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.

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 17β-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.

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.

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'.

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.

Pharmacokinetics of human chorionic gonadotropin after i.m. administration in goats (Capra hircus)

The present investigation addresses the pharmacokinetics of human chorionic gonadotropin (hCG), intramuscularly (i.m.) administered to goats. Nine pluriparous does of the Boer goat breed, 2-6 years of age and weighing 45-60 kg, were administered 500 IU hCG (2 ml Chorulon) deep into the thigh musculature 18 h after superovulatory FSH treatment. Blood samples were drawn from the jugular vein at 2  h intervals for the first 24h, at 6 h intervals until 42 h, and at 12 h intervals until 114 h after administration. After centrifugation, plasma hCG concentrations were determined by electrochemiluminescence immunoassay. Pharmacokinetical parameters were as follows: lag time, 0.4 (s.e.m. 0.1) h; absorption rate constant, 0.34 (s.e.m. 0.002) h; absorption half-life, 2.7 (s.e.m. 0.5) h; elimination rate constant, 0.02 (s.e.m. 0.002) h; biological half-life, 39.4 (s.e.m. 5.1) h; and apparent volume of distribution, 16.9 (s.e.m. 4.3) l. The plasma hCG profile was characterized by an absorption phase of 11.6 (s.e.m. 1.8) h and an elimination phase of 70.0 (s.e.m. 9.8) h, with considerable individual variation in bioavailability and pharmacokinetical parameters. Biological half-life was negatively correlated (P<0.05) with peak concentration (r=-0.76), absorption rate constant (r=-0.78), and elimination rate constant (r=-0.87). The results indicate that after rapid absorption, hCG remains in the circulation for an extended period. This has to be taken into account when assessing the stimulatory response to hCG treatment on an ovarian level.

Long-term effects of ovariectomy on osteoporosis and obesity in estrogen-receptor-β-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 ERβ 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 β (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.

Long-term treatment of ovariectomized mice with estradiol or phytoestrogens as a new model to study the role of estrogenic substances in the heart

Epidemiological data reveal that the overall risk for heart disease is lower for premenopausal women compared to age-matched men. However, the beneficial effect for the female sex is lost upon menopause. Thus, it has been suggested that estrogens convey the protective effect for the female sex against heart disease. Numerous natural plant products, i.e., phytoestrogens (PE), interfere with or alter the development or function of the endocrine system. Although PEs have been studied intensively with regard to the effects on the reproductive organs, such as the uterus or mammary gland, surprisingly little data are available about the effects of PEs on the heart. Here, we conducted a long-term study with ovariectomized mice to examine putative estrogenic effects of the PEs genistein (GEN), resveratrol (RES), and equol (EQ), using estradiol (E2) as a reference compound on heart size, morphology, and cardiac gene expression. We report for the first time significant changes in these parameters by GEN and E2. Changes in the size of cardiomyocytes were observed by GEN and E2. In line with these observations, cardiac expression of insulin-like growth factor 1 ( IGF1) was significantly induced by both GEN and E2. Thus, we speculate that endocrine active compounds, like the isoflavone GEN, which is used as a food additive or as a drug for the treatment of menopausal symptoms, may directly affect heart function.

Absence of positive effect of black cohosh (Cimicifuga racemosa) on fracture healing in osteopenic rodent model

The healing of predominantly metaphyseal fractures in postmenopausal osteoporosis is delayed and comparatively poor. Due to the potential side effects of HRT, natural alternatives are appealing. The aim of this study was to determine whether Cimicifuga racemosa extract BNO 1055 improves metaphyseal fracture healing in severe osteopenic bone in rats. Thirty-three 12-week-old female rats developed severe osteopenia during 10 weeks after ovariectomy. After metaphyseal tibial-osteotomy and standardized T-plate-osteosynthesis, the healing periods in ovariectomized rats (C), 17-α-estradiol (E) and Cimicifuga racemosa (CR) supplemented diets were assessed for 35 days. Changes in callus morphology were evaluated qualitatively by biomechanical testing and quantitatively in microradiographies and fluorochrome-labeled histological sections. The CR-supplementation slightly improved callus quality and trabecular bone formation. It significantly enhanced the endosteal callus density compared to C group (Cl.Dn.e C: 59.08 ± 21.89, E: 45.95 ± 18.39, CR: 60.85 ± 18.66*), though most of the other morphological parameters examined showed no improvement. The time course of fracture healing did not change due to CR. Estrogen-supplementation enhanced the biomechanical properties of the fracture site. Trabecular bone was improved indicating the physiological endosteal healing process. The CR-supplementation did not exhibit positive effects in severe (senile) osteopenic fracture healing as seen in early (postmenopausal) osteoporosis in rats. Callus formation was slightly improved under CR. Estrogen improved fracture healing in severe osteopenic bone, while the extent of callus formation played a minor role.

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). 17β-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/β. 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.

