Potent 5-HT1A Receptor Research Articles

Receptor interaction profiles of novel N-2-methoxybenzyl (NBOMe) derivatives of 2,5-dimethoxy-substituted phenethylamines (2C drugs)

BackgroundN-2-methoxybenzyl-phenethylamines (NBOMe drugs) are newly used psychoactive substances with poorly defined pharmacological properties. The aim of the present study was to characterize the receptor binding profiles of a series of NBOMe drugs compared with their 2,5-dimethoxy-phenethylamine analogs (2C drugs) and lysergic acid diethylamide (LSD) in vitro. MethodsWe investigated the binding affinities of 2C drugs (2C-B, 2C-C, 2C-D, 2C-E, 2C-H, 2C-I, 2C-N, 2C-P, 2C-T-2, 2C-T-4, 2C-T-7, and mescaline), their NBOMe analogs, and LSD at monoamine receptors and determined functional 5-hydroxytryptamine-2A (5-HT2A) and 5-HT2B receptor activation. Binding at and the inhibition of monoamine uptake transporters were also determined. Human cells that were transfected with the respective human receptors or transporters were used (with the exception of trace amine-associated receptor-1 [TAAR1], in which rat/mouse receptors were used). ResultsAll of the compounds potently interacted with serotonergic 5-HT2A, 5-HT2B, 5-HT2C receptors and rat TAAR1 (most Ki and EC50: <1 μM). The N-2-methoxybenzyl substitution of 2C drugs increased the binding affinity at serotonergic 5-HT2A, 5-HT2C, adrenergic α1, dopaminergic D1-3, and histaminergic H1 receptors and monoamine transporters but reduced binding to 5-HT1A receptors and TAAR1. As a result, NBOMe drugs were very potent 5-HT2A receptor agonists (EC50: 0.04–0.5 μM) with high 5-HT2A/5-HT1A selectivity and affinity for adrenergic α1 receptors (Ki: 0.3–0.9 μM) and TAAR1 (Ki: 0.06–2.2 μM), similar to LSD, but not dopaminergic D1–3 receptors (most Ki:>1 μM), unlike LSD. ConclusionThe binding profile of NBOMe drugs predicts strong hallucinogenic effects, similar to LSD, but possibly more stimulant properties because of α1 receptor interactions.

Discovery of novel potent and selective ligands for 5-HT2A receptor with quinazoline scaffold.

A series of compounds with quinazoline scaffold were designed, synthesized and evaluated as novel potent 5-HT2A receptor ligands. N-(4-Chlorophenyl)-2-(piperazin-1-yl)quinazolin-4-amine (5o) has a Ki value of 14.04 ± 0.21 nM, with a selectivity more than 10,000 fold over 5-HT1A receptors (D1 and D2-like receptors). The functional assay showed that this compound is an antagonist to 5-HT2A receptor with an IC50 value of 1.66 μM.

Studies on the metabolism and toxicological detection of the new psychoactive designer drug 2-(4-iodo-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)methyl]ethanamine (25I-NBOMe) in human and rat urine using GC-MS, LC-MSn, and LC-HR-MS/MS

25I-NBOMe, a new psychoactive substance, is a potent 5-HT2A receptor agonist with strong hallucinogenic potential. Recently, it was involved in several fatal and non-fatal intoxication cases. The aim of the present work was to study its phase I and II metabolism and its detectability in urine screening approaches. After application of 25I-NBOMe to male Wistar rats, urine was collected over 24h. The phase I and II metabolites were identified by LC-HR-MS/MS in urine after suitable workup. For the detectability studies, standard urine screening approaches (SUSA) by GC-MS, LC-MS(n), and LC-HR-MS/MS were applied to rat and also to authentic human urine samples submitted for toxicological analysis. Finally, an initial CYP activity screening was performed to identify CYP isoenzymes involved in the major metabolic steps. 25I-NBOMe was mainly metabolized by O-demethylation, O,O-bis-demethylation, hydroxylation, and combinations of these reactions as well as by glucuronidation and sulfation of the main phase I metabolites. All in all, 68 metabolites could be identified. Intake of 25I-NBOMe was detectable mainly via its metabolites by both LC-MS approaches, but not by the GC-MS SUSA. Initial CYP activity screening revealed the involvement of CYP1A2 and CYP3A4 in hydroxylation and CYP2C9 and CYP2C19 in O-demethylation. The presented study demonstrated that 25I-NBOMe was extensively metabolized and could be detected only by the LC-MS screening approaches. Since CYP2C9 and CYP3A4 are involved in initial metabolic steps, drug-drug interactions might occur in certain constellations.

