How selective is GR 43175? Interactions with functional 5-HT1A, 5-HT1B, 5-HT1C and 5-HT1D receptors

Summary GR 43175 (3-[2-dimethylamino]ethyl-N-methyl-1H-indole-5 methane sulphonamide) is a novel 5-HT₁-like receptor-selective agonist which was reported to be active in the treatment of migraine attacks. The effects of the compound were investigated in radioligand binding studies and in functional models for 5-HT_1A, 5-HT_1B, and 5-HT_1D receptors (inhibition of forskolin-stimulated adenylate cyclase activity in calf hippocampus, rat and calf substantia nigra, respectively) and 5-HT_1C receptors (stimulation of inositol phosphate production in pig choroid plexus).GR 43175 displayed the following order of affinity for 5-HT recognition sites (pK_D values, -log mol/l, in parentheses): 5-HT_1D (7.54) > 5-HT_1B (6.35) > 5-HT_1A (6.13) 5-HT_1C (4.13) > 5-HT₂ (3.67). The same order of potency was observed at functional 5-HT₁ receptors, at which GR 43175 acted as a full agonist, with the exception of the 5-HT_1C receptor, where the compound was a weak antagonist (pEC₅₀ or pK_B values, -log mol/l, in parentheses): 5-HT_1D (6.28) > 5-HT_1B (6.03) > 5-HT_1A (5.57) > 5-HT_1C (4.25).The present data show that GR 43175 interacts preferentially as an agonist with 5-HT_1B and 5-HT_1D receptors. Since 5-HT_1B receptors have not yet been identified in human brain, it seems possible that it is the 5-HT_1D receptor which is relevant to the reported antimigraine effects of this compound.Send offprint requests to D. Hoyer at the above address     

“5-HT1R” or 5-HT1D sites? Evidence for 5-HT 1D binding sites in rabbit brain

Summary Radioligand binding studies were performed in membranes of rabbit whole brain and striatum using the novel iodinated radioligand for 5-hydroxytryptamine 5-HT_1B and 5-HT_1D sites, Serotonin-5-O-Carboxymethyl-Glycyl[¹²⁵I]Tyrosinamide ([¹²⁵I]GTI).[¹²⁵I]GTI labelled a finite number of high affinity sites in rabbit brain membranes, B_max = 191 +- 47 fmol/mg protein, pK_D (-log mol/1) = 8.50 +- 0.13, n = 5. The pharmacological profile of [¹⁵²I]GTI binding was fully comparable to that reported previously in human and other brain preparations known to possess 5-HT_1D sites (using either [³H]5-HT or [¹²⁵I]GTI) and displayed a characteristic rank order of affinity: 5-carboxamidotryptamine > 5-HT = dihydroergotamine _> ergotamine _ sumatriptan >_ CGS 12066 >- metergoline > yohimbine >_ methysergide > ICYP > 8-OH-DPAT >_ CP 93129 > (-)pindolol > ketanserin > isamoltane > mesulergine > corynanthine > buspirone > MDL 72222.Autoradiographic studies were performed on rabbit brain slices using [³H]5-HT in the presence of 100 nmol/1 8-OH-DPAT and mesulergine (in order to mask 5-HT_1A and 5-HT_1c binding sites) and [¹²⁵I]CYP (iodocyanopindolol) in the presence of µmol/I isoprenaline and 100 nmol/l 8-OH-DPAT (in order to mask adrenoceptor and 5-HT_1A binding sites). There was no detectable specific binding of [¹²⁵I]CYP through the brain, thus excluding the presence of 5-HT_1B sites in rabbit brain. By contrast, [³H]5-HT labelled a high density of sites in globus pallidus, substantia nigra and superior colliculus. Other regions displaying labelling include the striatum, the dentate gyrus of the hippocampus and the periaqueductal grey matter. This pattern of distribution is compatible with that reported for 5-HT_1D sites in other species.The present data strongly suggest that rabbit brain has recognition sites with the pharmacological profile and distribution characteristic of the 5-HT_1D recognition site. These findings are in agreement with results obtained by Limberger et al. (1991), suggesting the terminal 5-HT autoreceptor of the rabbit brain to belong to the 5-HT_1D subtype. Except for limited species variations (see Bruinvels et al. 1992), the pharmacology of these sites does not justify an addition to the existing nomenclature (5-HT_1R), in contrast to what has been proposed by Xiong and Nelson (1989). The rabbit represents another laboratory species in which 5-HT_1D receptor mediated effects could be studied. Correspondence to D. Hoyer at the above address     

