疲劳应激对血管内皮功能障碍大鼠脂蛋白相关磷脂酶A2含量和4型G蛋白耦联受体表达的影响及通络干预的作用

目的方法探讨通络干预对疲劳应激致内皮功能障碍大鼠血清脂蛋白相关磷脂酶A2(lp-PLA2)水平和主动脉4型G蛋白耦联受体(GPR4)表达的影响。方法将60只雄性Wistar大鼠随机分为正常对照组、疲劳应激组、人参组和通心络组。采用"基础饮食+负重力竭游泳"方法建立疲劳应激模型。通过游泳时间、爬杆时间评价模型建立,扫描电镜观察血管内皮形态,并检测一氧化氮(NO)、内皮素(ET)评价内皮功能;应用ELISA方法检测血清lp-PLA2水平,应用Real Time PCR和Western印迹分析检测主动脉GPR4 mRNA、蛋白表达水平。结果疲劳应激组血管内皮结构损伤,内皮分泌NO明显减少,ET明显增加(均P<0.05)。疲劳应激组血清lp-PLA2水平显著升高(P<0.01),主动脉GPR4 mRNA和蛋白表达水平明显高于正常对照组(P<0.05)。人参、通心络干预后,血清NO水平明显增加,血浆ET含量明显降低(均P<0.01);血清lp-PLA2水平明显下降(均P<0.01),主动脉GPR4表达水平显著下降(均P<0.05)。结论疲劳应激模型大鼠血管内皮出现明显损伤,血清lp-PLA2含量明显增加,主动脉GPR4 mRNA和蛋白表达水平明显升高。通络治疗能显著降低疲劳应激大鼠血清lp-PLA2水平,抑制主动脉GPR4 mRNA和蛋白表达,因此通络治疗可有效抑制ox-LDL对血管内皮的损伤。     

5-HT1A受体对癫痫伴发抑郁的影响及神经保护研究

目的 通过建立氯化锂-匹罗卡品癫痫伴发抑郁的模型试验,评价5-HT1A受体激动剂8-OH-DPAT治疗癫痫伴发抑郁的疗效.方法 建立癫痫伴发抑郁大鼠模型,随机分为5组,生理盐水组、模型组、卡马西平组及卡马西加低、高剂量8-OH-DPAT组,分别给予相应药物,通过尼氏染色及胶质纤维酸性蛋白免疫组化的方法观察抗癫痫的疗效,通过强迫游泳,开放视野的行为学方法、荧光定量PCR方法测定5-HT1A受体表达量来评定抗抑郁的效果.结果 5-HT1A受体激动剂与卡马西平联合使用,且能明显的改善抑郁行为、可以增高5-HT1A受体mRNA的含量,同样也具有对抗神经元凋亡和胶质细胞活化的作用(P<0.05).结论 5-HT1A受体激动剂不仅具有抗癫痫和抑郁的作用,而且也具有神经保护的作用.     

高血压机体外周动脉G-蛋白偶联受体对缩血管物质的反应

目的 研究高血压患者及自发性高血压大鼠(SHR)阻力动脉G-蛋白偶联受体对缩血管介质的反应性.方法 将实验动脉血管分成高血压患者大网膜动脉组、非高血压患者大网膜动脉组、SHR肠系膜动脉组和Wistar-Kyoto(WKY)大鼠肠系膜动脉组4组.分别将4组动脉切成环置于浴槽中,累加浓度法加入去甲肾上腺素(NE),测定动脉环张力的变化,作量效曲线,考察α受体介导的收缩功能;分别加入5-羟色胺(5-HT)、蛇毒类似物(Sarafotoxin,S6c)、内皮索1(ET-1)3种物质,依次考察5-HT、ETB、ETA3种受体介导的收缩功能.同样试验方法在SHR组及WKY大鼠组用特异性5-HT2A受体拮抗剂氟哌喹酮(Ketanserin),α1受体拮抗剂哌唑嗪和α2受体拮抗剂西萝芙木碱(Rauwolscine)考察5-HT2A受体、α1受体、α2受体在血管收缩中的作用,作量效曲线.结果 1)高血压患者大网膜动脉ETB、ETA、α受体激动剂量效曲线的Emax均明显高于非高血压患者(P均＜0.01);高血压患者ETB、5-HT、α受体激动剂量效曲线的pEC50明显高于非高血压患者(P＜0.01或P＜0.05);2)在SHR肠系膜动脉α受体和5-HT受体激动剂量效曲线的Emax明显高于WKY大鼠(P均＜0.01);SHRETB、ETA、5-HT受体激动剂量效曲线的pEC50明显高于WKY大鼠(P＜0.05或P＜0.01),而α受体激动剂量效曲线pEC50明显降低(P＜0.01);3)应用氟哌喹酮引起5-HT量效曲线平行右移,在SHR和WKY大鼠,pA2值分别为(9.5±0.1)和(9.4±0.1);哌唑嗪引起NE量效曲线平行右移,在SHR和WKY大鼠,pA2值分别为(11.0±0.2)和(10.94±0.2);西萝芙木碱引起NE量效曲线平行右移,pA2值SHR(7.2±0.2)和WKY大鼠(7.1±0.2).结论 1)高血压机体外周阻力血管的ETB、ETA、5-HT以及α受体介导的收缩作用明显增强;2)在外周阻力血管5-HT主要通过激动5-HT2A受体引起血管收缩,NE主要通过激动α1受体引起血管收缩.     