Combined serotonin (5-HT)1A agonism, 5-HT2A and dopamine D2 receptor antagonism reproduces atypical antipsychotic drug effects on phencyclidine-impaired novel object recognition in rats

Subchronic administration of an N-methyl-d-aspartate receptor (NMDAR) antagonist, e.g. phencyclidine (PCP), produces prolonged impairment of novel object recognition (NOR), suggesting they constitute a hypoglutamate-based model of cognitive impairment in schizophrenia (CIS). Acute administration of atypical, e.g. lurasidone, but not typical antipsychotic drugs (APDs), e.g. haloperidol, are able to restore NOR following PCP (acute reversal model). Furthermore, atypical APDs, when co-administered with PCP, have been shown to prevent development of NOR deficits (prevention model). Most atypical, but not typical APDs, are more potent 5-HT2A receptor inverse agonists than dopamine (DA) D2 antagonists, and have been shown to enhance cortical and hippocampal efflux and to be direct or indirect 5-HT1A agonists in vivo. To further clarify the importance of these actions to the restoration of NOR by atypical APDs, sub-effective or non-effective doses of combinations of the 5-HT1A partial agonist (tandospirone), the 5-HT2A inverse agonist (pimavanserin), or the D2 antagonist (haloperidol), as well as the combination of all three agents, were studied in the acute reversal and prevention PCP models of CIS. Only the combination of all three agents restored NOR and prevented the development of PCP-induced deficit. Thus, this triple combination of 5-HT1A agonism, 5-HT2A antagonism/inverse agonism, and D2 antagonism is able to mimic the ability of atypical APDs to prevent or ameliorate the PCP-induced NOR deficit, possibly by stimulating signaling cascades from D1 and 5-HT1A receptor stimulation, modulated by D2 and 5-HT2A receptor antagonism.

Functional profile of a novel modulator of serotonin, dopamine, and glutamate neurotransmission.

RationaleSchizophrenia remains among the most prevalent neuropsychiatric disorders, and current treatment options are accompanied by unwanted side effects. New treatments that better address core features of the disease with minimal side effects are needed.ObjectivesAs a new therapeutic approach, 1-(4-fluoro-phenyl)-4-((6bR, 10aS)-3-methyl-2,3,6b,9,10,10a-hexahydro-1H,7H-pyrido[3′,4′:4,5]pyrrolo[1,2,3-de]quinoxalin-8-yl)-butan-1-one (ITI-007) is currently in human clinical trials for the treatment of schizophrenia. Here, we characterize the preclinical functional activity of ITI-007.ResultsITI-007 is a potent 5-HT2A receptor ligand (K i = 0.5 nM) with strong affinity for dopamine (DA) D2 receptors (K i = 32 nM) and the serotonin transporter (SERT) (K i = 62 nM) but negligible binding to receptors (e.g., H1 histaminergic, 5-HT2C, and muscarinic) associated with cognitive and metabolic side effects of antipsychotic drugs. In vivo it is a 5-HT2A antagonist, blocking (±)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI)-induced headtwitch in mice with an inhibitory dose 50 (ID50) = 0.09 mg/kg, per oral (p.o.), and has dual properties at D2 receptors, acting as a postsynaptic D2 receptor antagonist to block D-amphetamine hydrochloride (D-AMPH) hyperlocomotion (ID50 = 0.95 mg/kg, p.o.), yet acting as a partial agonist at presynaptic striatal D2 receptors in assays measuring striatal DA neurotransmission. Further, in microdialysis studies, this compound significantly and preferentially enhances mesocortical DA release. At doses relevant for antipsychotic activity in rodents, ITI-007 has no demonstrable cataleptogenic activity. ITI-007 indirectly modulates glutamatergic neurotransmission by increasing phosphorylation of GluN2B-type N-methyl-d-aspartate (NMDA) receptors and preferentially increases phosphorylation of glycogen synthase kinase 3β (GSK-3β) in mesolimbic/mesocortical dopamine systems.ConclusionThe combination of in vitro and in vivo activities of this compound support its development for the treatment of schizophrenia and other psychiatric and neurologic disorders.

