酒精依赖和戒断时大鼠伏隔核、杏仁核区内神经甾体水平的变化

目的:采用♂大鼠酒精依赖模型,观察酒精依赖及戒断对大鼠伏隔核、杏仁核中不同神经甾体水平的影响。方法:通过大鼠自由饮含6%的乙醇溶液,连续42d使大鼠形成酒精依赖,并撤除酒精使其自然戒断。断头取脑分离取出伏隔核、杏仁核脑区。使用液液萃取和固相萃取两步法提取脑组织中的孕烯醇酮(PREG)、脱氢表雄酮(DHEA)、别孕烯醇酮(AP)、脱氢表雄酮硫酸酯(DHEAS)、孕烯醇酮硫酸酯(PREGS),以高效液相色谱-质谱联用法测定神经甾体含量。结果:与对照组相比,酒精依赖大鼠伏隔核DHEA,PREG,AP,DHEAS,PREGS的水平显著降低(P<0.05),杏仁核AP,PREGS的水平显著降低(P<0.05);酒精戒断6h大鼠伏隔核DHEA,DHEAS,PREGS的水平显著降低(P<0.05),杏仁核PREGS的水平显著降低(P<0.05);酒精戒断24h大鼠杏仁核DHEA的水平显著上升(P<0.05),伏隔核、杏仁核DHEAS、PREGS的水平显著下降(P<0.01)。结论:酒精依赖形成和戒断对伏隔核、杏仁核中的神经甾体水平有不同的影响,具有区域特异性。     

吗啡依赖大鼠纹状体内神经甾体水平的变化

目的:探讨吗啡躯体依赖、精神依赖和戒断对♂大鼠纹状体内神经甾体水平的影响。方法:高效液相色谱-质谱法测定大鼠纹状体和血浆中脱氢表雄酮(DHEA)及其硫酸酯(DHEAS)、孕烯醇酮(PREG)及其硫酸酯(PREGS)和别孕烯醇酮(AP)的含量。结果:(1)与纳洛酮对照组比较,纳洛酮催促吗啡戒断大鼠的纹状体内PREG的含量显著升高(P<0.01);血浆中PREG、AP、DHEAS和PREGS的含量显著升高(P<0.01),而DHEA的含量显著降低(P<0.01);(2)与生理盐水对照组比较,吗啡精神依赖大鼠的纹状体内DHEA和PREG的含量显著升高(P<0.01),血浆中DHEA的水平显著降低(P<0.01)。结论:慢性吗啡处理可影响大鼠纹状体内某些神经甾体的水平,表明神经甾体可能参与吗啡依赖的形成。     

吗啡依赖和复吸时大鼠脑内神经甾体水平的变化

目的探讨吗啡精神依赖和复吸对大鼠脑内神经甾体水平的影响。方法采用条件性位置偏爱(CPP)实验,吗啡诱导大鼠CPP形成,足底电击应激诱发CPP重建,高效液相色谱-质谱法测定大鼠额叶皮质、海马及血浆中孕烯醇酮(PREG)及其硫酸酯(PREGS)、别孕烯醇酮(AP)、脱氢表雄酮(DHEA)及其硫酸酯(DHEAS)的含量。结果5 mg.kg-1吗啡训练10 d诱导大鼠产生了稳定的CPP,间歇足底电击有效诱发CPP的重建。与对照组比较,吗啡CPP形成时,大鼠额叶皮质内DHEA、PREG水平升高(P<0.05),海马内DHEA水平降低(P<0.05);与吗啡消退组比较,足底电击诱发CPP重现时,大鼠额叶皮质内PREG水平降低(P<0.01),而海马内PREG水平升高(P<0.05)。结论大鼠额叶皮质和海马内神经甾体水平的变化可能与吗啡依赖和复吸有关。     

