健乙液对老年大鼠神经,内分泌及血液流变性的影响

目的 探讨中药健乙液益智抗衰老的作用及其机理。方法 用２１月龄大鼠作为衰老模型，６月龄大鼠为青年对照组，应用健忆液进行治疗，检测血浆皮质醇、血液流变学及脑内单胺类神经递质的含量。结果 健忆液能使老年大鼠皮质醇含量下降；血液粘度改善；脑组织多巴胺（ＤＡ）、去甲肾上腺素（ＮＥ）、５－羟吲哚乙酸（５－ＨＩＡＡ）含量升高，５－羟色胺（５－ＨＴ）含量降低，以至５－ＨＴ／ＮＥ、５ＨＴ／ＤＡ、５ＨＴ／５－ＨＩＡＡ比值降低。给药组与模型组比较差异有显著性（Ｐ〈０．０５），而与６月龄组比较差异无显著性。结论 健忆液具有延缓衰老的作用，其抗衰老作用可能与改善大鼠下丘脑－垂体－肾上腺轴功能衰退和血液流变性有关。     

大鼠应激性胃溃疡的形成与中枢神经系统、胃和血浆中单胺类神经递质的关系

目的：了解应激性胃溃疡的形成与中枢神经系统、胃和血浆中单胺类神经递质的关系。方法：Ｗｉｓｔａｒ大鼠分成３个组，正常对照组、应激溃疡组和自然恢复组。应激溃疡组为应激７小时后立即取材检测，自然恢复组为应激性胃溃疡形成后自然恢复２４小时进行取材检测。取胃组织、血浆、端脑、间脑和脑干，采用荧光光度法测定单胺类神经递质。结果：应激在引起胃粘膜损伤的同时，中枢和外周神经系统的５羟色胺（５ＨＴ）和５羟吲哚乙酸（羟ＨＩＡＡ）以及去甲肾上腺素（ＮＥ）出现有意义的升高，而中枢和外周的多巴胺（ＤＡ）出现有意义的降低，经２４小时的自然恢复，随着胃粘膜损伤的逐渐修复，中枢和外周神经系统的５ＨＴ和５ＨＩＡＡ趋向正常，但中枢和外周神经系统的ＮＥ仍居高不下，ＤＡ仍维持低水平。结论：中枢和外周神经系统的单胺类神经递质参与了应激性胃溃疡的形成。     

钩体OmpL39和择时施灸对神经体液免疫的影响

本研究用不同时间艾灸，观察特异性钩体ＯｍｐＬ３９抗原对豚鼠抗体和外周血单胺类神经递质５ＨＴ、ＮＥ、ＤＡ及５ＨＩＡＡ的影响。结果表明，在免疫应答期，下午对钩体ＯｍｐＬ３９免疫的豚鼠施灸，免疫保护力可以达到８７５％，外周血５ＨＴ、ＤＡ、ＮＥ明显降低，５ＨＩＡＡ明显升高，与上午施术组有显著差异（ｐ＜００５）。提示，不同时间施灸可使免疫功能和体内神经递质水平产生差异，下午对豚鼠施灸较上午施灸效果好     

电磁脉冲辐照后大鼠小脑、海马中一氧化氮合酶的变化

目的拟从观察电磁脉冲（ＥＭＰ）辐照后大鼠小脑、海马中一氧化氮合酶（ＮＯＳ）的表达情况，探讨ＥＭＰ所致大鼠学习、记忆能力改变的可能机制。方法采用ＳＰ免疫组织化学染色检测ＥＭＰ辐照后大鼠小脑、海马组织中ＮＯＳ阳性神经元的变化。结果ＥＭＰ辐照后１．５、２４ｈ海马中ＮＯＳ阳性神经元数目较对照组显著下降，且着色变浅，照后４８ｈＮＯＳ阳性神经元数目恢复至对照水平，但着色仍浅。小脑中ＮＯＳ阳性细胞在照后无明显变化。结论ＮＯＳ在ＥＭＰ所致大鼠学习、记忆功能障碍过程中起一定作用     