The new drug phenomenon

The new drug phenomenon

Two cases of severe intoxication associated with analytically confirmed use of the novel psychoactive substances 25B-NBOMe and 25C-NBOMe

Context. A new group of novel psychoactive substance, the N-methoxybenzyl (NBOMe) derivatives of substituted phenethylamine, has recently emerged on the drug market, among which 25I-NBOMe and 25B-NBOMe have previously been implicated in clinical intoxications and fatalities. We report two cases of acute intoxication associated with these substances. Case details. Two male patients (17 and 31 years of age) had ingested drugs labelled as ‘NBOMe’ or ‘Holland film’ and developed confusion, agitation, hypertension, tachycardia, hyperthermia, sweating and dilated pupils. Other features included convulsion, rhabdomyolysis and deranged liver function. The patients required benzodiazepines and other drugs for the control of symptoms. Urine samples from both patients were analysed using liquid-chromatography tandem mass spectrometry (LC-MS/MS) following glucuronidase digestion and solid-phase extraction. Identification was based upon comparison of the retention time and enhanced product ion scan with reference standards. In both urine samples, 25B-NBOMe was detected. Additionally, 25C-NBOMe was identified in one of the urine samples. Discussion. The NBOMe compounds are highly potent 5HT2A receptor agonists and are also agonists at alpha-adrenergic receptors, which likely account for their serotonergic and sympathomimetic symptoms. The clinical testing of NBOMe drugs is not commonly available. Clinicians as well as laboratory staff play an important role in facilitating the detection of this group of potentially dangerous emerging drugs.

Application of Chromatographic Data in QSAR Studies of 3-[ -(4-Arylpiperazin-1-yl)alkyl]pyrimido[5,4-c]quinolin-4(3H)-one Derivatives as 5-HT1A Receptor Ligands

The activity of several 3-[ω-(4-arylpiperazin-1-yl)alkyl]pyrimido[5,4-c]quinolin-4(3H)-ones (LCAPs) with well-defined serotonin 1A (5-HT1A) receptor affinity was described by using chromatographic and calculated physicochemical parameters in quantitative structure-activity relationship analysis. Normal-phase thin-layer chromatography plates impregnated with solutions of L-aspartic acid, L-serine, L-phenylalanine, L-tryptophan, L-tyrosine, L-asparagine, L-threonine and their mixtures (denoted as S1-S11 biochromatographic models) were used with two mobile phases as a model of the interaction between LCAP and 5-HT1A receptors. Molecular descriptors for the investigated compounds were calculated by using HyperChem and ACD/Labs programs. The significant relationship explains that 82% of the variance was successfully validated by leave-one-out and leave-many-out tests. The results demonstrated that this model has significant predictive ability and can be used for the preliminary screening of newly synthesized potential 5-HT1A receptor ligands.

Synthesis and dual D2 and 5-HT1A receptor binding affinities of 5-piperidinyl and 5-piperazinyl-1H-benzo[d]imidazol-2(3H)-ones

A series of new 5-piperidinyl and 5-piperazinyl-1H-benzo[d]imidazol-2(3H)-ones have been synthesized and evaluated for dual D2 and 5-HT1A receptor binding affinities. The synthesized ligands are structurally related to bifeprunox, a potential atypical antipsychotic, having potent D2 receptor antagonist and 5-HT1A receptor agonist properties. The Suzuki–Miyaura reaction of cyclic vinyl boronate with appropriate aryl halide yielded arylpiperidine, which was eventually transformed to piperidinyl-1H-benzo[d]imidazol-2(3H)-one. The reductive amination of the latter with appropriate biarylaldehdyes rendered the synthesis of 5-piperidinyl-1H-benzo[d]imidazol-2(3H)-ones. Likewise, the Buchwald–Hartwig coupling reactions of 1-boc-piperazine with appropriate aryl halide and subsequent removal of the boc group rendered arylpiperazine. The reductive amination of the latter with appropriate biarylaldehdyes accomplished the synthesis of 5-piperazinyl-1H-benzo[d]imidazol-2(3H)-ones. The structure–activity relationship studies showed that cyclopentenylpyridine and cyclopentenylbenzyl groups contribute significantly to the dual D2 and 5-HT1A receptor binding affinities of these compounds.

