马来酸罗格列酮对去势大鼠骨微结构的影响

目的:研究马来酸罗格列酮对去势大鼠骨微结构的影响。方法:21只24周龄Wistar大鼠双侧卵巢切除,随机分为对照组、罗格列酮A(RA)组、罗格列酮B(RB)组,每组7只。RA组、RB组每只大鼠分别给予马来酸罗格列酮0.35 mg/d、0.70 mg/d(以生理盐水溶解灌胃),对照组以相同体积生理盐水灌胃。给药4周后使用micro-CT分别测定股骨、胫骨、椎骨的骨量/组织量(BV/TV)、骨小梁数目(Tb.N)、骨小梁厚度(Tb.Th)、骨小梁分离度(Tb.Sp)、骨表面积/骨量(BS/BV)。结果:与对照组相比,RA组及RB组各部位(股骨、胫骨、椎骨)Tb.N、Tb.Th和BS/BV(RA组胫骨除外)均减少(P<0.05或P<0.01);胫骨、椎骨Tb.Sp增加(P<0.05),股骨Tb.Sp无改变(P>0.05);各部位BV/TV差异无统计学意义(P>0.05)。上述检测指标在RA组与RB之间差异无统计学意义(P>0.05)。结论:使用罗格列酮后,骨微结构受到损伤,且主要集中于松质骨。     

A detailed microscopic study of the changes in the aorta of experimental model of postmenopausal rats fed with repeatedly heated palm oil

Hypercholesterolaemia, increase in lipid peroxidation and hyperhomocysteinaemia may contribute to the pathogenesis of atherosclerosis. This study was performed to examine the effects of repeatedly heated palm oil mixed with 2% cholesterol diet on atherosclerosis in oestrogen-deficient postmenopausal rats. Ovariectomy causes disruption of tunica intima layer of the rat aorta simulating a postmenopausal condition in females. Twenty-four ovariectomized female Sprague–Dawley rats were divided into four groups. The control group received 2% cholesterol diet without palm oil. A diet with 2% cholesterol content fortified with fresh, once-heated and five-times-heated palm oil was given to the other treatment groups. The rats were sacrificed at the end of 4 months of study and the aortic arch tissue was processed for histomorphometry and electron microscopy. On observation, there was disruption of the intimal layer of the ovariectomized rat aorta. There was no obvious ultrastructural change in the aorta of the rats fed with fresh palm oil. The ultrastructural changes were minimal with once-heated palm oil, in which there was a focal disruption of the endothelial layer. The focal disruption was more pronounced with five-times-heated palm oil. The results of this study show that the ingestion of fresh palm oil may have a protective effect on the aorta but such a protective action may be lost when the palm oil is repeatedly heated. The study may be clinically important for all postmenopausal women who are susceptible to atherosclerosis.     

The Ability of Oestradiol Administration to Regulate Protein Levels of Oestrogen Receptor Alpha in the Hippocampus and Prefrontal Cortex of Middle-Aged Rats is Altered Following Long-Term Ovarian Hormone Deprivation

Beneficial effects of oestrogen administration on cognition are attenuated if treatment is initiated following long-term ovarian hormone deprivation. The mechanisms underlying this attenuation are unknown. The present study aimed to assess the effects of long-term ovarian hormone deprivation on the ability of subsequent oestradiol treatment to regulate oestrogen receptor (ER) α and ERβ, and steroid receptor coactivator (SRC)-1 in the hippocampus and prefrontal cortex of middle-aged rats. In an initial experiment to assess oestradiol regulation of these proteins, 2-month-old rats were ovariectomised and immediately implanted with capsules containing cholesterol or oestradiol. Brains were collected 10 days later. In a second experiment, middle-aged (10-month-old) rats were ovariectomised or underwent sham surgeries. Five months later, sham-operated rats were ovariectomised and received oestradiol implants. Previously ovariectomised rats underwent sham surgeries and received oestradiol or cholesterol implants. Protein levels of ERα, ERβ, and SRC-1 were measured following 10 days of oestradiol treatment using western blotting. In young animals, oestradiol treatment significantly increased ERα in the hippocampus and prefrontal cortex relative to control treatment. In middle-aged animals, immediate oestradiol treatment significantly increased ERα in hippocampus, but not the prefrontal cortex. However, delayed oestradiol treatment failed to significantly increase ERα protein levels in hippocampus, but did so in prefrontal cortex. Levels of ERβ and SRC-1 were unaffected by oestradiol treatment in either brain area in either of the age groups. These data indicate that prolonged ovarian hormone deprivation alters the ability of subsequent oestradiol replacement to regulate ERα protein levels in brain areas important for cognition.     