Effects of isoflavones equol and genistein on bone quality in a rat osteopenia model

Phytoestrogens might be an alternative medication in prophylaxis and treatment of osteoporosis. In this study, the osteoprotective effects of genistein (GEN) and equol (EQO) were evaluated. After ovariectomy, 44 rats received soy-free food (Control, C) and developed substantial osteoporosis over the course of two months. After that period, the rats were divided into different groups and fed estradiol (E), GEN or EQO for 35 days. To analyze the osteoprotective effects of the tested substances, bone biomechanical properties and histomorphometric changes of the lumbar vertebrae were evaluated. In analyzing the vertebral body compression strength, we found that the EQO (103.8%) and GEN (96.8%) groups reached similar levels relative to the E group, while the C group reached 77.7% of the biomechanical properties of the E group. EQO was significantly superior to C. The histomorphometric evaluation demonstrated an increased number of nodes in EQO- and E-treated rats compared to GEN- and C-treated rats. E led to an improvement of cortical as well as trabecular bone, an advantage that was only partly seen in the other groups. Treatment with phytoestrogens induced improved bone quality. EQO and GEN might be alternatives for hormone replacement therapy, although further studies are needed to elucidate possible side effects.

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 17β 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 β (ERβ) 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 17β 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.

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.

Plant-derived alternative treatments for the aging male: facts and myths

Soy- or red clover- derived products containing isoflavones have been amply studied in climacteric and postmenopausal women, and confusing contradicting results have been published. The beneficial effects on climacteric complaints, cholesterol and the development of osteoporosis are marginally at best and there are no uterine and mammary safety studies. In males, however, isoflavones may protect the prostate to make them less prone to develop cancer. Cell biological and animal experimental data support this notion. Clinical data about possible beneficial effects on cholesterol or in the bone are largely missing. Hence, soy or red clover products containing the mild estrogenic isoflavones with a slightly higher affinity to the estrogen receptor of the beta in comparison to the alpha subtype may prove to have some beneficial effects in males.

Beneficial effects of beta-Ecdysone on the joint, epiphyseal cartilage tissue and trabecular bone in ovariectomized rats

Ecdysteroids are steroids found in invertebrates and plants. In mammals they have protein anabolic effects. We have recently published antiosteoporotic effects of Tinospora cordifolia (TC) extract and the search for the possible active ingredients yielded the presence of beta-Ecdysone (Ecd). Therefore, we investigated the effects of pure Ecd in ovariectomized rats on morphological changes in joint, epiphyseal cartilage and trabecular tissue. Following ovariectomy rats were fed for 1 month with Ecd containing food at a dose of 52.8 mg/day/animal. Positive and negative control animals received 17-beta Estradiol (E(2), 132 microg/day/animal) and soy free (sf) food respectively. At sacrifice, specimens consisting of upper tibiae-lower femurs and knee joint were harvested and processed for histomorphometry. The parameters measured included thickness of the joint cartilage, thickness of the whole epiphyseal growth plate and its three zones. Furthermore, the percentage of trabecular bone in the metaphysis region of tibiae was quantified. Ecd and E(2) induced a significant increase in the thickness of joint cartilage. The whole epiphyseal growth plate and its proliferative and hypertrophic zones were also increased by Ecd whereas E(2) reduced their size. The percentage of trabecular area in the metaphysis of tibia was significantly increased in Ecd and E(2) treated animals. Results provide a plausible explanation for the antiosteoporotic effects of TC. Hence, TC as well as other Ecd producing plants or pure Ecd may be of value in the prevention and treatment of osteoporosis and osteoarthritis which is of increasing importance due to aging and obesity among individuals.

Metabolic effects of 20-OH-ecdysone in ovariectomized rats

Postmenopausal women develop often obesity which may be prevented by 20-OH-Ecdysone (Ecd). This was investigated in ovariectomized (ovx) rats. They were orally treated with 3 doses of Ecd (18, 56 or 116 mg/day/animal). Positive controls received 159 microg estradiol (E2). Quantitative computer tomography at the level of the abdomen and the metaphysis of the tibia allowed estimation of surface, fat depots and muscles. The highest dose of Ecd resulted in serum concentrations of 0.4 x 10(-6)M. Serum E2 concentrations in the positive controls were 73.3+/-24.41 pg/ml. E2 but not Ecd stimulated uterine weights. Under Ecd ovx animals gained less fat but had more muscle mass. Serum TSH, T4 and T3 levels remained unaffected while E2 treatment increases T4 but decreases T3 levels. Ecd at the lowest dose lowered serum LDL and did not result in increased serum triglycerides, an effect seen in the E2 treated rats. At the Ecd highest dose serum HDL was higher than in the controls. In conclusion Ecd has beneficial effects on fat and muscle tissue and may be able to prevent the metabolic syndrome and sarcopenia by a non-estrogenic mechanism.

