1α-Hydroxyvitamin D2 Partially Dissociates Between Preservation of Cancellous Bone Mass and Effects on Calcium Homeostasis in Ovariectomized Rats

Vitamin D metabolites can prevent estrogen depletion-induced bone loss in ovariectomized (OVX) rats. Our aim was to compare the bone-protective effects of 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), 1α,25-dihydroxyvitamin D₂ (1,25(OH)₂D₂), 1α-hydroxyvitamin D₃ (1α(OH)D₃), and 1α-hydroxyvitamin D₂ (1α(OH)D₂) in OVX rats. 1α(OH)D₃ and 1α(OH)D₂ are thought to be activated in the liver to form 1,25(OH)₂D₃ and 1,25(OH)₂D₂, respectively. Forty-four 12-week-old female Fischer-344 rats were either OVX or sham-operated (SHAM). Groups of OVX rats (n = 7 each) received vehicle alone, 1,25(OH)₂D₃, 1,25(OH)₂D₂, 1α(OH)D₃, or 1α(OH)D₂, starting 2 weeks after surgery. All vitamin D metabolites were administered orally at a dose of 15 ng/day/rat. Urine and blood samples were collected 6, 9, 12, and 16 weeks after surgery. Serum samples were analyzed for total calcium and phosphate. Calcium, phosphate, creatinine, and free collagen cross-links (ELISA) were determined in urine. After tetracycline double labeling, the rats were sacrificed 16 weeks postsurgery, and the proximal tibiae and the first lumbar vertebrae were processed undecalcified for static and dynamic bone histomorphometry. 1,25(OH)₂D₃ and, to a slightly lesser extent, 1,25(OH)₂D₂ elevated vertebral cancellous bone mass in OVX rats to a level beyond that observed in SHAM animals, and both compounds increased serum calcium and urinary calcium excretion to similar extents. 1α(OH)D₃ and 1α(OH)D₂ resulted in a 64% and 84%, respectively, inhibition of ovariectomy-induced vertebral cancellous bone loss. In the proximal tibial metaphysis, all vitamin D metabolites tested could only partially prevent post-OVX trabecular bone loss, with a tendency for 1α(OH)D₃ to be the least active compound. The effects of 1α(OH)D₃ and 1α(OH)D₂ on calcium homeostasis differed markedly, however. The mean increase in urinary calcium excretion over the whole experiment was fivefold for 1α(OH)D₃, whereas the corresponding increase for 1α(OH)D₂ was only twofold. We conclude that, compared with 1α(OH)D₃, 1α(OH)D₂ combined at least equal or higher bone-protective activity in OVX rats with distinctly less pronounced effects on calcium homeostasis. This effect was not due to a differential action of the corresponding main activation products, 1,25(OH)₂D₃ and 1,25(OH)₂D₂. Received: 2 May 1996 / Accepted: 18 October 1996     

Effects of Clodronate on Cortical and Trabecular Bone in Ovariectomized Rats on a Low Calcium Diet

The aim of this study was to evaluate the contribution of a low calcium diet to the cortical and trabecular osteoporosis seen in ovariectomized rats after 7 weeks on a low calcium diet and to investigate the effects of the bisphosphonate clodronate on this development of osteoporosis. Thirty-six mature, female Wistar rats were randomized into four groups: Ovx−B (bisphosphonate) and Ovx−C (control) were ovariectomized, and Sham−Ca (low calcium) and Sham+Ca (normal calcium) were sham operated. The first three groups were fed a low calcium diet (0.01%) and Sham+Ca normal rat chow (Ca 1.1%). The Ovx−B received 10 mg/kg s.c. clodronate daily for nine weeks, and Ovx−C, Sham−Ca, and Sham+Ca received the same volumes of saline. Bone mineral turnover measured as ⁸⁵Sr-uptake was increased in all low calcium groups compared to Sham+Ca. The Sham+Ca femora had higher dry weight and ash weight than the other groups, and Ovx−C had higher dry weight compared with Ovx−B and Sham−Ca. Calcium content was lower in both Ovx groups compared to both Sham groups. Magnesium was lower in all groups compared to Sham+Ca and higher in Ovx−B compared with Ovx−C. In the femoral shaft, Sham+Ca had significantly higher ultimate bending moment, energy absorption, and deflection compared to the other three groups. Ultimate bending moment was higher in Sham−Ca than in Ovx−C. Stiffness was increased in both Sham+Ca and Ovx−B compared to Ovx−C. The maximum stress in the femoral midshaft was higher in Sham+Ca than in the other groups, and higher in Ovx−B than in Ovx−C. Histomorphometry showed increased medullary area in all low calcium groups compared to Sham+Ca and larger cortical area in Sham+Ca and Ovx−B compared to Ovx−C. Compared to Sham+Ca the trabecular bone volume was decreased to 30% in Sham−Ca and to 9% in Ovx−C, but was unchanged in Ovx−B. The low calcium diet generally increased bone mineral turnover and reduced the tibial bone volume. Femoral changes led to a reduction of cortical fracture strength and maximal stress. Ovariectomy in addition to a low calcium diet reduced femoral strength even more. Daily injections of clodronate to ovariectomized rats on a low calcium diet increased femoral shaft stiffness and maximum stress, and clodronate preserved both trabecular and cortical tibial bone volume completely. Received: 11 June 1996 / Accepted: 5 March 1997     