5-HT重摄取抑制/5-HT1A受体拮抗双重作用抗抑郁药研究进展

5-HT重摄取抑制/5-HT1A受体拮抗双重作用抗抑郁药是在单胺递质学说的基础上研发的新一代抗抑郁药,此类药物研发的策略主要是通过分子拼合原理,在单一分子中引入2种药效团在体内共同发挥抗抑郁作用.文中对该类药物中几种典型的结构构效关系及生物活性评价结果进行综述,以期为抗抑郁药物的研发提供参考.新型化合物在有效性、安全耐受性及起效时间等方面表现出很多优势,但是目前还没有相关的临床报道数据.     

5-HT家族中5-HT2亚家族研究

Elaine Sanders-Bush教授，现任Vanderbilt大学脑科学研究所所长，兼任《分子药理学》以及《神经精神药理学》等多家学术杂志的编委，担任美国药理和实验治疗学会和美国精神分裂症抑郁症研究学会等众多学术团体的委员。主要研究内容包括5-羟色胺5-HT2受体的分子基因组学多态性研究。     

Effects of acute selective 5-HT1, 5-HT2, 5-HT3 receptor andα 2 adrenoceptor blockade on naloxone-induced antinociception

Several studies have demonstrated a paradoxical form of antinociception induced by the repeated administration of opioid antagonists accompanied by exposure to a painful stimulus. The underlying mechanism of this naloxone-induced antinociception (NIA) is still unknown, but the results of several studies suggest that it is a non-opioid response. This study was designed to investigate serotonergic and noradrenergic involvement in NIA. Rats were treated daily with systemic injections of 5 mg/kg naloxone, followed by a 45-s hot plate test of nociception (temperature=51.5 ± 0.5°C). After rats reached plateau levels of NIA, they received a test trial in which they were treated with various doses of different selective 5-HT or ₂ adrenoceptor antagonists in addition to naloxone before the hot plate test. Rats treated with 0.16, 0.32 and 0.63 mg/kg pirenperone or 2.5 mg/kg ritanserin showed significant reductions in paw lick latency with respect to rats treated with vehicle. In addition, high doses of yohimbine (7.5–10 mg/kg) also effectively reversed NIA. In contrast, NIA was not affected by acute blockade of 5-HT₁ or 5-HT₃ receptors by methiothepin or MDL 72222, respectively, or by the ₂ adrenoceptor blocker idazoxan. None of the 5-HT or ₂ adrenoceptor antagonists had any effect on the paw lick latencies of saline-treated rats. A possible role of 5-HT₂ receptors in the antinociception induced by opioid receptor blockade is discussed.     

5-HT1A受体与抑郁症相关性研究

抑郁症的发病机制复杂,确切发病机制尚不清楚,目前普遍认为可能是心理社会因素、各种神经生物化学改变、遗传因素等多种因素交互作用的结果,其中神经生化改变是迄今最为肯定的,并成为临床治疗抑郁症的理论基础.脑内中枢去甲肾上腺素(NE)、5-羟色胺(5-HT)、多巴胺(DA)等单胺类神经递质含量过低、其受体功能低下、下丘脑-垂体-肾上腺轴(HPA)和下丘脑-垂体-甲状腺轴(HPT)等神经生化的改变都被认为是引起抑郁症的原因.近年来选择性5-HT受体激动剂类抗抑郁药的研究揭示5-HT1A受体是重要的作用靶点.现就5-HT1A受体与抑郁症相关性研究进展作一综述.     