Synthesis and biological evaluation of novel pyrrolidine-2,5-dione derivatives as potential antidepressant agents. Part 1

A series of 3-(1H-indol-3-yl)pyrrolidine-2,5-dione derivatives was synthesized and their biological activity was evaluated. The chemical structures of the newly prepared compounds were confirmed by 1H NMR, 13C NMR and ESI-HRMS spectra data. All tested compounds proved to be potent 5-HT1A receptor and serotonin transporter protein (SERT) ligands. Among them, compounds 15, 18, 19 and 30 showed significant affinity for 5-HT1A and SERT. Computer docking simulations carried out for compounds 15, 31 and 32 to models of 5-HT1A receptor and SERT confirm the results of biological tests. Due to high affinity for the 5-HT1A receptor and moderate affinity for SERT, compounds 31, 32, 35, and 37 were evaluated for their affinity for D2L, 5-HT6, 5-HT7 and 5-HT2A receptors. In vivo tests, in turn, resulted in determining the functional activity of compounds 15, 18, 19 and 30 to the 5-HT1A receptor. The results of these tests indicate that all of the ligands possess properties characteristic of 5-HT1A receptor agonists.

New 8-aminoalkyl derivatives of purine-2,6-dione with arylalkyl, allyl or propynyl substituents in position 7, their 5-HT1A, 5-HT2A, and 5-HT7 receptor affinity and pharmacological evaluation

BackgroundOur previous studies in a group of arylpiperazine derivatives of 1,3-dimethyl-3,7-dihydro-purine-2,6-diones, aimed at chemical diversification of the purine-2,6-dione by introduction of hydrophobic substituent in a 7- or 8- position or elongation of the linker length between arylpiperazine and purine core, allowed a selection of potent 5-HT1A, 5-HT2A and 5-HT7 receptor ligands displaying anxiolytic and antidepressant properties. Continuing our research in this field, in the present studies we designed a new series of 8-aminoalkylamino (15–35) and 8-arylpiperazinylpropoxy (36–42) derivatives of 7-substituted 1,3-dimethyl-3,7-dihydropurine- 2,6-dione as potential 5-HT1A, 5-HT2A and 5-HT7 receptor ligands with potential psychotropic activity. MethodsRadioligand binding assays were employed for determining the affinity and the selectivity profile of the synthesized compounds for native 5-HT1A, 5-HT2A, and cloned 5-HT6 and 5-HT7 receptors. The functional activity of the selected compounds at 5-HT1A and 5-HT2A receptors was tested in the commonly used in vivo models. Antidepressant and anxiolytic properties were evaluated in the forced swim (FST) and the four-plate test (FPT) in mice, respectively. ResultsAmong the evaluated series, selected 7-benzyl-8-((4-(4-(3-chlorophenyl)piperazin-1-yl)butyl)amino)-1,3-dimethyl- 1H-purine-2,6(3H,7H)-dione (21), a mixed 5-HT1A/5-HT2A/5-HT7 receptor ligand, produced an antidepressant-like effect in FST, and exerted anxiolytic-like activity in FPT. Another pharmacologically evaluated compound 42 (a mixed 5-HT1A/5-HT7 ligand) slightly, but non-significantly attenuated the immobility time of mice in FST and was devoid of activity in FPT. ConclusionsStudy revealed advantage of mixed 5-HT1A/5-HT2A/5-HT7 receptor ligands over 5-HT1A/5-HT7 agents to display antidepressant- and anxiolytic-like activity. Modification of arylalkyl/allyl substituent in position 7 of purine-2,6-dione opens possibility for designing new 5-HT ligands with preserved π electron system and lower molecular weight.

