariectomized (intact) and ovariectomized BERKO and wildtype mice. Body weight and estrogen-regulated fat were also measured. Mice underwent surgery (ovariectomy or sham) at 3 mo of age, and qCT analysis was performed every 2 to 4 mo until mice were 12 mo old. Ovariectomized wildtype mice gained body weight and their fat depot increased in size within 2 mo after ovariectomy. Obesity developed later in ovariectomized BERKO mice, which became significantly heavier than their wildtype counterparts. Ovariectomized wildtype mice lost trabecular density more rapidly than did ovariectomized BERKO mice, which did not show similar loss in trabecular density until at least 7 mo after ovariectomy. At the latest studied time point (9 mo after surgery), cortical area was significantly larger in ovariectomized BERKO mice than ovariectomized wildtype mice. The absence of ERß in ovariectomized BERKO mice during the first 3 to 5 mo after ovariectomy had protective effects against obesity and trabecular rarification; this protective effect disappeared at later time points.

20-OH-ecdysone prevents hot flushes in ovariectomized rats.

Hot flushes are due to the lack of estrogens and are the most characteristic climacteric complaints. Hormone replacement therapy was the standard treatment but now its use is limited because of side effects. Need therefore arises to search for non-estrogenic alternatives. The molting hormone 20-beta-hydroxyecdysone (Ecd) is produced by several plants including spinach and has no estrogenic or androgenic properties but enhances GABAergic effects in neurons. Since GABAergic compounds can ameliorate hot flushes, we investigated the effects of Ecd on subcutaneous body temperature of intact and ovariectomized (ovx) rats. The subcutaneous body temperature was recorded at 5-min intervals over a period of 3 hours. Rats were then ovx, and skin temperatures were recorded after an acute intravenous (5 mg) and during subchronic and chronic oral application of Ecd (73 mg/animal/day). For additional control purposes, a group of ovx rats received food containing estradiol-17 ß (E2). Skin temperature in individual ovx animals fluctuated largely with peaks (hot flushes) occurring every 20-40 minutes. Following the i.v. treatment with Ecd, skin temperature dropped by more than 1 °C, an effect much larger than in the controls. One and two weeks later, hot flushes were only seen in ovx controls but not in intact, E2-, or Ecd-treated animals. As a consequence, E2 and Ecd intake significantly (p < 0.05) reduced the mean temperature in ovx rats during the various time points of the study. These results suggest that Ecd is efficient to prevent hot flushes in ovx rats.

The effects of 20-hydroxyecdysone and 17ß-estradiol on the skin of ovariectomized rats.

OBJECTIVE: 20-hydroxyecdysone has numerous favorable effects on a variety of organs, including the skin, where it improves wound healing. It is devoid of estrogenic and androgenic effects. Therefore, application of 20-hydroxyecdysone might be a new approach to improve skin conditions in postmenopausal women, and this was investigated in ovariectomized (OVX) rats. METHODS: After ovariectomy, rats received Ecd (18, 57, or 116 mg/animal/day) or 17ß-estradiol (E2)-3-benzoate (60 µg/kg body weight) in food for 12 weeks, and skin samples were evaluated histologically to quantify two dermal layers, the subcutaneous fat and muscle layers. RESULTS: Epidermal thickness was lowest in the OVX animals, slightly higher in the E2-treated animals, and significantly higher in the Ecd-treated animals. Dermal thickness was lowest in the intact and E2-treated animals and highest in the Ecd-treated animals. The subcutaneous fat layer was thickest in the OVX animals, thinner in the intact animals, and intermediate in the Ecd-treated animals. The muscle layer was smallest in the OVX and intact animals and significantly larger in the E2- and Ecd-treated animals. The number of proliferating cell nuclear antigen antibody-positive cells was lowest in OVX controls and significantly higher in all other groups. CONCLUSIONS: The Ecd-induced increases in epidermal and dermal thickness are suggestive of functional changes of the skin. The decreased amounts of subcutaneous fat in the E2- and Ecd-treated animals point to either a fat catabolic or an antianabolic effect. The ovariectomy-induced decrease in subcutaneous musculature was prevented by Ecd but not by E2. The stimulatory effects of Ecd on epidermal and dermal thickness and the muscle-increasing effects in the skin of OVX rats may indicate functional changes of the skin.

