脑创伤后脑组织中α_1及β肾上腺素受体活性的改变及其意义研究

以家兔枕部受撞击的脑对冲伤模型，采用受体放射分析法，观测了伤后脑组织中α_１及β肾上腺素受体（α_１－ＡＲ及β－ＡＲ）活性的动态变化，以及阻断受体对伤后脑水肿的影响。结果表明，伤后２４ｈ内，β－ＡＲ显著降低，α_１－ＡＲ伤后３０ｍｉｎ显著增加，３ｈ后逐渐下降，伤后α_１－ＡＲ与β－ＡＲ的比值显著增大。伤后早期阻断α_１－ＡＲ显著抑制脑水含量增加；阻断β－ＡＲ增加脑水含量。本实验提示上述受体的活性变化是单胺递质参与继发性脑损伤的重要基础。     

杏仁核毁损对甲基苯丙胺大鼠脑内5-HT2A受体的影响

目的探讨杏仁核毁损对甲基苯丙胺（MAP）大鼠脑内5-HT2A受体表达的影响。方法24只SD大鼠分为对照组、模型组、假手术组和手术组，每组各6只；采用腹腔注射MAP制备精神分裂症模型，立体定向毁损杏仁核，采用Sams-Dodd法评定各组动物刻板行为的变化，以PCR技术测定脑组织中5-HT2A受体mRNA的表达。结果杏仁核毁损可明显降低MAP大鼠刻板行为评分（P〈0．05）。各组大鼠额叶、颞叶皮质和中脑均有5-HT2A受体mNRA（61lbp）的阳性表达，且均以额叶皮质表达最为强烈；模型组及假手术组大鼠中脑5-HT2A受体mRNA受体表达的水平明显低于对照组和手术组（P〈0．05）。结论杏仁核毁损可改善MAP大鼠的刻板行为，这可能是通过中脑5-HT2A受体mRNA表达的增高而起作用。     

脑损伤与神经细胞钙通道变化

脑损伤导致神经细胞钙通道开放、细胞内Ca~(2+)超载是加剧继发性脑损害的关键因素之一。本文着重综述脑损伤时神经细胞Ca~(2+)通道变化及细胞内Ca~(2+)超载对脑水肿等脑继发性损害的有关机理,以及钙拮抗剂治疗脑损伤的作用。     

5-HT2C受体与癫痫的关系

5-HT是人体中枢及外周神经系统重要的神经递质，研究发现它涉及感觉、运动和行为等多种生理活动，分为7个亚族，即5-HT1—5-HT7，5-HT2由5-HT2A、5-HT2B、和5-HT2C三部分组成，5-HT2C受体基因定位于Xq24区，由RNA来修饰调节的G蛋白偶联受体，其主要分布在中枢神经系统，除大量分布在脉络丛外（该位置仅有此一种亚型），还广泛分布在嗅核，梨状核，带状核，后夹肌，边缘系统的伏隔核，海马杏仁核和基底神经节的尾状核和黑质。     

弥漫性脑损伤大鼠脑皮质Ⅰ、Ⅱ组代谢型谷氨酸受体表达及意义

目的：研究弥漫性脑损伤（DBI）后大鼠脑皮质代谢型谷氨酸受体（mGluRs）的变化及其意义。方法：SD大鼠随机分为对照与DBI组，采用Marmarou 加速性DBI模型，在伤后不同时间取样行原位杂交和病理学研究。结果：与对照组相比，DBI组脑皮质I组mGluRs阳性神经元表达在伤后12h开始增加，24h达峰值（P＜0．01）；Ⅱ组mGluRs阳性神经元表达在伤后24h开始减少，48h显减少（P＜0．01）。病理学研究提示，DBI后24h脑皮质神经元损伤严重（P＜0．01），与mGluRs表达变化的时间吻合.结论：Ⅰ、Ⅱ组mGluRs作用不同，分别具有神经元损害和保护作用；脑损伤后，I组mGluRs表达增加，参与DBI引起的神经元损伤， Ⅱ组mGluRs表达减少，其神经元保护作用减弱。这为阐明DBI的损伤机制及应用mGluRs激动剂和／或拮抗剂治疗提供了理论依据。     