免疫应答期钩端螺旋体OmpL_(39)基因疫苗对豚鼠外周5-HT,DA、NE、5-HIAA的影响

本研究用含赖型强毒钩体单一蛋白ＯｍｐＬ３９的基因疫苗免疫豚鼠，观察ＯｍｐＬ３９的免疫保护力以及在免疫应答期影响体液免疫的单胺类神经递质５ＨＴ及其ＮＥ、ＤＡ、５ＨＩＡＡ的改变。结果表明，ＯｍｐＬ３９基因疫苗在豚鼠体内能产生较强的阳性抗体，对豚鼠有较强的免疫保护作用。同时发现ＯｍｐＬ３９疫苗在免疫应答期对５ＨＴ以及５ＨＩＡＡ、ＮＥ、ＤＡ有明显影响，其中５ＨＴ、ＤＡ、ＮＥ明显降低，５ＨＩＡＡ明显升高，与空白对照组有显著差异（ｐ＜００５）。提示，ＯｍｐＬ３９疫苗在免疫应答期能刺激机体产生较强的体液免疫功能，对神经系统有明显的调节作用，在炎症的吸收和保护内脏各器官组织等方面起到了积极的作用。     

定志小丸对老龄大鼠学习记忆能力的影响

目的:研究定志小丸对老龄大鼠学习记忆能力和脂质过氧化的影响。方法:选用自然老龄大鼠,采用Y电迷宫法测试行为学指标,用生化法测定血清和脑组织中的超氧化物歧化酶(SOD)、丙二酶(MDA),用荧光分光光度法测定脑内单胺类神经递质含量。结果:定志小丸200mg/kg给药组明显提高老龄大鼠学习记忆能力,提高记忆的正确反应率(70.5%,73.5%),与空白对照组(61.0%,64.0%)相比差异有显著性意义(P<0.05)。给药组升高老龄大鼠脑内单胺类神经递质的含量,使老龄大鼠脑内空白对照组:(128.2±10.3)Nu/mL;定志小丸200mg/kg组:(143.0±6.8)Nu/mL和血清中空白对照组:(190.0±4.65)Nu/mL;定志小丸200mg/kg组:(222.3±2.3)Nu/mL的SOD活力提高,MDA含量降低。结论:定志小丸能改善老龄大鼠的学习记忆功能,其机制可能与改善脑组织单胺类神经系统功能,降低脑组织中脂质过氧化物的含量有关。     

偏头痛的药物治疗

偏头痛的药物治疗浙江淳安县第二人民医院郑自敏，裴的善偏头痛是神经内科常见病，每年６～９月发病率较高。发病机理尚未阐明，可能与５－羟色胺（５－ＨＴ）、去甲肾上腺素（ＮＥ）、前列腺素（ＰＧ）、血栓烷Ａ２（ＴＸＡ２）及多巴胺（ＤＡ）等神经递质和血管活性物质...     

大鼠应激性胃溃疡的形成与中枢神经系统,胃和血浆中单胺…

目的：了解应激性胃溃疡的形成与中枢神经系统、胃和血浆中单胺类神经递质的关系。方法：Ｗｉｓｔａｒ大鼠分成３个组，正常对照组、应激溃疡组和自然恢复组。应激溃疡组为应激７小时后立即取材检测，自然恢复组为应激性胃溃疡形成后自然恢复２４小时进行取材检测。取胃组织、血浆、端脑、间脑和脑干，采用荧光光度法测定单胺类神经递质。结果：应激在引起胃粘膜损伤的同时，中枢和外周神经系统的５－羟色胺（５－ＨＴ）和５－羟吲哚     