Risperidone attenuates the increase of extracellular nitric oxide and glutamate levels in serotonin syndrome animal models

Serotonin (5-hydroxytryptamine; 5-HT) syndrome is a potentially life-threatening neurotoxic condition provoked by pharmacologically induced excess serotonergic activity. Several studies report that nitric oxide (NO) and glutamate play a role in psychostimulant-induced hyperthermia related to neurotoxicity. In the present study, the involvement of NO and glutamate, as well as the effect of risperidone, a potent 5-HT2A and D2 (and a less potent D1) receptor antagonist, were investigated in animal models of 5-HT syndrome. Two 5-HT syndrome animal models were utilized. The first model was induced by administration of tranylcypromine, a nonselective monoamine oxidase (MAO) inhibitor, and fluoxetine, a selective 5-HT reuptake inhibitor. The second model was induced by the administration of clorgyline, an MAO-A inhibitor, and 5-hydroxy-l-tryptophan, a precursor of 5-HT. Changes in the level of NO metabolites and glutamate in the anterior hypothalamus were measured using microdialysis. In both models, NO metabolite levels significantly increased, and this increase was significantly attenuated by risperidone pretreatment. Extracellular levels of glutamate were increased only in the tranylcypromine and fluoxetine model, and this increase was significantly attenuated by risperidone pretreatment. These results indicate that NO and glutamate may be involved in the development of 5-HT syndrome and that risperidone may be effective against neurotransmitter abnormalities in 5-HT syndrome.

Identification of fused bicyclic heterocycles as potent and selective 5-HT2A receptor antagonists for the treatment of insomnia

A series of fused bicyclic heterocycles was identified as potent and selective 5-HT2A receptor antagonists. Optimization of the series resulted in compounds that had improved PK properties, favorable CNS partitioning, good pharmacokinetic properties, and significant improvements on deep sleep (delta power) and sleep consolidation.

Synthesis of several MPP derivatives for 99mTc-labelling and evaluated as potential 5-HT1A receptor imaging agents

The (2-methoxyphenyl) piperazine (MPP) was selected as the functional group and conjugated to dithiocarbamate through different spacers. A series of new MPP derivatives (MPPnDTC, n = 2–6) were synthesized and radiolabelled with 99mTc-nitrido core or 99mTc-tricarboxyl core as potential 5-HT1A receptor imaging agents. All the six 99mTc-labelled complexes were lipophilic and neutral. Biodistribution results showed that those radiotracers had moderate initial brain and hippocampus uptake. There have no significant relation was observed between the biological properties of these tracers with the length of its carbon chain. The radioactivity concentrations of hippocampus of 99mTcN-MPP2DTC, 99mTcN-MPP3DTC, 99mTcN-MPP4DTC, 99mTcN-MPP5DTC, 99mTcN-MPP6DTC and 99mTc(CO)3-MPP3DTC at 2 min post-injection time (p.i.) were 0.43, 1.15, 0.99, 1.04, 1.13 and 0.83 %ID/g, respectively.

Risperidone in the treatment of Schizophrenia

Risperidone is a second generation antipsychotic agent, with potent serotonin 5-HT2A and dopamine D2 receptor blocking effects. Specifically, risperidone possesses a unique balance of serotonin and dopamine antagonism, namely that its affinity for 5-HT2A receptors is significantly greater than its affinity for D2 receptors. Risperidone is well-established medication, with the proven effects on positive and negative symptoms of schizophrenia. The aim of research was to establish the effectiveness and safety of risperidone in patients with schizophrenia. The sample consisted of 60 subjects, age ranged was between 18-60 years, both genders, who met the criteria for the diagnosis various types of schizophrenia, according to ICD-10 (International Statistical Classification of Diseases). They were enrolled in the study as outpatient and inpatient setting. All subjects signed informed consent before entering into this study which had been conducted at the Psychiatric Clinic, University Clinical Center Sarajevo. Study was designed for 8-week, open-label, flexible-dose observational study. The subjects had to have a total score > -40 on Positive and Negative scale -two parts of the Positive and Negative Syndrome Scale (PANSS), and to be able to discontinue current antipsychotic medications. The primary efficacy parameter was the percent of score difference between baseline and week 8 of therapy on two above-mentioned PANSS subscales. The difference was considered as significant improvement if decrease from the baseline was 20% or more. The secondary efficacy parameter was subjective clinical evaluation of efficacy with five possible answers: very good, good, moderate, not satisfactory, not possible to evaluate. It was measured at the end of observational period by the investigator. All 60 enrolled patients completed the study. After the 8 weeks of treatment, 54/60 patients (90%) had clinically significant improvement of 20% or more decreased total PANSS score (Positive and Negative subscale). In 6/60 patients (10%) clinical improvement was also reported with less of 20% decreased total PANSS score. The side effects were registered in 8/60 patients (13.32%). The mild extrapyramidal symptoms registered in 1/60 (11.66%) patients, whom dose of risperidone was reduced. Increase of prolactine in 7/60 (11.66%), patients, whose dose of risperidone also were reduced. Average weight gain was 0.84 kg. In this study Risperidone has shown very good effectiveness and safety.