5-HT2A受体基因多态性与单相抑郁及其自杀行为的关系

目的探讨中国汉族人群中单相抑郁患者及其自杀行为与5-HT2A受体基因T102C多态性的关系。方法采用PCR—RFLP方法,检测281例单相抑郁患者组和219名对照组5- HT2AT102C基因型及等位基因频率,分析患者组和对照组之间以及患者组内有无自杀行为之间该基因型及等位基因的差异。结果患者组中5-HT2AT102C基因型和等位基因与对照组相比,差异未见显著性,但患者组内有自杀行为的个体携带C 的基因型(A1/A2和A2/A2)的明显高于C-(A1/A1)基因型,差异有统计学意义(P＜0．05)。结论本研究提示,5-HT2AT102C基因多态性与单相抑郁症的自杀行为有关,C等位基因可能是单相抑郁症患者中有自杀行为的风险因子之一。     

谷氨酸及其受体变化与神经细胞损害

谷氨酸是最主要的兴奋性氨基酸之一,它不仅参与神经细胞的某些重要生理、生化功能,也是引起神经细胞毒性损害的重要因素之一。谷氨酸及其受体变化在脑损伤、脑缺血、脑缺氧及癫痫时造成神经细胞的兴奋毒性作用,引起和加剧继发性脑损害。本文着重综述谷氨酸及其受体变化对脑的兴奋毒性作用和有关的机理。     

大鼠脊髓内5-HT2C,5-HT3,5-HT6和5-HT7受体亚型mRNAs的表达

目的:观察5-HT2C,5-HT3,5-HT6和5-HT7受体亚型mRNAs在大鼠脊髓不同节段的表达.方法:反转录PCR方法.结果:5-HT2C受体亚型mRNA在颈、胸、腰、骶段脊髓的背角(DH)和前角(VH)均有较强的表达;5-HT3受体mRNA在各节段脊髓DH的表达水平较高,而在VH则较低;与5-HT3受体亚型相反,5-HT6受体亚型mR-NA在脊髓VH的表达水平高于DH;5-HT7受体mRNA在脊髓的表达则与5-HT3受体相似,在各节段的DH均有较高水平的表达.不同的受体亚型在脊髓同一节段以及同一受体亚型在不同脊髓节段的表达水平存在差异.结论:本研究结果表明,上述四种5-HT受体亚型在脊髓具有不同的表达特点,提示它们在脊髓水平可能发挥着不同的生理作用,并为深入探讨5-HT受体参与伤害性感受和运动的调节机制提供了依据.     

精神分裂症患者5-HT2A受体基因相关因素的研究

目的　分析汉族人 5 HT2A受体基因与精神分裂症易感性之间的关系以及影响患者 5 HT2A受体基因的相关因素。方法　 2 6 9例精神分裂症病人 ,310例正常对照 ,用聚合酶链式反应 (PCR)扩增及限制性片段长度多态性 (RFLPs)技术测定其 5 HT2A受体基因型和等位基因。结果　发现含 5 HT2A受体基因的等位基因A2的精神分裂症患者平均发病年龄明显大于含等位基因A1的患者 ,但 5 HT2A受体基因与精神分裂症的易感性、患者的性别、家族史、症状严重度均无显著相关。结论　 5 HT2A受体基因的等位基因A2可明显推迟精神分裂症患者的发病年龄 ,但 5 HT2A受体基因不影响汉族人精神分裂症的易感性、患者的症状严重度 ,患者 5 HT2A受体基因的频率分布也不受患者的性别、家族聚集性的影响     