吗啡依赖对大鼠伏隔核神经甾体和氨基酸递质的影响

目的　利用大鼠吗啡依赖模型,观察吗啡依赖及戒断对大鼠伏隔核中神经甾体和氨基酸类神经递质水平影响。方法　腹腔注射递增剂量的盐酸吗啡使雄性SD大鼠形成吗啡依赖,并用纳洛酮催促戒断。分离吗啡依赖和戒断大鼠的伏隔核。经液液萃取和固相萃取法提取脱氢表雄酮、孕烯醇酮、别孕烯醇酮、脱氢表雄酮硫酸酯和孕烯醇酮硫酸酯,并采用高效液相色谱质谱系统检测其含量。采用柱前衍生-电化学检测-高效液相色谱法测定甘氨酸、谷氨酸和γ氨基丁酸的含量。结果　与对照组相比,纳洛酮催促戒断时,吗啡依赖大鼠伏隔核脱氢表雄酮硫酸酯的水平下降(P<0 .05),孕烯醇酮(P<0 .01 )和谷氨酸(P<0 .05 )水平均升高。结论　吗啡戒断时大鼠伏隔核的谷氨酸系统处于兴奋状态,伏隔核中的内源性神经甾体在吗啡依赖和戒断的形成中发挥作用。     

高效液相色谱-质谱法测定大鼠血浆中硫酸酯型脱氢表雄酮和孕烯醇酮

建立同时测定 SD 大鼠血浆中脱氢表雄酮硫酸酯(DHEAS)和孕烯醇酮硫酸酯(PREGS)的高效液相色谱-质谱法。方法:选择雌酮硫酸酯(ES)作为内标。雄性 SD 大鼠的血浆使用乙腈沉淀除去蛋白后,经固相萃取、水解及衍生化后,以高效液相色谱质谱检测器测定脱氢表雄酮硫酸酯和孕烯醇酮硫酸酯的浓度。色谱柱为 Zorbax SB C_(18)柱温40℃,流动相为乙腈水,使用梯度洗脱;采用大气压化学离子源(HPLC/APCI-MS),负离子检测方式,用于选择离子检测(SM)定量分析的离子为 m/z 490.0(DHEAS)和 m/z 518.0(PREGS)及 m/z 472.1(ES)[M-H]~-。结果:血浆中脱氢表雄酮硫酸酯和孕烯醇酮硫酸酯线性范围分别为:0.05～2.0ng·mL~(-1),0.03～2.0 ng·mL~(-1),r 分别为0.9990和0.9979。低、中、高浓度血样的提取回收率在66.8%～82.3%之间,相对回收率为:98.4%～111.6%,日内、日间变异均小于15%。正常雄性 SD 大鼠的血浆脱氢表雄酮硫酸酯和孕烯醇酮硫酸酯分别为0.070±0.020 ng·mL~(-1)、0.13±0.031 ng·mL~(-1)。结论:本实验方法具有灵敏度高、准确度好及变异较小的特点,适合测定雄性 SD 大鼠血浆中脱氢表雄酮硫酸酯和和孕烯醇酮硫酸酯的含量。     

高效液相色谱-质谱法测定大鼠血浆中硫酸酯型脱氢表雄酮和孕烯醇酮

目的:建立同时测定SD大鼠血浆中脱氢表雄酮硫酸酯(DHEAS)和孕烯醇酮硫酸酯(PREGS)的高效液相色谱-质谱法。方法:选择雌酮硫酸酯(ES)作为内标。SD大鼠的血浆使用乙腈沉淀除去蛋白后,经固相萃取,水解,衍生化后,以高效液相色谱-质谱测定脱氢表雄酮硫酸酯和孕烯醇酮硫酸酯的浓度,采用大气压化学离子源(HPLC/APCI-MS),选择离子检测方式。结果:血浆中脱氢表雄酮硫酸酯和孕烯醇酮硫酸酯线性范围分别为:0.050~2.00ng,0.030~2.00ng,相关系数分别为0.9990和0.9979。低、中、高浓度血样的提取回收率在66.8%~82.3%之间,相对回收率为:98.4%~111.6%,日内、日间变异均小于15%。正常SD大鼠的血浆脱氢表雄酮硫酸酯和孕烯醇酮硫酸酯分别为0.070±0.020ng/ml、0.13±0.031ng/ml。结论:本实验方法具有灵敏度高、准确度好及变异较小的特点,适合测定SD大鼠血浆中脱氢表雄酮硫酸酯和孕烯酮硫酸酯的含量。     

