Glutamate in hypothalamic and limbic structures of diestrous, proestrous, ovariectomized and ovariectomized estrogen-treated rats

Concentrations of glutamic acid were determined in the nucleus accumbens (ACB), medial preoptic area (MPO), anterior and posterior mediobasal hypothalamus (AMBH, PMBH) and mediocortical amygdala (AMY) of diestrous (D), proestrous (P), ovariectomized (OVX) and OVX rats treated with estradiol-benzoate (EB) 12 h and 24 h before decapitation. Significant changes of glutamate concentrations were found in the ACV and PMBH. Glutamate is reduced in OVX when compared to D, P and OVX-EB rats. No significant changes of glutamate concentrations could be detected in the MPO, AMBH, and AMY.     

Dietary self-selection in intact, ovariectomized, and estradiol-treated female rats

The effects of estrogenic stimulation on diet selection were examined in intact, estrous cycling rats, ovariectomized (OVX) rats, and OVX rats given estradiol benzoate (EB) hormone replacement therapy. In Experiment 1, OVX was associated with the nearly exclusive choice of the more calorically dense diet of a pair of diets varying in the concentration of one of the three basic macronutrients (i.e., fat, carbohydrate, and protein), an effect that was decreased by EB administration. In the second experiment, dietary self-selection was examined in intact, estrous cycling rats given access to an isocaloric diet triplet of fat, carbohydrate (CHO), and protein. Total caloric intake and body weight did not vary across the estrous cycle. However, diet selection did vary. Fat intake increased; CHO and, to a lesser extent, protein intake decreased during estrus. An opposite diet selection occurred during diestrus. In Experiment 3, OVX resulted in progressive increases in CHO and protein intake, with a concurrent decrease in fat consumption. The EB treatment partially reversed this diet selection profile (Experiment 4). These results were confirmed by diet pairs with both naturally occurring and experimentally produced estrogenic stimulation (Experiments 5 and 6). These data are consistent with the findings of previous research demonstrating estrogenic reduction in CHO intake with standard high-CHO commercial diets. In addition, an increase in fat intake during estrogenic stimulation was found.     

Sandblasted titanium osteointegration in young, aged and ovariectomized sheep

To evaluate how aging and estrogen deficiency influence the success rate of Sandblasted Titanium (Ti/SA) implants, the osteointegration of Ti/SA rods was studied in the cortical and trabecular bone of 5 young, 5 aged and 5 ovariectomized (OVX) sheep. The characterization of the host bone by transiliac biopsies of the iliac crest showed a progressive rarefaction of trabecular bone in aged and OVX animals when compared to young ones. A significant reduction, both in cortical and trabecular bone, of the osteointegration rate of Ti/SA rods in the presence of estrogen deficiency compared to young animals was observed, while only a minor reduction was observed in aged animals. These results were confirmed by the pushout test in cortical bone. Bone quality affected the biological response of bone to Ti/SA implants in both trabecular and cortical bone; consequently, strategies to maximize the bone osteogenic properties of osteoporotic patients should be adopted.     

Skeletal effects of magnesium deficiency in normal,ovariectomized, and estrogen-treated rats

The effects of magnesium deficiency in ovariectomized and estrogen-treated rats were examined in histological sections of bones and various soft tissues. The changes observed in the femora of intact rats deprived of magnesium for three weeks were: 1. a general increase in diaphyseal thickness, 2. the presence of localized fibrous or bony-like masses in subperiosteal and metaphyseal sites, and 3. the occurrence, although rare, of endosteal hyperplasia. In ovariectomized, magnesium-deprived animals, the incidence and location of fibrous masses were similar to that in the femora of magnesium-deficient intact rats; however, no increase in diaphyseal thickness was noted. Daily injections of 25 μg estradiol caused a reduction of the frequency of skeletal hyperplasia from 80% to 20%, as well as a reduction in femoral diaphyseal thickness. Estradiol hormone administration also brought about a marked alleviation of the dermal and neural manifestations of magnesium deficiency, but, at the same time, caused an exacerbation of renal calcinosis.     