App17肽防治去卵巢大鼠海马神经细胞的凋亡

目的:观察去卵巢大鼠几种神经元凋亡相关蛋白的表达,并用TUNEL试剂盒检测,研究缺乏雌激素是否引起神经元凋亡;评估App17肽是否能改善去卵巢大鼠的神经细胞凋亡,初步探讨App17肽的神经保护作用机制。方法:雌性Wistar大鼠随机分3组:假手术组(shamcontrol组),卵巢去势对照组(OVX组),App17肽实验组(17P+OVX组)。Sham组做假手术,OVX组和17P+OVX组做双侧卵巢切除术。17P+OVX组从卵巢去势第7周开始用App17肽治疗6周,用免疫组化和Westernblot方法观察AIF、Bax、Bcl-2的表达,用TUNEL法检测凋亡情况。结果:免疫组织化学和Westernblot结果表明App17肽实验组AIF、Bax表达明显少于去卵巢组;Bcl-2在App17肽实验组的表达明显高于去卵巢组。TUNEL结果表明App17肽实验组凋亡细胞明显少于去卵巢组。结论:雌激素缺乏引起去卵巢大鼠海马和皮层神经细胞凋亡相关蛋白改变和出现凋亡细胞,App17肽具有明显的防治作用。     

Genetic obestiy: estrogenic influences on the body weight and food intake of lean and obese adult Zucker (fa/fa) rats

The effects of chronic estrogen withdrawal and subsequent hormone replacement on the feeding and body weight of adult lean and genetically obese Zucker rats were investigated. Following confirmation of a delay in the vaginal canalization of the fatty rat, subgroups of each genotype received either ovariectomy or sham surgery (Experiment 1). One hundred days later all subjects were injected subcutaneously (SC) with 1.0 microgram of estradiol benzoate (EB) daily for 16 treatment days (Experiment 2A). A second series of daily 2.0 microgram EB injections was administered intraperitoneally (IP) for 1 week (Experiment 2B). The first experiment revealed that ovariectomy produced overeating and similar weight gains in both genotypes. In the second experiment, SC hormone treatment completely reversed ovarian obesity in lean animals but failed to alter the food intake or weight gain of fatty rats. IP administration of EB depressed the feeding of fatty and lean animals to a comparable degree but a reduction in weight gain was observed only in the lean rats. These findings are discussed in light of current theories of estrogenic modulation of energy balance.     

Organization and expression of agonistic and socio-sexual behavior in golden hamsters over the estrous cycle and after ovariectomy

Paris of hamsters were housed in large enclosures that contained separate male and female living areas and observed over the 4-day estrous cycle and after ovariectomy. Agonistic elements exhibited frequently by females included on-back, boxing, lateral posturing, and biting, whereas males engaged frequently in boxing and on-back patterns of behavior. Furthermore, on-back and boxing by females were significantly higher on estrus than on any other day of the estrous cycle. Agonistic acts performed after ovariectomy did not differ in occurrence from those shown by animals on diestrus and proestrus. Vaginal marking increased during diestrus and attained a peak 24 hr prior to sexual receptivity. Both vaginal marking and mating occurred more frequently in the female's than male's home area suggesting that vaginal marks on days preceding behavioral estrus serve to attract males to the nest of females. Males also organized their marking patterns by location as shown by more flank marking in their own than their partner's area, albeit the significance for this difference in location is not known. The results demonstrate that when heterosexual paris of hamsters are tested in large and partially familiar habitats, a wide range of behavior is exhibited and organized in a manner that is not observed in small and unfamiliar cages.     

