Systemic administration of amperozide, a new atypical antipsychotic drug, preferentially increases dopamine release in the rat medial prefrontal cortex. 1994

G G Nomikos, and M Iurlo, and J L Andersson, and K Kimura, and T H Svensson
Department of Pharmacology, Karolinska Institutet, Stockholm, Sweden.

The putative atypical antipsychotic drug amperozide (APZ) shows high affinity for serotonin 5-HT2 receptors but only low affinity for dopamine (DA) D2 receptors. By employing microdialysis, we examined the effects of APZ on extracellular concentrations of DA in the nucleus accumbens (NAC), the dorsolateral striatum (STR) and the medial prefrontal cortex (MPC) of awake rats. A 5.0 mg/kg (SC) dose of APZ failed to affect DA concentrations in the NAC, while it increased DA outflow in the STR (by 46%) and the MPC (by 207%). A higher dose of APZ (10 mg/kg, SC) enhanced dialysate DA from the NAC and the STR by 30%, and from the MPC by 326%. Similarly, clozapine (2.5 and 10 mg/kg, SC) produced a greater release of DA in the MPC (+ 127 and + 279%) than in the NAC (+ 52 and + 98%). The selective 5-HT2 receptor antagonist ritanserin (1.5 and 3.0 mg/kg, SC) also produced a slightly higher increase of DA output in the MPC (+ 25 and + 47%) compared with the NAC (+ 19 and + 21%). In contrast, the selective D2 receptor antagonist raclopride (0.5 and 2.0 mg/kg, SC) increased DA release in the NAC (+ 65 and + 119%) to a greater extent than in the MPC (+ 45 and + 67%). These data suggest that the 5-HT2 receptor antagonistic properties of APZ and clozapine may contribute to their preferential effects on DA transmission in the MPC. Infusion of low doses (1, 10 microM, 40 min) of APZ through the probe in the DA terminal areas did not affect significantly DA outflow, while infusion of high doses (100, 1000 microM, 40 min) resulted in a more pronounced elevation of DA levels in the NAC (up to 961%) and the STR (up to 950%) than in the MPC (up to 316%). These findings indicate that the selective action of systemically administered APZ on DA in the MPC is most likely mediated at a level other than the terminal region. Taken together, the present results provide support for the notion that 5-HT2 receptor antagonism may be of considerable significance for the action of atypical antipsychotic drugs on mesolimbocortical dopaminergic neurotransmission.

