一氧化氮在糖皮质激素性骨质疏松发病中的作用和辛伐他汀对骨代谢的影响

目的探讨一氧化氮(NO)在糖皮质激素性骨质疏松症(GC-OP)发病机制中的作用和辛伐他汀对NO的调控。方法6个月龄SD雄性大鼠随机分为3组,实验组(A)给予辛伐他汀和地塞米松,模型组(B)给予生理盐水和地塞米松,对照组(C)给予生理盐水。8周后观察第3腰椎显微结构、股骨组织形态计量学、腰椎诱生型一氧化氮合酶(i NOS)和内皮细胞型一氧化氮合酶(eNOS)免疫组织化学。结果3组血清NO含量差异无统计学意义(P>0.05)。A组显微结构与C组相似,B组呈骨质疏松表现。3组eNOS表达的平均灰度值与平均积分吸光度分别为(179.08±4.38)与(0.455±0.019)、(169.42±3.00)与(0.401±0.010)、(181.08±2.31)与(0.463±0.150)。A组明显高于B组(P<0.01),与C组差异无统计学意义(P>0.05)。A组的骨体积、类骨质表面、类骨质宽度和成骨表面分别为(53.46±2.49)%、(9.52±1.11)%、(3.25±0.19)μm、(9.20±1.37)%,均比B组(42.48±1.95)%、(7.34±0.66)%、(2.72±0.32)μm、(7.43±0.58)%显著增高(P<0.01),与C组(54.69±1.87)%、(9.44±1.13)%、(3.44±0.28)μm、(9.83±1.06)%差异无统计学意义(P>0.05)。3组骨吸收表面的差异无统计学意义(P>0.05)。结论eNOS依赖性NO的低表达是GC-OP的重要发病机制,辛伐他汀增强eNOS的表达而有效预防该症的发生。     

Growth hormone is not able to counteract osteopenia of rat cortical bone induced by Glucocorticoid with protracted effect

Osteopenia and inhibited longitudinal growth in childhood are serious side effects during glucocorticoid therapy. The effects of glucocorticoids on bone have been confirmed in animal experiments. Long-term glucocorticoid administration to rats results in reduced body weights, reduced bone growth (length and cross-sectional area), and bone strength. Glucocorticoid treatment also resulted in a reduced bending stress, indicating reduced bone quality. Growth hormone, on the other hand, increased body weights, bone dimensions, and bone strength. The aim of the present study was to evaluate if growth hormone administration would have an anabolic effect on rat bone when given to animals also receiving a high dosage of glucocorticoid. Five groups of female rats, 3.5 months old, were treated as follows: (1) saline control; (2) glucocorticoid (prednisolone: Delcortol 5 mg/kg/day); (3) growth hormone (recombinant human growth hormone 5 mg/kg/day); (4) glucocorticoid and growth hormone; and (5) food restriction, consisting of restricted access to food to reduce their weight gain to match that of the glucocorticoid injected rats. After 80 days of hormone administration the animals were sacrificed. The right femur was removed and tested biomechanically in a three-point bending procedure. The left femur was used for determination of bone dimensions. Biomechanical parameters (ultimate load and ultimate stiffness) were then normalized to diaphyseal cross-sectional diameters of the femur, giving the values of ultimate bending stress and Young's modulus. Results: administration of both hormones simultaneously could not reverse the decrease in body weights, bone length, and diameters, or the decreased bone strength induced by glucocorticoid administration. In conclusion, growth hormone cannot prevent cortical osteopenia in female rats induced by a high dose of glucocorticoid with protracted effect.     

Apoptosis of ileal Peyer's patch B cells is increased by glucocorticoids or anti-immunoglobulin antibodies