定志小丸对老龄大鼠学习记忆能力的影响

目的：研究定志小丸对老龄大鼠学习记忆能力和脂质过氧化的影响。方法：选用自然老龄大鼠，采用Y电迷宫法测试行为学指标，用生化法测定血清和脑组织中的超氧化物歧化酶(SOD)、丙二酶(MDA)，用荧光分光光度法测定脑内单胺类神经递质含量。结果：定志小丸200mg／kg给药组明显提高老龄大鼠学习记忆能力，提高记忆的正确反应率(70．5％，73．5％)，与空白对照组(61．0％，64．0％)相比差异有显著性意义(P&;lt;0．05)。给药组升高老龄大鼠脑内单胺类神经递质的含量，使老龄大鼠脑内[空白对照组：(128．2&;#177;10．3)Nu／mL；定志小丸200mg／kg组：(143．0&;#177;6．8)Nu／mL]和血清中[空白对照组：(190．0&;#177;4．65)Nu／mL；定志小丸200mg／kg组：(222．3&;#177;2．3)Nu／mL]的SOD活力提高，MDA含量降低。结论：定志小丸能改善老龄大鼠的学习记忆功能，其机制可能与改善脑组织单胺类神经系统功能，降低脑组织中脂质过氧化物的含量有关.     

N—甲基天冬氨酸受体拮抗剂AP—5在海马对兔P3波电位的 …

目的 推测Ｎ－甲基天冬氨酸受体（Ｎ－ｍｅｔｈｙｌ－Ｄ－ａｓｐａｒａｔｅ ｒｅｃｅｐｔｏｒ,ＮＭＤＡＲ）的兴奋性突触后电位（ｅｘｃｉｔａｔｏｒｙ ｐｏｓｔｓｙｎａｐｔｉｃ ｐｏｔｅｎｔｉａｌｓ,ＥＰＳＰ）活动对兔Ｐ３波的作用。方法 采用ＮＭＤＡＲ竞争性拮抗剂ＡＰ－５（３．１２５,６．２５,１２．５ｍｍｏｌ／Ｌ）在海马ＣＡ１,ＣＡ３微量注入,观察Ｐ３波电位变化。     

Antiallodynic effect of intrathecally administered 5-HT(2) agonists in rats with nerve ligation

We examined the antiallodynic effect of intrathecally administered serotonin receptor agonists including 5-HT(1A), 5-HT(1B), 5-HT(2) and 5-HT(3) receptor subtypes in a rat model using spinal nerve ligation at L5 and L6. Administration of the 5-HT(2) receptor agonist, alpha-methyl-5-hydroxytryptamine maleate (alpha-m-5-HT; 3-100 microg) or (+/-)-1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane hydrochloride (DOI; 10-100 microg), showed dose-dependent antiallodynic actions with no associated motor weakness. The antiallodynic action of alpha-m-5-HT was more potent than that of DOI. The effects of 5-HT(2) agonists on tactile allodynia were reversed by intrathecal pretreatment with the selective 5-HT(2) antagonist ketanserin and with the mixed 5-HT(1) and 5-HT(2) antagonist methysergide. Neither the mixed 5-HT(1A) and 5-HT(1B) antagonist cyanopindolol nor the selective 5-HT(3) antagonist MDL72222 attenuated antiallodynic effects induced by 5-HT(2) agonists. In contrast, the selective 5-HT(1A) agonist 8-hydroxy-2-(di-n-propylamino)-tetralin hydrobromide (8-OH-DPAT; 1-50 microg), the 5-HT(1B) agonist 5-methoxy-3-(1,2,5,6-tetrahydro-4-pyridinil)-1H-indol (RU-24969; 10-100 microg) and the 5-HT(3) agonist 2-methyl-5-hydroxytryptamine maleate (2-m-5-HT; 30-300 microg) all lacked significant antiallodynic action with intrathecal administration. These results indicate that the 5-HT(2) receptor plays an essential role in spinal suppression of neuropathic pain by 5-HT.     