Changes in the histomorphometric and biomechanical properties of the proximal femur of ovariectomized rat after treatment with the phytoestrogens genistein and equol

The isoflavonoids found in soy have attracted great interest as dietary phytoestrogens that might be effective for postmenopausal hormone replacement therapy. Special attention has been devoted to the hormonal effects of various isoflavonoids, like genistein (GEN) and daidzein's (DAID) potent metabolite, equol (EQ). Here we aimed to investigate the short-term effects of genistein and equol on the proximal femur of ovariectomized (OVX) rats. Forty-eight, 3-month-old female Sprague-Dawley rats were ovarectomized; after eight weeks the bilateral osteotomy and osteosynthesis (OS) of their tibiae was performed and the rats were randomly divided into the following four groups: OVX control group (C), treated with estradiol-17beta (E2) -benzoate (E; daily intake 0.086 mg/d per animal), genistein (GEN; daily intake 12.7 mg/d per animal) and equol (EQ; daily intake 4.65 mg/d per animal). At 5 weeks postoperatively (OS), the breaking test was performed on the trochanteric region of femur. Additionally, histomorphometric assessment, and trabecular and cortical bone microstructure analyses were performed. The relative gain of body weight (BW) in the EQ (24 %) group was significantly (p < 0.05) lower than in the C (33 %) and GEN (30 %) groups. After treatment for 5 weeks, the maximal load (F(max)) and yield load (yL) were higher (p < 0.05 for the weight-adapted results) in the E (188.4 N resp. 113.1 N) and EQ (177.3 N resp. 112 N) groups as compared to C (162.8 N resp. 109.1 N) and GEN (165.7 N resp. 108.8 N). In the histomorphometric tests the E- (trabecular area (Tb.Ar) = 74.93 %, trabecular nodes/mm(2) (N.Nd/mm(2)) = 48.65) and EQ-treated (Tb.Ar = 63.13 %, N.Nd/mm(2) = 43.72) animals showed significant improvement with regard to Tb.Ar and trabecular connectivity (N.Nd./mm(2)) in comparison to C (Tb.Ar = 46.84, N.Nd/mm(2) = 31.86) and GEN (Tb.Ar = 48.22 %, N.Nd/mm(2) = 34.15). There were no differences in relative cortical width (Ct.Wi) among the four groups. The treatment with EQ resulted in improved biomechanical and histomorphometric properties as compared to the treatment with GEN. Thus, of the studied substances, EQ seems to be a possible alternative to hormone replacement therapy, but further studies are needed.

Estrogen and raloxifene improve metaphyseal fracture healing in the early phase of osteoporosis. A new fracture-healing model at the tibia in rat

BACKGROUND

Fracture healing in osteoporosis is delayed. Quality and speed of fracture healing in osteoporotic fractures are crucial with regard to the outcome of patients. The question arises whether established antiosteoporotic drugs can further improve fracture healing.

MATERIALS AND METHODS

Osteoporosis manifests predominantly in the metaphyseal bone. Nevertheless, an established metaphyseal fracture model is lacking. A standardized metaphyseal fracture-healing model with stable plate fixation was developed for rat tibiae. The healing process was analyzed by biomechanical, gene expression, and histomorphometric methods in ovariectomized (OVX) and sham-operated rats (SHAM), compared to standardized estrogen (E)- and raloxifene (R)-supplemented diets.

RESULTS

Estrogen and raloxifene improved the biomechanical properties of bone healing compared to OVX (Yield load: SHAM = 63.1 +/- 20.8N, E = 60.8 +/- 17.9N, R = 44.7+/-17.5N, OVX = 32:5 +/- 22.0N). Estrogen vs OVX was significant based on a denser trabecular network. Raloxifene greatly induced total callus formation ((R = 5.3 +/- 0.9 mm2, E = 4.7 +/- 0.5 mm2, SHAM = 4.51 +/- 0.61 mm2, OVX =4.1 +/- 0.6 mm2), whereas estrogen mainly enhanced new endosteal bone formation. There was no correlation between the gene expression (osteocalcin, collagen1alpha1, IGF-1, tartrate-resistant phosphatase) in the callus and the morphology and quality of callus formation.

CONCLUSION

Raloxifene and estrogen improve fracture healing in osteoporotic bone significantly with regard to callus formation, resistance, and elasticity. The biomechanically stable metaphyseal osteotomy model with T-plate fixation presented here has proven to be appropriate to investigate fracture healing in osteoporosis.

Do estrogen and alendronate improve metaphyseal fracture healing when applied as osteoporosis prophylaxis?

Osteoporosis is accompanied by predominantly metaphyseal fractures with a delayed and qualitatively reduced healing process. This study addressed the question of whether fracture healing in the context of osteoporosis prophylaxis is improved with estrogen (E) or alendronate (ALN). Thirty-six ovariectomized and 12 sham-operated 12-week-old rats received soy-free (osteoporotic C, sham), E-, or ALN- supplemented diets. After 10 weeks, a metaphyseal tibia osteotomy and standardized T-plate fixation were performed. After a 5-week healing process, the fracture callus was evaluated qualitatively by biomechanical bending test and quantitatively in microradiographic sections. The time course of callus formation was examined using fluorochrome-labeled histological sections. Administration of E improved the biomechanical properties of callus (stiffness [N/mm]: sham: 110.2 + or - 76.07, C: 41.28 + or - 33.70, E: 85.72 + or - 47.24, ALN: 72.07 + or - 34.68). The resistance to microfracturing seen in E-treated animals was significantly enhanced and even superior to sham (yield load [N] sham: 27.44 + or - 9.72, C: 21.04 + or - 12.47, E: 42.85 + or - 13.74(Delta), ALN: 25.28 + or - 6.4(.)) (* P < 0.05 vs. sham group, (Delta) P < 0.05 vs. C group, (*) P < 0.05 vs. E group). Trabecular bone in particular was improved, indicating the presence of physiological endosteal bridging (Tr.Dn [%] sham: 10.53 + or - 18.9, C: 1.01 + or - 0.14, E: 24.13 + or - 34.09(Delta), ALN: 3.99 + or - 8.3(.)). ALN did not help bone healing, as shown by mechanical tests. Compared to the C group, statistically, ALN did not show worse properties. The induction of callus formation under ALN treatment was slightly delayed (Tt.Cl [mm(2)] sham: 3.68 + or - 0.66, C: 3.44 + or - 0.42, E: 3.69 + or - 0.58, ALN: 3.06 + or - 0.56). Osteoporotic metaphyseal fracture healing was qualitatively and quantitatively improved by E prophylaxis. The process of fracture healing occurred nearly physiologically (shamlike). Notably, ALN hardly improved metaphyseal callus properties when assessed as osteoporosis prophylaxis, but to a lesser extent than E.