The ileal Peyer's patch (PP) in sheep plays a central role in the development and production of B cells. Associated with a tremendous amount of B cell proliferation in this site is the extensive diversification of the Ig repertoire by somatic hypermutation. Very few (<5%) of the B cells produced in the ileal PP differentiate and emigrate; instead, the vast majority of these cells soon die, and we have previously shown that death is associated with apoptosis. When placed in culture, ileal PP B cells die rapidly by apoptosis, such that after 24h, 60 ± 1 % of DNA is fragmented. Here, we show that the extent of this spontaneous B cell apoptosis in culture, as quantitated by DNA fragmentation, was significantly increased in a dose-dependent manner by the glucocorticoids hydrocortisone or dexamethasone. Furthermore, treatment of lambs with 2–2.5 mg/kg of dexamethasone resulted in a marked increase in the number of apoptotic cells in the ileal PP and an increase in ileal PP B cell DNA fragmentation to 20 ± 6%, compared with 2.4 ± 0.1 % in untreated lambs. Anti-immunoglobulin (Ig) antibodies also increased the extent of DNA fragmentation in cultured ileal PP B cells. After 24 or 48 h of culture with anti-Ig (PIg47A), DNA fragmentation was 74 ± 2 % and 75 ± 3 %, respectively. Ileal PP B cells are rescued from apoptosis by agents that activate protein kinase C and increase cytosolic Ca²⁺, and here we show that this treatment also results in apoptotic rescue in the presence of dexamethasone or anti-Ig. We speculate that the apoptosis of ileal PP B cells in situ may be modulated by glucocorticoids and by the cross-linking of surface Ig. Apoptosis, induced by a signal through surface Ig, may be an important mechanism in the deletion of self-reactive B cells during the expansion of the Ig repertoire in the ileal PP.     

糖皮质激素对前列腺素E2介导的主动脉平滑肌细胞cAMP生成的影响

目的观察地塞米松对前列腺素Ｅ２介导的离体培养兔主动脉平滑肌细胞的ｃＡＭＰ生成的影响。方法用蛋白竞争结合法测定细胞ｃＡＭＰ含量,并确定腺苷酸环化酶的活性。结果从１０ｐｍｏｌ／Ｌ到１０ｎｍｏｌ／Ｌ地塞米松对培养细胞的ｃＡＭＰ生成有明显抑制作用并呈现剂量依赖性,作用时间愈长,该抑制作用愈强。经地塞米松预处理８小时的培养细胞,其前列腺素Ｅ２介导的腺苷酸环化酶活性显著下降。结论糖皮质激素在腺苷酸环化酶水平抑制前列腺素Ｅ２介导的培养平滑肌细胞ｃＡＭＰ生成。另外还观察到地塞米松拮抗前列腺素Ｅ２的抑制培养细胞增生效应,但未发现地塞米松对培养平滑肌细胞增生的直接促进作用     

糖皮质激素受体对大鼠中性粒细胞粘附的影响

本文通过Percoll梯度离心法分离获得大鼠中性粒细胞(PMNS)后,采用PMNS与玻璃珠粘附的模型,通过给予Dex及糖皮质激素受体(GR)阻断剂Mifepristone(RU_(38486))研究大鼠PMNS粘附过程中GR的作用。结果显示,Dex可以明显抑制PMNS的粘附,其作用随着Dex浓度的增大而增强;单纯给予不同浓度的RU_(38486)未发现明显的PMNS粘附增强,说明RU_(38486)本身对离体的PMNS粘附没有明显的作用;若同时给予Dex和RU_(38486),则Dex抑制PMNS粘附的作用逐渐减小,直至完全逆转。该结果强烈提示:糖皮质激素(GC)具有抑制PMNS粘附的作用,其作用是通过GR介导的,当GR被阻断时,这一抑制作用减弱,甚至消失。     

长链非编码RNA HOTAIR对急性淋巴细胞白血病细胞增殖与凋亡的影响

目的:研究长链非编码RNA HOTAIR调控糖皮质激素受体的表达对急性淋巴细胞白血病细胞增殖及凋亡的作用。方法:采用RT-qPCR法检测人正常骨髓基质细胞系HS-5及急性淋巴细胞白血病细胞系MOLT-4、CCRF-CEM和CEM-C1中HOTAIR和糖皮质激素受体的表达。用si RNA沉默CEM-C1细胞中HOTAIR的表达,CCK-8法检测si-HOTAIR对CEM-C1细胞活力的影响; Brd U法检测si-HOTAIR对CEM-C1细胞增殖的影响以及对地塞米松抑制CEM-C1细胞增殖的增效作用; Hoechst 33342染色法和caspase 3/7活性检测法研究si-HOTAIR对CEM-C1细胞凋亡的影响;并采用Western blot法检测糖皮质激素受体的蛋白表达水平。结果:人急性淋巴细胞白血病细胞系MOLT-4、CCRF-CEM和CEM-C1中HOTAIR的表达显著高于人正常骨髓基质HS-5细胞(P 0. 01)。在CEM-C1细胞中干扰HOTAIR表达后,细胞活力降低,细胞增殖被抑制并发生凋亡,地塞米松抑制CEM-C1增殖的作用被增强,糖皮质激素受体表达上调(P 0. 01)。结论:长链非编码RNA HOTAIR增强急性淋巴细胞白血病的活力,促进其增殖并抑制其凋亡,该作用可能与其抑制糖皮质激素受体的表达有关。     