Subclassification of presynaptic 5-HT autoreceptors in the human cerebral cortex as 5-HT1Dβ receptors

Human cerebral cortical synaptosomes were used to determine the 5-hydroxytryptamine (5-HT) receptor subtype to which the inhibitory presynaptic 5-HT autoreceptor belongs. The synaptosomes preincubated with [³H]5-HT were superfused and tritium overflow was stimulated by high K⁺. The K⁺-evoked tritium overflow, which was Ca²⁺-dependent but tetrodotoxin-resistant, was concentration-dependently inhibited by the nonselective 5-HTlD_1D/1D receptor agonist, 5-carboxamidotryptamine. Ketanserin at a concentration which should block the 5-HT_1D but not the 5-HT_1D receptor failed to antagonize the inhibitory effect of 5-carboxamidotryptamine. In contrast, the non-selective 5-HT_1D/1D receptor antagonist, methiothepin, at a concentration which should block both the 5-HT_1D and the 5-HT_1D receptor abolished the effect of 5-carboxamidotryptamine. It is concluded that the presynaptic 5-HT autoreceptor, which has previously been classified as 5-HT_1D, belongs to the 5-HT_1D subtype.     

What would 5-HT do? Regional diversity of 5-HT1 receptor modulation of primary afferent neurotransmission

5-HT (serotonin) is a significant modulator of sensory input to the CNS, but the only analgesics that selectively target G-protein-coupled 5-HT receptors are highly specific for treatment of headache. Two recent papers in BJP shed light on this puzzling situation by showing that primary afferent neurotransmission to the superficial layers of the spinal and trigeminal dorsal is inhibited by different subtypes of the 5-HT₁ receptor – 5-HT_{1B(and 1D)} in the trigeminal dorsal horn and 5-HT_1A in the spinal dorsal horn. The inputs being studied probably include nociceptive afferents, and the similarities of the methods employed in the two studies minimize the possibility that the different findings are an experimental artefact. Rather, the findings raise interesting questions about the possible anatomical or functional basis for the apparent regional selectivity of 5-HT₁ receptor actions, and whether these differences could be exploited for therapy. The results also emphasize the relative lack of information we have about the molecular details of the pro- or anti-nociceptive actions of 5-HT itself on primary afferent neurotransmission.

LINKED ARTICLE

This article is a commentary on Choi et al., pp. 356–367 of this issue. To view this paper visit http://dx.doi.org/10.1111/j.1476-5381.2012.01964.x     

Differences in ligand binding profiles between cloned rabbit and human 5-HT1Dα and 5-HT1Dβ receptors: ketanserin and methiothepin distinguish rabbit 5-HT1D receptor subtypes

The study of serotonin receptor function has been complicated by the extreme molecular diversity of serotonin receptor subtypes, the lack of selective agonists and antagonists for many of the subtypes, and divergence in the pharmacological properties of a single receptor subtype across different animal species. An example of this pharmacological diversity between species homologues is provided by the 5-HT_1D receptor subfamily. To further advance the ability to characterize and pharmacologically compare functional responses mediated by native 5-HT_1D receptors, we have cloned the 5-HT_1D and 5-HT_1D receptor subtypes from the rabbit and evaluated their pharmacological profiles using radioligand binding assays. The deduced amino acid sequences of the rabbit 5-HT_1D and 5-HT_1D receptor genes displayed 60% overall identity [75% transmembrane (TM) identity] to each other and > 90% overall identity (95% TM identity) to their corresponding human homologues. Two compounds were identified in binding assays which discriminated between the closely-related 5-HT_1D receptors. Ketanserin exhibited high affinity (pK_i = 7.66) and selectivity ( > 20-fold) for the 5-HT_1D receptor while methiothepin displayed high affinity (pK_i = 7.86) and selectivity (16-fold) for the 5-HT_1D receptor subtype. The rabbit and human recombinant 5-HT_1D receptors showed significant intraspecies (rabbit 5-HT_1D vs. 5HT_1D) and interspecies (i.e. rabbit vs. human 5-HT_1D) similarities in their ligand binding profiles. These data suggest that 5-HT_1D-mediated responses in rabbit preparations may provide information relevant to the pharmacology of the 5-HT_1D receptor subtypes in humans.     