Importance of feeding time in pair-fed, ovariectomized rats

The present investigation was designed to determine the effects of feeding time on body weight gain in ovariectomized (OVX) rats pair-fed with sham operated control rats. In pair feeding, a test and a control rat were each fed the same amount of food. In the first experiment, OVX rats and controls were pair-fed at 1900, just before the dark phase of the light-dark cycle. Body weight gain was observed for 36 days. There was no significant difference in weight gain between the two groups. In the second experiment, when rats were pair-fed chow, starting from 1200, there was a significant increase in the body weight of the OVX group compared to the sham operated control group. Observation continued for 56 days. In the third experiment, the OVX group in the pair-fed condition and the sham control group were pair-fed at 1900 for 56 days and feeding was then switched to 0500 (just before the beginning of the light cycle) for 28 days. The body weight gain in the OVX pair-fed group was quite similar to that of the sham control group when feeding started at 1900, but a significant increase in body weight gain of the OVX group was observed after switching the starting time of feeding to 0500. In conclusion, the results suggest that the time of daily feeding may be important for body weight gain during the dynamic phase after ovariectomy.     

Skeletal effects of magnesium deficiency in normal, ovariectomized, and estrogen-treated rats.

The effects of magnesium deficiency in ovariectomized and estrogen-treated rats were examined in histological sections of bones and various soft tissues. The changes observed in the femora of intact rats deprived of magnesium for three weeks were: 1. a general increase in diaphyseal thickness, 2. the presence of localized fibrous or bony-like masses in subperiosteal and metaphyseal sites, and 3. the occurrence, although rare, of endosteal hyperplasia. In ovariectomized, magniesium-deprived animals, the incidence and location of fibrous masses were similar to that in the femora of magnesium-deficient intact rats; however, no increase in diaphyseal thickness was noted. Daily injections of 25 mug estradiol caused a reduction of the frequency of skeletal hyperplasia from 80% to 20%, as well as a reduction in femoral diaphyseal thickness. Estradiol hormone administration also brought about a marked alleviation of the dermal and neural manifestations of magnesium deficiency, but, at the same time, caused an exacerbation of renal calcinosis.     

The median eminence in normal,ovariectomized, and ovariectomized-estradiol-treated hamsters: An ultrastructural study

In an effort to define more clearly the effect various plasma concentrations of estrogen have on the morphology and function of tanycytes, the present investigation examined the median eminence (ME) of normally cycling, ovariectomized, and ovariectomized-estradiol-treated hamsters. In normally-cycling animals, when endogenous estrogen was at its highest level (day 4 or proestrus), numerous microappendages arose from the luminal surfaces of tanycytes located in the ventrolateral region of the ME. Large blebs (1.0–5.0-μm diameter), miniblebs (1.0-μm diameter), and microvilli dominated the surfaces of these cells. Large blebs appeared to have been formed by the coalescence of several miniblebs and were composed of cytoplasmic ground substance devoid of organelles. The peduncular shape of many of these blebs suggested their involvement in an apocrinelike secretion by the tanycyte. When endogenous estrogen levels were low (day 1 of the estrous cycle), the tanycytes of normally cycling hamsters possessed slightly fewer microappendages. Following ovariectomy, large blebs were nearly absent from the luminal surfaces of tanycytes, and the number of miniblebs and microvilli were also greatly reduced. Subcutaneous injections of 17-beta estradiol benzoate restored the large blebs to the tanycyte surface. The number and variety of tanycytic microappendages in these animals resembled those in normally cycling hamsters on day 4 of the estrous cycle. The present study demonstrates that tanycytes of the hamster ME are sensitive to estrogen and vary in their morphology in relation to the animal's reproductive status. These changes in tanycyte morphology can be correlated directly to functions of absorption (microvilli) and secretion (blebs). The sensitivity of tanycytes to estrogen suggests that these cells may also play a role in the hypophyseal-ovarian feedback mechanism.     