Red clover Trifolium pratense (Linn.) isoflavones extract on the pain threshold of normal and ovariectomized rats – a long‐term study

Depletion of estrogens occurs in women during menopause, while in experimental animals, oophorectomy is a common method to deplete the animals of their gonadal hormones. Recently, phytoestrogens derived from plants have been tried as estrogen substitutes during menopause. In the present study an isoflavones methanol extract from red clover Trifolium pratense (Linn.) was administered orally (500 mg/kg of body weight) to ovariectomized (OVX) and normal (controls) rats for 90 and 180 days. Their pain threshold was monitored using tail flicking and formalin test methods. Observations showed that the OVX rat pain threshold was reduced due to estrogen deprivation, whereas the pain threshold levels in OVX rats treated with isoflavones extract was similar to the control animals. The present study demonstrated the influence of phytoestrogen on long‐term OVX rats in pain perception in the absence of ovarian estrogen and without toxic side effects. However, the actions of gonadal hormones on nociceptive axis are myriad and complex, so further studies on the exact physiological mechanism of the phytoestrogen action on nociceptive axis is warranted. Copyright © 2010 John Wiley & Sons, Ltd.     

Longitudinal assessment of the effects of oestrogen on blood pressure and cardiovascular autonomic activity in female rats

• 1 Published data concerning the effects of ovarian hormones on haemodynamic variability are contradictory. For the first time, the present study used radiotelemetric haemodynamic monitoring to investigate the long‐term effects of chronic oestrogen depletion and repletion on cardiovascular autonomic control and arterial baroreflex sensitivity (BRS) in female rats.
• 2 Blood pressure (BP), heart rate (HR) and +dP/dt_max of arterial pressure (an estimate of myocardial contractility) were monitored in sham‐operated (SO), ovariectomized (OVX) and oestrogen‐replaced OVX rats (OVXE2) for 16 weeks. Cardiovascular autonomic control and baroreflexes were assessed by frequency domain analysis of interbeat intervals (IBI) and systolic BP (SBP).
• 3 Compared with SO rats, OVX rats exhibited no changes in BP, short‐lived decreases in HR and sustained reductions in +dP/dt_max of arterial pressure. The high‐ (HF; 0.75–3 Hz) and low‐frequency (LF; 0.25–0.75 Hz) components of spectral power of IBI were significantly decreased and increased, respectively, by ovariectomy. An increase in the IBI_LF/HF ratio in OVX rats suggests a shift in the cardiac sympathovagal balance towards sympathetic dominance. Index α, the spectral index of spontaneous BRS, was reduced by OVX.
• 4 Oestrogen replacement caused significant reductions in BP and HR and reversed OVX‐induced changes in +dP/dt_max of arterial pressure and cardiac autonomic activity. The LF oscillations of SBP were reduced in OVXE2 rats, suggesting a reduction in vascular sympathetic tone by oestrogen.
• 5 These findings highlight the importance of long‐term oestrogen therapy in rectifying the detrimental effects of depletion of ovarian hormones on the cardiovascular system and baroreflex.

     

Comparison of the bone protective effects of an isoflavone-rich diet with dietary and subcutaneous administrations of genistein in ovariectomized rats

Administration of the isoflavone genistein (GEN) has been described to result in bone protection but also to induce uterotrophic responses. To compare bone protective effects of GEN with an isoflavone-rich diet (IRD) and to further elucidate molecular mechanisms involved in bone-protection, ovariectomized rats (OVX) received either a diet low in isoflavone content (IDD) enriched with GEN (42 mg kg⁻¹ b.wt d⁻¹) (GEN^d), an IRD (14 mg kg⁻¹ b.wt d⁻¹ GEN, 14 mg kg⁻¹ b.wt d⁻¹ daidzein) or were treated subcutaneously (s.c.) with GEN (10 mg kg⁻¹ b.wt d⁻¹) (GEN^sc) for 12 weeks. Intact (SHAM), vehicle treated OVX animals and those substituted with 17β-estradiol (2 μg kg⁻¹ b.wt d⁻¹) (E₂), served as controls.     

运动对去卵巢大鼠骨大小和骨量的影响

用测定骨大小和骨量的方法,观察运动对去卵巢大鼠骨大小和骨量的影响。将健康4月龄雌性SD大鼠32只随机分成4组:正常对照组、假去卵巢组、去卵巢组、去卵巢+运动组。去卵巢+运动组大鼠于去卵巢术后第7 d开始运动训练,每周5 d,每天连续匀速跑45 min,16 m/min,跑道倾角0°,持续10周。结果表明,去卵巢大鼠骨直径、骨体积、骨湿重、骨湿重/体重、骨干重、骨干重/体重、骨干重/骨体积等指标均低于假去卵巢组。去卵巢大鼠运动训练后,骨直径、骨体积、骨湿重、骨湿重/体重、骨干重、骨干重/体重、骨干重/骨体积等指标均较去卵巢组增加,并且基本上恢复至对照组水平。提示运动有利于改善去卵巢大鼠的骨大小和骨量。     

