Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In vivo occupation of dopamine D1 and D2 and serotonin (5-HT)2 receptors by typical and atypical antipsychotic drugs (APD) was examined using N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline, which nonselectively and irreversibly inactivates these receptor sites. APD were classified as typical or atypical based on their capacity to induce extrapyramidal side effect in humans and/or catalepsy in laboratory rodents. Pretreatment of rats with typical APD (haloperidol, 0.25-3 mg/kg; chlorpromazine, 5-10 mg/kg; cis-flupenthixol, 1 mg/kg; zotepine, 5 mg/kg; nemonapride, 0.5-2 mg/kg) potently reversed the N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline-induced D2 receptor inactivation in rat striatum. In contrast, some atypical APD or its candidates (clozapine, 5-30 mg/kg; fluperlapine, 10 mg/kg; risperidone, 0.25-3 mg/kg; setoperone, 0.025-0.25 mg/kg; ORG 5222, 0.25 mg/kg) showed considerable occupation of 5-HT2 receptors in cerebral cortex with smaller or negligible occupation of D2 and D1 receptors. Pretreatment with the other atypical APD (sulpiride, 30 mg/kg; amperozide, 1 mg/kg) had no effect on these three receptors, although at higher doses, sulpiride (60 mg/kg) and amperozide (5 mg/kg) slightly but significantly reversed D2 and 5-HT2 receptor inactivation, respectively. It was concluded that a certain group of atypical APD is characterized by high occupancy of 5-HT2 receptor with lower or minimal occupancy of D2 and D1 receptors in vivo. The relevance of these characteristics of atypical APD was discussed in relation to extrapyramidal side effects and the therapeutic effects on schizophrenia.
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PMID:Dopamine D1, D2 and serotonin2 receptor occupation by typical and atypical antipsychotic drugs in vivo. 768 43

A series of 3-[[(aryloxy)alkyl]piperidinyl]-1,2-benzisoxazoles was synthesized and evaluated as potential antipsychotic D2/5-HT2 antagonists. Most of these compounds showed potent antipsychotic-like activity in an apomorphine-induced climbing mouse paradigm, with many also showing preferential mesolimbic activity, as indicated by their weaker effects in an apomorphine-induced stereotypy model. In receptor binding assays, many displayed a moderate affinity for the D2 receptor coupled with a significantly greater affinity for the 5-HT2 receptor: a property that has been suggested as necessary for atypicality. From this series, compound 45, 1-[4-[3-[4-(6-fluoro-1,2-benzisoxazol-3-yl)-1- piperidinyl]propoxy]-3-methoxyphenyl]ethanone (iloperidone, HP 873), was further evaluated in a battery of in vivo and in vitro assays. This compound showed a 300-fold greater potency in inhibition of climbing than in inhibition of stereotypy or induction of catalepsy, and when evaluated chronically in an electrophysiological model, 45 caused a depolarization blockade of dopamine neurons in the A10 area of the rat brain but not in the A9 area. Additionally, it showed positive activity in a social interaction paradigm, suggesting potential efficacy against asociality, a component of the negative symptoms of schizophrenia. In chronic ex vivo studies, 45, similar to clozapine, caused a down regulation of 5-HT2 receptors but had no effect on the number of D2 receptors. Compound 45 is currently undergoing clinical evaluation.
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PMID:3-[[(Aryloxy)alkyl]piperidinyl]-1,2-benzisoxazoles as D2/5-HT2 antagonists with potential atypical antipsychotic activity: antipsychotic profile of iloperidone (HP 873). 770 15