Effects of estradiol benzoate, raloxifen and an ethanolic extract of Cimicifuga racemosa in nonclassical estrogen regulated organs of ovariectomized rats

The special extract of Cimicifuga racemosa (CR) BNO 1055 was shown to have bone protective effects without exerting estrogenic effects in the uterus or mammary gland. Whether the effects of CR BNO 1055 would be exerted in other organs that also express estrogen receptors (ERs) but in which the effects of estrogens and of the selective estrogen receptor modulator raloxifen (Ral) were not thoroughly studied was therefore investigated in the present contribution. Rats were ovariectomized (ovx) and their food immediately substituted with estradiol benzoate (EB), Ral or 2 doses of CR BNO 1055 for 3 months. Expressions of estrogen receptor alpha (ERalpha), estrogen receptor beta (ERbeta) and of insulin-like growth factor-1 (IGF-1) genes were determined in the vagina, liver, thyroid gland, lung, spleen, colon and kidney by means of quantitative RT-PCRs. Body weights in all treatment groups were significantly reduced and uterine weights in the EB treated animals were largely and in the Ral treated animals slightly but significantly increased. CR BNO 1055 was without effects in the uterus. We tested 3 genes: ERalpha gene expression was significantly reduced in the vagina, liver and kidney and remained unaffected in all other organs with the exception of the thyroid gland where ERalpha gene expression was stimulated by EB, Ral had--if any--similar effects in these organs. The CR extract BNO 1055 was devoid of any effect on ERalpha gene expression. ERbeta gene expression was suppressed in the vagina and colon by EB and this effect was shared by Ral in the colon. In the thyroid, EB and Ral stimulated ERbeta gene expression. Expression of IGF-1 gene was stimulated by EB and CR BNO 1055 in the vagina and kidney and inhibited by EB and Ral in the liver. No effects were observed by CR BNO 1055 in these organs. The effects of Ral, if occurring, were similar to those of EB while CR BNO 1055 was ineffective in all organs but the vagina. In the colon, reduced ERbeta gene activity may augment ERalpha mediated effects. In all other organs the effects of ER await further investigation. The CR BNO 1055 did not show any activity pattern which would be similar to the pattern observed under EB or Ral. Therefore the observed effects of CR BNO 1055 in these organs are most likely not estrogenic in nature.

Short-term effects of parathyroid hormone on rat lumbar vertebrae

STUDY DESIGN

This study is an experimental study in the rat osteopenia model.

OBJECTIVE

The aim of this study was to evaluate the short-term effects of daily application of parathyroid hormone (PTH) on bone quality and quantity using a new biomechanical compression test for intact rat lumbar vertebrae.

SUMMARY OF BACKGROUND DATA

Because of their high clinical relevance, trabecular content and thick cortical shell vertebrae are of high interest for osteoporosis research. Biomechanical stability depends on both trabecular and cortical bone. Anabolic effects on bone after long-term application of PTH have already been proven.

METHODS

After an intraindividual comparison (n = 20), the capability of a new test to identify biomechanical properties of the mature rat model was assessed. In the following, 33 three-month-old rats were ovariectomized. After 10 weeks, the animals were divided into 3 groups. The control group (C) received no additional food supplementation. The other groups received hormone treatment with either estradiol (E) or PTH for another 5 weeks. The effects on bone biomechanical properties and bone microstructure were analyzed.

RESULTS

After establishing the new biomechanical test for intact rat lumbar vertebrae, PTH-treated (yield stress: 2.95 N/mm, elastic limit: 2.39 N/mm) and then E-treated (yield stress: 2.13 N/mm, elastic limit: 1.68 N/mm) animals showed superior biomechanical results. Compression strength was significantly improved in these rats in comparison to the control group rats (yield stress: 1.86 N/mm, elastic limit: 1.38 N/mm). In the microradiographic evaluation, PTH significantly improved the morphologic results to produce thicker trabeculae. E led to a more densely branched trabecular network, which was not as important as trabecular thickness for bone stability.