低氧诱导大鼠肺动脉中5-HT_(1B)受体的过度表达

目的:观察低氧对大鼠肺动脉中5-羟色胺1B(5-HT1B)受体表达的影响,初步探讨了5-HT1B受体在低氧性肺动脉高压形成中的变化。方法:40只健康雄性SD大鼠随机分为正常组、低氧3周组、低氧4周组和低氧6周组,每组10只。除正常组外,其余3组大鼠分别在低氧环境中饲养3周、4周和6周。测定各组大鼠的平均肺动脉压力(mPAP)、右心室收缩压(RVSP)和右心室肥厚度。应用免疫组化染色法检测大鼠肺动脉上5-HT1B的分布和表达;用Western blot法测定大鼠肺组织中5-HT1B受体蛋白的含量。结果:与正常组相比,低氧3周组大鼠的mPAP、RVSP和右心室肥厚度均显著升高(均P0.05),并且随着低氧时间的延长而持续升高(均P0.05)。免疫组化染色的结果显示,5-HT1B受体主要分布在正常大鼠肺动脉的内膜层,平滑肌肌层中仅有少量表达;与正常组相比,低氧3周组大鼠肺动脉平滑肌肌层中5-HT1B受体的表达显著增多(P0.05);随着低氧时间的延长,表达持续增多。Western blot的结果表明,大鼠肺组织中5-HT1B受体蛋白含量的变化与免疫组化染色法检测的结果相一致。结论:低氧可以诱导大鼠肺动脉中5-HT1B受体的过度表达,这可能是5-羟色胺系统参与低氧性肺动脉高压形成的机制之一。     

通心络对高血压大鼠血管内皮功能的保护作用

目的探讨通心络对高血压大鼠血管内皮的保护作用。方法实验动物分为3组,分别为自发性高血压大鼠组(SHR组),SHR服用通心络组(TXL组)和正常血压大鼠组(WKY组)。通过放射免疫及聚合酶链反应检测主动脉一氧化氮(NO)、内皮素(ET)、血管内皮生长因子(VEGF)基因表达。结果SHR组NO水平低于WKY组,TXL组NO水平高于SHR组。SHR组ET-1含量及mRNA均高于WKY组,TXL组ET-1含量及mRNA表达低于SHR组,SHR组及TXL组mRNA表达均高于WKY组,以SHR组为最高。结论通心络可能对高血压大鼠血管内皮功能有保护作用。     

中枢5-羟色胺系统在快速动眼期睡眠剥夺导致大鼠内脏感觉降低中的作用

我们既往的研究证实睡眠剥夺导致大鼠内脏感觉降低，但机制尚不清楚。5-羟色胺（5-HT）是一种与睡眠密切相关的神经递质，同时中枢5-HT系统作为下行抗伤害性作用的主要神经递质之一，在内脏感觉敏感性的调节方面起着重要作用。本实验选取5-HT1A受体及5-HT特异性转运体（SERT）作为反映中枢5-HT系统功能的指标。通过比较睡眠剥夺大鼠和睡眠剥夺加中枢给予5-HT受体拮抗剂二甲麦角新碱干预大鼠的内脏感觉，来证实睡眠剥夺降低内脏感觉敏感性和中枢5-HT系统之间的关系。另通过观察5-HT1A受体和SERT在不同部位的表达变化来反映快速动眼期（REM）睡眠剥夺后中枢5-HT系统的改变。     

