Responses of gonadotropin secretion to short-term dietary supplementation in ovariectomized goats with different body weights

The responses of luteinizing hormone (LH) and follicle stimulating hormone (FSH) secretion to acute dietary supplementation were studied in goats with different body weights. Ovariectomized Shiba goats (n = 11) were used and were maintained with a feed of 100% of their energy requirement. They were implanted subcutaneously with an oestradiol capsule and were divided into light (LBW; ≤24 kg, n = 6, mean ± S.D., 21.8 ± 2.7 kg) and heavy body weight (HBW; >24 kg, n = 5, mean ± S.D., 32.0 ± 6.3 kg) groups on the basis of their body weights at 8 days before the start of treatment. At the start of treatment (Day 1), the level of a feed changed to 250% of their energy requirement and this level was maintained for 7 days in both groups. Blood samples were collected daily from Day −7 to Day 7 for the analysis of FSH, glucose, and insulin profiles in plasma. Frequent blood samples were also collected at 10 min intervals for 6 h on Day 0, Day 3, and Day 7 for analysis of LH pulses. LH pulse frequency increased significantly on Day 3 as compared with that on Day 0 in both the HBW (7.4 ± 0.5 pulses/6 h vs. 6.2 ± 0.8 pulses/6 h, p < 0.05) and LBW (6.5 ± 0.8 pulses/6 h vs. 5.5 ± 0.5 pulses/6 h, p < 0.05) groups, whereas it decreased on Day 7 (HBW, 6.4 ± 0.9 pulses/6 h; LBW, 6.3 ± 1.6 pulses/6 h, p > 0.05 vs. Day 0). Plasma glucose and insulin concentrations increased temporarily from Day 2 to Day 4 and then decreased to the level before the start of dietary supplementation in both groups. There was no significant difference in the LH pulse frequency or daily concentrations of FSH, glucose, or insulin between the HBW and LBW groups throughout the experimental period. The present study indicated that acute dietary supplementation stimulates pulsatile LH secretion in parallel with a rise of blood glucose and insulin levels. However, the influence of body weight on these responses between light and heavy animals was not observed.     

Plasma luteinizing hormone concentrations in cows given repeated treatments or three different doses of gonadotropin releasing hormone

We hypothesized that: (i) repeated GnRH treatments would increase the magnitude and duration of the LH surge and would increase progesterone (P4) concentrations after ovulation; and (ii) the release of pituitary LH would be greater in response to larger doses of GnRH. In Experiment 1, ovary-intact cows were given an intravaginal P4 (1.9 g) insert (CIDR) for 10 d and 500 μg cloprostenol (PGF) at CIDR removal to synchronize estrus. On Days 7 or 8 after estrus, cows received two PGF treatments (12 h apart) and 100 μg GnRH at 36 (Control), 36 and 38 (GnRH38), or 36 and 40 h (GnRH40) after the first PGF. Mean plasma LH concentration (ng/mL) was greater (P < 0.05) in GnRH38 (8.8 ± 1.1) than in Control (5.1 ± 1.3), with that in GnRH40 (5.8 ± 1.3) being intermediate. Although the duration (h) of the LH surge was longer in GnRH40 (8.0 ± 0.4) than in either GnRH38 (P < 0.05; 7.0 ± 0.3) or Control (P < 0.09; 7.1 ± 0.4), mean postovulatory P4 (ng/mL) was greater (P < 0.01) in Control (4.2 ± 0.7) than in GnRH38 (2.9 ± 0.6) or GnRH40 (3.0 ± 0.7) cows. In Experiment 2, ovariectomized cows were given a CIDR for 10 d and 2 mg of estradiol cypionate im at CIDR insertion. Thirty-six hours after CIDR removal, cows received, 50, 100, or 250 μg of GnRH. Cows given 250 μg GnRH released more LH (9.4 ± 1.4 ng/mL) than those given 50 or 100 μg (6.1 ± 1.3 and 5.4 ± 1.4 ng/mL, respectively), and had an LH surge of longer duration than those given 50 μg (6.8 ± 0.4 vs. 5.1 ± 0.3 h). In summary, ovary-intact cows in the GnRH38 group had greater mean and peak LH concentrations, but subsequent plasma P4 concentrations were lower than in Control cows. Ovariectomized cows given 250 μg GnRH had a greater pituitary release of LH.     