Genistein alters coagulation gene expression in ovariectomised rats treated with phytoestrogens.

Recent data has shown that hormone therapy (HT) increases the risk of cardiovascular and thromboembolic disease, particularly in users of oral HT. Phytoestrogens are popular alternatives to oestrogen therapy; however, their effects on cardiovascular risk are unknown. We investigated the effect of the phytoestrogen, genistein on the expression of genes and proteins from the haemostatic system in the liver in an ovariectomised rat model. Fifty-nine virgin female Sprague-Dawley rats were fed with soy-free chow supplemented with 17ß estradiol (E2) (daily uptake 0.19 or 0.75 mg/kg body weight), or genistein (daily uptake 6 or 60 mg/kg body weight), for three months and compared to soy-free control rats. Gene expression of prothrombin, factor VII, fibrinogen alpha and fibrinogen beta was increased with E2 and genistein compared to the soy-free control group (p<0.001). Genistein increased factor VII significantly more than E2 (p<0.005). Plasminogen mRNA was increased in both treatment groups compared to the soy-free control, with genistein expression significantly higher than E2 (p<0.001). Tissue plasminogen inhibitor (tPA), plasminogen activator inhibitor-1 (PAI-1) and C-reactive protein (CRP) expression were also increased in both groups relative the soy-free control. Results of protein analysis largely concurred with those of the mRNA. Oestrogen receptor ß (ERß) was undetected while oestrogen receptor α (ERα) was detected in each sample group. Genistein can increase the expression of coagulation and fibrinolytic genes. This effect was similar and in some cases higher than 17ß estradiol. These results suggest that genistein may not be neutral with respect to the haemostatic system.

The Cimicifuga racemosa special extract BNO 1055 prevents hot flashes in ovariectomized rats.

Hot flashes are a disorder of thermoregulation due to the lack of estrogens and are the most common and characteristic climacteric complaint. Hormone replacement therapy is the gold standard treatment but now its use is limited due to several side effects. Need therefore arises to search for non-estrogenic alternatives. It is well established that extracts of Cimicifuga racemosa (CR) ease climacteric complaints but solid animal experimental data supporting such effects are not available. The availability of sensitive transponders which record subcutaneous temperature continuously enables nowadays experiments in rats to establish whether they have hot flashes following ovariectomy (Seidlova-Wuttke et al. 2003) and if so, whether they can be influenced by the extract of CR BNO 1055. Intact Sprague-Dawley rats (n=16) were acclimatized and their subcutaneous body temperature was measured in 5 min intervals and mean values from 3h recordings were calculated. Thereafter, the rats were ovx and fed either with soy free (sf) or CR BNO 1055 (25 mg/animal/day) food. Temperature was recorded again after acute and sub-acute application of CR. In individual intact animals temperature was stable over the 3h recording period. Following ovx temperature pulses appeared with peaks occurring every 20-40 min. These fluctuations were not seen in CR BNO 1055 treated animals resulting in significantly higher mean temperatures in ovx in comparison to intact or ovx CR BNO treated rats. This reduction of hot flashes by BNO 1055 outlasted the experimental period of 3 weeks. These results suggest that the ovx rats and the new temperature-sensitive device may be useful for the study of hot flashes. Furthermore the results prove that the CR BNO 1055 exerts hot flash reducing effects.

Contribution of a membrane estrogen receptor to the estrogenic regulation of body temperature and energy homeostasis.

