Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P08908 (5-HT1A)
 5,574 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Spiroxatrine has been reported to be a 5-HT1A serotonin receptor antagonist. Therefore [3H]spiroxatrine was synthesized and its 5-HT1A receptor binding properties in homogenates of rat hippocampal membranes were characterized with the expectation that it would be the first 5-HT1A antagonist radioligand. [3H]8-Hydroxydipropylaminotetralin [( 3H]8-OH-DPAT), a well-characterized 5-HT1A agonist radioligand, was studied in parallel for comparative purposes. Scatchard analyses of saturation studies of [3H]spiroxatrine and [3H]8-OH-DPAT binding produced KD values of 0.9 nM and 1.8 nM, with Bmax values of 424 and 360 fmol/mg protein, respectively. A highly significant correlation (r = 0.98; p less than 0.001) exists between Ki values obtained for a series of drugs in competing for [3H]-spiroxatrine and [3H]8-OH-DPAT binding. Of special interest was the observation that 5-HT1A agonists such as serotonin, 8-OH-DPAT, and ipsapirone competed with equal high affinities for [3H]spiroxatrine or [3H]8-OH-DPAT-labelled 5-HT1A receptors. [3H]Spiroxatrine and [3H]8-OH-DPAT binding to 5-HT1A receptors was inhibited by guanosine 5'-(beta,gamma-imido)triphosphate (a nonhydrolyzable analog of GTP) in a concentration-dependent manner whereas adenosine 5'-(beta,gamma-imido)triphosphate (a nonhydrolyzable analog of ATP) had no effect. The similarities in the 5-HT1A receptor radiolabelling properties of [3H]spiroxatrine and [3H]8-OH-DPAT, i.e., the high affinities of agonists and the guanyl nucleotide sensitivity, indicate that [3H]spiroxatrine has "agonist-like" binding properties in its interaction with the 5-HT1A receptor.
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PMID:[3H]spiroxatrine: a 5-HT1A radioligand with agonist binding properties. 296 50

Buspirone (Buspar; Bristol) marks a departure from established concepts of anxiolysis. Differing substantially both in its mode of action and in the clinical expression of its action from agents such as barbiturates and benzodiazepines, it would seem to operate chiefly via the 5-HT1A subtype of serotonin receptor. Such receptor selectivity is likely to be responsible for the novel action of this anxiolytic in that sedation and psychomotor and cognitive dysfunction are minimal, and because dependence is unlikely. The slower onset of full therapeutic benefit further delineates the differences between buspirone and other anxiolytics. However, it is apparent that the benzodiazepines will not readily be displaced from all of their varied applications by buspirone. This review examines buspirone and provides some guidelines for its use.
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PMID:Buspirone--frontrunner of a new genre of anxiolytics. 305 61

Male Wistar rats were trained to discriminate the interoceptive effects of 5-methoxy-N,N-dimethyltryptamine (5-OMe-DMT; 1.25 mg/kg, IP) from saline in a two-lever operant chamber. Following discrimination learning, the following drugs (with ED50 dose in mg/kg IP) dose-dependently generalized: lysergic acid diethylamide (LSD, 0.04), 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT, 0.11), 6-methoxy-4-(dipropyl-amino)-1,3,4,5-tetrahydrobenz(c,d)indole hydrochloride (BAY R 1531, 0.15), 5-OMe-DMT itself (0.63), ipsapirone (TVX Q 7821, 2.7), and buspirone (3.8). The potencies of these drugs in generalization tests were best correlated with their binding affinities for the 5-HT1A serotonin receptor subtype (as measured by displacement of 3H-ipsapirone in the hippocampus). Drugs not, or only partially generalizing included quipazine, bufotenin, m-trifluoromethylphenylpiperazine (TFMPP), 5-methoxy-3(1,2,3,6-tetrahydropyridine-4-yl)-1H-indole succinate (RU 24969), citalopram, clomipramine, 1,4-dihydro-2,6-dimethyl-3-nitro-4(2-trifluoromethylphenyl)-pyridine-5- carboxylate (BAY K 8644), the buspirone metabolite 1-pyrimidinyl-piperazine (1-PP), methysergide, metergoline, and metitepine. Of the last three compounds with antagonistic activity at 5-HT receptors, as well as ketanserin, pizotifen, and ritanserin, only metitepine and pindolol could fully block the 5-OMe-DMT stimulus. Pizotifen blocked the generalization of quipazine fully, that of 5-OMe-DMT only partially, and that of ipsapirone not at all. These data indicate that the 5-HT1A receptor subtype is strongly involved in the transduction of the interoceptive discriminative stimuli induced by 5-OMe-DMT, with 5-HT2 agonism also playing a possible role.
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PMID:Serotonin receptor subtype mediation of the interoceptive discriminative stimuli induced by 5-methoxy-N,N-dimethyltryptamine. 312 48