Both acute and long-term effects of haloperidol and clozapine on Fos-like immunoreactive nuclei in several rat forebrain areas were quantified. Rats were treated with saline (1 ml/kg.day, control), haloperidol (1 mg/kg.day) and clozapine (20 mg/kg.day) i.p. for 21 days. Two hours before perfusion fixation a single (acute treatment) or last (long-term treatment) dose of the drug was given. Drug-induced catalepsy and gain in body weight were also measured. A single dose of haloperidol produced large increases in Fos-like immunoreactive nuclei in the striatum, the nucleus accumbens and central amygdala. Following long-term treatment these increases were reduced in all nuclei studied, except the lateral septum. Acute clozapine treatment had slight (if any) effects on the number of Fos-like immunoreactivity-expressing nuclei in the striatum, but the increases in the nucleus accumbens, the lateral septum, the paraventricular and supraoptic nuclei of the hypothalamus and the central amygdala were substantial. Long-term clozapine treatment reduced the acute response significantly in all the areas except the nucleus accumbens. Both haloperidol and clozapine treatment reduced the weight gain of the rats. Haloperidol, but not clozapine, induced catalepsy that remained maximal during the long-term haloperidol treatment. These results indicate that in most brain areas high Fos-protein levels are not necessary to maintain antipsychotic activity or side-effects. The persisting effect of clozapine in the nucleus accumbens may be of significance to the efficacy of this drug in treatment-refractory schizophrenia.
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PMID:Differential Fos-protein induction in rat forebrain regions after acute and long-term haloperidol and clozapine treatment. 773 11

The theoretical role of sigma receptors in psychosis has led to the development of selective sigma receptor ligands as potential antipsychotic agents. BMY 14802 has its most potent binding at the sigma binding site, with some degree of serotonin subtype 1A and negligible dopamine receptor binding. It is atypical of standard neuroleptics in that it does not induce catalepsy in rats. It has been shown to have efficacy in animal models of psychosis. It was hypothesized that the drug would have antipsychotic effects in humans without producing the extrapyramidal side effects typical of standard neuroleptics. We report here the results of an uncontrolled, multicenter safety and efficacy study of patients with acute exacerbations of schizophrenia treated with BMY 14802. After 1 week of single-blind placebo treatment, 28 patients were treated with BMY 14802 (up to 3000 mg/day) for up to 4 weeks. There was no significant improvement in psychiatric symptoms, as measured by the total Brief Psychiatric Rating Scale scores or Clinical Global Improvement. There were no changes in involuntary movements, as measured by the Abnormal Involuntary Movement Scale, or in extrapyramidal symptoms as measured by the Simpson-Angus Scale.
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PMID:BMY 14802, a sigma receptor ligand for the treatment of schizophrenia. 791 21

Progress toward understanding the role of the 5-hydroxytryptamine (5-HT)2 receptor in the therapy for schizophrenia has been hampered by the lack of highly selective antagonists. We now report on the effects of MDL 100,907 [R(+)-alpha-(2,3-dimethoxyphenyl)-1- [2-(4-fluorophenylethyl)]-4-piperidine-methanol], a highly selective and potent 5-HT2 receptor antagonist, in behavioral, electrophysiological and neurochemical models of antipsychotic activity and extrapyramidal side-effect liability. In mice, MDL 100,907 blocked amphetamine-stimulated locomotion at doses that did not significantly affect apomorphine-stimulated climbing behavior. Neither MDL 100,907 nor clozapine reduced apomorphine-induced stereotypies or produced catalepsy in rats. MDL 100,907 blocked the slowing of ventral tegmental area (A10) dopaminergic neurons by amphetamine but, like clozapine, produced only small increases in the number of active substantia nigra zona compacta (A9) and A10 dopamine neurons after acute administration. When administered chronically, MDL 100,907 and clozapine selectively reduced the number of spontaneously active A10 neurons, whereas haloperidol reduced activity in both the A9 and A10 regions. Consistent with their acute effect on A9 and A10 activity, neither MDL 100,907 nor clozapine increased dopamine metabolism in the striatum or nucleus accumbens, whereas acute haloperidol accelerated dopamine turnover in both regions. The administration of the dopamine uptake blocker amfonelic acid with haloperidol produced a massive increase in DA metabolism characteristic of typical antipsychotics. In contrast, MDL 100,907 and clozapine were without effect on dopamine turnover when given in the presence of amfonelic acid. These data indicate that MDL 100,907 has a clozapine-like profile of potential antipsychotic activity with low extrapyramidal sid-effect liability.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Characterization of the 5-HT2 receptor antagonist MDL 100907 as a putative atypical antipsychotic: behavioral, electrophysiological and neurochemical studies. 810 46