Melatonin and estradiol effects on food intake, body weight, and leptin in ovariectomized rats

OBJECTIVE: The study in ovariectomized (Ovx) rats, as a model of menopausal status, of the effects of melatonin (M) and/or estradiol (E), associated or not with food restriction, on body weight (BW) and serum leptin levels. METHODS: Female SD rats (200-250 g) were Ovx and treated with E, M, E+M or its diluents. Control sham-Ovx rats were treated with E-M diluents. After 7 weeks being fed ad libitum, the animals were exposed for 7 more weeks to a 30% food restriction. We measured: food intake, BW, nocturnal and diurnal urinary excretion of sulphatoxymelatonin (aMT6s), leptin in midday and midnight blood samples, glucose, total cholesterol, LDL, HDL and triglycerides. RESULTS: Day/night rhythm of aMT6s excretion was preserved in all cases. The increase of aMT6s excretion in M-treated animals basically affected the nocturnal period. In animals fed ad libitum, E fully prevented Ovx-induced increase of BW, leptin and cholesterol. Melatonin reduced food intake and partially prevented the increase of BW and cholesterol, without changing leptin levels. Under food restriction, M was the most effective treatment in reducing BW and cholesterol. Leptin levels were similar in M, E or E+M treated rats, and lower than in untreated Ovx rats. CONCLUSIONS: Our result gives a preliminary experimental basis for a post-menopausal co-treatment with estradiol and melatonin. It could combine the effectiveness of estradiol (not modified by melatonin) with the positive effects of melatonin (improvement of sleep quality, prevention of breast cancer, etc.). The possible beneficial effects of melatonin which could justify its use, need to be demonstrated in clinical trials.     

Time course of behavioral, physiological, and morphological changes after estradiol treatment of ovariectomized rats

Previous studies showed that treatment with 17-β-estradiol-3-benzoate (EB) reduces isoproterenol (ISOP) stimulated water intake by ovariectomized rats. This effect was observed 48h after the second of two EB injections, suggesting that the attenuation is attributable to classic EB actions to alter gene expression. However, in addition to classic, slowly-occurring, genomic effects, estrogens have more rapidly-occurring effects that may be nongenomic or 'nonclassical' genomic effects. Thus, it is possible that the EB attenuation of water intake stimulated by ISOP is genomic, nongenomic, or both. Accordingly, we measured ISOP-induced water intake by OVX rats at different times after EB injections, using time points likely to indicate classic genomic effects (48h or 24h) or nonclassical genomic or nongenomic effects (90min). We also examined EB effects on body weight, uterine weight, and plasma volume and Na(+) concentration in the same animals using the same time points and EB dose. EB treatment decreased water intake stimulated by ISOP in both the 24-h and 48-h groups; however, water intake in the 90-min group was not affected by EB. Uterine weight was unchanged 90min after EB, but was increased 24h after the first injection of EB. In contrast, body weight decreased after EB, but not until 48h after the second EB injection. Finally, EB did not alter plasma Na(+) concentration or hematocrit, though plasma protein concentration increased transiently 24h after EB treatment. Taken together, these findings suggest that the behavioral, morphological, and physiological effects of EB likely are attributable to slowly-occurring, classic genomic actions of estrogens. Moreover, the time course of the observed effects varied, suggesting tissue-specific differences in estrogen receptor density or subtype, or in co-activators or co-repressors that, ultimately, determine the timing and direction of EB effects.     