Alterations in brain serotonergic function have been implicated in the mechanism of action of LSD, mescaline, and other similarly acting hallucinogenic drugs of abuse such as STP (2,5-dimethoxyphenylisopropylamine; DOM). In order to test the hypothesis that the mechanism of action of LSD and phenylisopropylamine hallucinogens is through stimulation of a specific brain serotonin receptor sub-type, the affinities of these compounds for radiolabelled 5-HT2, 5-HT1A, 5-HT1B, and 5-HT1C receptors have been determined using recently developed in vitro radioligand binding methodologies. The 5-HT2 receptor was labelled with the agonist/hallucinogen radioligand 3H-DOB (4-bromo-2,5-dimethoxyphenylisopropylamine). The 5-HT1A, 5-HT1B, and 5-HT1C receptors were labelled with 3H-OH-DPAT, 3H-5-HT, and 3H-mesulergine, respectively. In general, the phenylisopropylamines displayed 10-100 fold higher affinities for the 5-HT2 receptor than for the 5-HT1C receptor and 100-1000 fold higher affinities for the 5-HT2 receptor than for the 5-HT1A or 5-HT1B receptor. There was a strong correlation between hallucinogenic potencies and 5-HT2 receptor affinities of the phenylisopropylamines (r = 0.90); the correlation coefficients for the 5-HT1A, 5-HT1B, and 5-HT1C were 0.73, 0.85, and 0.78, respectively. Because there is no evidence that 5-HT1A-selective or 5-HT1B-selective agonists are hallucinogenic and because the phenylisopropylamines are potent hallucinogens, a 5-HT2 receptor interaction is implicated and supports our previous suggestions to this effect. A secondary role for 5-HT1C receptors cannot be discounted at this time.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Radioligand binding evidence implicates the brain 5-HT2 receptor as a site of action for LSD and phenylisopropylamine hallucinogens. 312 47

In order to elucidate the role of putative indoleaminergic amacrine cells in visual processing, we have employed pharmacological agents specific for the two classes of serotonin receptor, 5-HT2 and 5-HT1, which have been identified in both the retina and brain. Perfusion of the rabbit retina with 5-HT2 selective antagonists decreases the ON-excitation of all classes of ganglion cell as well as the spontaneous activity of these cells. The effect on OFF-responses depends on the cell type: OFF-excitation of center-surround brisk and sluggish cells is increased or not affected by these drugs, but OFF excitation of ON/OFF direction selective cells is reduced. No disruption of the trigger features of direction selective or orientation selective cells was discovered, suggesting that indoleaminergic amacrine cells do not play a role in the generation of the complex properties of these cells. 5-HT1 receptors are heterogeneous and classified as a, b, or c subtypes. Since no selective antagonists are available for these sites, we have employed specific agonists. The most specific of these are for the 5-HT1A receptor. Perfusion with these agonists had physiological effects similar to those with perfusion of 5-HT2 antagonists. Thus, we have suggested that these two classes of serotonin receptors mediate opponent processes in the neural pathway. Since indoleaminergic cells make reciprocal synaptic connections with rod bipolar cell terminals, which are depolarizing in the rabbit retina, we hypothesize that 5-HT2 receptors facilitate the synaptic transmission from the depolarizing rod bipolar cell thus facilitating ON-excitation in the retinal network while 5-HT1A receptors mediate an inhibitory process. Similar self-opponent processing appears to take place in the hypothalamic and hippocampal serotonergic systems as well as in the dopaminergic retinal system. Thus, it is likely that this organization is a general feature of monoamine signal transmission in the central nervous system.
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PMID:Neuropharmacological analysis of the role of indoleamine-accumulating amacrine cells in the rabbit retina. 315