CONCLUSION

After a short-term application, PTH is superior to E in recreating bone biomechanical propertiesand lumbar vertebral microstructure in advanced osteoporosis. The cortical shell and trabecular thickness are primarily responsible for the biomechanical strength of vertebrae.

The inhibitory effect of beta-endorphin on LH release in ovariectomized rats does not involve the preoptic GABAergic system

In rats, beta-endorphin (beta-END) and gamma-aminobutyric acid (GABA) suppress LH secretion by hypothalamic mechanisms involving the preoptic area (POA). Systemic injection of naloxone (NAL) increases LH secretion in male rats, an effect which can be prevented by coadministration of GABA agonists. Application of NAL into the POA of ovariectomized (ovx), progesterone substituted sheep modulates preoptic GABA release. These findings have been interpreted such that the endogenous opioids act via the preoptic GABAergic system to regulate LH release. To evaluate this hypothesis we implanted ovx rats with push pull cannula into the POA and measured GABA secretion prior to and during the preoptic application of either NAL or beta-END. Blood samples were collected to assess the effects of the drugs on LH secretion. In addition, ovx rats were substituted with estradiol (E2) to induce a negative feedback effect on LH release. Intrapreoptic application of beta-END caused a rapid decline of LH release in ovx rats which was completely reversible after termination of beta-END perfusion. Though LH levels were clearly suppressed, no change of GABA release in the POA was observed. During preoptic NAL perfusion both LH secretion and GABA release remained unaffected. Likewise, during beta-END perfusion into the POA of E2 treated rats neither LH nor GABA secretion changed. In contrast, NAL perfusion rapidly increased LH release but again this action of the opioidergic drug was not accompanied by alterations of GABA release. We conclude from these data: 1) Intrapreoptically applied beta-END inhibits LH release only in the absence of steroids. In turn, blockade of opioid receptors is effective only in the presence of steroids. Both findings indicate that in the POA opioidergic activity is low in ovx rats, but high during negative feedback of E2. 2) No changes of GABA secretion were observed during manipulations of the opioidergic tonus in the POA suggesting that both beta-END and GABA do not interact to regulate LH release. Thus, beta-END may directly inhibit the activity of GnRH neurons located in the POA or acts via a neurotransmitter other than GABA.

Effects of angiotensin II and atrial natriuretic peptide on LH release are exerted in the preoptic area: possible involvement of gamma-aminobutyric acid (GABA)

The preoptic/anterior hypothalamic area (PO/AH) contains the majority of LHRH neurons of which the function is regulated by a variety of neurotransmitters and peptides. In this area, numerous estrogen-receptive neurons utilize gammaaminobutyric acid (GABA) as neurotransmitter and these neurons communicate directly with LHRH neurons. Angiotensin II (AII) and atrial natriuretic peptide (ANP) are known to be involved in the regulation of LH secretion. The site of action of these peptides and the mechanisms by which they influence LHRH neurons, are largely unknown. Therefore the effects of intrapreoptic application of AII and ANP on serum LH levels of ovariectomized (ovx) and of ovx estrogen-primed rats were investigated. The peptides were applied into the PO/AH by means of push-pull cannula and in the effluent fractions GABA was measured. In the ovx estrogen-primed rat, prominent LH and prolactin surges were observed. At the time of increased LH levels preoptic GABA release was significantly reduced. At this time application of AII or ANP into the PO/AH was without effect on either LH or prolactin levels in the serum or on preoptic GABA release rates. In ovx, not steroid-primed rats intrapreoptic AII application suppressed serum LH levels significantly and this treatment had a slight stimulatory effect on preoptic GABA release rates. This effect of AII could be antagonized by prior preoptic treatment with saralasin, a specific AII receptor blocking peptide. Preoptic treatment with ANP resulted in a slight increase in serum LH levels which was accompanied by a slight, but significant reduction of preoptic GABA release rates.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhanced cAMP production mediates the stimulatory action of pituitary adenylate cyclase activating polypeptide (PACAP) on in vitro catecholamine secretion from bovine adrenal chromaffin cells

The 38 amino acid peptide pituitary adenylate cyclase activating polypeptide (PACAP) induced a dose dependent increase of catecholamine secretion in cultures of bovine chromaffin cells. This secretagogue activity of PACAP was strictly dependent on the presence of calcium in the culture medium. If calcium was omitted from the medium no effect of PACAP on catecholamine secretion could be detected during an incubation of 20 min. Preincubation of cells with 1 nM PACAP for 5 min facilitated the subsequent nicotine stimulated catecholamine secretion during a 20 min incubation without addition of the peptide. PACAP induced catecholamine secretion was clearly accompanied by a dose dependent increase of intracellular cAMP concentrations. The percentage of cells responding to PACAP with increased catecholamine secretion was assessed by immunocytochemistry of the transient appearance of dopamine-beta-hydroxylase, associated with the membranes of the chromaffin granules on the cell surface during the secretory process. About 70% of adrenal medullary cells responded to 100 nM PACAP with enhanced secretory activity. Though PACAP stimulated catecholamine secretion, we did not observed major effects on intracellular free calcium concentrations ([Ca2+]i) as determined with fura-2 by single cell fluorescence microscopy. In maximally 20% of the cells a rise in [Ca2+]i in response to a challenge with 500 nM PACAP was observed. Lower concentrations of PACAP were without an effect on [Ca2+]i. These data indicate that the stimulatory action of PACAP on in vitro catecholamine secretion from bovine chromaffin cells is linked to a rise of intracellular cAMP.

