Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.6.1.1 (adenylate cyclase)
19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cDNA of RDC4, a putative receptor of the G protein-coupled receptor family, has been cloned by PCR methodology. The primary structure of this receptor showed homology with the serotonin 5-HT1A receptor. In this work, RDC4 mRNA has been injected in Y1 adrenal cells and Xenopus oocytes and RDC4 cDNA has been transfected transiently in cos-7 cells. In all these systems serotonin elicited a rise in cyclic AMP levels. Binding studies on membranes of the transfected cos-7 cells using [3H]-LSD showed a pattern of drug affinities consistent with the known properties of a 5-HT1D receptor. RDC4 therefore codes for a 5-HT1D receptor which in the studied systems is positively coupled to adenylate cyclase.
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PMID:The orphan receptor cDNA RDC4 encodes a 5-HT1D serotonin receptor. 165 18

Serotonin (5-HT) stimulated adenylate cyclase activity in homogenates of rat hippocampus. This effect was pharmacologically characterised with a series of agonists and antagonists of various structural classes. These compounds where also tested in radioligand binding studies using selective ligands for the various subtypes of 5-HT1 and 5-HT2 receptors. 5-HT1A, 5-HT1B and 5-HT1C recognition sites were labelled with [3H]8-OH-DPAT([3H]8-hydroxy-2-(di-n-propylamino)-tetralin) in pig cortex membranes, [125I]CYP([125I]iodocyanopindolol) in rat cortex and [3H]mesulergine in pig choroid plexus membranes, respectively. The rank order of potency of 13 agonists stimulating adenylate cyclase activity in homogenates of rat hippocampus was in good agreement with the rank order of affinity of these agonists for the 5-HT1A binding site: N,N-dipropyl-5-carboxamidotryptamine (DP-5-CT) greater than 5-carboxamidotryptamine (5-CT) greater than 8-OH-DPAT greater than 5-HT greater than 5-methoxytryptamine (5-OCH3T) greater than d-LSD greater than 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H-indole (RU 24969) greater than alpha-methylserotonin (alpha-CH3-5-HT) greater than dopamine greater than 2-methylserotonin (2-CH3-5-HT). The correlation between the respective potencies and affinities of these agonists was r = 0.934, P less than 0.001. There was no correlation between stimulation of adenylate cyclase activity by these agonists and their affinity for 5-HT1B, 5-HT1C or 5-HT2 binding sites. r = 0.381-0.108, P less than 0.20-0.73.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:5-HT1A-receptors mediate stimulation of adenylate cyclase in rat hippocampus. 294 92

5-HT binding sites of the 5-HT1 type are heterogeneous and appear to comprise several subtypes (5-HT1A, 5-HT1B and 5-HT1C); their physiological role is as yet unclear. The stimulation of adenylate cyclase induced by 5-HT has been investigated in membrane fractions prepared from rat brain cortex. Enzymatic activity was determined by measuring cAMP production with an HPLC technique. It was shown that 5-HT stimulates adenylate cyclase activity with 2 activation constants (Kact): one shows a high apparent affinity (Kact = 0.8 nM) and the other a lower apparent affinity (Kact = 0.30 microM). The latter activity, induced by micromolar concentrations of 5-HT, was inhibited by spiperone at concentrations that block 5-HT1A binding. 5-Methoxytryptamine, bufotenin, and LSD also had a stimulatory biphasic effect on adenylate cyclase activity, whereas trifluoromethylphenylpiperazine, 5-carboxyamidotryptamine, 8-hydroxy-(2-di-n-propylamino)tetralin, RU 24969 had a monophasic effect. Enzyme activation by drugs acting in the micromolar range was inhibited by spiperone (1 microM), suggesting a link between this activation and 5-HT1A sites. On the other hand, the high-affinity activation of the enzyme induced by 5-HT, 5-methoxytryptamine, bufotenin, LSD, and the activation induced by TFMPP were not inhibited by spiperone (1 microM), by propranolol (3 microM), or by mesulergine (0.1 microM), which selectively block 5-HT1A, 5-HT1B, and 5-HT1C sites. Inhibition was produced by dihydroergotamine, methysergide, cinanserin, and mianserin, but not by naloxone, phenoxybenzamine, and phentolamine. Therefore, these activations seem related to 5-HT1 receptors but not to 5-HT1A, 5-HT1B, or 5-HT1C sites. Accordingly, binding of [3H]5-HT to 5-HT1-like sites was examined in the presence of spiperone (1 microM) and propranolol (3 microM); in these conditions, a high-affinity site (KD = 3.4 nM) was indeed revealed. The relative potencies of a series of drugs that stimulate or inhibit the activation of the adenylate cyclase with a high affinity and their ability to inhibit this binding of [3H]5-HT showed a positive correlation, strongly suggesting a direct relation between this recognition site for 5-HT and the production of a second messenger (cAMP). Moreover, this potential receptor is shown to be heterogeneously distributed within the brain, and was localized postsynaptically at serotonergic synapses.
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PMID:5-Hydroxytryptamine stimulates two distinct adenylate cyclase activities in rat brain: high-affinity activation is related to a 5-HT1 subtype different from 5-HT1A, 5-HT1B, and 5-HT1C. 340 98