Rat brain cortex slices and synaptosomes preincubated with [3H] serotonin were used to study the effects of the 5-HT1 receptor agonist RU 24969 (5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H-indole) on the electrically (3 Hz) evoked 3H overflow from superfused slices and the potassium (12 mmol/l)-evoked 3H overflow from superfused synaptosomes. In slices superfused in the presence of 6-nitroquipazine (an inhibitor of serotonin uptake), the electrically evoked overflow was inhibited by RU 24969 and the reference compound serotonin (maximum inhibition obtainable: by about 50 and 60%, respectively; IC25 and IC30: 33 and 150 nmol/l, respectively). The inhibitory effect of RU 24969 on the evoked overflow was attenuated by cyanopindolol (a beta-adrenoceptor blocker with antagonistic properties at 5-HT1 receptors). In the absence of 6-nitroquipazine, RU 24969 did not increase the basal efflux and tended to be more potent in inhibiting the evoked overflow than in the presence of 6-nitroquipazine. The correlation of the release-inhibiting potencies of serotonin receptor agonists with their affinities for 5-HT1B binding sites (Engel et al., 1986) was slightly improved by inclusion of RU 24969, whereas that with the affinities for 5-HT1A binding sites (which was worse than the former correlation) was not changed. In synaptosomes superfused in the presence of 6-nitroquipazine, RU 24969 inhibited the potassium-evoked overflow. The inhibitory effect of RU 24969 was antagonized by cyanopindolol, which by itself did not affect the evoked overflow. It is concluded that RU 24969 acts as a highly potent agonist (with an intrinsic activity of about 0.8) at the presynaptic serotonin autoreceptor in the rat brain cortex. Furthermore, the present results support the assumption that these receptors belong to the 5-HT1B subtype.
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PMID:Effects of RU 24969 on serotonin release in rat brain cortex: further support for the identity of serotonin autoreceptors with 5-HT1B sites. 366 97

The affinities of putative serotonin receptor agonists and antagonists for 5-HT1A, 5-HT1B, 5-HT1C, and 5-HT2 receptors were assayed using radioligand binding assays. The 5-HT1 sites were labeled with the agonist radioligands [3H]-8-hydroxy-2-(di-n-propylamino)-tetralin [3H]-8-OH-DPAT, [3H]-5-HT, and [3H]mesulergine. The 5-HT2 receptor was labeled with the antagonist radioligand [3H]ketanserin or the agonist radioligand [3H]-4-bromo-2,5-dimethoxyphenylisopropylamine ([3H]DOB). The apparent 5-HT1 receptor selectivity of agonist compounds was found to be 50- to 100-fold higher when the 5-HT2 receptor affinity was determined using the antagonist radioligand [3H]ketanserin than when the agonist radioligand [3H]DOB was used. Quipazine, a putative specific 5-HT2 agonist, appeared to be only 3-fold more potent at 5-HT2 than at 5-HT1A receptors when [3H]ketanserin was used as the 5-HT2 radioligand. When [3H]DOB was used as the 5-HT2 radioligand, quipazine was determined to be 100-fold more potent at 5-HT2 receptors than at 5-HT1A receptors. 1-(3-trifluoromethylphenyl)piperazine (TFMPP), a putative specific 5-HT1B receptor agonist was apparently 10-fold more potent at 5-HT1B receptors than at 5-HT2 receptors when [3H]ketanserin was used as the 5-HT2 radioligand. When [3H]DOB was used as the 5-HT2 radioligand, TFMPP was found to be equipotent at 5-HT1B and 5-HT2 receptors. Using the 5-HT2 antagonist radioligand [3H]ketanserin, a similar pattern of underestimating 5-HT2 receptor selectivity and/or overestimating 5-HT1A or 5-HT1B receptor selectivity was observed for a series of serotonin receptor agonists. Antagonist receptor selectivity was not affected significantly by the nature of the 5-HT2 receptor assay used. These data indicate that, by using an antagonist radioligand to label 5-HT2 receptors and agonist radioligands to label 5-HT1 receptors, the 5-HT1 receptor selectivity may be overestimated. This may be an especially severe problem in serotonin drug development as drugs that interact potently with 5-HT2 receptors have been reported to be psychoactive and/or hallucinogenic.
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PMID:Selectivity of serotonergic drugs for multiple brain serotonin receptors. Role of [3H]-4-bromo-2,5-dimethoxyphenylisopropylamine ([3H]DOB), a 5-HT2 agonist radioligand. 366 39