In vivo-effect of intraadrenal nicotine and substance P application on rat adrenal medullary catecholamine secretion

The present study was conducted to characterize in vivo the intraadrenal catecholamine (CA) secretion in rats. This was possible by using a microdialysis system (MDS) which mimics some properties of an artificial capillary. One end of this system was connected to a peristaltic pump, from the other end fractions were sampled at 5 min intervals. Concentrations of epinephrine (E) and norepinephrine (NE) in adrenal dialysate fractions were determined by HPLC electrochemical detection. Through this MDS nicotine was administered directly into the adrenal medulla of freely moving rats and the response of catecholamine release was determined. In the second part of the study the effect of exogenous substance P (SP) on spontaneous as well as on nicotine-stimulated CA release was investigated. Like nicotine, SP was administered directly into the adrenal medulla. At a flow rate of 25 microliter/min the transfer rates of CA and nicotine were approximately 1% whereas SP passed at a rate of 01.-0.2%. Under resting conditions CA release remained constant. In response to 2 x 10(-7) M nicotine (which resulted in local concentration of 2 x 10(-7) M), E and NE secretion increased 2.9 and 5.4-fold, respectively. However, due to an increased E response this difference attenuated with a later onset of the first stimulus. The higher concentrations of 10(-4) M resulted in 8.1 and 10.8-fold increases for E and NE. This latter response is clearly supraphysiologic and therefore the 2 x 10(-5) M concentration was used for further experimentation. CA secretion was stimulated with nicotine four times at 30 min intervals.(ABSTRACT TRUNCATED AT 250 WORDS)

Different steroidogenic response of young and aged porcine small and large luteal cells to prostaglandin F2 alpha, oxytocin and estradiol

The role of oxytocin (OXT) and prostaglandin F2 alpha (PGF2 alpha) in the process of luteal regulation, particularly their function in the early luteal phase is poorly understood. Therefore the effects of both compounds on in vitro steroid release of porcine luteal cells harvested from young/middle-aged (day 4-6, day 0 = 1st estrous day) or old (day 12-14) corpora lutea were tested. As corpora lutea (CL) contain at least two different steroidogenic cell populations, fractions of the so called small (SLC) and large (LLC) luteal cells were prepared and tested in separate experiments. In SLC as well as LLC from young CL OXT and PGF2 alpha inhibited progesterone (P) production but induced a strong increase of estradiol (E2) release. In old SLC and LLC OXT and PGF2 alpha were still inhibitory to P release but OXT was ineffective and PGF2 alpha had a moderate stimulatory effect on luteal E2 secretion. In SLC cultures from young but not from old CL E2 exerted a powerful stimulatory effect on progesterone (P) secretion, i.e. E2 has strong luteotrophic effects in the early luteal phase. Indeed, the pronounced inhibitory effect of OXT and PGF2 alpha on P release from SLC could be counteracted by the addition of exogenous E2 to the culture media. Therefore, we suggest that in the early luteal phase OXT as well as PGF2 alpha have an indirect, E2-mediated luteotrophic effect on P release which is stronger than the direct inhibitory action on P secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Paracrine cell to cell interactions determine the effects of pituitary adenylate cyclase activating polypeptide (PACAP) on in vitro prolactin release from rat pituitary cells

In static cultures of dispersed rat pituitary cells and in the reverse hemolytic plaque assay PACAP inhibits prolactin (Prl) secretion, while in vivo application of PACAP stimulates Prl release in rats. To elucidate the mechanism of this contradictory action, we compared the in vitro effects of PACAP on Prl secretion in cultures of dispersed or reaggregated cells and in pituitary fragments. While in monolayer cultures Prl release was inhibited by PACAP, in cultures of aggregated cells and in pituitary fragments Prl release was stimulated. Dopamine (DA) inhibited Prl release in either type of culture. PACAP also stimulated interleukin 6 (IL6) release under each of the experimental conditions. We conclude that PACAP has a direct inhibitory action on lactotropes. In addition, PACAP may induce the release of a paracrine acting factor within the pituitary which stimulates Prl release and which may be IL6. In the intact pituitary tissue and in reaggregated cells this paracrine factor stimulates Prl release more potently than PACAP directly inhibits Prl secretion resulting in a net effect of enhanced hormone release. In monolayer cultures, however, the direct inhibition is dominant, because the stimulatory paracrine factor is diluted in the culture medium. Therefore we suggest that paracrine cell to cell communication is crucial for the action of PACAP on Prl release.