吗啡依赖对大鼠不同脑区内神经甾体水平的影响

目的建立大鼠条件性位置偏爱(CPP)模型，探讨吗啡精神依赖对大鼠脑内神经甾体水平的影响。方法 大鼠连续10 d腹腔注射吗啡5 mg·kg^-1，诱导CPP形成。高效液相色谱-质谱法测定大鼠伏隔核、杏仁核、下丘脑和血浆中脱氢表雄酮、孕烯醇酮、别孕烯醇酮、脱氢表雄酮硫酸酯及孕烯醇酮硫酸酯的含量。结果经10 d吗啡训练后，吗啡组大鼠在伴药侧的停留时间显著长于对照组，吗啡诱导的大鼠CPP形成。与对照组相比，吗啡组大鼠下丘脑内孕烯醇酮明显降低，伏隔核和血浆中的脱氢表雄酮明显降低。结论吗啡诱导CPP形成，吗啡处理影响大鼠脑内某些神经甾体的水平，表明内源性神经甾体可能参与吗啡依赖的形成。     

吗啡对原代培养大鼠皮质神经元神经甾体水平的影响

目的探讨吗啡慢性处理对大鼠大脑皮质神经元合成释放神经甾体水平的影响及其机制。方法建立原代培养大鼠大脑皮质神经元吗啡依赖样模型,固相萃取结合高效液相色谱-质谱联用法测定细胞培养液中神经甾体水平;免疫印迹法检测神经元中p-CREB水平。结果与盐水对照组相比,吗啡(1μmol.L-1)处理使PREG和DS的水平降低(P<0.01);μ-受体激动剂DAMGO使PREG、DS和PS水平下降,AP水平增高;与吗啡单独处理组相比,μ-阿片受体拮抗剂CTAP与吗啡联合处理使PREG增加(P<0.01)。与盐水对照组相比,吗啡或DAMGO慢性处理均可增加神经元内p-CREB的水平(P<0.01);与吗啡处理组相比,CTAP抑制吗啡诱导的p-CREB的增加。结论μ-阿片受体参与了介导吗啡慢性处理对皮质神经元神经甾体合成释放的影响;神经元内p-CREB水平的变化反映了吗啡引起的神经元适应性改变,提示神经甾体水平的变化可能与吗啡依赖有关。     

病生理条件下星形胶质细胞中内向整流钾通道2．1的表达

星形胶质细胞是胶质细胞中体积最大的一种,不仅具有支持作用,而且具有转运代谢物质的作用,其参与神经递质的吸收,如谷氨酸(Glu)和γ-氨基丁酸(GABA)的吸收及脑内免疫功能的调节。同时星形胶质细胞的离子通道也参与脑内离子稳态的调节。其中一个重要功能是调节胞外钾离子的浓     

mGluR5拮抗剂SIB-1893逆转6-OHDA抑制星形胶质细胞摄取谷氨酸的作用

目的 :研究亲代谢型谷氨酸受体 5 (mGluR5 )拮抗剂 (E) 2 甲基 6 (2 苯乙烯 )嘧啶 (SIB 1893)及6 羟基多巴胺 (6 OHDA)对星形胶质细胞摄取谷氨酸功能的影响。方法 :取新生大鼠脑星形胶质细胞作原代培养 ,根据 [3 H]标记的D ,L 谷氨酸摄入量判断细胞的谷氨酸摄取功能。应用高效液相色谱法(HPLC)与荧光检测器联用的方法检测培养液中的谷氨酸水平 ;乳酸脱氢酶 (LDH)释放法测定细胞活力。结果 :6 OHDA呈浓度依赖性抑制星形胶质细胞谷氨酸摄取功能、降低细胞活力 ,但不诱导细胞释放谷氨酸 ;SIB 1893不影响正常星形胶质细胞的谷氨酸摄取量 ,但可以增加 6 OHDA损伤组的谷氨酸摄取量。结论 :6 OHDA的神经损伤机制可能与其抑制星形胶质细胞谷氨酸摄取功能有关 ,SIB 1893则能逆转 6 OHDA引起的谷氨酸摄取抑制效应 ,具有神经保护作用     