5-HT1A受体的作用及其临床意义

5-羟色胺再摄取抑制剂（SSRI）是近十余年临床广泛应用的抗抑郁剂,有疗效好、不良反应轻和服药简便等多方面的优点,但在应用过程中也有起效较慢的缺点,特别是在抑郁症状严重需尽快解除时更显得不足。随着神经生理学和药理学的研究进展,人们已经发现SSRI类抗抑郁药起效慢的部份原因,并找到使其加快起效和疗效加强的一些措施。众所周知SSRI类抗抑郁药主要作用于中枢神经系统的5-羟色胺（5-HT）系统,抑制突触前膜对5-HT的再摄取、提高突触间隙的5-HT浓度是其主要药理作用机制。但抑郁症状的发生并非仅仅由于5-HT系统的功能不足所致,其中还包括去甲上腺素（NE）、多巴胺（DA）、γ-氨基丁酸（GABA）等系统的功能不足和／或紊乱,以及神经内分泌紊乱和受体后第二信使系统功能异常等多方面的因素。我们在本文中仅就5-HT1A受体的功能和5-HT1A激动剂和拮抗剂的药理作用和他们与SSRI疗效的关系进行综述。     

大鼠创伤性颅脑损伤后EPO及受体的表达与意义

目的观察创伤性颅脑损伤大鼠皮层中促红细胞生成素（EPO）及其受体（EPOR）的分布与表达变化,并探讨其意义。方法35只雄性Wistar大鼠,随机分为正常对照组和颅脑损伤后2h、6h、12h、24h、3d和7d共7组,每组各5只。采用Myneurolab脑立体定向仪和Benchmark颅脑损伤撞击器制作创伤性颅脑损伤模型。应用免疫组化和Westernblot分别检测上述时间点损伤灶周围皮层中EPO及EPOR的蛋白表达变化。结果EPO与EPOR广泛表达于神经元、少突胶质细胞和血管内皮细胞中。EPO与EPOR在创伤性颅脑损伤后2h即可见表达增强,6～12h表达继续升高,至24h达高峰,随后EPO的表达开始减弱,而EPOR的表达在24h后持续维持在高水平,无明显降低。结论创伤性颅脑损伤后EPO与EPOR的表达随时间变化不一致。EPOR的持续高水平表达是外源性EPO发挥神经保护作用的分子基础。     

Behavioral effects of 5-HT receptor ligands in the aversive brain stimulation, elevated plus-maze and learned helplessness tests

In order to illustrate the use of animal models in the study of the anxiolytic and antidepressant properties of drugs acting on 5-HT receptors, a series of experiments is described. With electrical stimulation of the midbrain central gray (CG), an aversive area of the brain, the 5-HT-1 receptor antagonist propranolol raised the aversive threshold in a dose-dependent way, following its microinjection into the CG. This antiaversive effect of propranolol, which is similar to that of benzodiazepine anxiolytics, was prevented by microinjection into the same brain site of the 5-HT-2 receptor blocker ritanserin. Ritanserin itself and the 5-HT-1A receptor ligand ipsapirone caused either little or no effect. In another animal model of anxiety, the elevated plus-maze, intra-CG propranolol also caused an anxiolytic-like effect, antagonized by ritanserin, indicating a 5-HT mediation. However, systemically injected isamoltane, a congener of propranolol, was ineffective in the elevated plus-maze, whereas ipsapirone caused an anxiolytic effect. Ritanserin was again inactive. Finally, both ipsapirone as well as another 5-HT-1A receptor ligand BAY R 1531, given IP, reversed the learning deficit resulting from exposure to uncontrollable foot-shocks, an effect characteristic of antidepressant drugs.     