The stimulatory effect of pituitary adenylate cyclase activating polypeptide (PACAP) on LH release from rat pituitary cells in vitro does not involve calcium mobilization

The hypothalamic peptide "pituitary adenylate cyclase activating polypeptide (PACAP)" stimulates cAMP production in cultured rat pituitary cells and enhances LH release. It has been suggested that the stimulation of LH release by PACAP comprises two distinct mechanisms: a direct stimulatory action on LH secretion and a potentiation of the response of the gonadotrophes to LHRH. Thus the possibility exists that PACAP may enhance LH secretion not only by increased cAMP production but also by increasing cytosolic Ca2+ concentrations ([Ca2+]). In the present study we examined whether PACAP affects cytosolic [Ca2+] in identified rat gonadotrophes (as determined by the fura-method) and whether the suggested potentiating effect of PACAP on LHRH induced LH release is dependent on Ca2+. PACAP (1 nM) and 0.1 nM LHRH significantly increased LH concentrations in the culture medium after 5 hrs of incubation. Coincubation of cells with both peptides resulted in an additive increase of LH release. While the stimulatory effect LHRH was blunted in Ca(2+)-free medium, PACAP remained stimulatory to LH release. PACAP stimulated cAMP formation regardless whether the culture medium contained Ca2+ or not. Gonadotrophes were selected by their response to LHRH (1 microM) and were subsequently challenged with PACAP (1 microM). About 75% of gonadotrophes responded also to PACAP with an increase of cytosolic [Ca2+] which was blunted by removal of extracellular Ca2+. We suggest that in the rat pituitary the majority of the gonadotrophes are PACAP responsive as determined by an increase of cytosolic [Ca2+].(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro prolactin but not LH and FSH release is inhibited by compounds in extracts of Agnus castus: direct evidence for a dopaminergic principle by the dopamine receptor assay

Women suffering from premenstrual mastodynia often respond to stimuli of prolactin (Prl) release with a hypersecretion of this hormone. Pharmacological reduction of Prl release by dopamine agonists or treatment with extracts of Agnus castus (AC) improve the clinical situation of patients with such premenstrual symptoms. Extracts of AC contain compounds which inhibit in vivo Prl release in women as well as in vitro from dispersed rat pituitary cells. It is yet unknown whether this inhibitory action of AC is only exerted on Prl release or whether release of other pituitary hormones like LH and FSH is also affected. The effects of AC on LH and FSH release were examined in vitro using rat pituitary cell cultures. To rule out that the Prl-inhibiting properties of AC are at least in part due to a cytotoxic component, pituitary cell cultures were subjected to the MTT test. To assess whether the Prl inhibitory effect of AC preparations is due to compounds acting as dopamine (DA) agonists, we used the corpus striatum membrane DA receptor binding assay. Our results demonstrate for the first time that AC extract contains an active principle that binds to the D2 receptor. Thus, it is very likely that it is this dopaminergic principle which inhibits Prl release in vitro from rat pituitary cells. Furthermore we give evidence for the specificity of action of AC on hormone release, since gonadotropin secretion remained unaffected. The findings of the present study support the therapeutical usefulness of AC extracts for treatment of premenstrual mastodynia which is associated with hypersecretion of Prl. Furthermore, the beneficial effects of AC appear to be due to the inhibition of pituitary Prl release.

Vitex agnus castus as prophylaxis for osteopenia after orchidectomy in rats compared with estradiol and testosterone supplementation

Osteoporosis research undertaken in males is rare and there are only a few therapeutic options. Phytoestrogens might be a safe alternative for prophylaxis. Sixty 3-month-old male rats were orchidectomized and divided into five groups. The groups either received soy-free food (C), estradiol (E), testosterone (T) or Vitex agnus castus in different concentrations (AC high/AC low) for 12 weeks. The tibia metaphysis was tested biomechanically and histomorphometrically. The AC high group reached 87% of the biomechanical values of the estradiol group and was significantly superior to the control group. Testosterone supplementation resulted in poor biomechanical properties. The cortical bone parameters of the AC group were similar to the control group, while supplementation with estradiol and testosterone demonstrated a reduction of cortical bone. The AC high group reached 88.4% of trabecular bone area, 80.7% of trabecular number and 66.9% of the number of trabecular nodes compared with estradiol supplementation. Vitex agnus castus demonstrated osteoprotective effects in males. It preserves the cortical as well as the trabecular bone and might be a safe alternative for HRT. Testosterone supplementation has positive effects on trabecular bone, which are concurrently counteracted by the loss of cortical bone.

Phytoestrogens: endocrine disrupters or replacement for hormone replacement therapy?

OBJECTIVES

This review presents findings with clear statements from the literature as well as own results of effects of soy, red clover and their isoflavones as well as of the Cimicifuga racemosa extract BNO 1055. Experimental and clinical effects on climacteric complaints, osteoprotective effects, activity in the urogenital tract, and risks concerning cardiovascular diseases and mammary and endometrial tissue will be compared, also in comparison to classical hormone preparations. The question whether soy and red clover products and/or Cimicifuga racemosa (CR) preparations are endocrine disrupters or may fulfill the criteria of the so-called phyto-SERMs will be discussed.

METHODS

Review of selected publications since 1980 and summary of unpublished own results of the authors.