Effects of morphine dependence and withdrawal on levels of neurosteroids in rat brain

AIM: To investigate the effects of morphine dependence and withdrawal on the concentrations of neurosteroids in rat brain. METHODS: A method of simultaneous quantification of neurosteroids by gas chromatography-mass spectrometry (GC-MS) had been established. RESULTS: The chronic morphine administration (ip) resulted in a marked decrease in the brain concentrations of pregnenolone (PREG), progesterone (PROG), and pregenenolone sulfate (PREGS) in rats killed 6 h after the last treatment. In contrast, there were no significant effects of morphine dependence on the brain concentrations of allopregnanolone (AP), dihydroepiandrosterone (DHEA), and dihydroepiandrosterone sulfate (DHEAS). Naloxone-induced withdrawal produced a significant increase in the concentrations of PREG, PROG, AP, DHEA, PREGS, and DHEAS as compared with the control group. CONCLUSION: Morphine dependence and withdrawal affected the concentrations of neurosteroids in rat brain, which suggests that endogenous neurosteroids in brain might be     

The effects of neurosteroids on picrotoxin-, bicuculline- and NMDA-induced seizures, and a hypnotic effect of ethanol

The effects of intraperitoneally (IP) or intracerebroventricularly (ICV) administered neurosteroids [allopregnanolone (AP); 5beta-tetrahydrodeoxycorticosterone (5beta-THDOC); dehydroepiandrosterone sulfate (DHEAS); pregnenolone sulfate (PS)] and their precursors [progesterone (PROG), pregnanedione (PREG)] on N-methyl-D-aspartic acid (NMDA)-, picrotoxin (PTX)- and bicuculline (BIC)-induced seizures and ethanol-induced sleep were studied in mice. It was found that IP injections of (+)MK-801 most potently antagonized NMDA-, PTX- and BIC-induced seizures, as compared to diazepam (DZP), PROG and PREG. Both precursors of neurosteroids appeared only marginally active in the applied models of convulsions. ICV injections of AP selectively blocked PTX- and BIC-induced seizures, whereas 5beta-THDOC and (+)MK-801 also antagonized NMDA-induced convulsions. ICV administered DHEAS induced seizures in a dose-dependent way. ICV injections of AP and midazolam shortened the latency and prolonged the duration of sleep induced by IP injections of ethanol (5.0 g/kg). On the contrary, DHEAS and PS significantly reduced the hypnotic-like effect of ethanol. The obtained results suggest that neurosteroids may modulate in an agonistic (AP, 5beta-THDOC), or antagonistic way (PS, DHEAS), the GABA(A) receptor complex functions. Some of them (5beta-THDOC) also interact with NMDA receptors. AP appeared to be the most selectively acting compound, with its profile of action fully comparable to that of midazolam. AP also enhanced the hypnotic effect of ethanol, pointing out to the propensity to interact with centrally depressant agents. These findings, together with the possibility of conversion of some neurosteroids in the brain to other steroid hormones (testosterone, estradiol and aldosterone), indicate the limitations of their use for the treatment of neurological and psychiatric disorders.     