5-HT1B／1D受体激动剂的临床应用

偏头痛不同于头痛,其发作是由于血管的舒缩功能不稳定而发生障碍所出现的暂时性头痛。其病因较复杂,可与遗传、内分泌(雌激素、黄体酮及催乳素等水平过高)、内源性活性物(阿片样物质、5-羟色胺、去甲肾上腺素、缓激肽、前列腺素)有关。此外,包括心理、神经、精神(焦虑、紧张、疲劳)、食物(饮酒、咖啡、食用含酪胺食品)、物理(光、冷、     

5-HT1A受体拮抗剂WAY-100635的合成

2-氨基吡啶和2-氯乙酰氯经酰胺化、与N'-(邻甲氧基苯基)哌嗪缩合、氢化铝锂还原得4-(邻甲氧基苯基)-1-[2-[(2-吡啶基)氨基]乙基]哌嗪,再与环己甲酰氯缩合得到5-HT1A受体拮抗剂WAY-100635,总收率35%.     

选择性5-HT1F受体激动剂拉米地坦

拉米地坦为一种选择性5-HT1F受体激动剂,由Eli Lilly制药公司生产,于2019年10月获美国食品和药物管理局批准用于偏头痛急性期的治疗,Ⅲ期临床研究表明拉米地坦可明显增加无头痛患者比例.拉米地坦耐受性好,常见的不良反应包括头晕、感觉异常、嗜睡、疲劳及恶心.     

5-羟色胺（5-HT）1A受体配体的研究进展

5-羟色胺（5-HT）是重要的神经递质，5-HT受体（5-HTR）在认知、情感等众多神经活动中发挥着重要作用，是重要的药物靶标。5-HT1A受体（5-HT1AR）是众多5-HTR亚型中研究最为广泛和深入的一类受体，研究5-HT1A受体配体（5-HT1ARL）对于临床上治疗焦虑、抑郁、疼痛等疾病都具有重要的价值。该文主要从5-HT1ARL结构类型的角度综述5-HT1ARL的最新研究进展，并简要介绍定向多靶标配体的研究成果，展望5-HT1ARL药物的开发前景。     

Pharmacological characterizations of recombinant human 5-HT1D1Dα and 5-HT1Dβ receptor subtypes coupled to adenylate cyclase inhibition in clonal cell lines: apparent differences in drug intrinsic efficacies between human 5-HT1D subtypes