RESULTS

Experimental and clinical evidences suggest that soy/red clover and their isoflavones do not fulfill the criteria of an ideal SERM. They appear to have mild osteoprotective effects but do not improve climacteric complaints. Furthermore, they seem to stimulate uterine growth and mammary epithelial proliferation. In ovariectomized rats, the CR extract BNO 1055 showed many of the beneficial effects of 17beta-estradiol, including effects in the brain/hypothalamus to reduce serum LH levels, effects in the bone to prevent osteoporosis and estrogenic effects in the urinary bladder. The CR extract BNO 1055 had no uterotrophic effect.

CONCLUSION

If clinical studies confirm these results, the Cimicifuga racemosa preparation BNO 1055 would appear as an ideal SERM and may therefore be an alternative to hormone replacement therapy.

Androgenic action of Tinospora cordifolia ethanolic extract in prostate cancer cell line LNCaP

AIM OF THE STUDY

Recently, Tinospora cordifolia (TC) was shown to affect prostate growth in rats. It is not known whether this is a direct effect of TC or whether it is induced by altered hormone release. To investigate the actions of TC on the prostate, human LNCaP cells were exposed to an ethanolic extract of TC.

MATERIALS AND METHODS

LNCaP cells were incubated with the test substances for 48 h. Proliferation was measured by MTT test and prostate-specific antigen (PSA) secretion was determined with ELISA.

RESULTS

TC showed a dose-dependent stimulation of proliferation of LNCaP cells. Co-incubation with the anti-androgen flutamide (FLU) reversed the TC-induced stimulation of PSA secretion.

CONCLUSIONS

The reference compound dihydrotestosterone (DHT) caused a significant increase of growth of LNCaP cells. Similarly, TC stimulated proliferation of these prostate cells. The anti-androgen FLU reversed the increase of PSA release caused by either DHT or TC. Thus, we suggest that TC may contain androgenic compounds, which appear to act via androgen receptor (AR).

Expression of estrogen receptors in the hypothalamo-pituitary-ovarian axis in middle-aged rats after re-instatement of estrus cyclicity

During reproductive aging female rats enter an anovulatory state of persistent estrus (PE). In an animal model of re-instatement of estrus cyclicity in middle-aged PE rats we injected the animals with progesterone (0.5 mg progesterone/kg body weight) at 12:00 for 4 days whereas control animals received corn oil injections. After the last injection animals were analyzed at 13:00 and 17:00. Young regular cycling rats served as positive controls and were assessed at 13:00 and 17:00 on proestrus. Progesterone treatment of middle-aged PE rats led to occurrence of luteinizing hormone (LH), follicle stimulating hormone (FSH), and prolactin surges in a subset of animals that were denoted as responders. Responding middle-aged rats displayed a reduction of ER-β mRNA in the preoptic area which was similar to the effect in young rats. Within the mediobasal hypothalamus, only young rats showed a decline of ER-α mRNA expression. A decrease of ER-α mRNA levels in the pituitary was observed in progesterone-responsive rats and in young animals. ER-β mRNA expression was reduced in young regular cycling rats. ER-β mRNA levels in the ovary were reduced following progesterone treatment in PE rats and in young rats. Taken together our data show that cyclic administration of progesterone reinstates ovulatory cycles in intact aging females which have already lost their ability to display spontaneous cyclicity. This treatment leads to the occurrence of preovulatory LH, FSH and prolactin surges which are accompanied by differential modulation of ERs in the hypothalamus, the pituitary and the ovary.

The use of flat panel volumetric computed tomography (fpVCT) in osteoporosis research

RATIONALE AND OBJECTIVES

Improvements in imaging technology have led to the increased use of computed tomography (CT). For example, micro-CT and quantitative CT (QCT) are now often used in osteoporosis research, in which micro-CT is able to analyze small bones or bone samples with high spatial resolution. In contrast, QCT is able to investigate large samples with low spatial resolution. The aim of this study was to test the usefulness of flat-panel volumetric CT (fpVCT) in a rat model of osteopenia.

MATERIAL AND METHODS

Twenty-two 3-month-old rats underwent ovariectomy and were either left untreated or supplemented with estradiol for 15 weeks. After sacrificing, the rats' second lumbar vertebral body bone mineral density (BMD) was analyzed using fpVCT and ashing. The results were compared to those of a microstructural analysis of the first lumbar vertebrae and a biomechanical evaluation of the fourth lumbar vertebrae.

RESULTS

BMD measurements using both fpVCT (0.39 vs 0.35 mg/cm(3)) and ashing (0.52 vs 0.48 mg/cm(3)) demonstrated a significant improvement after estradiol supplementation. The correlation coefficient of the two methods was 0.858. After estradiol supplementation, the bone microstructural and bone biomechanical parameters were improved, compared to no treatment. The correlations of both the microstructural and the biomechanical evaluations were closer for BMD measured using fpVCT (r = 0.482-0.769) than on the basis of ashing (r = 0.345-0.573). FpVCT was not able to display the trabecular microstructure of the rat lumbar vertebrae.

CONCLUSION

The use of fpVCT demonstrated a close relationship between morphologic and biomechanical evaluations in a rat model of osteopenia. Because of its different proportions, fpVCT might be able to bridge the gap between micro-CT and QCT in analyzing larger animals.