The present study has examined the glycine/N-methyl-D-aspartate antagonist, L-701-324 [7-chloro-4-hydroxy-3-(3-phenoxy)-phenyl-2 (H)quinolone] in rodent behavioral tests commonly used to predict antipsychotic potential and side effect liability in humans. Pretreatment with L-701,324 dose-dependently antagonized amphetamine-induced hyperactivity in the mouse (ED50 = 1.12 +/- 0.45 mg/kg p.o.), an effect which was similar to that of the classical neuroleptic, haloperidol, and the atypical neuroleptic, clozapine. In addition, p.o. administration of L-701,324 (2.5 or 5 mg/kg) attenuated the hyperactivity response induced by amphetamine infusion into the rat nucleus accumbens. In contrast to haloperidol, however, stereotyped sniffing and licking/biting, induced by either the systemic administration of apomorphine or infusion of amphetamine into the striatum, was not altered in rats pretreated with L-701,324 (30 or 100 mg/kg p.o.). Furthermore, L-701,324 failed to impair spontaneous locomotor activity or induce catalepsy in the mouse at doses > or = 100 mg/kg. Although a significant reduction in spontaneous activity was observed in rats pretreated with L-701,324, the minimum effective dose (10 mg/kg p.o.) was 2-fold greater than that which abolished amphetamine-induced hyperactivity in this species. Thus, L-701,324 selectively blocks behaviors associated with the activation of the mesolimbic dopamine system suggesting that glycine/N-methyl-D-aspartate receptor antagonists may offer a novel approach to the treatment of schizophrenia in humans.
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PMID:The atypical neuroleptic profile of the glycine/N-methyl-D-aspartate receptor antagonist, L-701,324, in rodents. 862 34

Recent studies have implicated the thalamus as a possible site for neuroanatomical and neurochemical changes in schizophrenia. In the present study, we investigated thalamic neurochemical correlates of behaviors potentially linked to schizophrenia. Whole thalamic DOPAC levels were elevated in rats that had poor extinction of the acoustic startle response. The dopamine agonist apomorphine microinjected into the ventromedial thalamus (VmT) disrupted prepulse inhibition of startle. Catalepsy was induced by VmT microinjections of the GABA-A agonist muscimol. A previous study revealed attentional disturbances and suppression of frontal cortical metabolic activity after muscimol microinjections into the mediodorsal thalamic nucleus. Together with recent findings of neuron cell loss and elevated DA levels in the thalamus of schizophrenics, these data suggest the involvement of disturbances of thalamic neurotransmission in schizophrenia.
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PMID:Startle and sensorimotor correlates of ventral thalamic dopamine and GABA in rodents. 874 49

Amisulpride is a benzamide derivative which displays a pharmacological profile distinct from that of classical neuroleptics such as haloperidol. In vitro, amisulpride selectively binds to dopamine (DA) receptors and is devoid of any affinity for serotonergic, alpha-adrenergic, histaminergic or muscarinic receptors. It has high and equal affinities for human D2 and D3 receptors, without affinity for D1 and D4 receptors. In vivo, in rats, amisulpride preferentially blocked D2 and D3 receptors localized in limbic structures in comparison with receptors found in the striatum. In addition, amisulpride selectively blocked presynaptic DA receptors. Thus, amisulpride antagonized apomorphine-induced effects (yawning, hypomotility) related to presynaptic DA receptor stimulation at very low doses (ED50 = 0.3-1 mg/kg, ip) compared to those needed to inhibit hypermotility and gnawing (60-80 mg/kg, ip) which involve post-synaptic DA receptor stimulation. The high affinity of amisulpride for D2 and D3 receptors, and its high degree of limbic selectivity may explain the lack of catalepsy in rats and the low incidence of neurological side effects in clinical studies. The enhancement of DA function produced by its selective presynaptic receptor DA blockade may account for the clinical efficacy of amisulpride against negative symptoms of schizophrenia.
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PMID:[The place of amisulpride in the atypical neuroleptic class]. 876 34

