大鼠杏仁核5—HT3受体参与免疫调制

实验通过大鼠侧脑室和杏仁核给予5－HT3受体激动剂1－phenylbiguanide(PBG),用3H－TdR掺入法测定脾细胞丝裂原（concanavalin A,Con A和lipopolysaccharide,LPS)刺激增殖效应,用活化脾细胞增殖法测定IL－2生成,MTT法测定自然杀伤（natural killer,NK)细胞活性和用放射免疫测定血浆皮质酮水平,以探讨大鼠杏仁核5－HT3受体在免疫调控中的作用。结果表明：5－HT3受体拮抗剂granisetron(GNT,0.1-0.4mg/kg ip)剂量依赖地增强Con A和LPS刺激的脾细胞增殖,作用在连续给药5d最明显,双侧脑室给予PBG（5ug/side)可增强ConA和LPS刺激的脾细胞增殖效应,作用在连续给药3d最明显,双侧和单侧中共杏仁核给予PBG0．5ug均增强ConA刺激的脾细胞增殖和IL－2生成,底内侧杏仁核给予同剂量PBG仅增强LPS刺激的脾细胞增殖效应,不影响ConA刺激的脾细胞增殖和IL－2生成,中央杏仁核给予PBG升高血浆皮质酮的作用较底侧杏仁核给予等量PBG引起的升高血浆皮质酮作用明显（P＜0．01）,侧脑室,中央杏仁核和底内杏仁核给予PBG对丝裂原刺激的脾细胞增殖效应影响不同,但均被同时同部位给予GNT所拮抗,提示杏仁核中央核和底内侧核的5－HT3受体可能以不同方式参与ConA或LPS刺激的脾细胞增殖效应的调制。     

大鼠中央杏仁核5-HT3受体参与胸腺功能调制

本研究旨在探讨大鼠中央杏仁核(central amygdala,CeA)内5-HT3受体激动之后,对丝裂原刀豆球蛋白A(concanavalin A,ConA)刺激的胸腺细胞增殖反应的影响,及其潜在的神经内分泌调节环路.分别经大鼠腹腔(intraperitoneal,i.p.)、双侧侧脑室(intracerebroventricle,i.c.v.)和双侧CeA(intracentral amygdala,i.c.a.)注射选择性5-HT3受体激动剂1-phenylbiguanide(PBG),同时制备正常大鼠胸腺细胞悬液与不同浓度PBG(1×10-8～1×10-5 mol/L)体外共同孵育.经MTT法测定显示,无论有无ConA刺激,正常大鼠离体胸腺细胞在与PBG(1×10-8～1×10-5 mol/L)体外共同孵育时其增殖反应均不受后者影响;PBG i.p.(每天0.5 mg/kg,连续5 d)对ConA刺激的胸腺细胞的增殖反应亦无影响,而PBG i.c.v.(每天10 μg/侧,连续5 d)则显著增强之;当PBG i.c.a.(每天1.0 μg/侧,1 d或连续3、5、7 d)时,ConA刺激的胸腺细胞的增殖反应于给药后第1天即开始增强且日益显著,第5天达到高峰,第7天则趋于减弱.在给予PBG 5 min前相同给药部位先给予5-HT3受体拮抗剂tropisetvon(TRP)预处理可逆转PBG的促胸腺细胞增殖效应.免疫组织化学SABC法检测显示,PBG(1.0 μg/侧,i.c.a.)单次给药后各脑区可相继出现大量c-Fos阳性细胞(CeA1 h;海马及皮层1～2 h;下丘脑4 h;中脑导水管周围灰质8 h),并迅速达到各自高峰(CeA1 h;海马及皮层2 h;下丘脑4 h),与相应的生理盐水对照组及TRP预处理组相比均有显著性差异.随后,这一表达在各脑区中逐步减弱并消失(CeA4 h;海马、皮层及下丘脑8 h).由此推论,大鼠CeA内5-HT3受体至少可部分通过边缘系统-皮层-下丘脑-中脑导水管周围灰质这一神经内分泌环路调制胸腺细胞功能.     