补肾中药与阿法骨化醇联合应用对卵巢摘除大鼠原发性骨质疏松的防治作用

 目的 研究补肾中药与阿法骨化醇联合应用对卵巢去势（ovariectomy,OVX）大鼠原发性骨质疏松的防治作用。方法 手术摘除6月龄雌性大鼠双侧卵巢,随机分成4组：OVX组（ovariectomy,OVX）、OVX给予补肾中药组（OVX administrated with Bushen Chinese drugs,OVX+TCM）、OVX给予补肾中药和阿法骨化醇组（OVX administrated with Bushen Chinese drugs and alfacalciferol,OVX+TCM+VD）和OVX给予尼尔雌醇组（OVX administrated with nilestriol,OVX+CEE₃）,另设假手术对照组（SHAM）。术后35 d起给予药物至13周后处死取血、子宫、腰椎、股骨等标本,并测定比较各组以下变化：取子宫称重,计算子宫重/体重、子宫内膜厚度;放免法血测血清雌二醇（E₂）应用固体物理密度仪自动测量左股骨和腰椎L₂的骨密度;应用图像分析仪IPP计量软件分析椎体骨的组织病理形态计量;以万能材料测试仪检测右股骨与腰椎L₃的骨生物力学性能的指标;自动生化仪检测血清碱性磷酸酶（ALP）;酶免法检测尿吡啶酚（Pyd）,测尿肌酐（Cr）,计算Pyd/Cr作为骨代谢生化标志物,综合判断骨质疏松情况。结果 OVX大鼠双侧卵巢摘除完全,雌激素缺乏诱发骨质疏松指标明显;联合给药组骨量明显增加,骨结构明显改善,抗骨折性能明显提高,骨形成和骨吸收生化标志物降低;其防治骨质疏松的作用优于单用补肾中药组,并与尼尔雌醇组相仿。结论 补肾中药与阿法骨化醇联合应用对卵巢去势大鼠原发性骨质疏松有明显防治作用,避免了雌激素引起的子宫内膜增生等毒副作用。     

Estrogen deficiency and its effect on the jaw bones

Estrogen deficiency-induced postmenopausal osteoporosis has become a worldwide problem, inducing low bone mass and microarchitectural deterioration of the bone scaffolding in the vertebrae and long bones. With the prevalence of such osteoporosis on the increase, the influence of this estrogen deficiency on the jaw bones has drawn the attention of researchers and clinicians in the field of dentistry. The aim of this article is therefore to review the microstructural changes occurring after ovariectomy in the jaw bones of animal subjects. Induced estrogen deficiency clearly led to structural changes in the jaw bones and alveolar bone of animal subjects (rats and monkeys). Severe bone loss in the rat alveolar bone was principally caused by high bone resorptive activity. This activity accelerated greatly immediately after ovariectomy, and was then followed by more moderate resorptive activity, which continued over an extended period. Additionally, occlusal hypofunction further greatly accelerated the fragility of the alveolar bone structure in ovariectomized rats. Microstructural damage also seen in the alveolar bone of ovariectomized monkeys was found to be directly connected to their systemic osteoporosis. Recent investigations of the relationship in humans between systemic osteoporosis and jaw bone loss have also suggested that a connection may exist between these two. However, more research is required to confirm this connection in humans as well.     

Characterization of a new experimental model of osteoporosis in rabbits

To characterize an experimental model of osteoporosis in rabbits induced either by ovariectomy (OVX), glucocorticoids, or by a combination of both. Thirty-five rabbits were randomly allocated into five groups: bilateral OVX, daily methylprednisolone hemisuccinate (MPH) injections at a 1.5 mg/kg/day dose for 4 consecutive weeks (MPH group), or variable dose of MPH between 0.5 and 2 mg/kg/day in combination with OVX (OVX + MPH at low, medium, and high dose). Twenty-two animals were killed 6 weeks after OVX, and 13 were killed 16 weeks later. Dual-energy X-ray absorptiometry was obtained at baseline and 6 and 16 weeks after OVX. High-resolution magnetic resonance imaging (MRI) was carried out at 0 and 6 weeks after OVX. Glucose, total cholesterol, triglyceride, and oestradiol blood levels before and 16 weeks after OVX were determined. Bone mineral density (BMD) decreased significantly at lumbar spine in MPH and OVX + MPH medium-dose groups, and at global knee and subchondral bone of the knee in MPH, OVX + MPH low- and medium-dosage groups (P < 0.05). BMD variations in OVX rabbits were not significant in any of the three anatomical locations analyzed. BMD variation 16 weeks after OVX was significant at lumbar spine and global knee in the OVX + MPH medium-dose group and only at global knee in the OVX + MPH low-dose group (P < 0.05). MRI did not show bone or cartilage changes. Osteoporosis can be induced experimentally in rabbits through isolated MPH or by a combination of OVX and medium dose corticosteroid for 4 weeks. OVX alone was not sufficient to induce osteoporosis. Part of this study was presented at the 28th annual meeting of the American Society for Bone and Mineral Research, Philadelphia, PA, USA, September 15–19, 2006 [J Bone Miner Res 2006;21(suppl 1):S178]