何首乌提取物对血管性痴呆大鼠5-HT受体及生化指标的影响

目的研究何首乌提取物对血管性痴呆大鼠学习记忆的影响,初步探讨血管性痴呆大鼠5-HT2A受体的表达及血清超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量的变化。方法采用双侧颈总动脉永久性结扎法建立大鼠血管性痴呆模型,随机分为假手术组、模型组、阳性对照组、何首乌组。通过水迷宫实验检测各组大鼠的学习记忆能力和血清SOD活性、MDA含量的变化;通过免疫组化技术检测各组大鼠丘脑前核内5-HT2A受体的表达水平。结果模型组大鼠d4逃避潜伏期(38.95±27.42)s,平台象限游泳时间(20.35±3.52)s,穿过平台次数(1.50±0.76),SOD活性(0.855±0.094)kU/g prot,MDA含量(5.187±1.237)μmol/g prot,5-HT2A受体的阳性细胞积分光密度值增高。何首乌组大鼠d4逃避潜伏期(15.28±9.83)s,平台象限游泳时间(24.66±3.56)s,穿过平台次数2.75±1.28,SOD活性(0.968±0.158)kU/g prot,MDA含量(4.595±1.104)μmol/g prot,5-HT2A受体的阳性细胞积分光密度值降低。其机制与何首乌组与模型组差异显著(P<0.05),假手术组、阳性对照组与何首乌组差异不显著。结论何首乌提取物能够改善血管性痴呆大鼠学习记忆功能,其机制与使5-HT2A受体表达增强以及抗氧化损伤有关。     

高血压机体外周动脉G-蛋白偶联受体对缩血管物质的反应

目的研究高血压患者及自发性高血压大鼠(SHR)阻力动脉G-蛋白偶联受体对缩血管介质的反应性。方法将实验动脉血管分成高血压患者大网膜动脉组、非高血压患者大网膜动脉组、SHR肠系膜动脉组和Wistar-Kyoto(WKY)大鼠肠系膜动脉组4组。分别将4组动脉切成环置于浴槽中,累加浓度法加入去甲肾上腺素(NE),测定动脉环张力的变化,作量效曲线,考察α受体介导的收缩功能;分别加入5-羟色胺(5-HT)、蛇毒类似物(Sarafotoxin,S6c)、内皮素1(ET-1)3种物质,依次考察5-HT、ETB、ETA3种受体介导的收缩功能。同样试验方法在SHR组及WKY大鼠组用特异性5-HT2A受体拮抗剂氟哌喹酮(Ketanserin),α1受体拮抗剂哌唑嗪和α2受体拮抗剂西萝芙木碱(Rauwolscine)考察5-HT2A受体、α1受体、α2受体在血管收缩中的作用,作量效曲线。结果1)高血压患者大网膜动脉ETB、ETA、α受体激动剂量效曲线的Emax均明显高于非高血压患者(P均<0·01);高血压患者ETB、5-HT、α受体激动剂量效曲线的pEC50明显高于非高血压患者(P<0·01或P<0·05);2)在SHR肠系膜动脉α受体和5-HT受体激动剂量效曲线的Emax明显高于WKY大鼠(P均<0·01);SHRETB、ETA、5-HT受体激动剂量效曲线的pEC50明显高于WKY大鼠(P<0·05或P<0·01),而α受体激动剂量效曲线pEC50明显降低(P<0·01);3)应用氟哌喹酮引起5-HT量效曲线平行右移,在SHR和WKY大鼠,pA2值分别为(9·5±0·1)和(9·4±0·1);哌唑嗪引起NE量效曲线平行右移,在SHR和WKY大鼠,pA2值分别为(11·0±0·2)和(10·9±0·2);西萝芙木碱引起NE量效曲线平行右移,pA2值SHR(7·2±0·2)和WKY大鼠(7·1±0·2)。结论1)高血压机体外周阻力血管的ETB、ETA、5-HT以及α受体介导的收缩作用明显增强;2)在外周阻力血管5-HT主要通过激动5-HT2A受体引起血管收缩,NE主要通过激动α1受体引起血管收缩。     

通心络对高血压大鼠血管内皮功能的保护作用研究

目的 探讨通心络对高血压大鼠血管内皮的保护作用.方法 实验动物分为3组,分别为自发性高血压大鼠组(SHR组),SHR服用通心络组(TXL组)和正常血压大鼠组(WKY组).通过放射免疫及聚合酶链反应检测主动脉一氧化氮(NO)、内皮素(ET)、血管内皮生长因子(VEGF)基因表达.结果 SHR组NO水平低于WKY组,TXL组NO水平高于SHR组.SHR组及TXL组mRNA表达均高于WKY组,以SHR组为最高.结论 通心络可能对高血压大鼠血管内皮功能有保护作用.     