5-HT2和5-HT3受体在外周初级感觉神经末梢痛反应和痛调制中的相互作用

目的：探讨5-HT2和5-HT3受体亚型在5-HT引起外周痛反应和痛调制中的相互作用及其机制;方法：在大鼠三又神经节神经元标本上应用全细胞膜片钳技术记录5-羟色胺激活电流（15_HT）,并结合痛行为实验进行观察。结果：在大多数受检细胞（54／88,61．4％）特别是中、小型细胞外加5-HT可引起一快去敏感的内向电流,此内向电流能被5-HT,受体特异性激动剂2-甲基-5-羟色胺所模拟,被5-HT3受体拮抗剂ICS250-930可逆性阻断,而5-HT2受体激动剂α-甲基-5-羟色胺则有明显增强15-HT的作用,5-HT1受体激动剂R-（＋）-UH301无明显反应。在进一步的整体清醒动物的行为学试验中我们观察到,大鼠后肢掌底皮下注射5-HT（10-5,10-4和10-3mol／L）引起浓度依赖性的痛行为反应,而用5-HT2和5-HT3受体特异性拮抗剂Cyproheptadine和ICS250-930分别阻断相应受体亚型后,5-HT引起的痛行为反应的强度序列为：5-HT〉5-HT＋ICS〉5-HT＋Cyp。结论：本文结果提示：5-HT所引起的痛反应中,在初级感觉神经元水平5-HT3受体可能仅起着启始作用,而5-HT,受体则在伤害性信息的维持和调制过程中发挥更大的作用。     

5-HT_(1A)受体参与学习记忆的分子机制研究进展

5-HT(五羟色胺)能神经元是起源最早的神经元之一,在传统的神经元形成前,成长中的轴突就可释放5-HT,并且通过5-HT的各种亚型受体来实现不同的功能。近年来,随着5-HT、5-HTRs(五羟色胺受体)的基因克隆及5-HT受体选择性激动剂和拮抗剂的研究发展,5-HT系统在学习记忆中的作用越发明确,许多研究结果表明:5-HT系统在记忆的巩固、短时程记忆(STM)及长时程记忆(LTM)中起重要作用,5-HT1A受体更是在非脊椎动物及哺乳动物的脑中都高度表达,并通过相似的信号转导途径参与学习与记忆的形成和巩固。本文将介绍5-HT1A受体、5-HT1A受体激动剂、5-HT1A受体拮抗剂及其与学习记忆的联系,重点综述5-HT1A受体参与学习记忆的信号转导途径研究进展,讨论5-HT1A受体参与学习记忆的可能性分子神经生物学机制。     

5-HT1A受体对新生大鼠离体延髓脑片呼吸节律性放电的调制

本研究探讨5-HT1A受体在延髓基本节律性呼吸放电发生和调节中的作用。以改良Kreb＇s液恒温灌流新生Sprague-Dawley大鼠离体延髓脑片标本,稳定记录与之相连的舌下神经根的呼吸节律性放电活动（respiratory rhythmical discharge activity,RRDA）后,第一组在灌流液中分别单独给予5-HT1A受体的特异性激动剂8-羟四氢萘[（＋／-）-8-hydroxy-2-（di-N-propylamino）tetralin hydrobromide,8-OHDPAT]和特异性拮抗剂多次甲基多苯基多异氰酸酯[4-iodo-N-[2-[4-methoxyphenyl]-1-piperazinyl]ethyl]-N-2-pyridynyl-benzamide hydrochloride,PMPPI];第二组分别先后给予8-0HDPAT和8-0HDPAT＋PMPPI,观察舌下神经根RRDA的变化,探讨5-HT1A受体对其调节作用。结果显示,给予8-OHDPAT后,呼吸周期（respiratory cycle,RC）和呼气时程（expiratory time,TE）显著延长,放电的积分幅度（integral amplitude,IA）持续降低,吸气时程（inspiratory time,TI）无明显变化;给予PMPPI后RC、TI和TE明显缩短,舌下神经根IA无明显变化,且8-OHDPAT的作用可部分被PMPPI逆转。结果提示,5-HT1A受体参与了哺乳动物基本呼吸节律的产生和调节。     