N‐[3‐[4‐(2‐methoxyphenyl) piperaziny‐1‐yl]propyl]cyclam: synthesized as a potential 5‐HT1A receptor ligand and labelled with 99mTc‐nitrido core

AbstractThis paper reports the synthesis of new potential 5‐HT1A receptor ligand N‐[3‐[4‐(2‐methoxyphenyl)piperaziny‐1‐yl]propyl]cyclam (MPPC) and radiolabelling of it with 99mTc‐nitrido core. The novel neutral complex 99mTcN‐MPPC combines 1,4,8,11‐tetraazacyclotetradecane (cyclam) ligand as chelate moiety for 99mTc‐nitrido with a 1‐(2‐methoxyphenyl)piperazine moiety derived from WAY 100635 via a 3‐carbon alkyl chain. This provided a reliable and reproducible method for attaching the technetium to the pharmacophore moiety of WAY 100635. 99mTcN‐MPPC was prepared by a two‐step procedure and the radiochemical purity was found to be greater than 95%. It was hydrophilic and stable for at least 4 h at room temperature. In vivo stability study in normal rats showed that no degradation of 99mTcN‐MPPC was found in deproteinated blood samples at 2 h post‐injection. This effective 99mTc‐labelling strategy for obtaining neutral 99mTc nitrido complexes would be a useful tool to prepare new SPECT agents to image 5‐HT1A receptor with cyclam conjugated ligands. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Aripiprazole-Induced Psychosis

Article AbstractBecause this piece does not have an abstract, we have provided for your benefit the first 3 sentences of the full text.Sir: Aripiprazole is a new atypical antipsychotic with a partial agonist activity at D2 and 5-HT1A receptors and with potent 5-HT2A receptor antagonism. Dose titration is considered necessary by some authors,1 but not by others.2,3 Recently, multiple cases of worsening of psychotic symptoms after add-on treatment with aripiprazole have been reported.4-8

P.1.d.006 Behavioral phenotyping of sodium-myo-inositol cotransporter knockout mice with reduced brain inositol

Our previous studies in a group of arylpiperazine derivatives of 1,3-dimethyl-3,7-dihydro-purine-2,6-diones, aimed at chemical diversification of the purine-2,6-dione by introduction of hydrophobic substituent in a 7- or 8- position or elongation of the linker length between arylpiperazine and purine core, allowed a selection of potent 5-HT1A, 5-HT2A and 5-HT7 receptor ligands displaying anxiolytic and antidepressant properties. Continuing our research in this field, in the present studies we designed a new series of 8-aminoalkylamino (15–35) and 8-arylpiperazinylpropoxy (36–42) derivatives of 7-substituted 1,3-dimethyl-3,7-dihydropurine- 2,6-dione as potential 5-HT1A, 5-HT2A and 5-HT7 receptor ligands with potential psychotropic activity.Radioligand binding assays were employed for determining the affinity and the selectivity profile of the synthesized compounds for native 5-HT1A, 5-HT2A, and cloned 5-HT6 and 5-HT7 receptors. The functional activity of the selected compounds at 5-HT1A and 5-HT2A receptors was tested in the commonly used in vivo models. Antidepressant and anxiolytic properties were evaluated in the forced swim (FST) and the four-plate test (FPT) in mice, respectively.Among the evaluated series, selected 7-benzyl-8-((4-(4-(3-chlorophenyl)piperazin-1-yl)butyl)amino)-1,3-dimethyl- 1H-purine-2,6(3H,7H)-dione (21), a mixed 5-HT1A/5-HT2A/5-HT7 receptor ligand, produced an antidepressant-like effect in FST, and exerted anxiolytic-like activity in FPT. Another pharmacologically evaluated compound 42 (a mixed 5-HT1A/5-HT7 ligand) slightly, but non-significantly attenuated the immobility time of mice in FST and was devoid of activity in FPT.Study revealed advantage of mixed 5-HT1A/5-HT2A/5-HT7 receptor ligands over 5-HT1A/5-HT7 agents to display antidepressant- and anxiolytic-like activity. Modification of arylalkyl/allyl substituent in position 7 of purine-2,6-dione opens possibility for designing new 5-HT ligands with preserved π electron system and lower molecular weight.