The influence of 2-(2-oxo-3-piperidyl)-1,2-benzisothiazoline-3-one-1, 1-dioxide (supidimide), a representative of a new class of sedative drugs, on the noradrenergic, dopaminergic, serotoninergic and gamma-aminobutyric acid (GABA)ergic neuronal systems of rodent brains was investigated. In each case the brain transmitter levels after administration of supidimide were determined. Utilisation of noradrenaline (norepinephrine, NE), dopamine (DA), and 5-hydroxytryptamine (5-HT) was also investigated ex vivo. The study was complemented with in vitro investigations of biosynthesis, synaptosomal uptake, degradation, and receptor binding of the transmitters. Based on a preliminary study of the distribution of [35S]-supidimide in rat brain, in vitro effects observed at greater than 10(-4) mol/l were considered irrelevant. Similarly, in vivo effects requiring dosages higher than 300 mg/kg i.p. were not regarded adequate to explain the sedative and antiaggressive efficacy of supidimide. With the above restrictions, the following parameters can be rated as not influenced by supidimide: levels of tryptophan in rat brain and serum (free and total); 5-HT biosynthesis in vivo (rat brain; 5-HT accumulation after monoamine oxidase (MAO) blockade); activity of MAO-A and MAO-B (rat brain mitochondria); uptake of 5-HT, NE and DA (rat synaptosomes); 5-HT receptor binding ( [3H]-LSD binding assay in rat cortical membranes); tyrosine hydroxylase activity (rat adrenal glands); catechol-O-methyl transferase (COMT) (rat liver); NE binding to central alpha 1- and alpha 2-receptors (rat brain; radioligand assay with [3H]-dihydroergocryptine, [3H]-prazosin and [3H]-WB 4101 (2',6'-dimethoxy-(G-3H]-phenoxy]-ethylaminomethylbenzo-1,4-dioxane ); DA levels (whole rat brain and striata); dihydroxyphenylacetic acid (DOPAC) levels (whole rat brain without cerebellum and striata); elevated DOPAC levels after pretreatment with haloperidol; DA-dependent adenylate cyclase in vitro (rat striatum); D2 receptor binding ( [3H]-spiperone binding assay, rat striatum); GABA levels (mouse brain); GABA transaminase activity (mouse brain stem); sodium-independent [3H]-GABA receptor binding (rat brain) and benzodiazepine binding (rat cortical membranes, [3H]-diazepam binding assay). Two effects on the GABAergic system were induced by supidimide. Starting at 300 mg/kg i.p., supidimide slowed down the GABA accumulation in brains of aminooxyacetate-treated mice. At 10(-4) mol/l supidimide caused a significant inhibition of GABA uptake (rat synaptosomes).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Influence of supidimide on brain neurotransmitter systems of rats and mice. 608 11

The ergot alkaloids studied do exert selective effects on monoamine receptor systems. Lisuride acts as a very potent stimulator of adenylate cyclase in cortical brain regions, and may function as a mixed agonist-antagonist at high concentrations. It is most likely that in cortex, lisuride effects both dopamine and serotonin receptors, but predominantly serotonin receptors coupled to adenylate cyclase. The antagonist molindone exhibits selectivity for cortical serotonin-stimulated cyclase versus dopamine-stimulated cyclase and may prove useful for further elucidating the sites of lisuride action. LSD interacts with serotonin-stimulated cortical adenylate cyclase at higher concentrations than are needed for lisuride stimulation but, nevertheless, at lower concentrations than for serotonin itself (2-4). Bromocriptine, lergotrile and ergonovine may also act as agonists in stimulating adenylate cyclase, but with considerably less potency, and with differences in regional specificity for this stimulation, from lisuride and LSD. Each of these ergots may act as a mixed agonist-antagonist at high concentrations. With respect to the regions studied, antagonist effects on cyclase appear to be more prominent in striatum than in the cortical regions. The greater specificity of lisuride for serotonergic cortical receptors should make this compound useful in further studies of this system.
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PMID:Selective influence of ergot alkaloids on cortical and striatal dopaminergic and sergotonergic receptors. 624 92