跑台运动对攻击行为大鼠内侧下丘脑和中脑导水管周围灰质5-HT1A受体、5-HT2A受体蛋白表达的影响

目的:探讨跑台运动对攻击行为大鼠内侧下丘脑(MH)和中脑导水管周围灰质(PAG)5-HT1A受体、5-HT2A受体蛋白表达的影响,为研究运动对攻击行为改善的神经生物学机制提供实验基础.方法:3月龄雄性SD大鼠40只,体重160～180 g,随机分为4组:安静组(A)、攻击模型组(G)、攻击跑台组(GP)、入侵组(R)....     

P2X3受体在感觉神经节的表达

用免疫组织化学与原位杂交研究P2X3受体在背根神经节,三叉神经节和结状神经节的分布。结果显示：1、原位杂交;在三种感觉神经节中,95%左右的神经节细胞为P2X3mRNA阳性,中、小型神经节细胞的杂交信号一般要比大型的神经节细胞强一些,2、免疫组织化学;免疫组织化学结果与原位杂交结果基本一致。此外,在各神经节内,均显示出许多P2X3免疫阳性神经纤维,在足掌表皮也显示许多P2X3免疫反应阳性纤维,结果提示：P2X3不仅参与机体的痛觉的形成,还可能参与其它感觉,如本体感觉等的形成。     

P物质对大鼠三叉神经节神经元GABA-和5-HT-激活电流的反向调制作用

实验采用全细胞膜片钳技术观察P 物质(SP)对大鼠同一三叉神经节(TG)神经元γ-氨基丁酸激活电流(IGABA)和5-羟色胺激活电流(I5-HT)的调制作用。在受检的47 个 TG 细胞中,多数情况下可在同一细胞记录到IGABA 和 I5-HT 两种电流(63.8%,30/47)。在 30 个同时对 GABA 和 5-HT 敏感的细胞,其中 22 个细胞预加 SP(0.01 μmol/L)后,IGABA 减小(35.7 ± 6.1)%,而I5-HT 增加(65.2 ±8.7)%。此种调制作用可被SP 受体拮抗剂GR82334 及胞内透析GDP-β -S 或GF109203X 所阻断。以上结果表明:SP 受体激活后经G 蛋白耦联,通过相同的PLC-DAG-PKC 转导途径对同一感觉神经元共存的GABAA 受体和5-HT3 受体产生相反的调制效应。     

IL－3、GM－CSF和IL－5受体及其信号传导

ＩＬ—３、ＧＭ－ＣＳＦ和ＩＬ—５是一类功能相似的造血因子,它们的受体至少包括配体特异性的α亚基和共用β亚基（βｃ）两部分。βｃ识别三因子的Ｎ端α－螺旋,而α亚基则识别三因子的Ｃ端α－螺旋,两者均为功能性的高亲和力受体所必需．由于βｃ胞内区较长,能结合Ｊａｂ和Ｓｔａｔ等信号分子,所以,三种因子受体受配体刺激后能诱导相似蛋白的酪氨酸磷酸化。另外,激酶的不同剪切型、转录因子的同分异构体、受体亚基的细胞型特异性以及信号传导通路的多重性等则为三因子作用特异性的基础。本文就对其主要内容作一综述。     