Spinal cord injury-specific depression of monosynaptic spinal reflex transmission by l-5-hydroxytryptophan results from loss of the 5-HT uptake system and not 5-HT receptor supersensitivity

We studied changes in the spinal segmental reflex and serotonergic (5-HT) responses in rats after spinal cord injury (SCI) produced by the weight-dropping method at the T8 level. The spinal monosynaptic reflex amplitude (MSR) was recorded from the L5 ventral root following stimulation of the ipsilateral L5 dorsal root. The 5-HT precursor l-5-hydroxytryptophan (L-5-HTP) depressed MSR in the spinal cord injured rats but not in normal rats. We investigated whether the SCI-specific depression of MSR by L-5-HTP was attributable to postsynaptic supersensitivity of 5-HT receptors or presynaptic loss of the 5-HT uptake system. Sumatriptan, a selective 5-HT(1B/1D) receptor agonist that is not taken up by 5-HT transporters, depressed the MSR similarly in both SCI and normal rats, suggesting that SCI resulted in the loss of 5-HT terminals and not postsynaptic supersensitivity of 5-HT receptors.     

5-HT1A受体对双相呼气和吸气神经元电活动的调制

目的探讨5-HT1A受体对延髓脑片双相呼气神经元和吸气神经元电活动的影响。方法在新生大鼠延髓脑片上同步记录舌下神经根和双相呼气神经元／吸气神经元单位的放电活动，并在灌流的改良Kreb’s液中先后加以5-HT1A受体的特异性激动剂（＋／-）-8-hydroxy-2-（di-N-propylamino）tetralin hydrobromide（8-OH-DPAT）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）观察对神经元单位放电的影响。结果给予5-HT1A受体激动剂8-OH-DPAT后，双相呼气神经元／吸气神经元的呼吸周期和呼气时程明显延长，积分幅度降低，单位放电峰频率显著性降低；给予特异性拮抗剂PMPPI后，对呼吸周期，呼气时程的作用相反，而积分幅度和单位放电峰频率无明显变化。结论5-HT1A受体可能通过影响双相呼气神经元的电活动参与了呼吸时相的转换，同时也可能介导了吸气神经元的抑制性突触输入。     

Gene structure and expression of the mouse 5-HT2 receptor.

Serotonin (5-hydroxytryptamine, 5-HT) is an important neurotransmitter which mediates numerous physiological functions. Using the SacI-EcoRI restriction fragment of the rat brain 5-HT2 receptor cDNA as a probe, we have screened a mouse brain cDNA library, created by random priming and constructed in SWAJ vectors, and have isolated a cDNA encoding a 1.4 kb open reading frame which codes for a functional mouse 5-HT2 receptor identified from pharmacological binding profiles and coupling of phosphoinositide formation in a stably transfected fibroblast cell line. The deduced amino acid sequence is 97.4% identical to the rat 5-HT2 receptor. Using the same 5-HT2 receptor cDNA probe, ten positive genomic clones were isolated from two mouse genomic libraries constructed in the pWE15 cosmid vector and the EMBL-3 phage vector. Extensive mapping and sequencing of these genomic clones indicate the mouse 5-HT2 receptor coding region spans over 20 kb and is composed of three exons split by two introns. Northern blot analysis shows one band of 5-6 kb in the mouse brain, but not in the heart, lung, liver, or kidney total RNA. Southern analysis of mouse liver genomic DNA shows a simple pattern of digestion by several restriction enzymes, which suggests that one copy of the 5-HT2 receptor gene may exist in the mouse genome.     

Pre- and post-synaptic effects of the 5-HT3 agonist 2-Methyl-5-HT on the 5-HT system in the rat brain