龟鹿胶、淫羊藿及红景天对骨质疏松大鼠骨密度及破骨细胞的影响

背景：中药研究骨质疏松症目前缺乏系统的药效学研究,中药组方尚欠精简,机制研究与中医理论指导不够紧密。 目的：观察中药复方龟鹿胶、淫羊藿、红景天对去卵巢大鼠血清各指标、骨密度及破骨细胞的的调控作用。 方法：建立去卵巢大鼠模型,分别用自拟中药组方龟鹿胶组、淫羊藿组、红景天组进行灌胃,以假手术组和模型组进行对比。造模后第4周开始称体质量,每周1次。造模后12周后测定大鼠骨密度、血清中钙、磷含量、血碱性磷酸酶活性等指标比较治疗效果,应用体外培养破骨细胞观察各组中药对破骨细胞抑制率的影响。 结果与结论：龟鹿胶能显著减少去卵巢大鼠体质量的增加幅度(P < 0.05)。相比模型组3种中药治疗组大鼠血清中钙含量明显升高(P < 0.05),血磷与碱性磷酸酶活性明显降低(P < 0.01或P < 0.05)。龟鹿胶组和淫羊藿组大鼠骨密度显著高于模型组(P < 0.05)。3种中药治疗组与假手术组相比吸收陷窝数明显减少(P < 0.05),其中红景天组吸收陷窝数减少较显著(P < 0.01),红景天组对破骨细胞吸收功能具有抑制作用,抑制率为86.85%(P < 0.01)。结果证实,中药组方龟鹿胶、淫羊藿、红景天对去卵巢骨质疏松均具有显著疗效,其中龟鹿胶组和淫羊藿组主要以增加骨密度为主,红景天组具体表现在对破骨细胞吸收功能具有抑制作用。     

Hyperviscosity syndrome in ovariectomized rats

Ovariectomy reduces blood levels of sex hormones and considerably increases blood viscosity due to an increase in hematocrit and plasma fibrinogen content, disorders in viscoelastic characteristics of erythrocytes, and increase of their aggregation activity. Changes in the macrorheology are mainly responsible for the development of the hyperviscosity syndrome. __________ Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 146, No. 7, pp. 101–104, July, 2008     

Effects of raloxifene on bone density,biomarkers, and histomorphometric and biomechanical measures in ovariectomized cynomolgus monkeys

OBJECTIVE: The purpose of this study was to determine the effect of raloxifene on bone density, strength, metabolism, and histomorphometric characteristics in ovariectomized cynomolgus monkeys. DESIGN: A prospective, longitudinal study was designed to examine the effects of conjugated equine estrogens (0.04 mg/kg, CEE) and raloxifene (1 or 5 mg/kg, R1 and R5, respectively) on bone density, biomarkers, histomorphometry, and strength. Control groups included ovariectomized and sham-operated monkeys. Treatment was initiated the day after ovariectomy and continued for 24 months. Bone biomarker data were collected at baseline and every 3 months after surgery. Bone mass was determined at baseline and every 6 months after ovariectomy. Iliac biopsies were collected at baseline and 16 months postovariectomy, and the second lumbar vertebra and left midshaft femur collected at necropsy were examined histomorphometrically. Bone biomechanical properties were determined for the right femur and vertebrae. RESULTS: Compared with the placebo-treated ovariectomized monkeys, the high-dose raloxifene group had lower levels of alkaline phosphatase, tartrate-resistant acid phosphatase, urinary CrossLaps (collagen degradation products), and greater bone mass in the lumbar vertebrae. In the endocortical compartment, the high-dose raloxifene group had significantly lower mineralizing surface, mineral apposition rate, and bone formation rate in the iliac biopsy collected at 16 months and lower bone formation rate in the second lumbar vertebra. Within the midshaft femur, low-dose raloxifene significantly decreased the osteonal and total bone formation rates and also prevented the decrease in Young's modulus induced by ovariectomy in the midshaft femur. CONCLUSIONS: High-dose raloxifene prevented the development of osteopenia in the ovariectomized monkey by reducing bone turnover, albeit to a lesser extent than CEE. Histomorphometric and biomarker data suggest that mechanisms underlying the effect of raloxifene differ somewhat from that of CEE.     

Comparative effects of risedronate,atorvastatin, estrogen and SERMs on bone mass and strength in ovariectomized rats

Objective

The aim of this study was to investigate bone protective effects of risedronate, atorvastatin, raloxifene and clomiphene citrate in ovariectomized rats.