脊髓5—HT1A受体和5HT3受体参与的心血管反应

给清醒大鼠脊髓蛛网膜下腔注射(ith)5-羟色胺(5-HT)1.56、3.125、6.25和12.5μg/1Oμl后引起明显血压升高,并呈量效关系,但心率(HR)无明显改变。Ith 5-HT 再摄取抑制剂 fluoxetine(10μg/10μ1)后也使平均动脉压(mABP)明显上升,这一效应可被5-HT 受体阻断剂肉桂硫胺(cinanserin 25μg/1Oμl)完全阻断。8-OH-DPAT 和2-Methylhydroxy-tryptamine 分别为5-HT_(1A)受体和5-HT_3受体的激动剂,在 ith 8-OH-DPAT(2.5,5.0,1Oμg/1Oμl)后 mABP 明显上升,但 HR 减慢;相反,ith 2-Methylhydroxytryptamine 之后则使 mABP 明显降低,HR 无明显变化。以上结果表明,脊髓中5-HT 可通过激活5-HT_(1A)受体引起血压升高,激活5-HT_3受体则引起血压降低。这一发现对有关5-HT 中枢效应的不同报道提出了一种可能的解释。     

The role of 5‐HT2A receptor and 5‐HT2A/5‐HT1A receptor interaction in the suppression of catalepsy

In the present study, the 5‐HT_2A and 5‐HT_1A receptors functional activity and 5‐HT_2A receptor gene expression were examined in the brain of ASC/Icg and congenic AKR.CBAD13Mit76C mouse strains (genetically predisposed to catalepsy) in comparison with the parental catalepsy‐resistant AKR/J and catalepsy‐prone CBA/Lac mouse strains. The significantly reduced 5‐HT_2A receptor functional activity along with decreased 5‐HT_2A receptor gene expression in the frontal cortex was found in all mice predisposed to catalepsy compared with catalepsy‐resistant AKR/J. 5‐HT_2A agonist DOI (0.5 and 1 mg/kg, i.p.) significantly reduced catalepsy in ASC/Icg and CBA/Lac, but not in AKR.CBAD13Mit76C mice. Essential increase in 5‐HT_1A receptor functional activity was shown in catalepsy‐prone mouse strains in comparison with catalepsy‐resistant AKR/J mice. However, in AKR.CBAD13Mit76C mice it was lower than in ASC/Icg and CBA/Lac mice. The inter‐relation between 5‐HT_2A and 5‐HT_1A receptors in the regulation of catalepsy was suggested. This suggestion was confirmed by prevention of DOI anticataleptic effect in ASC/Icg and CBA/Lac mice by pretreatment with 5‐HT_1A receptor antagonist p‐MPPI (3 mg/kg, i.p.). At the same time, the activation of 5‐HT_2A receptor led to the essential suppression of 5‐HT_1A receptor functional activity, indicating the opposite effect of 5‐HT_2A receptor on pre‐ and postsynaptic 5‐HT_1A receptors. Thus, 5‐HT_2A/5‐HT_1A receptor interaction in the mechanism of catalepsy suppression in mice was shown.     

Structural basis of ligand recognition in 5-HT3 receptors

The 5‐HT₃ receptor is a pentameric serotonin‐gated ion channel, which mediates rapid excitatory neurotransmission and is the target of a therapeutically important class of anti‐emetic drugs, such as granisetron. We report crystal structures of a binding protein engineered to recognize the agonist serotonin and the antagonist granisetron with affinities comparable to the 5‐HT₃ receptor. In the serotonin‐bound structure, we observe hydrophilic interactions with loop E‐binding site residues, which might enable transitions to channel opening. In the granisetron‐bound structure, we observe a critical cation–π interaction between the indazole moiety of the ligand and a cationic centre in loop D, which is uniquely present in the 5‐HT₃ receptor. We use a series of chemically tuned granisetron analogues to demonstrate the energetic contribution of this electrostatic interaction to high‐affinity ligand binding in the human 5‐HT₃ receptor. Our study offers the first structural perspective on recognition of serotonin and antagonism by anti‐emetics in the 5‐HT₃ receptor.     