通心络对高血压大鼠血管内皮功能的保护作用

目的探讨通心络对高血压大鼠血管内皮的保护作用。方法实验动物分为3组,自发性高血压大鼠（SHR）组,SHR服用通心络（TXL）组和正常血压大鼠（WKY）组。通过放免及聚合酶链反应检测主动脉一氧化氮（NO）、内皮素（ET-1）、血管内皮生长因子（VEGF）基因表达。结果SHR组NO水平低于WKY组（P<0.05）,TXL组NO水平高于SHR组（P<0.05）。SHR组ET-1含量及mRNA均高于WKY组（P<0.05）,TXL组ET-1含量及mRNA表达低于SHR组（P<0.05）,SHR组及TXL组的mRNA表达均高于WKY组（P<0.05）,以SHR组为最高。结论通心络可能对高血压大鼠的内皮功能有保护作用。     

Involvement of 5-HT1, 5-HT2, and 5-HT3 receptors in the mediation of the prolactin response to serotonin and 5-hydroxytryptophan.

Serotonin (5-HT) is involved in the neuroendocrine regulation of prolactin (PRL) secretion as a stimulator. Within the last decade several 5-HT receptor types have been identified, but their individual role in the mediation of the PRL response to 5-HT is only partly understood. We investigated in conscious male rats the effect of different 5-HT1, 5-HT2, and 5-HT3 receptor antagonists on the PRL response to 5-HT or to the 5-HT precursor 5-hydroxytrytophan (5-HTP) which was administered in combination with the 5-HT reuptake inhibitor fluoxetine. 5-HT (0.5-5.0 mg/kg BW i.v.) or 5-HTP (25-100 mg/kg i.p.) in combination with saline or fluoxetine (10 mg/kg i.p.) increased the plasma PRL concentration dose-dependently. Pretreatment with the 5-HT1+2 receptor antagonist methysergide (2.5 mg/kg i.p.) prevented the stimulatory effect of 5-HT or 5-HTP + fluoxetine. Pretreatment with the 5-HT2 receptor antagonists ketanserin or LY 53857 (2.5 mg/kg i.p.) inhibited the PRL response to 5-HT by approximately 80% and to 5-HTP + fluoxetine approximately 100%. A higher dose (10 mg/kg) of the 5-HT2 receptor antagonists possessed only 50% inhibitory effect. Pretreatment with the 5-HT3 receptor antagonists ICS 205-930 or GR 38032F (0.05-2.5 mg/kg i.p.) inhibited the PRL response induced by 5-HT or by 5-HTP + fluoxetine. The maximal inhibitory effect (approximately 80%) was obtained by a dose of 0.1 mg/kg of both compounds.(ABSTRACT TRUNCATED AT 250 WORDS)     

Estradiol induces expression of 5-hydroxytryptamine (5-HT) 4, 5-HT5, and 5-HT6 receptor messenger ribonucleic acid in rat anterior pituitary cell aggregates and allows prolactin release via the 5-HT4 receptor