Methods

Our study was conducted on 63 rats at Experimental Research Center of Celal Bayar University. Six-month-old rats were divided into seven groups. There were five drug administered ovariectomized groups, one ovariectomized control group without drug administration and one non-ovariectomized control group without drug administration. Eight weeks postovariectomy, rats were treated with the bisphosphonate risedronate sodium, the statin atorvastatin, the estrogen 17β-estradiol and the selective estrogen receptor modulators (SERMs) raloxifene hydrochloride and clomiphene citrate by gavage daily for 8 weeks. At the end of the study, rats were killed under anesthesia. For densitometric evaluation, left femurs and tibiae were removed. Left femurs were also used to measure bone volume. Right femurs were used for three-point bending test.

Results

Compared to ovariectomized group, femur cortex volume increased significantly in non-ovariectomized group (p = 0.016). Compared to non-ovariectomized group, distal femoral metaphyseal and femur midshaft bone mineral density values were significantly lower in ovariectomized group (p = 0.047). In ovariectomy + atorvastatin group, whole femur and femur midshaft bone mineral density and three-point bending test maximal load values were significantly higher than ovariectomized group (p = 0.049, 0.05, and 0.018). When compared to the ovariectomized group, no significant difference was found with respect to femoral maximum load values in groups treated with risedronate, estrogen, raloxifene and clomiphene (p = 0.602, 0.602, 0.75, and 0.927). In ovariectomy + risedronate group, femur midshaft bone mineral density values were significantly higher than the values in ovariectomized group (p = 0.023). When compared to ovariectomized group, no significant difference was found with respect to femur midshaft bone mineral density values in groups treated with estrogen, raloxifene and clomiphene (p = 0.306, 0.808, and 0.095).

Conclusions

While risedronate sodium prevented the decrease in bone mineral density in ovariectomized rats, atorvastatin maintained mechanical characteristics of bone and also prevented the decrease in bone mineral density as risedronate sodium.     

Localization of relaxin in endometrial gland cells of pregnant,lactating, and ovariectomized hormone-treated guinea pigs

Uteri taken from guinea pigs in different stages of pregnancy and during lactation, as well as animals that had been ovariectomized and treated with hormones, were examined for relaxin with the peroxidase-antiperoxidase (PAP) technique employing an antiserum produced against porcine relaxin. While relaxin was not detected in uteri of day 15 pregnant animals, small amounts were noted in a few endometrial glands in day 30 pregnant animals. Uteri from day 45, day 60, and late-pregnant animals exhibited heavy amounts of relaxin; however, endometrial gland cells from lactating animals contained very little or no relaxin. Injections of estrogen and progesterone that brought a relaxation of the pelvic ligaments in ovariectomized guinea pigs also induced an accumulation of relaxin in the endometrial glands. Relaxin was not detected in nonendometrial portions of the uterus, endometrial stromal components, luminal surface epithelium, or uterine cervical glands. Extracts prepared from uteri of day 45, day 60, and late-pregnant animals showed positive responses for relaxin in the mouse uterus bioassay.     

Androgens and reproductive behavior in ovariectomized ring doves

Eighteen ovariectomized ring doves (Streptopelia risoria) received subcutaneous silastic implants of either testosterone propionate (TP), 5 alpha-dihydrotestosterone propionate (DHTP) or cholesterol. Birds were paired daily for 1-hr with intact males. Eleven days after implantation the pairs were observed. Both TP and DHTP activated wingflipping behavior in the females. None of the females showed receptive crouching. Aromatization of testosterone to estrogen does not appear to be involved in wingflipping in female doves. The results suggest that wingflipping in females is not as hormone specific as it appears to be in male doves.     