Reduced histamine levels and H3 receptor antagonist-induced histamine release in the amygdala of Apoe-/- mice

The histamine H(3) receptor is a constitutively active G protein-coupled receptor for the neurotransmitter histamine that serves a negative feedback function. A role for the histamine H(3) receptor has been suggested in neurodegenerative diseases, such as Parkinsons disease and Alzheimer's disease. Mice deficient in apolipoprotein E (apoE), a protein involved in development, regeneration, neurite outgrowth, and neuroprotection, show increased measures of anxiety and reduced sensitivity to effects of histamine H(3) receptor antagonists on measures of anxiety. In this study, we tested whether in mice lacking apoE (Apoe-/-) histamine levels and histamine release in brain areas involved in the regulation of anxiety are altered. H(3) receptor antagonist-induced histamine release was lower in the amygdala of Apoe-/- than wild-type mice. In contrast, there were no genotype differences in histamine release in the hypothalamus. Consistent with these data, histamine immunohistochemistry revealed lower total and synaptic histamine levels in the central nucleus of the amygdala of Apoe-/- than wild-type mice. Such changes were not seen in the hypothalamus, hippocampus, or cortex. In Apoe-/- mice, chronically decreased histamine levels and reduced histamine release in the amygdala might contribute to increased measures of anxiety.     

5-HT2 receptors in Drosophila are expressed in the brain and modulate aspects of circadian behaviors

Dysregulation of 5-HT(2) receptor function has been strongly implicated in many neuropsychiatric disorders, including schizophrenia. At present, the molecular mechanisms linking 5-HT(2) receptor activation to behaviors is not well understood. In efforts to elucidate these processes, the fruit fly, Drosophila melanogaster, is proposed to serve as a powerful genetically tractable model organism to study 5-HT(2) receptor function. Data are presented here on the expression of the fly ortholog of the mammalian 5-HT(2) receptor, 5-HT(2)Dro, in the larval and adult brain of the fly, and on the involvement of these circuits in certain circadian behaviors. In the adult brain, 5-HT(2)Dro is expressed in the protocerebrum and ellipsoid body, areas believed to participate in higher order behaviors including learning, locomotion, and sensory perception. In the third instar larva, 5-HT(2)Dro receptor expression is detected in a specific pattern that markedly changes from early to late third instar. To probe the function of this receptor we have examined the effects of the 5-HT(2) receptor-specific agonist DOI in wild type and 5-HT(2)Dro hypomorphic flies on circadian behaviors. DOI was found to increase early day activity, eliminate anticipatory behavior, and reduce viability. The effects of DOI were significantly diminished in a 5-HT(2)Dro hypomorphic strain. Identifying the 5-HT(2)Dro receptor circuitry and behaviors they mediate are significant steps towards developing this model system to study conserved molecular mechanisms underlying behaviors mediated by 5-HT(2) receptors in mammalian systems.     

选择性5-HT1A受体拮抗剂WAY-100635增加6-羟多巴胺损毁大鼠杏仁基底外侧核的神经活动

本文采用玻璃微电极细胞外记录法,观察正常大鼠和6-羟多巴胺(6-hydroxydopamine,6-OHDA)损毁黑质致密部大鼠杏仁基底外侧核(basolateral nucleus,BL)神经元电活动的变化,以及体循环给予选择性5-HT1A受体拮抗剂WAY-100635对神经元电活动的影响.结果显示,正常大鼠BL投射神经元和中间神经元的放电频率分别足(O.39±0.04)Hz和(0.83±0.16)Hz,6-OHDA损毁大鼠BL投射神经元和中间神经元的放电频率分别足(0.32±0.04)Hz和(0.53±0.12)Hz,与正常大鼠相比无显著差异.在正常大鼠,所有投射神经元呈现爆发式放电;94%的中间神经元为爆发式放电,6%为不规则放电.在6.OHDA损毁大鼠,85%的投射神经元呈现爆发式放电,15%为不规则放电;86%的中间神经元为爆发式放电,14%为不规则放电,与正常大鼠相比无显著差别.静脉给予0.1 mg/kg体重的WAY-100635不改变正常大鼠和6-OHDA损毁人鼠BL投射神经元和中间神经元的放电频率.然而,0.5 mg/kg体重的WAY-100635却显著降低正常大鼠BL投射神经元的平均放电频率(P<0.01),明显增加6-OHDA损毁大鼠BL投射神经元的平均放电频率(P<0.004).高剂量WAY-100635不影响正常大鼠和6-OHDA损毁大鼠BL中间神经元的平均放电频率.结果表明,黑质多巴胺能损毁后内在和外在的传入调节BL神经元的活动,在正常大鼠和6-OHDA损毁大鼠5-HT1A 受体调节投射神经元的活动,并且在6-OHDA损毁大鼠WAY-100635诱发投射神经元平均放电频率增加.结果提示,5-HT1A 受体在帕金森病情感性症状的产生中起重要作用.     