The atypical antipsychotic agents zisprasidone, risperdone and olanzapine as treatment for and prophylaxis against progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is an unremitting, advancing disease of central nervous system white matter. PML is caused by infection of the JC polyoma virus, most always in patients with immunosupression due to, for example, cancer, anti-rejection transplant medications or HIV. There is no specific treatment or cure for PML, and untreated it has a median life expectancy is less than four months. Highly active antiretroviral treatment (HAART) has greatly reduced the incidence and prevalence of PML in HIV+ patients likely, however, even in the best case scenario of an HIV+ patient with PML and taking HAART, a significant mortality remains. Novel treatments for PML are needed. Recently Atwood and colleagues have found that the cellular receptor for JC virus is the serotonin 5HT2A receptor. In vitro they used the older antipsychotic medications chlorpromazine and clozapine to block the serotonin 5HT2A receptor and block JC virus cell entry. Unfortunately, however, chlorpromazine and clozapine have such significant side effects and toxicities, e.g., extrapyramidal symptoms and the possibility of bone marrow dyscrasias - that they may be problematic to use clinically. Here, we point out that some newer atypical antipsychotics such as zisprasidone, risperidone and olanzapine--medicines with much better side effect and toxicity profiles than the older antipsychotics--in vitro are significantly more potent 5HT2A receptor antagonists than chlorpromazine or clozapine by in some cases more than a factor of 10, and thus may be useful as treatment for or prophylaxis against PML.

4-Bromo-2,5-dimethoxyphenethylamine (2C-B) and structurally related phenylethylamines are potent 5-HT2A receptor antagonists in Xenopus laevis oocytes.

1. We recently described that several 2-(2,5-dimethoxy-4-substituted phenyl)ethylamines (PEAs), including 4-I=2C-I, 4-Br=2C-B, and 4-CH(3)=2C-D analogs, are partial agonists at 5-HT(2C) receptors, and show low or even negligible intrinsic efficacy at 5-HT(2A) receptors. These results raised the proposal that these drugs may act as 5-HT(2) antagonists. 2. To test this hypothesis, Xenopus laevis oocytes were microinjected with the rat clones for 5-HT(2A) or 5-HT(2C) receptors. The above-mentioned PEAs and its 4-H analog (2C-H) blocked the 5-HT-induced currents at 5-HT(2A), but not at the 5-HT(2C) receptor, revealing 5-HT(2) receptor subtype selectivity. The 5-HT(2A) receptor antagonism required a 2-min preincubation to attain maximum inhibition. 3. All PEAs tested shifted the 5-HT concentration-response curves to the right and downward. Their potencies varied with the nature of the C(4) substituent; the relative rank order of their 5-HT(2A) receptor antagonist potency was 2C-I>2C-B>2C-D>2C-H. 4. The present results demonstrate that in X. laevis oocytes, a series of 2,5-dimethoxy-4-substituted PEAs blocked the 5-HT(2A) but not the 5-HT(2C) receptor-mediated responses. As an alternative hypothesis, we suggest that the psychostimulant activity of the PEAs may not be exclusively associated with partial or full 5-HT(2A) receptor agonism.