Serotonin [5-hydroxytryptamine (5-HT)] is known to control prolactin (PRL) release at a hypothalamic level, but a pituitary site of action remains poorly studied. The present study explores the acute effect of 5-HT on PRL release in rat anterior pituitary aggregate cell cultures, the influence of steroid and thyroid hormones, and the 5-HT receptor (5-HTR) subtype(s) involved. 5-HT elicited a prompt increase in basal PRL release, an effect strongly potentiated by estradiol (E(2)) in the culture medium (dose response 1-100 nm). In E(2) condition, the PRL response was not affected by the nonselective 5-HTR antagonists methysergide and methiothepin nor by 5-HTR1, 5-HTR2, 5-HTR3, 5-HTR6, and 5-HTR7/5 antagonists, but was fully blocked by the 5-HTR4 antagonist GR 113808. Among various agonist analogs, only the 5-HTR4 agonist cisapride and the 5-HTR2 agonist alpha-methyl-5-HT evoked PRL release. The effect of alpha-methyl-5-HT also required E(2) during culture and was abolished by GR 113808 but not by combined 5-HTR2A, B, and C blockade. In E(2)-treated aggregates, 5-HT caused a 5-fold increase in cAMP levels. The intact anterior pituitary expressed mRNA of all known members of the 5-HTR family. In aggregates, 5-HTR4, 5-HTR5, and 5-HTR6 mRNA expression required E(2) during culture. The effect of 5-HT on PRL release was not affected by blocking the serotonin transporter or the vesicular monoamine transporter. The present data suggest a widespread expression of 5-HTRs in the rat anterior pituitary, several of which are up-regulated by estrogen, and that, in the presence of estrogen, one of these, the 5-HTR4, mediates acute PRL release.     

5-HT transporter sites and 5-HT1A and 5-HT3 receptors in Fawn-Hooded rats: a quantitative autoradiography study

BACKGROUND: The neuroanatomical profiles of 5-HT1A receptors, 5-HT3 receptors, and 5-HT transporters (5-HTT) in the brain of the Fawn-Hooded (FH) rat, particularly mesocorticolimbic regions, are not fully elucidated. METHODS: By means of in vitro quantitative autoradiography, we used [3H]citalopram, [3H]8-OH-DPAT, and [3H]GR65630 to label 5-HTT, 5-HT1A receptors, and 5-HT3 receptors in the brain of alcohol-na?ve FH rats, Wistar-Kyoto (WKY) rats, and FH rats given free access to 5% ethanol and/or after 24 to 48 hr withdrawal. RESULTS AND CONCLUSIONS: In alcohol-na?ve rats, FH rats displayed significantly higher (p < 0.05) densities of [3H]citalopram binding in the nucleus accumbens (+30%), lateral septum (+37%), ventral pallidum (+21%), and ventral tegmental area (+24%), as well as an increased binding of [3H]8-OH-DPAT to 5-HT1A receptors in the frontal and parietal cortex (+33%), occipital and temporal cortex (+25%), and hippocampal CA3 region (+31%), compared with WKY rats, whereas both strains exhibited comparable [3H]GR65630 binding to 5-HT3 receptors. Compared with control FH (naive) rats, chronic ethanol consumption significantly decreased (p < 0.(15)[3H]8-OH-DPAT binding in the frontal and parietal cortex (-15%) but significantly increased binding (p < 0.05) in the entorhinal cortex (+25%), retrosplenial granular cortex (+20%), and hippocampal CA1 (+14%) and CA3 regions (+18%). Moreover, ethanol withdrawal induced the same extent of increased [3H]8-OH-DPAT binding in the entorhinal and retrosplenial cortex as seen in FH (chronic) rats. In contrast, [3H]8-OH-DPAT binding in the hippocampal CA1 and CA3 regions was decreased by -9% and -20% from the level of chronic ethanol-treated FH rat (p < 0.05) and returned to the control level seen in FH (na?ve) rats. SIGNIFICANCE: The elevated 5-HT transporters and 5-HT1A receptors in the mesocorticolimbic areas in FH rats may reflect a potential innate altered transmission at serotonergic synapses, which possibly may affect the high intake of alcohol in FH rats. The region-specific alterations of 5-HT1A receptors in FH rat brain after ethanol challenges suggest that 5-HT1A receptors are sensitive to ethanol challenges, whereas 5-HTT are apparently insensitive.     

Effects of 5-HT2B, 5-HT3 and 5-HT4 receptor antagonists on gastrointestinal motor activity in dogs

AIM:To study the effects of 5-hydroxytryptamine(5-HT)receptor antagonists on normal colonic motor activity in conscious dogs.METHODS:Colonic motor activity was recorded using a strain gauge force transducer in 5 dogs before and after 5-HT2B,5-HT3 and 5-HT4 receptor antagonist administration.The force transducers were implanted on the serosal surfaces of the gastric antrum,terminal ileum,ileocecal sphincter and colon.Test materials or vehicle alone was administered as an intravenous bolus injection during a quiescent period of the whole colon in the interdigestive state.The effects of these receptor antagonists on normal gastrointestinal motor activity were analyzed.RESULTS:5-HT2B,5-HT3 and 5-HT4 receptor antagonists had no contractile effect on the fasting canine terminal ileum.The 5-HT3 and 5-HT4 receptor antagonists inhibited phaseⅢof the interdigestive motor complex of the antrum and significantly inhibited colonic motor activity.In the proximal colon,the inhibitory effect was dose dependent.Dose dependency,however,was not observed in the distal colon.The 5-HT2B receptor antagonist had no contractile effect on normal colonic motor activity.CONCLUSION:The 5-HT3 and 5-HT4 receptor antagonists inhibited normal colonic motor activity.The5-HT2B receptor antagonist had no contractile effect on normal colonic motor activity.     