Acute effects of deflazacort and prednisone on rates of mineralization and bone formation

The aims of this study were to determine (1) whether acute suppression of bone formation could be evaluated after the administration of corticosteroids in man by quantitative bone histomorphometry; and (2) whether there were significant differences between the effects of prednisone and its analog deflazacort. Thirteen patients who needed high-dose corticosteroid therapy were randomly allocated to two groups of treatment (prednisone or deflazacort). Quantitative bone histomorphometry, using the technique of triple labeling, and biochemical measurements of bone turnover were studied. There were no differences in biochemical indices of bone turnover between prednisone and deflazacort at the beginning and end of the 15 days of treatment course. During corticosteroid treatment, there were no significant changes in biochemical indices of bone turnover but a significant decline in total alkaline phosphatase (P<0.01). Histomorphometric indices, as revealed by measurements of tetracycline interval and extent of labeling, showed no significant differences in either mineral apposition rate or bone formation rate in the two groups. We conclude that the acute glucocorticoid suppression of bone turnover by glucocorticoids is not detectable within the first 2 weeks of treatment by histomorphometric techniques. No differences in bone effects of prednisone and deflazacort were detected in this short-term study.     

Ginkgo biloba extract EGb761 reduces the development of amphetamine-induced behavioral sensitization: effects on hippocampal type II corticosteroid receptors

Pretreatment of rats with the extract of Ginkgo biloba termed EGb761 reduced the behavioral sensitization induced by successive -amphetamine administrations (0.5 mg/kg) as estimated by increasing values of locomotor activity. EGb761 pretreatment also prevented the reduced density of [³H]dexamethasone binding sites in the dentate gyrus and the CA1 hippocampal regions of -amphetamine treated animals. These observations suggest that EGb761, by reducing glucocorticoid levels, could modulate the activity of the neuronal systems involved in the expression of the behavioral sensitization.     

Effects of dexamethasone on the differentiation of membrane structure in cultured astrocytes.

Astrocytic processes investing vascular structures or forming the surface of mammalian brain have large numbers of orthogonally packed aggregates of intramembrane particles, termed "assemblies." Similar particle aggregates are expressed by astrocytes derived from neonatal rat forebrain in secondary culture, but they are much more uniformly distributed across the membranes of the cultured cells. Dexamethasone, a potent glucocorticoid, affects the differentiation of astrocyte membrane structure in two patterns, depending on the rate of proliferation in the culture. When confluent secondary cultures of astrocytes are exposed to 5 microM dexamethasone, the densities of assemblies increase, and in some cells approach the values present in the glial limitans in vivo. However, when rapidly proliferating astrocytes are exposed to dexamethasone during the first week of secondary culture, most of the astrocytes fail to express any assemblies. The rate of astrocyte proliferation is slowed, and a lower cell density is reached during the first 2 weeks of secondary culture in dexamethasone. The suppression of assemblies is transient: as the cultures approach confluence, the proportion of cells expressing assemblies increases to nearly control levels, and the density of assemblies increases to greater than control values in some astrocytes. Certain of the effects of dexamethasone on cultured astrocytes may have relevance for understanding the mechanism(s) of its action in treating cerebral edema.     

糖皮质激素受体--虚证相关蛋白之一?

以已有实验与临床研究为依据，提出糖皮质激素受体(GR)是虚证相关蛋白之一的理论假说。分析了进一步深入研究论证的途径：①改进糖皮质激素受体检测方法；②应用酵母双杂交检测技术，了解GRβ与GRα之间的相互作用，并分析这些作用特征与阴虚、阳虚之间的关系；②运用良好的前瞻性设计，对临床虚证患者进行大量、反复的检测观察与统计分析。指出对该假说的研究论证，很有可能在蛋白质(受体)水平为中医证的微观诊断提供一个符合中医基本理论，具有现代科学依据的检测指标，并有可能发现能上调GR含量的药物。