Subunit-specific modulation of glycine receptors by neurosteroids

The effects of pregnene and androstane steroids were studied on recombinant human glycine receptors (GlyRs) by whole-cell voltage-clamp electrophysiology. The 3beta-sulphates of pregnenolone (PREGS) and dehydroepiandrosterone (DHEAS) inhibited GlyR currents with K(I) values of 2-20 microM for different (alpha(1), alpha(2), alpha(4) and beta) GlyR subunits. PREGS resulted in a parallel shift of the response curve of glycine for alpha(1) GlyRs. The inhibitory potencies of DHEAS relative to PREGS were decreased in transition from embryonic alpha(2) towards adult alpha(1)beta GlyRs. A decreased potency of DHEAS for alpha(4) versus alpha(2) GlyRs represents the first pharmacological difference reported between these subunits. A negative charge at C3 is required for GlyR antagonism but androsterone sulphate epimers at C3 inhibited without stereoselectivity. Some point mutations of alpha(1) GlyRs with characteristic functional consequences did not significantly affect the inhibitory potency of PREGS. Progesterone selectively inhibited alpha(2) GlyRs, while PREG and its acetic ester potentiated alpha(1) GlyRs. Coexpression of the alpha subunits with the beta subunit eliminated the enhancing effects of PREG and attenuated the inhibitory potencies of the neurosteroids. Based on these data we propose that neurosteroids might modulate perinatal GlyR activity and thereby influence neuronal development.     

Aβ_(25-35)对大鼠大脑皮质神经元神经甾体水平的影响

目的研究Aβ25-35对大鼠大脑皮质神经元合成神经甾体的影响。方法采用Aβ25-35(1μmol·L-1)处理原代培养的大鼠大脑皮质神经元,固相萃取结合高效液相色谱-质谱联用法测定细胞培养液中神经甾体的浓度,四甲基偶氮唑(MTT)法检测细胞活性。结果与对照组相比,Aβ25-35处理后神经元存活率降低约50%(P<0.01),胆固醇处理组神经元存活率未见改变(P>0.05),但Aβ+胆固醇组的神经元存活率明显高于Aβ处理组(P<0.01)。与胆固醇组相比,Aβ25-35处理后神经甾体PREG水平略有降低(P>0.05),PROG水平明显下降(P<0.01),AP水平明显增高(P<0.01)。结论神经甾体PREG-PROG-AP代谢通路在Aβ25-35引起的大鼠大脑皮质神经元损伤时发生明显改变,并能部分地对抗Aβ的神经毒性作用。     

Continuous de novo synthesis of neurosteroids is required for normal synaptic transmission and plasticity in the dentate gyrus of the rat hippocampus

Both in vivo and in vitro studies have shown that neurosteroids promote learning and memory by modulating synaptic functions in the hippocampus. However, we do not know to what degree endogenously synthesized neurosteroids contribute to the hippocampal synaptic functions. Cytochrome P450scc is the enzyme that converts cholesterol to pregnenolone (PREG), which is required for the biosynthesis of all other neurosteroids. To investigate the physiological roles of endogenous neurosteroids in synaptic functions, we electrophysiologically examined the effects of aminoglutethimide (AG), a selective inhibitor of P450scc, on the synaptic transmission and plasticity in the dentate gyrus of rat hippocampal slices. The application of AG (100 μM) decreased the slope of the field excitatory postsynaptic potentials (fEPSPs) in granule cells by 20-30% in 20 min through the modulation of postsynaptic AMPA receptors, while it did not affect the presynaptic properties, including the paired-pulse ratio and the probability of glutamate release from presynaptic terminals. The AG-induced depression was nearly completely rescued by exogenously applied 500 nM PREG or by 1 nM dehydroepiandrosterone sulfate (DHEAS), one of the neurosteroids synthesized from PREG, suggesting that the AG-induced depression was caused by the loss of DHEAS. AG also reduced NMDA receptor activity, and suppressed high-frequency stimulation (HFS)-induced long-term potentiation (LTP). These findings provide novel evidence that the endogenous neurosteroids locally synthesized in the brain are required to maintain the normal excitatory synaptic transmission and plasticity in the dentate gyrus of the rat hippocampus.