title: 5-HT(1A) and 5-HT(2A) receptors minimally contribute to clozapine-induced acetylcholine release in rat medial prefrontal cortex.
abstract: The atypical antipsychotic drugs (APDs) clozapine, olanzapine, risperidone, and ziprasidone preferentially increase dopamine (DA) release in rat medial prefrontal cortex (mPFC). These effects have been shown to depend upon potent 5-HT(2A) relative to weak D(2) antagonism, and 5-HT(1A) agonism as well. Atypical APDs also increase acetylcholine (ACh) release in the mPFC, but not the nucleus accumbens (NAC) or striatum (STR), whereas typical APDs such as haloperidol, S(-)-sulpiride and thioridazine do not produce either effect in the mPFC. This study examined the role of 5-HT(1A) agonism, 5-HT(2A) and D(2) antagonism, and the combination thereof, in the ability of clozapine to increase ACh release in rat mPFC. R(+)-8-OH-DPAT (0.2 mg/kg), a 5-HT(1A) agonist, WAY100635 (0.2-0.5 mg/kg), a 5-HT(1A) antagonist, and DOI (0.6-2.5 mg/kg), a 5-HT(2A/2C) agonist, increased ACh release in the mPFC, whereas M100907 (0.03-1 mg/kg), a 5-HT(2A) antagonist, did not. DOI (2.5 mg/kg) and M100907 (0.1 mg/kg) had no effect on ACh release in the NAC or STR. WAY100635 and M100907 inhibited the ability of R(+)-8-OH-DPAT and DOI, respectively, to increase ACh release in the mPFC. WAY100635, which inhibits clozapine-induced DA release in the mPFC, failed to inhibit clozapine (20 mg/kg)-induced ACh release in that region. Similarly, the combination of M100907 and haloperidol (0.1 mg/kg), which enhances DA release in the mPFC, failed to increase ACh release in that region. These results suggest that 5-HT(1A) agonism and 5-HT(2A) antagonism, as well as DA release, contribute minimally to the ability of clozapine, and perhaps other atypical APDs, to increase ACh release in the mPFC.
authors.affiliation: Division of Psychopharmacology, Departments of Psychiatry and Pharmacology, Ther Psychiatric Hospital at Vanderbilt, Vanderbilt University School of Medicine, 1601 23rd Avenue South, Nashville, TN 37212, USA. ichikaj@crtvax.vanderbilt.edu
authors.forename: Junji
authors.initials: J
authors.lastname: Ichikawa
authors.forename: Jin
authors.initials: J
authors.lastname: Dai
authors.forename: Herbert Y
authors.initials: HY
authors.lastname: Meltzer
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D003024:Clozapine / Q000494:pharmacology*; D003342:Corpus Striatum / Q000378:metabolism; D018492:Dopamine Antagonists / Q000494:pharmacology; D005464:Fluorobenzenes / Q000494:pharmacology; D006220:Haloperidol / Q000494:pharmacology; D007215:Indophenol / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D017551:Microdialysis; D009714:Nucleus Accumbens / Q000378:metabolism; D010879:Piperazines / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin / Q000187:drug effects / Q000378:metabolism*; D044263:Receptors, Serotonin, 5-HT1; D012702:Serotonin Antagonists / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013997:Time Factors
chemical_list: D018492:Dopamine Antagonists; D005464:Fluorobenzenes; D010879:Piperazines; D010880:Piperidines; D011725:Pyridines; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; C113896:dimethoxy-4-indophenyl-2-aminopropane; D007215:Indophenol; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; C079049:volinanserin; D003024:Clozapine; D006220:Haloperidol; D000109:Acetylcholine