Microiontophoretic applications of 5-HT and of the 5-HT₃ agonist 2-methyl-5-HT produced a current-dependent suppression of firing activity of both hippocampal (CA₁ and CA₃) and cortical neurons in anesthetized rats. Concomitant microiontophoretic applications of the 5-HT₃ antagonists BRL 46470A and S-zacopride, as well as their intravenous injection, did not antagonize the inhibitory effect of 5-HT and 2-methyl-5-HT. In contrast, the 5-HT_1A antagonist BMY 7378, applied by microiontophoresis or administered intravenously, significantly reduced the inhibitory action of 5-HT and 2-methyl-5-HT. The firing activity of dorsal raphe 5-HT neurons was also reduced by 5-HT, 2-methyl-5-HT and the 5-HT_1A agonist 8-OH-DPAT applied by microiontophoresis. While BRL 46470A (0.1 and 1 mg/kg, i.v.) did not antagonize the inhibitory effect of the three 5-HT agonists on 5-HT neuronal firing activity, only that of 8-OH-DPAT was attenuated by the 5-HT_1A antagonist (+) WAY 100135. R-zacopride significantly reduced the duration of suppression of firing activity of CA₃ pyramidal neurons induced by the electrical stimulation of the ascending 5-HT pathway, and this reducing effect was prevented by the three 5-HT₃/5-HT₄ antagonists renzapride, S-zacopride and tropisetron, but not by BRL 46470A. Finally, in in vitro superfusion experiments, both BRL 46470A and S-zacopride antagonized the enhancing action of 2-methyld-HT on the electrically-evoked release of [³H]-5-HT in both rat frontal cortex and hippocampus slices. These findings suggest that, in vivo, the suppressant effect of 2-methyl-5-HT on the firing activity of dorsal hippocampus pyramidal, somatosensory cortical, and dorsal raphe 5-HT neurons is not mediated by 5-HT₃ receptors, but rather by 5-HT_1A receptors. The attenuating effect of R-zacopride on the effectiveness of the stimulation of the ascending 5-HT pathway is not mediated by 5-HT₃ receptors. In contrast, in vitro, the enhancing action of 2-methyl-5-HT on the electrically-evoked release of [³H]5-HT in both frontal cortex and hippocampus slices is mediated by 5-HT₃ receptors. © 1995 Wiley-Liss, Inc.     

Involvement of 5-HT3 and 5-HT4 receptors in the motor activity of isolated vascularly perfused rat duodenum

The involvement of serotonin (5-HT) receptor subtypes in motor activity of the ex vivo vascularly perfused rat duodenum was investigated. Clusters of phasic contractions (CPCs), migrating in an oral to anal direction, were obtained without any stimulation. Drug effects were evaluated by changes in different components of the pressure waves, such as motor index (MI), frequency, amplitude and duration of the CPC. The effect of 5-HT depletion on motor activity was examined in animals treated with p-chlorophenylalanine (PCPA). The MI, frequency and duration of CPC were decreased by PCPA, but the amplitude was not affected, suggesting that endogenous 5-HT may play an important role in regulation of the motor activity of the rat intestine. The importance of the 5-HT receptor subtypes in the regulation of motor activity was examined. Neither the nonselective 5-HT1 and 5-HT2 receptor antagonist, methysergide, nor the 5-HT2 receptor antagonist, ketanserin, affected motor activity. However, the 5-HT3 receptor antagonists, granisetron and azasetron, decreased percentage MI, frequency, percentage amplitude and percentage duration of CPC. The 5-HT4 receptor antagonist, SB204070, exerted both excitatory and inhibitory actions, with a higher dose (10 nM) stimulating percentage MI, frequency, percentage amplitude and percentage duration, and a lower dose (0.1 nM or 1 nM) decreasing percentage MI and percentage duration of CPC. These results suggest that endogenous 5-HT regulates the motor activity of the rat duodenum through 5-HT3 and 5-HT4 receptors, with the former mediating the stimulatory influence and the latter mediating both stimulatory and inhibitory influences.     

Evidence for 5-HT autoreceptor-mediated,nerve impulse-independent,control of 5-HT synthesis in the rat brain