Identification of multiple receptors for neurotransmitters has had important theoretical and practical therapeutic relevance. With the advent of receptor-binding techniques, the ability to detect heterogeneity of receptors has been greatly enhanced. There appear to be multiple serotonin (5-HT) receptors in the central nervous system. At least two distinct 5-HT receptors can be differentiated by binding techniques. 5-HT1 sites are labeled preferentially by [3H]5-HT, whereas [3H]spiroperidol selectively labels 5-HT2 receptors. 5-HT and other agonists display 50-1000 times greater affinity for 5-HT1 than 5-HT2 sites, whereas most known 5-HT antagonists have 100-1000 times greater affinity for 5-HT2 than 5-HT1 receptors. Ergot-related drugs, such as LSD and lisuride, have similar affinities for 5-HT1 and 5-HT2 receptors. Drug potencies in blocking 5-HT behavioral effects in rodents and in antagonizing vascular effects of 5-HT in several blood vessel systems correlate best with influences on 5-HT2 receptors. In some adenylate cyclase systems drug effects on the 5-HT response of adenylate cyclase correlate with 5-HT1 receptor affinity. Chronic treatment with antidepressants lowers the numbers of 5-HT2 but not 5-HT1 receptors. With most antidepressants the reduction of 5-HT2 receptor site number is greater than the reduction in beta-adrenergic receptors. Thus, influences of antidepressants on 5-HT2 receptors may provide a useful predictive test for antidepressant drug action.
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PMID:Multiple serotonin receptors and their physiological significance. 633 63

Serotonin (5-HT) receptors coupled to adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] in the liver fluke Fasciola hepatica have been characterized by adenylate cyclase activation studies and by direct binding studies using [3H]-d-lysergic acid diethylamide ([3H]LSD) as a radioligand. Inhibition of 5-HT stimulation of adenylate cyclase by a series of 5-HT antagonists revealed a potency order of LSD = 2-bromo-LSD greater than methiothepin greater than metergoline = cyproheptadine greater than methysergide greater than spiroperidol. [3H]LSD binding to a cell-free fluke particle preparation was rapid, stereospecific, and proportional to protein concentration. Scatchard analysis indicated multiple binding sites which, when resolved into two components, gave for the high affinity site an apparent dissociation constant of 25 nM and a receptor concentration of 160 fmoles/mg protein. The ability of a series of compounds to compete for [3H]LSD binding sites correlated closely with their ability to inhibit 5-HT stimulation of adenylate cyclase. [3H]LSD binding sites were most concentrated in the anterior region of the fluke which was consistent with the higher levels of 5-HT activated adenylate cyclase found in this region. GTP and 5'-guanylyl imidophosphate, a poorly hydrolyzable GTP analog, decreased the affinity of the agonist 5-HT for the binding sites but had little effect on the affinity of the antagonist 2-bromo-LSD. Calcium at concentrations above 300 microM significantly reduced both [3H]LSD binding and 5-HT activation of adenylate cyclase. The results indicate that [3H]LSD can be used to label the 5-HT receptors coupled to adenylate cyclase activity. The pharmacological specificity and other characteristics of the fluke receptors appear to differ from the properties of reported mammalian 5-HT receptors. As a result, serotonin receptors in the fluke represent sites that may be amenable to selective manipulation by new chemotherapeutic agents useful in the treatment of these parasite infections.
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PMID:Novel serotonin receptors in Fasciola. Characterization by studies on adenylate cyclase activation and [3H]LSD binding. 646 86