Effect of serotonin 5-HT1, 5-HT2, and 5-HT3 receptor antagonists on the prolactin response to restraint and ether stress.

Serotonin (5-HT) appears to be involved in the central control of the prolactin (PRL) response to suckling and estrogen. Furthermore, 5-HT may participate in the mediation of stress-induced PRL release. In order further to elucidate the role of 5-HT and the type of 5-HT receptor(s) involved in the PRL response to stress, we investigated the effect of blockade of 5-HT1, 5-HT2 or 5-HT3 receptors on the restraint or ether stress-induced release of PRL in male rats. Pretreatment with the 5-HT1 + 2 receptor antagonist methysergide (0.5 or 2.5 mg/kg i.p.) inhibited or prevented the PRL response to restraint or ether stress. Pretreatment with the 5-HT2 receptor antagonists ketanserin or LY 53857 (0.5 or 2.5 mg/kg i.p.) inhibited the response to restraint or ether stress approximately 30 or 60%, respectively. Higher doses of both 5-HT2 receptor antagonists (10 mg/kg i.p.) had a minor inhibitory effect (5-30% for ketanserin and 50% for LY 53857). Prior intraperitoneal administration of the 5-HT3 receptor antagonists ICS 205-930 or GR 38032F (0.05-2.5 mg/kg i.p.) inhibited the restraint stress-induced PRL release dose-dependently. Both compounds inhibited the PRL response to ether stress, but only the effect of GR was dose-related. The maximal inhibitory effect (70% inhibition of the PRL response to restraint or ether stress) was obtained for both compounds at a dose of 0.1 mg/kg. We conclude that serotonergic neurons are involved in the mediation of the stress-induced PRL release by activation of 5-HT1, 5-HT2 as well as 5-HT3 receptors.     

5-HT及5-HT4R在心房颤动中的研究

在心房,5-羟色胺通过与G蛋白偶联的5羟色胺4受体结合,使L型Ca2+电流和起搏电流If增加,发挥正性肌力、快速收缩和舒张的作用,参与心脏节律的调控.本文就5-羟色胺及5-羟色胺4受体对心房颤动的影响进行综述,并探讨其在心房颤动中的作用机制.     

大鼠心肌组织中5-HT和AngⅡ含量在心肌肥厚前后的变化

目的 :探讨心肌组织中 5 -羟色胺 （ 5 - HT）及血管紧张素 （ Ang ）含量与心肌肥厚发生的关系。方法 :采用腹主动脉缩窄法建立压力超负荷心肌肥厚模型 ;腹腔注射甲状腺素法建立体液性心肌肥厚模型 ;荧光分光光度法和放射免疫分析法测定 5 - HT及 Ang 含量。结果 :压力超负荷和甲状腺素致心肌肥厚大鼠心肌组织中 5 - HT含量较对照组显著增加 （ 2 98± 5 7vs4 2 8± 5 8ng· g- 1 ,P<0 .0 1;2 77± 4 7vs3 62± 76ng· g- 1 ,P<0 .0 5 ） ;同样 ,在两种心肌肥厚大鼠心肌组织中 Ang 含量也有不同程度的增加 （ 190± 75 vs3 2 3± 63 pg· g- 1 ,P<0 .0 1;167± 5 5 vs2 78± 4 6pg· g- 1 ,P<0 .0 1）。结论 :提示 5 - HT及 Ang 与压力超负荷和体液性因素致心肌肥厚的形成有关。     

5-HT2 and 5-HT3 receptor subtypes mediate cholera toxin-induced intestinal fluid secretion in the rat