5-Hydroxytryptamine2 and 5-hydroxytryptamine3 receptors mediate serotonin-induced short-circuit current in pig jejunum

The purpose of this study was to determine the effect of methysergide, ketanserin, granisetron, cisapride, and renzapride on serotonin 5-hydroxytryptamine-evoked short-circuit current in muscle and myenteric plexus-stripped pig jejunum using the Ussing chamber technique. Ketanserin, granisetron, cisapride, and renzapride all reduced the 5-hydroxytryptamine-induced increase in short-circuit current by about 50%. Combination of ketanserin and granisetron only reduced the 5-hydroxytryptamine-induced peak increase in short-circuit current by 25%. Cisapride caused a small concentration-dependent increase in short-circuit current. Atropine and hexamethonium both almost completely suppressed the cisapride-induced peak increase in short-circuit current. Ketanserin, granisetron, methysergide, and renzapride did not alter the basal short-circuit current. These results suggest that 5-hydroxytryptamine elicits an increase in short-circuit current by activating epithelial and submucosal 5-hydroxytryptamine₂ and 5-hydroxytryptamine₃ receptor subtypes. Furthermore, the short-circuit current-increasing effect of cisapride, is due to activation of at least muscarinic and nicotinic receptors.Abbreviations 5-HT 5-hydroxytryptamine, serotonin - AUC area under the curve - EC enterochromaffin - ENS enteric nervous system - GI gastrointestinal - MW molecular weight - 5-HTP-DP N-acetyl-5-hydroxytryptophyl-5-hydroxytrytophan amide - SSC short-circuit current - TTX tetrodotoxin     

Acute and chronic effects of citalopram on postsynaptic 5-hydroxytryptamine(1A) receptor-mediated feedback: a microdialysis study in the amygdala

Microdialysis was used to assess the involvement of postsynaptic 5-hydroxytryptamine(1A) (5-HT(1A)) receptors in the regulation of extracellular 5-HT in the amygdala. Local infusion of the 5-HT(1A) receptor agonist flesinoxan (0.3, 1, 3 microM) for 30 min into the amygdala maximally decreased 5-HT to 50% of basal level. Systemic administration of citalopram (10 micromol/kg) increased 5-HT to 175% of basal level. Local infusion of 1 microM of the 5-HT(1A) receptor antagonist WAY 100.635 into the amygdala augmented the effect of citalopram to more than 500% of basal 5-HT level. 5-HT(1A) receptor responsiveness after chronic citalopram treatment was determined in two ways. First, by local infusion of 1 microM flesinoxan for 30 min into the amygdala, which showed a significant 63% reduction in response (area under the concentration-time curve; AUC) for the citalopram group compared to the saline group. Second, by systemic administration of citalopram (10 micromol/kg), which increased 5-HT to 350% of basal level. The effect was larger than in untreated animals, but more important, local infusion of 1 microM WAY 100.635 into the amygdala now failed to augment the effect of citalopram. Both the flesinoxan and WAY 100.635 data suggest an involvement of postsynaptic 5-HT(1A) receptor-mediated feedback in the amygdala, which diminishes following chronic citalopram treatment.