UI MeSH Term Description Entries
D008297 Male Males
D009435 Synaptic Transmission The communication from a NEURON to a target (neuron, muscle, or secretory cell) across a SYNAPSE. In chemical synaptic transmission, the presynaptic neuron releases a NEUROTRANSMITTER that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across ELECTRICAL SYNAPSES. Neural Transmission,Neurotransmission,Transmission, Neural,Transmission, Synaptic
D009714 Nucleus Accumbens Collection of pleomorphic cells in the caudal part of the anterior horn of the LATERAL VENTRICLE, in the region of the OLFACTORY TUBERCLE, lying between the head of the CAUDATE NUCLEUS and the ANTERIOR PERFORATED SUBSTANCE. It is part of the so-called VENTRAL STRIATUM, a composite structure considered part of the BASAL GANGLIA. Accumbens Nucleus,Nucleus Accumbens Septi,Accumbens Septi, Nucleus,Accumbens Septus, Nucleus,Accumbens, Nucleus,Nucleus Accumbens Septus,Nucleus, Accumbens,Septi, Nucleus Accumbens,Septus, Nucleus Accumbens
D010879 Piperazines Compounds that are derived from PIPERAZINE.
D003024 Clozapine A tricylic dibenzodiazepine, classified as an atypical antipsychotic agent. It binds several types of central nervous system receptors, and displays a unique pharmacological profile. Clozapine is a serotonin antagonist, with strong binding to 5-HT 2A/2C receptor subtype. It also displays strong affinity to several dopaminergic receptors, but shows only weak antagonism at the dopamine D2 receptor, a receptor commonly thought to modulate neuroleptic activity. Agranulocytosis is a major adverse effect associated with administration of this agent. Clozaril,Leponex
D004298 Dopamine One of the catecholamine NEUROTRANSMITTERS in the brain. It is derived from TYROSINE and is the precursor to NOREPINEPHRINE and EPINEPHRINE. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. A family of receptors (RECEPTORS, DOPAMINE) mediate its action. Hydroxytyramine,3,4-Dihydroxyphenethylamine,4-(2-Aminoethyl)-1,2-benzenediol,Dopamine Hydrochloride,Intropin,3,4 Dihydroxyphenethylamine,Hydrochloride, Dopamine
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D012702 Serotonin Antagonists Drugs that bind to but do not activate serotonin receptors, thereby blocking the actions of serotonin or SEROTONIN RECEPTOR AGONISTS. 5-HT Antagonist,5-HT Antagonists,5-Hydroxytryptamine Antagonist,5-Hydroxytryptamine Antagonists,Antiserotonergic Agent,Antiserotonergic Agents,Serotonin Antagonist,Serotonin Blockader,Serotonin Blockaders,Serotonin Receptor Antagonist,Serotonin Receptor Blocker,Antagonists, 5-HT,Antagonists, 5-Hydroxytryptamine,Antagonists, Serotonin,Serotonin Receptor Antagonists,Serotonin Receptor Blockers,5 HT Antagonist,5 HT Antagonists,5 Hydroxytryptamine Antagonist,5 Hydroxytryptamine Antagonists,Agent, Antiserotonergic,Agents, Antiserotonergic,Antagonist, 5-HT,Antagonist, 5-Hydroxytryptamine,Antagonist, Serotonin,Antagonist, Serotonin Receptor,Antagonists, 5 HT,Antagonists, 5 Hydroxytryptamine,Antagonists, Serotonin Receptor,Blockader, Serotonin,Blockaders, Serotonin,Blocker, Serotonin Receptor,Blockers, Serotonin Receptor,Receptor Antagonist, Serotonin,Receptor Antagonists, Serotonin,Receptor Blocker, Serotonin,Receptor Blockers, Serotonin
D014150 Antipsychotic Agents Agents that control agitated psychotic behavior, alleviate acute psychotic states, reduce psychotic symptoms, and exert a quieting effect. They are used in SCHIZOPHRENIA; senile dementia; transient psychosis following surgery; or MYOCARDIAL INFARCTION; etc. These drugs are often referred to as neuroleptics alluding to the tendency to produce neurological side effects, but not all antipsychotics are likely to produce such effects. Many of these drugs may also be effective against nausea, emesis, and pruritus. Antipsychotic,Antipsychotic Agent,Antipsychotic Drug,Antipsychotic Medication,Major Tranquilizer,Neuroleptic,Neuroleptic Agent,Neuroleptic Drug,Neuroleptics,Tranquilizing Agents, Major,Antipsychotic Drugs,Antipsychotic Effect,Antipsychotic Effects,Antipsychotics,Major Tranquilizers,Neuroleptic Agents,Neuroleptic Drugs,Tranquillizing Agents, Major,Agent, Antipsychotic,Agent, Neuroleptic,Drug, Antipsychotic,Drug, Neuroleptic,Effect, Antipsychotic,Major Tranquilizing Agents,Major Tranquillizing Agents,Medication, Antipsychotic,Tranquilizer, Major
D016713 Ritanserin A selective and potent serotonin-2 antagonist that is effective in the treatment of a variety of syndromes related to anxiety and depression. The drug also improves the subjective quality of sleep and decreases portal pressure. 6-(2-(4-(Bis(4-fluorophenyl)methylene)-1-piperidinyl)ethyl)-7-methyl-5H-thiazolo(3,2-a)pyrimidin-5-one,R-55667,Ritanserin Hydrochloride,Ritanserin Tartrate,R 55667,R55667

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