1192U90 was developed on the assumption that antagonism of 5-HT2 receptors efficacy yields more potently than D2 receptors against positive and negative symptoms of schizophrenia with minimal liability for extrapyramidal side effects (EPSs), and that 5-HT1A agonism further reduces EPSs and provides anxiolytic and antidepressant activity. 1192U90 was submitted to four tests that predict antipsychotic efficacy (antagonism of apomorphine-induced climbing in mouse, antagonism of apomorphine-induced circling in rats with unilateral 6-OHDA lesions, antagonism of amphetamine-induced hyperlocomotion in rat, and inhibition of conditioned avoidance in rat), two tests of 5-HT2 function (antagonism of 5-MeODMT-induced head twitches in mouse and antagonism of 5-HTP-induced wet dog shakes in rat), and three tests that predict EPS liability (antagonism of apomorphine-induced stereotypy in mouse and rat and induction of catalepsy in mouse). ED50s (mg/kg PO) were as follows: climbing 10.1, circling 7.9, hyperlocomotion 6.6, and avoidance 5.7; head twitches 5 and wet dog shakes 4.6; stereotypy in mouse 91.1, stereotypy in rat 133.4, and catalepsy 192.4. The ratio of ED50 for stereotypy antagonism to ED50 for climbing antagonism was 9 (compared to 4, 3, and 4 for clozapine, risperidone, and haloperidol). The ratio of ED50 for catalepsy induction to ED50 for climbing antagonism was 19 (compared to 7, 2, and 17 for clozapine, risperidone, and haloperidol). 1192U90 was also submitted to three tests that predict anxiolysis: It produced only a small increase in punished lever pressing for food in rat (Geller-Seifter conflict test), which is specific for rapid-onset efficacy, but produced large increases in punished key pecking for food in pigeon and cork gnawing in rat, which identify the delayed onset 5-HT1A agonists such as buspirone. The results suggest that 1192U90 would be effective for positive and negative symptoms of schizophrenia, with minimal liability for EPSs, and may also have anxiolytic properties.
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PMID:1192U90 in animal tests that predict antipsychotic efficacy, anxiolysis, and extrapyramidal side effects. 887 6

Clozapine is an 'atypical' neuroleptic that improves symptoms of many patients with schizophrenia whose illness is resistant to treatment with other neuroleptics. Unlike the 'typical neuroleptics (chlorpromazine, haloperidol), clozapine does not induce extrapyramidal symptoms such as Parkinsonism and tardive dyskinesia in humans or catalepsy in the rat. However, clozapine frequently causes epileptiform EEG changes and causes seizures in 3-5% of patients treated with this drug in therapeutic doses. Clozapine also induces dose dependent myoclonus in the partially restrained rat. In the experiments reported here, partially restrained rats were administered repeated alternate day or weekly low, fixed doses of clozapine (1 mg/kg). This dose initially caused no behavioral change. Following the third and subsequent administrations, the same dose elicited an increasing number of myoclonic seizure-like jerks reaching 140/h following the 15th injection in rats receiving the same low dose of clozapine on alternate days and 160/h following the 9th injection in animals that received the same dose once weekly. These effects are consistent with kindling, i.e. a progressive increase of brain excitability following repeated administration of a fixed subconvulsive dose of an excitatory agent. Clozapine kindled animals exhibited a significantly different pattern of early gene expression in ventral tegmental area, origin of the mesolimbic-mesocortical dopamine system and in the anterior thalamic nuclei, compared with saline treated controls subjected to exactly the same recording conditions. The evidence of central nervous system excitation with clozapine may be important to the unique therapeutic effect of this atypical antipsychotic in the treatment of symptoms, especially the deficit symptoms, of schizophrenia.
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PMID:Kindling with clozapine: behavioral and molecular consequences. 898 8


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