To gain further insight into the operation of 5-HT autoreceptor-mediated feedback control of 5-HT biosynthesis in serotonergic nerve terminal areas, the effect of the 5-HT_1B and the 5-HT_1A receptor agonists, TFMPP and 8-OH-DPAT, respectively, were investigated in the rat central nervous system (CNS) using in vivo and in vitro neurochemical approaches. TFMPP suppressed 5-HT synthesis (5-HTP accumulation after decarboxylase inhibition) both in vivo and in vitro. In vivo, the 5-HT synthesissuppressing effect of the drug (3.0 mg/kg, s.c.) proved resistant to either acute hemitransection or reserpine (5 mg/kg, i.p.; 90 min before) pretreatment. In vitro, in cortical, hippocampal and striatal slice preparations, TFMPP (0.1–10 μM) decreased 5-HT synthesis under basal and stimulated (30 mM K⁺) conditions, an effect which was unaltered by prior in vivo reserpine-induced 5-HT depletion but was attenuated in the presence of 5-HT_1B receptor antagonists such as methiothepin, cyanopindolol or propranolol. The 8-OH-DPAT (0.1 mg/kg, s.c.)-induced decrease of 5-HT synthesis in vivo was abolished by hemitransection but resistant to acute reserpine pretreatment; 8-OH-DPAT (10 μM) did not decrease 5-HT synthesis in vitro. In conclusion, the present study confirms the importance of 5-HT autoreceptors in the feedback control of nerve terminal 5-HT biosynthesis. Specifically, our data indicate: (1) that the reduction of rat brain 5-HT synthesis after TFMPP is mediated by 5-HT_1B autoreceptors located on the serotonergic axon terminals, and (2) that the effect is directly mediated and occurs independently of 5-HT neuronal firing and intact monoamine stores. © 1995 Wiley-Liss, Inc.     

Serotonin-induced increase in cAMP in ganglia isolated from the myenteric plexus of the guinea pig small intestine: Mediation by a novel 5-HT receptor

Serotonin (5-HT) is a mediator (through 5-HT_1P receptors) of slow EPSPs in myenteric ganglia of the small intestine. The effect of 5-HT can be mimicked by elevating cAMP; therefore, we tested the hypothesis that the slow EPSP-like response to 5-HT is cAMP-mediated. Guinea pig gut was enzymatically dissociated; myenteric ganglia remained intact and were collected by filtration. Neurons in the isolated ganglia retained their ability to manifest the slow EPSP-like response to 5-HT. Exposure to 5-HT raised the ganglionic level of cAMP (ED₅₀ 0.3 μM). This effect was not antagonized by the 5-HT_1P antagonist, N-acetyl-5-hydroxytryptophyl-5-hydroxytryptophan amide (100.0 μM), or mimicked by the 5-HT_1P agonist, 5-hydroxyindalpine (10.0 μM). Increases in cAMP were also evoked by the 5-HT₁ agonist, 5-carboxyamidotryptamine (10.0 μM), the 5-HT₂ agonist, (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI; 1.0–10.0 μM), and by the 5-HT₄ agonists, renzapride (1.0–10.0 μM) and 5-methoxytryptamine (1.0–10.0 μM); however, neither the 5-HT₁/5-HT₂ antagonists, spiperone, methysergide, and methiothepin, nor the 5-HT₄ antagonist, tropisetron (ICS 205–930; 10.0 μM), were able to inhibit the rise in cAMP evoked by these compounds or by 5-HT (0.1–10.0 μM). The 5-HT-evoked elevation of cAMP was antagonized by ketanserin (10.0 μM), which also blocked the effects of 5-methoxytryptamine and DOI, but not those of renzapride. The effective concentration of DOI, however, was higher than that needed for activation of 5-HT₂ receptors, and Northern analysis using a cDNA probe encoding the rat 5-HT₂ receptor failed to reveal the presence of 5-HT₂ mRNA in myenteric ganglia, although it hybridizes with mRNA of the right size in the guinea pig brain. Compounds that failed to change levels of cAMP or to antagonize the action of 5-HT included 8-hydroxy-di-n-propylamino tetralin, R58639, R88226, and sumatriptan. It is concluded that the receptor responsible for the 5-HT-induced rise in cAMP in ganglia isolated from the guinea pig myenteric plexus is not a known subtype of 5-HT receptor. Since the pharmacology of this novel receptor is different from that of the slow EPSP-like response to 5-HT, the receptor probably does not mediate the slow EPSP. © 1993 Wiley-Liss, Inc.