Roles of 5-hydroxytryptamine (5-HT) receptor subtypes in the inhibitory effects of 5-HT on C-fiber responses of spinal wide dynamic range neurons in rats

5-Hydroxytryptamine (5-HT; serotonin) plays an important role in the descending control of nociception. 5-HT and its receptors have been extensively studied in the modulation of nociceptive transmission at the spinal level using behavioral tests that may be affected by the effects of 5-HT on motor performance and skin temperature. Using electrophysiological methods, the present study aimed to systematically investigate the roles of 5-HT receptor subtypes on the inhibitory effects of 5-HT on responses of the spinal wide dynamic range (WDR) neurons to C-fiber inputs in rats. Under basal conditions, topical application of 5-HT to the spinal cord inhibited the C-fiber responses of WDR neurons dose-dependently, whereas antagonists of 5-HT(1A) [WAY 100635 [N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinyl-cyclohexanecarboxamide maleate salt]], 5-HT(1B) [GR 55562 [3-[3-(dimethylamino)propyl]-4-hydroxy-N-[4-(4-pyrid-dinyl)phenyl]benzamide dihydrochloride]], 5-HT(2A) [ketanserin [3-[2-[4-(fluorobenzoyl)-1-piperidinyl]ethyl]-2,4[1H,3H]-quinazolinedione tartrate]], 5-HT(2C) [RS 102221 [8-[5-(2,4-dimethoxy-5-(4-trifluoromethylphenylsulfonamido)phenyl-5-oxopentyl]-1,3,8-triazaspiro[4.5]decane-2,4-dione hydrochloride]], 5-HT(3) [MDL 72222 [3-tropanyl-3,5-dichlorobenzoate]], and 5-HT(4) [GR 113808 ([1-[2-[(methylsulfonyl)-amino]ethyl]-4-piperidinyl]methyl 1-methyl-1H-indole-3-carboxylate)] had no effect on their own. The inhibitory effects of 5-HT were reversed by antagonists of 5-HT(1B) (GR 55562), 5-HT(2A) (ketanserin), 5-HT(2C) (RS 102221), 5-HT(3) (MDL 72222), and 5-HT(4) (GR 113808) but not by 5-HT(1A) (WAY 100635) receptor antagonists. Topical administration of agonists of 5-HT(1A) [(2R)-(+)-8-hydroxy-2-(di-n-propylamino)tetralin hydrobromide], 5-HT(1B) [CGS 12066 [7-trifluoromethyl-4-(4-methyl-1-piperazinyl)pyrrolo-[1,2-a]quinoxaline maleate salt]], 5-HT(2A) (alpha-methyl-5-hydroxytryptamine maleate), 5-HT(2C) [MK 212 [6-chloro-2-(1-piperazinyl)pyrazine hydrochloride]], 5-HT(3) [1-(3-chlorophenyl)biguanide hydrochloride], and 5-HT(4) [2-[1-(4-piperonyl)piperazinyl]benzothiazole] also inhibited the C-responses. These results suggest that, under basal conditions, there is no tonic serotonergic inhibition on the C-responses of dorsal horn neurons, and multiple 5-HT receptor subtypes including 1B, 2A, 2C, 3, and 4 may be involved in mediating the inhibitory effects of 5-HT.     

Selective and divergent regulation of cortical 5-HT(2A) receptors in rabbit.

It is well established that repeated administration of both 5-hydroxytryptamine(2) (5-HT(2)) receptor agonists and antagonists decreases the density of 5-HT(2A) and 5-HT(2C) receptors. However, the regulation of these two receptors has not been studied in the same tissue. Therefore, we examined the effects of repeated daily injections of the 5-HT(2) receptor agonists (+/-)-2,5-dimethoxy-4-iodoamphetamine (DOI) and D-lysergic acid diethylamide (LSD) and the antagonists d-2-bromolysergic acid diethylamide hydrogen tartrate (BOL) and alpha-phenyl-2-(2-phenylethyl)-4-piperidinemethanol (MDL 11,939) on rabbit cortical 5-HT(2A) and 5-HT(2C) receptors. Repeated administration of DOI, LSD, or BOL decreased cortical 5-HT(2A) receptor density but had no effect on the density of cortical 5-HT(2C) receptors. Repeated administration of the selective 5-HT(2A) receptor antagonist MDL 11,939 significantly increased 5-HT(2A) receptor density. This unexpected outcome also occurred without any change in cortical 5-HT(2C) receptor density. The down-regulation of 5-HT(2A) receptors produced by chronic administration of BOL was associated with a decrease in DOI-elicited head bobs, whereas 5-HT(2A) receptor up-regulation produced by MDL 11,939 was associated with an increase in DOI-elicited head bobs compared with controls. These studies demonstrate that 5-HT(2A) receptor antagonists can both down- and up-regulate the density of cortical 5-HT(2A) receptors and these changes in receptor density have functional consequences for 5-HT(2A) receptor-mediated behaviors. Furthermore, because DOI, LSD, and BOL have approximately equal affinities for the 5-HT(2A) and 5-HT(2C) receptors, these results suggest that different mechanisms regulate 5-HT(2A) and 5-HT(2C) receptor density, in that chronic occupation of 5-HT(2C) receptors does not modulate their density in rabbit frontal cortex.     