The hypothalamus is a key region of the central nervous system involved in the control of homeostasis, including energy and core body temperature (Tc). 17ß-Estradiol (E2) regulates Tc, in part, via actions in the basal hypothalamus and preoptic area. E2 primarily controls hypothalamic functions via the nuclear steroid receptors, estrogen receptor α/ß. However, we have previously described an E2-responsive, Gq-coupled membrane receptor that reduces the postsynaptic inhibitory γ-aminobutyric acid-ergic tone and attenuates postovariectomy body weight gain in female guinea pigs through the administration of a selective Gq-mER ligand, STX. To determine the role of Gq-mER in regulating Tc, energy and bone homeostasis, ovariectomized female guinea pigs, implanted ip with temperature probes, were treated with STX or E2 for 7-8 wk. Tc was recorded for 4 wk, whereas food intake and body weight were monitored daily. Bone density and fat accumulation were determined postmortem. Both E2 and STX significantly reduced Tc in the females compared with controls. STX, similar to E2, reduced food intake and fat accumulation and increased tibial bone density. Therefore, a Gq-mER-coupled signaling pathway appears to be involved in maintaining homeostatic functions and may constitute a novel therapeutic target for treatment of hypoestrogenic symptoms.

Beta-ecdysone has bone protective but no estrogenic effects in ovariectomized rats.

Estrogens exert beneficial effects in the bone. Their chronic use however bares several risks. Therefore intensive search for non-estrogenic, bone protective compounds is going on. We observed that an extract of Tinospora cordifolia has antiosteoporotic effects and identified 20-OH-Ecdysone (beta-Ecdysone=Ecd) as a possible candidate for this action. Ovariectomized (ovx) rats were treated orally over 3 months with no Ecd (control) or 18, 57 or 121 mg Ecd/day/animal. Estradiol-17beta benzoate (E2) 159 microg/day/animal) fed animals served as positive controls. Bone mineral density (BMD) of tibia was measured by quantitative computer tomography, serum Osteocalcin and CrossLaps were measured in a ligand binding assay. Utilizing an estrogen receptor (ER) containing cytosolic extract of porcine uteri the capability of Ecd to bind to ER was tested. Ecd did not bind to ER. BMD was reduced by more than 50% in the control. In the Ecd animals BMD was dose dependently higher. Serum CrossLaps was lower in the Ecd and E2 group while serum Osteocalcin levels were decreased in the E2 but increased in the Ecd fed animals. Ecd has an antiosteoporotic effect which does not involve activation of ER.

Effects of black cohosh (Cimicifuga racemosa) and estrogen on metaphyseal fracture healing in the early stage of osteoporosis in ovariectomized rats.

Osteoporosis and its accompanying, predominantly metaphyseal, fractures are a major health problem. Black cohosh (Cimicifuga racemosa) and estrogen positively influence osteoporotic bone. Both substances may improve fracture healing in early osteoporosis as well. In 48 twelve-week-old ovariectomized or, respectively, sham-operated (SHAM) rats, a standardized metaphyseal tibia osteotomy with bridging T-plate fixation was performed. During the healing process of 35 days, rats received soy-free (SHAM, osteopenic C), estrogen- (E) or Cimicifuga racemosa- (CR) supplemented diets. After sacrifice, the callus formation was analyzed with regard to biomechanical quality, morphology, quantity, time course of new bone built and gene expression. CR induced a high rate of metaphyseal callus formation. The biomechanical properties and the amount of new callus formation indicated that fracture healing was still in progress. Therefore, gene expression of osteoblasts was comparatively high. Body weight and the trabecular structure were influenced little by CR. Estrogen improved the biomechanical properties of the callus. Resistance to microfracturing was significantly enhanced in the E group and even superior to SHAM. Remodeling of the callus formation had already begun. The trabecular network and the typical endosteal fracture healing were especially improved. Osteoporotic metaphyseal fracture healing was improved by estrogen more than by Cimicifuga racemosa. The process of fracture healing occurred nearly physiologically. The generation of callus formation was supported by Cimicifuga racemosa as well, but the five-week duration of application was too short for Cimicifuga racemosa to show its complete potential. Already-initiated Cimicifuga racemosa therapy for menopausal symptoms could be continued during fracture healing without hesitation.