The mechanisms of diarrhea in Asiatic cholera have been studied extensively. Cyclic adenosine monophosphate, 5-hydroxytryptamine (5-HT), prostaglandins, and the function of neuronal structures have been implicated in the pathogenesis of cholera. To elucidate the action of 5-HT in mediating cholera secretion, in vivo experiments were performed in the rat jejunum. The inhibitory effects of the 5-HT2 receptor antagonist ketanserin and the 5-HT3 receptor antagonist ICS 205-930 were studied in cholera toxin- and 5-HT-induced fluid secretion. Both ketanserin and ICS 205-930 dose-dependently but only partially reduced the secretory effect of cholera toxin. The combination of the two blockers totally abolished cholera toxin-induced secretion without any influence on cholera toxin-induced increase in cyclic adenosine monophosphate. Prostaglandin E2- and bisacodyl-induced secretion was not affected by the combined administration of 5-HT2 and 5-HT3 antagonists. The present results provide evidence for an important role of 5-HT in cholera toxin-induced secretion. The data suggest a model in which cholera toxin may initiate the release of 5-HT from enterochromaffin cells. 5-Hydroxytryptamine may then cause prostaglandin E2 formation via 5-HT2 receptors and activation of neuronal structures via 5-HT3 receptors. These two effects may finally lead to the profuse fluid secretion which can be totally blocked by the combination of a 5-HT2 blocker and a 5-HT3 blocker.     

Autoradiographic analyses of the effects of restraint-induced stress on 5-HT1A, 5-HT1C and 5-HT2 receptors in the dorsal hippocampus of male and female rats.

Quantitative autoradiography was used to evaluate the effects of sex and either 1 or 5 daily 2-hour sessions of restraint stress on binding at 5-HT1A, 5-HT1C and 5-HT2 receptors in the rat dorsal hippocampus. Neither sex nor restraint stress were found to have effects on binding at 5-HT1C or 5-HT2 receptors. However, restraint stress increased binding of [3H]8-hydroxy-2-(di-n-propylamino)tetralin at 5-HT1A receptors in the CA4 region and in the infrapyramidal dentate gyrus. In addition, levels of binding at 5-HT1A receptors in the oriens and lacunosum moleculare layers of the CA1 region were significantly higher in female rats. Neither estradiol benzoate nor estradiol benzoate plus progesterone had effects on binding at hippocampal 5-HT1A receptors in ovariectomized rats, making it unlikely that the sex differences were related to stages of the estrous cycle. Stress-induced levels of corticosterone (CORT) were higher in females. Although CORT levels in blood obtained during restraint decreased from session 1 to session 5 in both male and female rats, the decrease became significant in females only. Female rats also displayed higher levels of activity in the open field. Although activity in the open field was reduced in male and female rats after restraint, these decreases were not significant. Results are discussed in relation to anxiety and depression.     

Influence of 5-HT1 and 5-HT2 receptor antagonists on insulin-induced adrenomedullary catecholamine release.

Previous works have indicated that insulin stress activates the serotonin (5-HT) and sympathoadrenal systems in the fasted rat. In addition, recent studies have shown that activation of either the 5-HT1A, the 5-HT1C or the 5-HT2 receptor triggers adrenal catecholamine release. Then, the aim of this study was to investigate whether brain 5-HT, by means of these receptors, mediates insulin-induced adrenal catecholamine release. For that purpose, both plasma epinephrine (Epi), norepinephrine (NE) and glucose levels were measured in conscious rats bearing intracardiac catheters. The intravenous administration of insulin (1 IU/kg) triggered hypoglycemia throughout the following 120 min in both fed and overnight fasted rats. Insulin stress elicited within 30 min a 5- and 38-fold increase in plasma Epi levels in fed and fasted rats, respectively. This change was associated with significant elevations in plasma NE levels in the fasted rats only. The intravenous administration of the mixed 5-HT1A receptor/beta-adrenoceptor blocker (-)-propranolol (5 mg/kg) to fasted rats did not modify plasma glucose and catecholamine peak responses to insulin; however, at later times, insulin triggered hypoglycemic convulsions in (-)-propranolol- but not in saline-pretreated rats. Besides, pretreatments with the 5-HT1C/5-HT2 receptor blocker LY 53857 (0.5 mg/kg), or the 5-HT1/5-HT2 receptor antagonist metergoline (3 mg/kg), did not diminish plasma catecholamine responses to insulin stress. Similarly, none of these antagonists affected plasma glucose recovery. These results seem to indicate that the sympathoadrenal response to insulin administration is not mediated by 5-HT.