Serotonin receptor subtypes involved in the spinal antinociceptive effect of 5-HT in rats

The present study was designed to investigate which subtypes of spinal 5-HT receptors are involved in 5-HT-induced antinociception using the mechanical pain test. Serotonin and various selective antagonists or agonists for 5-HT receptor subtypes (5-HT(1A), 5-HT(1B), 5-HT(2A), 5-HT(2C), 5-HT(3) and 5-HT(4)) were administered intrathecally (i.t.) in rats. The i.t. injection of 5-HT (1 microg) produced significant antinociceptive effects using the paw pressure test. Pretreatment with the 5-HT(2C) receptor antagonist mesulergine (1 and 10 microg) and the 5-HT(3) receptor antagonist tropisetron (1 and 10 microg) reversed totally the antinociception induced by 5-HT. Furthermore, at a dose of 10 microg, both the 5-HT(2A) receptor antagonist ketanserin and the 5-HT(1B) receptor antagonist penbutolol, but neither the 5-HT(1A) receptor antagonist WAY 100635 nor the 5-HT(4) receptor antagonist GR113808, attenuated the antinociceptive effect induced by 5-HT. In addition, an i.t. injection of the 5-HT(3) agonist mCPBG induced significant antinociceptive effects whereas the 5-HT(2) agonist DOI did not produce analgesia. These results suggest that although the precise degree of the involvement of spinal serotonergic 5-HT(3) receptors remains to be elucidated due to some differences in the effect of agonists or antagonists, these receptors seem to play a role in the antinociceptive effect of 5-HT against a mechanical acute noxious stimulus. The involvement of 5-HT(2C) is more questionable due to the observed discrepancies between the effects of the used agonist and antagonist. 5-HT(1A) and 5-HT(4) receptors do not seem to be involved. In addition, a possible functional interaction between spinal serotonergic receptors may exist.     

Differential actions of antiparkinson agents at multiple classes of monoaminergic receptor. III. Agonist and antagonist properties at serotonin, 5-HT(1) and 5-HT(2), receptor subtypes

Although certain antiparkinson agents interact with serotonin (5-HT) receptors, little information is available concerning functional actions. Herein, we characterized efficacies of apomorphine, bromocriptine, cabergoline, lisuride, piribedil, pergolide, roxindole, and terguride at human (h)5-HT(1A), h5-HT(1B), and h5-HT(1D) receptors [guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding], and at h5-HT(2A), h5-HT(2B), and h5-HT(2C) receptors (depletion of membrane-bound [(3)H]phosphatydilinositol). All drugs stimulated h5-HT(1A) receptors with efficacies (compared with 5-HT, 100%) ranging from modest (apomorphine, 35%) to high (cabergoline, 93%). At h5-HT(1B) receptors, efficacies varied from mild (terguride, 37%) to marked (cabergoline, 102%) and potencies were modest (pEC(50) values of 5.8-7.6): h5-HT(1D) sites were activated with a similar range of efficacies and greater potency (7.1-8.5). Piribedil and apomorphine were inactive at h5-HT(1B) and h5-HT(1D) receptors. At h5-HT(2A) receptors, terguride, lisuride, bromocriptine, cabergoline, and pergolide displayed potent (7.6-8.8) agonist properties (49-103%), whereas apomorphine and roxindole were antagonists and piribedil was inactive. Only pergolide (113%/8.2) and cabergoline (123%/8.6) displayed pronounced agonist properties at h5-HT(2B) receptors. At 5-HT(2C) receptors, lisuride, bromocriptine, pergolide, and cabergoline were efficacious (75-96%) agonists, apomorphine and terguride were antagonists, and piribedil was inactive. MDL100,907 and SB242,084, selective antagonists at 5-HT(2A) and 5-HT(2C) receptors, respectively, abolished these actions of pergolide, cabergoline, and bromocriptine. In conclusion, antiparkinson agents display markedly different patterns of agonist and antagonist properties at multiple 5-HT receptor subtypes. Although all show modest (agonist) activity at 5-HT(1A) sites, their contrasting actions at 5-HT(2A) and 5-HT(2C) sites may be of particular significance to their functional profiles in vivo.     