Recombinant human 5-HT_1D and 5-HT_1D receptor subtypes were stably expressed in NIH-3T3 fibroblasts (1D cell line) and Y-1 adrenocortical tumor cells (1D cell line), respectively, for pharmacological evaluations of serotonergic compounds to inhibit forskolin-stimulated CAMP accumulation (FSCA). [³H]LSD saturation studies indicated that 5-HT_1D receptor expression levels were slightly higher in the 1D cell line (B _max = 1334 ± 134 fmol/mg protein) than in the (1D) cell line (B _max = 900 ± 900 fmol/mg protein). 5-HT inhibited FSCA with similar potencies (EC₅₀ 2 nM) in both assay systems. The rank order of agonist potencies in both clonal cell lines matched their pharmacological profiles previously determined in binding studies: dihydroergotamine >- 5-carboxamidotryptamine (5-CT) > LSD >- 5-HT > sumatriptan > 1-naphthylpiperazine (1-NP) > yohimbine > 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH DPAT) > 1-(2,5-dimethoxy4-iodophenyl)-2-aminopropane (DOI), with K_i/EC₅₀ ratios greater than unity. Methiothepin acted as a silent antagonist at both human 5-HT_1D and 5-HT_1D receptors with apparent dissociation constants (K_b values) of 12 ± 1 nM and 3 ± 1 nM, respectively. Whereas GR 127,935, metergoline, DOI, and quipazine acted as full agonists in the 1D cell line, these compounds behaved as partial agonists in the 1D cell line.To determine whether high levels of receptor reserve might mask partial agonist activity in the two second messenger assay systems, studies were performed using the irreversible receptor alkylating agent N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ). The relationships between receptor occupancy and inhibition of FSCA were determined for 5-HT, sumatriptan, and 1-NP in both clonal cell lines after partial receptor inactivation using Furchgott analysis. Hyperbolic relationships between receptor occupancy and second messenger response were determined for 5-HT in both transfected cell lines. Steep hyperbolic relationships were also found for sumatriptan and 1-NP in the 1D cell line whereas nearly linear relationships were observed for these two compounds in the 1D cell line. Moreover, K_A/EC₅₀ ratios of these compounds were significantly larger in the (1D)(10–32) as compared to the 1D (0.9–2.5) cell line. These data are consistent with the hypothesis that the two heterologous expression systems contain a differential amount of receptor reserve. Despite the presence of an apparently larger receptor reserve in the 1D cell line, GR 127,935, metergoline, DOI, and quipazine behaved as partial agonists.Although the potencies (EC₅₀ values) of compounds matched their respective affinity constants (K_i values) for the closely-related 5-HT_1D subtypes, differences in intrinsic activities were observed for a few compounds between the two 5-HT_1D receptor expression systems. Since receptor reserve is dependent on the properties of both the assay system and drug, the observed variations in intrinsic activity, although influenced by the variable amounts of receptor reserve in the two transfected cell lines, reflect primarily system-independent differences in the intrinsic efficacy of the tested compounds at the two human 5-HT_1D receptors. Higher intrinsic efficacies of compounds at the human 5-HT_1D receptor relative to the human 5-HT_1D subtype may be responsible for the higher intrinsic activities observed in the (1D) cell line, even though receptor reserve is apparently lower in this system.Abbreviations CRC Concentration-response curve - FSCA forskolin-stimulated cAMP accumulation - KA pseudo-dissociation constants - 5-CT 5-carboxamidotryptamine - 5-HT 5-hydroxytryptamine - 5MeOT 5-methoxytryptamine - PAPP 1-[2-(4-aminophenyl) ethyl] -4-(3-trifluoromethylphenyl)-piperazine - 1-NP 1-(1-naphthyl) piperazine - 8-OH-DPAT 8-hydroxy-2-(di-n-propylamino) tetralin - DOI 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane - MK-462 (N,N-dimethyl-2-[5-(1, 2, 4-triazol-l-yl methyl)-1H-indole3-yl]ethylamine - GR 127,935 (2-methyl-4-(5-methyl-[1, 2, 4]oxadiazol-3-yl)-biphenyl-4-carboxylic acid [4-methoxy-3-(4-methyl-piperazin-1-yl)-phenyl]-amide) - GR 46611 5-[4-methoxybenzyl ethylene]-1H-indole3-yl]ethyl amine) - L-694,247 (2-[5-[3-(4-methylsulfonylamino)benzyl-1, 2, 4-oxadiazol-5-yl]-1H-indole3-yl]ethylamine)     

血小板5-HT受体与摄取

血小板、肥大细胞、嗜铬细胞颗粒及5-羟色胺(5-HT)神经小体都可摄取5-HT。这一过程可被摄取抑制剂三环类抗抑郁药阻断。而5-HT和受体的结合则易于为受体拮抗剂甲基麦角酰胺等阻断。利用上述细胞与[~3H]5-HT进行受体结合实验应注意排除摄取过程的干扰。在建立放射配基结合实验初期,应严格区分受体结合与其它各种非受体结合,以免干扰实验结果,造成错误解释。     

新型5-HT1A受体激动和5-HT重摄取抑制双重活性化合物YL-0919抗抑郁作用的行为学评价

目的研究兼有5-HT1A受体激动和5-HT重摄取抑制双重活性化合物YL-0919的抗抑郁作用。方法分别采用小鼠悬尾实验、小鼠强迫游泳实验、小鼠自发活动实验和大鼠获得性无助模型,观察不同剂量（0.625、1.25、2.5和5mg/kg）YL-0919的抗抑郁作用。结果在小鼠悬尾实验和小鼠强迫游泳实验中,单次灌胃给予YL-0919（0.625～2.5mg/kg）能够显著缩短小鼠悬尾不动时间和游泳不动时间;在小鼠自发活动实验中,YL-0919在上述剂量范围对自发活动无影响;在大鼠获得性无助模型上,灌胃给予YL-0919〔0.625～1.25mg/（kg·d）,1~4d〕能显著减少逃避失败次数。结论 YL-0919在小鼠和大鼠模型上具有明确的抗抑郁活性,并且在抗抑郁的有效剂量范围内无中枢兴奋和抑制作用,具有成为新型抗抑郁药物的研发潜力。