不同干预疗法对去卵巢骨质疏松大鼠肱骨骨矿物质含量影响

目的:对比观察不同干预疗法对去卵巢骨质疏松大鼠肱骨骨矿物质含量的影响。方法:按体重将80只成年雌性SD大鼠分层后随机分为假手术组和去卵巢组。手术11周时,将去卵巢组大鼠按体重分层后又随机分为去卵巢组、跑台运动组、振动组、金雀异黄酮组、氯化锂组和雌激素组。跑台运动组每周进行4次45 min、速度18 m/min、跑道倾角5°的跑台训练;振动组每天进行2次15 min、频率90 HZ/min、7次/周的振动治疗;金雀异黄酮组每天按体重灌胃1次金雀异黄酮,剂量为1 mg/kg体重;氯化锂组每周按体重腹腔注射氯化锂3次,剂量为15 mg/kg;雌激素组每周按体重颈部皮下注射3次17β-雌二醇,剂量为25μg/kg。持续处理8周时,于末次处理结束36-48小时内,按解剖位置截取双肱骨,称量肱骨湿重、去脂肪干重以及煅烧后的灰重。结果:与假手术组比较,去卵巢组肱骨湿重/体重、去脂肪干重/体重和灰重/体重均显著下降;与去卵巢组比较,跑台运动组、振动组、金雀异黄酮组和雌激素组肱骨湿重/体重、去脂肪干重/体重、灰重/体重均显著增加,而氯化锂组虽有所升高,但差异无显著性。结论:除氯化锂处理外,其他几种处理均能减缓去卵巢骨质疏松大鼠肱骨骨量的丢失,对防治去卵巢骨质疏松大鼠的骨质疏松有一定的作用。     

Estrogen receptors mediate estradiol's effect on sensitization and CPP to cocaine in female rats: Role of contextual cues

Preclinical studies show that estradiol enhances sensitization to cocaine in females by mechanisms not fully understood. These studies consistently show that ovariectomized (OVX) rats exhibit little or no sensitization to cocaine compared to OVX rats administered estradiol. In this study we varied the dose of cocaine (10, 15, and 30 mg/kg), the length of cocaine treatment (from 5 to 10 days) and the context of cocaine injections to determine if these factors play a role on estradiol's effects on cocaine sensitization. Because OVX rats are hormonally compromised, they are not representative of the natural state of the animal, and thus the physiological context of these studies remains unclear. To address this issue, we blocked ERs in gonadally intact females by icv administration of the antiestrogen ICI-182,780.     

不同疗法对去卵巢大鼠子宫ERα和ERRα蛋白表达的影响

目的:本研究旨在对比观察全身垂直振动、跑台运动、金雀异黄酮和氯化锂等不同干预疗法对去卵巢骨质疏松大鼠子宫雌激素受体α(ERα)和雌激素受体相关受体α(ERRα)蛋白表达的影响。方法:将80只3月龄雌性SD大鼠按体重分层后随机分为假手术组和去卵巢组。去卵巢10周时,将去卵巢组大鼠按体重分层后又随机分为去卵巢组、振动组、跑台组、金雀异黄酮组、氯化锂组和雌激素组,并开始进行不同的干预处理。干预处理8周时,腹主动脉取血处死各组大鼠,用放射免疫方法检测血清E_2水平,用Western blot检测子宫ERα和ERRα蛋白表达水平的变化。结果:大鼠去卵巢后,血清E_2水平显著下降,经雌激素处理后,血清E_2水平显著回升,但经其他几种方法处理后均无显著变化。Western blot结果显示,大鼠去卵巢后,子宫ERα蛋白表达水平显著增加,经雌激素、跑台运动、全身垂直振动和氯化锂处理后,子宫ERα蛋白表达水平显著下降,而经金雀异黄酮处理后,子宫ERα蛋白表达水平无显著变化。大鼠去卵巢后,子宫ERRα蛋白表达水平显著下降,经雌激素和金雀异黄酮干预后,子宫ERR-α表达水平显著增加,而经跑台运动、全身振动和氯化锂干预后,子宫ERR-α表达水平却显著下降。结论:跑台运动和全身垂直振动能抑制去卵巢骨质疏松大鼠子宫ERα和ERRα蛋白的表达,氯化锂能抑制ERα蛋白的表达,但促进ERRα蛋白的表达,金雀异黄酮能促进ERRα蛋白的表达,但对ERα蛋白的表达没有影响。     

Effects of the gonadotropin-releasing hormone associated peptides (GAP) on the release of luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL) in vivo

Six peptide sequences residing between basic amino acid residues in GAP were tested for effects on the release of FSH, LH and PRL in vivo in ovariectomized, estrogen-progesterone-primed (OEP) rats. Synthetic GAP peptides (1–13, 1–23, 15–23, 25–36, 38–53 and 41–53) were injected intravenously (IV) into conscious OEP rats and plasma levels of FSH, LH and PRL were measured by RIA. The activity of GAP peptides in the control of PRL was further examined in ether-stressed male rats which were injected IV with GAP peptides just prior to a 1-min etherization. GAP(1–13) significantly stimulated FSH release at doses of 1, 10 and 100 μg, whereas it stimulated LH release only at the highest dose of 100 μg. GAP(1–23) elevated plasma levels of FSH and LH only at a dose of 100 μg. The other 4 peptides had no effect on the release of gonadotropins. Of these 6 peptides, only GAP(1–13) partially lowered the plasma levels of PRL at the high dose of 100 μg in OEP rats, but it had no effect on the ether-induced PRL surge at doses of 10 and 100 μg. In conclusion, both GAP(1–13) and GAP(1–23) stimulate FSH and LH release in vivo; these 2 peptides are much less potent in stimulating gonadotropin release than is LHRH. GAP(1–13) exerts a preferential FSH-releasing activity, but its PRL-inhibiting activity is minimal.     