General anesthetic-induced channel gating enhancement of 5-hydroxytryptamine type 3 receptors depends on receptor subunit composition

5-Hydroxytryptamine (serotonin) (5-HT) type 3 (5-HT(3)) receptors are members of an anesthetic-sensitive superfamily of Cys-loop ligand-gated ion channels that can be formed as homomeric 5-HT(3A) or heteromeric 5-HT(3AB) receptors. When the efficacious agonist 5-HT is used, the inhaled anesthetics halothane and chloroform (at clinically relevant concentrations) significantly reduce the agonist EC(50) for 5-HT(3A) receptors but not for 5-HT(3AB) receptors. In the present study, we used dopamine (DA), a highly inefficacious agonist for 5-HT(3) receptors, to determine whether the difference in sensitivity between 5-HT(3A) and 5-HT(3AB) receptors to the potentiating effects of halothane and chloroform is due to differential modulation of agonist affinity, channel gating, or both. Using the two-electrode voltage-clamp technique with 5-HT(3A) and 5-HT(3AB) receptors expressed in Xenopus oocytes, we found that chloroform and halothane enhanced currents evoked by receptor-saturating concentrations of DA for both receptor subtypes in a concentration-dependent manner but that the magnitude of enhancement was substantially greater for 5-HT(3A) receptors than for 5-HT(3AB) receptors. Isoflurane induced only a small enhancement of currents evoked by receptor-saturating concentrations of DA for 5-HT(3A) receptors and no enhancement for 5-HT(3AB) receptors. For both receptor subtypes, none of the three test anesthetics significantly altered the agonist EC(50) for DA, implying that these anesthetics do not affect agonist binding affinity. Our results show that chloroform, halothane, and (to a much lesser degree) isoflurane enhance channel gating for 5-HT(3A) receptors and that the incorporation of 5-HT(3B) subunits to produce heteromeric 5-HT(3AB) receptors markedly attenuates the ability of these anesthetics to enhance channel gating.     

5-Hydroxytryptamine (5-HT)-induced endothelium-dependent relaxation of pig coronary arteries is mediated by 5-HT receptors similar to the 5-HT1D receptor subtype