The activity of the adenylate cyclase located in membranes prepared from hippocampus of adult rat can be stimulated by serotonin (5-HT) (Ka = 4 X 10(-7) M). The maximal effect is obtained with 10 microM 5-HT. Freezing of the tissue decreases the 5-HT stimulation; this stimulation is optimal in the presence of 82.5 mM Tris-maleate buffer (pH 7.4) and 50 microM GTP. The adenylate cyclase activity of membranes prepared from cortex, hypothalamus, and colliculi of adult rats is not significantly stimulated by 5-HT. Dopamine (DA) also stimulates adenylate cyclase located in hippocampal membranes; its effect can be blocked by haloperidol (10(-6) M), which fails to inhibit 5-HT stimulation. Moreover, p-chlorophenylalanine treatment for 2 weeks or selective lesion of 5-HT axons afferent to the hippocampus increases the Vmax of 5-HT stimulation, but fails to change that of DA stimulation. The 5-HT stimulation can be inhibited by metergoline, spiroperidol, and pizotyline (10(-6) M), but not by the same concentrations of mianserin, ketanserine, alprenolol, phenoxybenzamine, and mepyramine. The 5-HT stimulation of adenylate cyclase of hippocampal membranes can be mimicked by tryptamine, 5-methoxytryptamine, bufotenine, and to a lesser extent by LSD; N-methyltryptamine, N-methyltryptophan, and 5-hydroxytryptophan are inactive. Studies with kainic acid suggest that the 5-HT recognition site (5-HT1) linked to adenylate cyclase is located on the membrane of intrinsic hippocampal neurons.
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PMID:Serotonin-elicited amplification of adenylate cyclase activity in hippocampal membranes from adult rat. 685 25

The distribution of receptors for serotonin and dopamine has been studied in various neuronal and non-neuronal tissues from Aplysia californica using: (1) a [3H]LSD binding assay; and (2) stimulation of adenylate cyclase activity. High levels of specific [3H]LSD binding were found in all ganglia and nerves examined. Lower levels of binding were present in a number of muscle tissues and in the sheath surrounding the central ganglia. The ability of serotonin and dopamine to inhibit [3H]LSD binding depended upon the tissue examined. In muscle tissue, most of the binding was sensitive to serotonin. In contrast, a number of ganglia (e.g. the pleural, abdominal or cerebral) contained a considerable proportion of dopamine-sensitive binding. A limited pharmacological analysis of serotonin-sensitive [3H]LSD binding indicated that Aplysia serotonin receptors are closely related to those found in the snail, Helix pomatia, and in rat brain. Adenylate cyclase activity in membranes from Aplysia ganglia, muscles and connective nerves was stimulated by serotonin (but not by dopamine). The amount of serotonin-sensitive adenylate cyclase correlated well with the amount of serotonin-sensitive [3H]LSD binding in most tissues. D-LSD was a partial agonist on the serotonin-sensitive adenylate cyclase, whereas the pharmacologically inactive stereoisomer L-LSD was without effect. The high density of serotonin receptors in pleuro-abdominal connective nerves, and their presence in the connective tissue sheaths surrounding the ganglia, suggests that not all of these receptors are located at synapses. On the other hand, the tissue distribution of dopamine and serotonin receptors, as measured by these techniques, is consistent with that expected from electrophysiological data.
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PMID:Distribution of serotonin and dopamine receptors in Aplysia tissues: analysis by [3H]LSD binding and adenylate cyclase stimulation. 735 15

Glial cell membrane fractions were prepared using glial cells preparations isolated from horse brain striatum. [3H]5-HT binding was measured by the filtration technique and the adenylate cyclase activity determined by measuring the cAMP production using a radioimmunoassay. Serotonin binds to glial membrane fractions with an affinity corresponding to a dissociation constant Kd = nM. The corresponding site is serotoninergic specific: [3H]5-HT binding is inhibited by 5-HT agonists (5 OH NM-DMT, 5-MeOHT, 5-MeOH-DMT, NN-DMT) or antagonists (cinanserine, cyproheptadine, methysergide, LSD) and not (or poorly) inhibited by non-serotoninergic related drugs. The population of sites binding 5-HT, present in neuronal membrane preparations and determined in parallel assays is distinct from that observed in glial preparations. The glial membrane fractions contains an adenylate cyclase activated by 5-HT with an apparent affinity constant close to 1 microM. It is serotonin-specific and clearly distinct from the DA-stimulated adenylate cyclase present in the same preparation. The sites binding 5-HT and activating the adenylate cyclase with low affinities might be directly related. This system, clearly distinct from the postsynaptosomal serotoninergic receptor, represents presumably a glial serotoninergic receptor; however, it cannot be totally excluded that these sites may refer to presynaptic membranes.
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PMID:[3H]5-HT binding sites and 5-HT-sensitive adenylate cyclase in glial cell membrane fraction. 740 3


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