Changes in tension of helical strips from human saphenous veins and reversible aggregation of human platelets were recorded in vitro. Comparison of the activities of 12 serotonin receptor agonists revealed that only 4 of the investigated tryptamine derivatives acted as full agonists on both tissues. 5-Carboxamidotryptamine, a drug with selective affinity for both 5-HT1A and 5-HT1B binding sites, though the most potent agonist on veins, failed to produce platelet aggregation but acted as a weak antagonist of the 5-HT-induced reversible aggregation. The tetralin derivative 8-OH-DPAT, a drug with selective affinity for 5-HT1A binding sites, was a weak partial agonist on veins and completely devoid of any activity on the platelets. The antagonism of 5-HT by spiperone was monophasic on platelets but biphasic on veins. These data are in line with the contention that the 5-HT-induced reversible aggregation of human platelets is initiated by 5-HT2-like recognition sites while the evidence suggests that the contractile response of human saphenous vein to 5-HT reflects activation of both 5-HT2- and 5-HT1-like recognition sites.
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PMID:Comparison of the actions of serotoninergic agents on human saphenous veins and platelets. 372 Aug 31

The authors investigated the presence of serotonin receptor type 1A (5-HT1A) as labeled by the specific ligand 3H-8 hydroxy-2-(di-N-propylamino)tetralin (3H-8-OH-DPAT) in saturation experiments, and the expression of the mRNA encoding them, in human peripheral blood mononuclear cells (PBMC). In situ hybridization experiments were performed as well. The results, showing that the binding of [3H]-8-OH-DPAT to lymphocyte membranes increased linearly up to 100 nM without reaching saturation, may indicate that the 3H-8-OH-DPAT was not specifically labeling the 5-HT1A receptor. By contrast, the expression studies revealed 5-HT1A mRNA in PBMC. These findings suggest that, despite the presence of mRNA, 5-HT1A receptors are not expressed in PBMC, at least in healthy controls.
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PMID:Presence of serotonin1A (5-HT1A) receptor mRNA without binding of [3H]-8-OH-DPAT in peripheral blood mononuclear cells. 747 72

The serotonin system has long been thought to play a role at several steps in the cycle of alcohol abuse. Initial motivation may be triggered by anxiety, which may exhibit a serotonergic component (5-HT1A receptor). Alcohol can potentiate the opening of 5-HT3 receptor ion channels, and agents which elevate serotonergic tone, including serotonergic agonists, uptake inhibitors and releasers, have shown promise in assisting with recovery from alcoholism. In this review, recent advances in serotonin receptor research are presented, with a special emphasis on the impact and interpretation of molecular biological data. Genetic and pharmacological concepts of receptor subtypes are reviewed and related to a new classification system for the 14 currently recognized subtypes of serotonin receptors. The current and likely future impact on drug design of the molecular approach to serotonin receptors is discussed. Finally, the question of why there are so many serotonin receptor subtypes is examined, along with possible roles of multiple G protein and second messenger pathways, and their effect on conserved domains of these receptor proteins.
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PMID:Molecular pharmacology of serotonin receptors. 751 66


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