The 5-hydroxytryptamine (5-HT) receptor mediating endothelium-dependent relaxation of pig coronary arteries was characterized using a variety of 5-HT receptor agonists and antagonists. Unrubbed (with endothelium preserved) rings precontracted by prostaglandin F2 alpha in the presence of ketanserin relaxed in an endothelium-dependent manner to 5-HT, 5-carboxamidotryptamine and 5-methoxytryptamine with about equal potency and efficacy. By comparison, bufotenine, 3-(dimethylamino)ethyl-N-methyl-1H-indole-5-methane sulfonamide, (-)-alpha-methyl-5-HT,N,N-dipropyl-5-carboxamidotryptamine and 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H indole were half-efficient and other drugs [in particular the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin] were inactive as agonists up to 0.1 mM. The effect of 5-carboxamidotryptamine was antagonized in an apparently competitive manner by 15 drugs. Among the most potent antagonists (mean pKB value) were the nonselective 5-HT receptor antagonists, methiothepin (7.30) and metergoline (6.86), the 5-HT1A/5-HT1D receptor ligand, 1-[2-(4-amino-phenyl)ethyl]-4-(3-trifluoromethylphenyl)-piperazine (7.02), the 5-HT1A/5-HT1B/5-HT1D receptor ligand, 7-trifluoromethyl-4-(4-methyl-1-piperazinyl)-pyrrolo[1,2,-a]quinoxaline 1 (6.73) and yohimbine (6.37). Selective ligands for 5-HT1A receptors were either inactive [8-hydroxy-2-(di-n-propylamino)tetralin hydrobromide] or poorly active (spiperone, 4.44). Beta-adrenoceptor antagonists with affinity for 5-HT1A and 5-HT1B receptors weakly antagonized the effect of 5-carboxamidotryptamine (pKB values less than or equal to 5.32), as did the 5-HT1c/5-HT2 receptor antagonist, mesulergine (5.30) and the yohimbine isomer, corynanthine (4.85). Methysergide was clearly a noncompetitive antagonist.(ABSTRACT TRUNCATED AT 250 WORDS)     

Characterization of the contractile 5-hydroxytryptamine receptor in the renal artery of the normotensive rat

Our goal was to characterize the 5-hydroxytryptamine (5-HT) receptor(s) mediating contraction in the isolated right renal artery, testing the hypothesis that the 5-HT(2A) receptor would be the primary and likely only 5-HT receptor involved in contraction. Contraction of arteries was investigated in isolated tissue baths, and expression of 5-HT receptors was measured using immunohistochemical and Western analyses. Compared with endothelium-denuded rat aorta, a tissue with an established 5-HT(2A) receptor, endothelium-denuded renal artery contracted to 5-HT with a 10-fold greater potency. Surprisingly, the 5-HT(2B) receptor agonist alpha-methyl-5-(2-thienylmethoxy)-1H-indole-3-ethanamine hydrochloride (BW723C86) caused a concentration-dependent contraction that was antagonized by the 5-HT(2B) receptor antagonist 6-methyl-1,2,3,4-tetrahydro-1-[3,4-dimethoxyphenyl) methyl-9H-pyrido[3,4b]indole] hydrochloride (LY272015) and nonselective 5-HT(2) receptor antagonist 6-methyl-1-(1-methylethyl)-ergoline-8b-carboxylic acid 2-hydroxy-1-methylpropyl ester maleate (LY53857). Correlation of -log EC(50) values with binding affinities (pK(i)) indicated that contraction of the renal artery elicited by 13 different agonists was likely consistent with activation of a 5-HT(2A) (r = 0.928) and 5-HT(2B) (r = 0.843) receptor. 5-HT-induced contraction was shifted by the 5-HT(2A) receptor antagonist ketanserin (3 and 10 nM) and the 5-HT(2B) receptor antagonist LY272015 (10 and 50 nM). Higher than expected concentrations of the 5-HT(2A)/5-HT(2B) receptor antagonist LY53857 were needed to antagonize 5-HT-induced contraction and the 5-HT(2B) receptor antagonist 2-amino-4-(4-fluoronaphth-1-yl)-6-isopropylpyrimidine (RS127445) was virtually inactive. Western and immunohistochemical analyses of the renal artery validated the presence of 5-HT(2A) and 5-HT(2B) receptor protein. These results suggest that the renal artery possesses a complex 5-HT receptor population, including ketanserin- and LY272015-sensitive receptors. This unique pharmacology may reflect differences in 5-HT receptor coupling between tissues or heterogeneity in the subtype(s) of 5-HT receptors expressed in the renal artery.     