脱脂豆粉对去卵巢大鼠骨质量的保护作用

目的 探讨脱脂豆粉对去卵巢大鼠骨质量减低的预防作用。方法 ３０只３月龄ＳＤ大鼠随机分为３组：假手术（ｓｈａｍ,Ｓ）组、脱脂粉（ｌｉｐｉｄ－ｆｒｅｅ ｓｏｙ ｐｏｗｄｅｒ,ＳＰ）组和酪蛋白（ｃａｓｅｉｎ,Ｃ）组。８周后测骨密度（ＢＭＤ）等指标。结果 ①ＳＰ组的腰椎ＢＭＤ低于Ｓ组（Ｐ〈０．０５）,股骨ＢＭＤ与Ｓ组无差异,两者均高于Ｃ组（Ｐ均〈０．０５）。②ＳＰ组腰椎的抗压强底低于Ｓ组（Ｐ〈０．０１）,股骨的抗弯强度与Ｓ组无差异,两者均高于Ｃ组（Ｐ均〈０．０１）。③ＳＰ组和Ｃ组的子宫重量均代于Ｓ组（Ｐ均〈０．０５）。结论 脱脂豆粉可以预防去卵巢大鼠股骨及部分预防其腰椎骨质量的降低,对子宫无不良影响。     

Simple, Rapid Enzyme-Linked Immunosorbent Assay (ELISA) for the Determination of Rat Osteocalcin

Determination of the concentration of osteocalcin in rat serum is frequently performed using a commercially available radioimmunoassay (RIA). However, this assay takes 3 days to complete, uses radioactive material, and has a narrow linear range. The limited range of the RIA makes it necessary to test multiple dilutions of the sample which frequently results in values that differ, depending on the dilution. In order to overcome these limitations, we have developed an ELISA that utilizes the same standards and anti-rat osteocalcin antiserum, as is used in the RIA. The principle of the ELISA is that the osteocalcin in the sample competes with osteocalcin previously immobilized on a microtiter plate to bind to the available anti-rat osteocalcin antibodies. The amount of antibody bound to the immobilized osteocalcin is determined colorimetrically using a secondary antibody coupled to alkaline phosphatase. This ELISA has a three-log linear response with a sensitivity of 0.1–0.15 ng/ml and intra- and interassay coefficient of variance (CV) values of less than 10%. Most importantly, the assay is rapid and only requires a 2-hour incubation of the sample with the antiserum. The incubation time is important since we and others have observed a significant decrease in the osteocalcin level from serum samples incubated for long periods of time with the antiserum, presumably due to degradation of the osteocalcin. In general, the commercially available RIA gives osteocalcin values that are one-half to one-fourth that of the ELISA because the RIA requires a 48-hour incubation time. Received: 14 November 1997 / Accepted: 9 July 1998     

针刺对去势雌性大鼠血脂的影响

目的　观察去势雌性大鼠模型血脂的变化及针刺对其的影响。方法　采用 6月龄 wistar雌性大鼠 80只 ,随机分成假手术组、针刺组和空白对照组。结果　去卵巢大鼠的血清胆固醇高于假手术组 ( P<0 .0 5 ) ,血清甘油三酯无明显差异。针刺组治疗后血清胆固醇低于空白对照组 ( P<0 .0 5 ) ,与假手术组对比无明显差异 ;针刺组血清甘油三酯治疗前后无明显差异 ;空白对照组血脂无明显变化。结论　去势后雌性大鼠血清胆固醇显著升高 ,血清甘油三酯无明显变化 ;针刺治疗能使去势后雌性大鼠升高的血清胆固醇水平降低到未去势大鼠血清胆固醇水平     

大豆黄酮对卵巢切除大鼠鼻黏膜上皮细胞凋亡的保护作用

目的　观察双侧卵巢切除诱导大鼠鼻黏膜上皮细胞凋亡 ,研究尼尔雌醇、大豆黄酮对此的保护作用。方法　将 60只大鼠随机分为 4组 :健康对照组 ,卵巢切除组 ,卵巢切除 +尼尔雌醇组 ,卵巢切除 +大豆黄酮组。各组动物分期分 3批处死 ,流式细胞仪检测各组动物鼻中隔黏膜的早期凋亡细胞。结果　双侧卵巢切除后 ,大鼠鼻黏膜的早期凋亡细胞百分数增高 ,术后 60d达到新的平衡。大豆黄酮、尼尔雌醇干预组与健康组比较 ,早期凋亡细胞无明显改变。结论　雌激素替代和大豆黄酮可通过减少凋亡细胞而保护鼻黏膜免受雌激素缺乏的损害