Curculigo orchioides, a traditional Chinese medicinal plant, prevents bone loss in ovariectomized rats

OBJECTIVE: Natural medicines derived from plants have aroused increasing interest in the prevention and treatment of osteoporosis. This is due to their unique characteristics as these are more suitable for long-term use compared with synthesized chemicals and have apparently fewer adverse effects. Curculigo orchioides (CO) has a long history in the treatment of postmenopausal osteoporosis in traditional Chinese medicine. The present study was designed to investigate the protective effects of ethanol extracts of CO on ovariectomy-induced bone loss. METHODS: Sixty female (4.5-month-old) Sprague-Dawley rats were assigned to sham and OVX groups. The OVX rats were further divided into five subgroups treated respectively, with vehicle, nylestriol (1 mg/kg, i.g.) and CO extract (0.5, 1.0, and 2.0 g/kg, i.g.) for 12 weeks. Bone mineral density (BMD) and bone mineral content (BMC) were measured by peripheral quantitative computerized tomography (pQCT) densitometry. Serum phosphorus, calcium, ACTH, corticosterone, deoxypyridinoline crosslinks to creatinine ratio (DPD/Cr), alkaline phosphate (ALP), tartrate-resistant acid phosphatase (TRAP), osteoprotegerin (OPG), IL-6, and TNF-alpha were also determined. RESULTS: Administration of CO extract prevented bone loss in the trabecular bone of the tibia in ovariectomized rats without affecting the weight of the body and the uterus, and increased serum phosphorus, calcium, and OPG levels, decreased serum DPD/Cr, TRAP, ACTH, and corticosterone levels, but did not alter serum TNF-alpha, IL-6, and ALP levels in ovariectomized rats. CONCLUSION: CO ethanol extract has a definite protective effect on bone loss in ovariectomized rats by inhibiting bone resorption and increasing serum phosphorus and calcium levels, without affecting bone formation. Therefore, CO can be considered a potential antiosteoporosis herbal plant, although more studies are needed to clarify its real potential chemical constituents and their mechanism of action.     

Effects of alfacalcidol on muscle strength, muscle fatigue, and bone mineral density in normal and ovariectomized rats

Vitamin D affects not only bone but also muscle to prevent falls and osteoporotic fractures. However, these effects on muscle and the mechanisms of fall prevention are still unclear. The purpose of this study was to investigate the effects of alfacalcidol [1α(OH)D(3)] on muscle strength, muscle fatigue, and bone mineral density (BMD) in ovariectomized rats. Seven-month-old female Wistar rats were orally administered 1α(OH)D(3) or its vehicle everyday for 4 weeks after ovariectomy (OVX) or sham operation. Calf muscle strength and fatigue were evaluated by electrical stimulation of the sciatic nerve under general anesthesia. 1α(OH)D(3) administration significantly increased the maximum muscle strength in the sham-operated (P < 0.01) and the OVX (P < 0.01) groups compared to their respective control groups. However, 1α(OH)D(3) administration did not significantly affect muscle fatigue in these groups. The BMD of the femur in the 1α(OH)D(3)-treated OVX group was significantly higher than that in the vehicle-treated OVX group (P = 0.04). These results suggested that 1α(OH)D(3) increases muscle strength but does not affect muscle fatigue in this rat model. The effectiveness of activated vitamin D in preventing bone fractures may be partly owing to its effect on muscle strength in addition to its known effect on bone metabolism.     

Serum oestriol, oestrone and oestradiol concentrations during oral oestriol succinate treatment in ovariectomized women

Serum oestriol, oestrone and 17β-oestradiol concentrations during oral oestriol succinate treatment were investigated in ovariectomized women. Either a single dose of 8 mg or two doses of 4 mg were given daily. With the second divided dosage the serum oestriol levels remained uniform. The oestriol concentrations were clearly higher than in the beginning or in the middle of the normal menstrual cycle in the fertile woman. With both treatment schemes the ratio E₃/(E₂ + E₁) was clearly higher than before treatment and during the normal menstrual cycle. Oestriol succinate treatment lowered the ratio E₁/(E₂ + E₃), which was rather similar to the one during normal menstrual cycle.