Cholesterol-fed ovariectomized monkeys are good animal models for human atherosclerosis of postmenopausal women

Although it is well known that the incidence of atherosclerosis is markedly increased in postmenopausal women, antiatherosclerotic effects of estrogen replacement therapies are not clear. One of the reasons for this is due to the lack of appropriate animal models for atherosclerosis of postmenopausal women. Therefore, we attempted to develop an animal model for atherosclerosis of postmenopausal women and examined the antiatherosclerotic effects of estrogen replacement therapy. Adult ovariectomized Japanese monkeys were fed 2% cholesterol diet alone (C-group) or in combination with conjugated estrogen (CE-group) for 30 months. The serum estradiol-17β levels of the CE-group were varied between 10 and 204.5 ng/dl during treatment. In the C-group, the serum total cholesterol levels were increased from 110 to 270 mg/dl, and atheroma was first observed after 3-months treatment with angioscopy. In the CE-group, the levels of the serum total cholesterol during treatment were 30% lower than those of the C-group, and the aortic lesions were first observed after 12-months treatment with angioscopy. The aortic intimal thickness of the CE-group was 58% of the C-group. This finding showed good agreement with the angioscopic observation. The aortic lesions were of a fibromuscular type in both groups. In conclusion, a cholesterol-fed ovariectomized monkey is an appropriate animal model for atherosclerosis of postmenopausal women. Furthermore, angiofiberscopic and histopathological observations suggested that estrogen replacement therapy was valid for atherosclerosis of postmenopausal women.     

Dietary supplementation with dried plum prevents ovariectomy-induced bone loss while modulating the immune response in C57BL/6J mice

This study was designed to investigate the effects of dried plum on the changes in bone metabolism and the immune response associated with ovarian hormone deficiency. Adult female C57BL/6J mice were either sham-operated (Sham) and fed AIN-93 diet (control) or ovariectomized (OVX) and fed a control diet with 0%, 5%, 15% or 25% dried plum (w/w), corresponding to control, low- (LDP), medium- (MDP) and high (HDP)-dose dried plum. Four weeks of HDP supplementation prevented the decrease in spine bone mineral density and content induced by OVX. The OVX compromise in trabecular bone of the vertebra and proximal tibia was prevented by the higher doses of dried plum, and in the vertebra these effects resulted in greater (P<.05) bone strength and stiffness. In the bone marrow, OVX suppressed granulocyte and committed monocyte populations and increased the lymphoblast population, but the MDP and HDP restored these myeloid and lymphoid populations to the level of the Sham. Dried plum also suppressed lymphocyte tumor necrosis factor (TNF)-α production ex vivo by splenocytes, in response to concanavalin (Con) A stimulation. These data indicate that dried plum's positive effects on bone structural and biomechanical properties coincide with the restoration of certain bone marrow myeloid and lymphoid populations, and suppressed splenocyte activation occurring with ovarian hormone deficiency.     

跑台运动训练和停训对去卵巢大鼠体成分和骨密度的影响

目的:研究中等强度跑台运动训练和停训对去卵巢大鼠骨密度和体成分的影响。方法:将60只成年雌性SD大鼠按体重分层后随机分为假手术组、去卵巢静止组和去卵巢运动组,每组20只。去卵巢运动组大鼠每周进行4次时间45min、速度18m/min、跑道倾角5℃的跑台训练,持续训练14周时,将各组大鼠又随机分为两个亚组,即:假手术-16周(Sham-16)和假手术32周(Sham-32)组、去卵巢-16周(OVX-16)和去卵巢-32周(OVX-32)组以及去卵巢运动(EX)和停训组(DEX)。分别在末次训练结束36-48小时内或停训16周时,用双能X线骨密度仪检测各组大鼠体成分和骨密度的变化。结果:(1)训练结束时,OVX-16组大鼠体脂重量和含量显著高于Sham-16和EX组,而瘦体含量、全身骨密度和腰椎骨密度显著低于Sham-16和EX组,各组其他检测指标无显著变化。(2)停训16周时,OVX-32组大鼠体重、脂肪重量和体脂含量显著高于Sham-32组,而全身、腰椎和左右股骨骨密度以及瘦体含量显著低于Sham-32组;DEX组大鼠脂肪重量和体脂含量显著高于OVX-32组,而瘦体含量显著低于OVX-32组。结论:跑台运动对去卵巢大鼠体成分和骨密度的改善效应在停训16周时均未能被保持。