Contribution of serotonin (5-hydroxytryptamine; 5-HT) 5-HT2 receptor subtypes to the hyperlocomotor effects of cocaine: acute and chronic pharmacological analyses

The role of serotonin (5-hydroxytryptamine; 5-HT) 5-HT2 receptor subtypes (5-HT2AR, 5-HT2BR, and 5-HT2CR) in acute cocaine-evoked hyperactivity was compared with their contribution to the development and expression of locomotor sensitization upon repeated, intermittent treatment with cocaine (10 mg/kg/day for 5 days) in male Wistar rats. Cocaine-evoked hyperactivity was significantly enhanced by pretreatment with the preferential 5-HT2AR agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) and the 5-HT2CR antagonist SDZ SER-082 [(+)-cis-4,5,7a,8,9,10,11,11a-octahydro-7H-10-methylindolo(1,7-BC)(2,6) naphthyridine fumarate]. The 5-HT2AR antagonist SR 46349B [1(Z)-[2-(dimethylamino)ethoxyimino]-1(2-fluorophenyl)-3-(4-hydroxyphenyl)-2(E)-propene] and the preferential 5-HT2CR agonist MK 212 [6-chloro-2-(1-piperazinyl)pyrazine HCl] (2 mg/kg) significantly attenuated acute cocaine-evoked hyperactivity; however, a lower dose of MK 212 (0.3 mg/kg) enhanced cocaine-evoked hyperactivity. The 5-HT2BR agonist BW 723C86 (1-[5-(2-thienylmethoxy)-1H-3-indolyl]propan-2-amine HCl) and the 5-HT2BR antagonist SB 204741 [N-(1-methyl-5-indolyl)-N'-(3-methyl-5-isothiazolyl) urea] had no effect on cocaine-evoked hyperactivity. Repeated treatment with cocaine alone resulted in a 2-fold increase in hyperactivity upon challenge with cocaine 5 days after termination of the cocaine regimen (sensitization). The 5-HT2AR antagonist SR 46349B also blocked cocaine-evoked hyperactivity following repeated cocaine treatment, whereas the other 5-HT2R ligands were ineffective. When any of the 5-HT2R ligands was coadministered with cocaine during the treatment regimen (10 mg/kg/day for 5 days), the development of sensitization was unchanged as measured by the level of cocaine-evoked hyperactivity upon challenge 5 days after termination of the treatment. The present study implies that 5-HT2AR and 5-HT2CR exert oppositional influence upon hyperactivity evoked by acute administration of cocaine; this balance is altered following repeated cocaine administration.     

Toward selective drug development for the human 5-hydroxytryptamine 1E receptor: a comparison of 5-hydroxytryptamine 1E and 1F receptor structure-affinity relationships

The 5-hydroxytryptamine (5-HT) 1E receptor is highly expressed in the human frontal cortex and hippocampus, and this distribution suggests the function of 5-HT(1E) receptors might be linked to memory. To test this hypothesis, behavioral experiments are needed. Because rats and mice lack a 5-HT(1E) receptor gene, knockout strategies cannot be used to elucidate this receptor's functions. Thus, selective pharmacological tools must be developed. The tryptamine-related agonist BRL54443 [5-hydroxy-3-(1-methylpiperidin-4-yl)-1H-indole] is one of the few agents that binds 5-HT(1E) receptors with high affinity and some selectively; unfortunately, it binds equally well to 5-HT(1F) receptors (K(i) ≈ 1 nM). The differences between tryptamine binding requirements of these two receptor populations have never been extensively explored; this must be done to guide the design of analogs with greater selectivity for 5-HT(1E) receptors versus 5-HT(1F) receptors. Previously, we determined the receptor binding affinities of a large series of tryptamine analogs at the 5-HT(1E) receptor; we now examine the affinities of this same series of compounds at 5-HT(1F) receptors. The affinities of these compounds at 5-HT(1E) and 5-HT(1F) receptors were found to be highly correlated (r = 0.81). All high-affinity compounds were full agonists at both receptor populations. We identified 5-N-butyryloxy-N,N-dimethyltryptamine as a novel 5-HT(1F) receptor agonist with >60-fold selectivity versus 5-HT(1E) receptors. There is significant overlap between 5-HT(1E) and 5-HT(1F) receptor orthosteric binding properties; thus, identification of 5-HT(1E)-selective orthosteric ligands will be difficult. The insights generated from this study will inform future drug development and molecular modeling studies for both 5-HT(1E) and 5-HT(1F) receptors.