Effects of novel antipsychotics with mixed D(2) antagonist/5-HT(1A) agonist properties on PCP-induced social interaction deficits in the rat

Neuropharmacology. 2005 Dec;49(7):996-1006. doi: 10.1016/j.neuropharm.2005.05.013. Epub 2005 Jul 11.


Considerable interest has arisen in identifying antipsychotic agents with improved efficacy against negative symptoms, such as social withdrawal. In rats, a social interaction deficit can be induced by the NMDA antagonist phencyclidine (PCP). Here, we examined the effects of antipsychotics, reported to exert dual 5-HT(1A)/D(2) actions, on PCP-induced social interaction deficits. Drugs were administered daily for 3 days in combination with either vehicle or PCP (2.5mg/kg, SC) and social interaction was measured on the last day of drug treatment. Pairs of unfamiliar rats receiving the same treatment were placed in a large open field for 10 min and the number of social behaviors were scored. The results indicate that: (1) PCP significantly reduced social interaction by over 50% compared with vehicle-treated controls; (2) haloperidol (0.0025-0.16 mg/kg, SC) and clozapine (0.04-10mg/kg, IP) did not reverse PCP-induced social interaction deficits; (3) the substituted benzamide remoxipride reversed PCP-induced deficits at 0.63 and 2.5mg/kg (4) the 5-HT(1A) agonist 8-OH-DPAT was inactive (at 0.01-0.63 mg/kg, SC); (5) among compounds reported to exert dual 5-HT(1A)/D(2) actions, SSR181507 (at 0.16 mg/kg, SC) and aripiprazole (at 0.04 and 0.16 mg/kg, IP), but not ziprasidone (0.04-2.5mg/kg, IP), SLV313 (0.0025-0.16 mg/kg, SC) or bifeprunox (0.01-0.63 mg/kg, IP), significantly reversed PCP-induced social interaction deficits; and (6) the 5-HT(1A) receptor antagonist WAY100635 blocked the effects of SSR181507 and aripiprazole. These findings indicate that the balance of activity at 5-HT(1A) and D(2) receptors profoundly influences the activity of antipsychotics in this model of social withdrawal, and their potential benefit on at least some of the negative symptoms of schizophrenia.

MeSH terms

  • 8-Hydroxy-2-(di-n-propylamino)tetralin / pharmacology
  • Animals
  • Antipsychotic Agents / pharmacology*
  • Aripiprazole
  • Clozapine / pharmacology
  • Dioxanes / pharmacology
  • Dopamine Antagonists / pharmacology*
  • Dopamine D2 Receptor Antagonists*
  • Excitatory Amino Acid Antagonists / pharmacology*
  • Haloperidol / pharmacology
  • Interpersonal Relations*
  • Male
  • Phencyclidine / pharmacology*
  • Piperazines / pharmacology
  • Pyridines / pharmacology
  • Quinolones / pharmacology
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, Serotonin, 5-HT1A / drug effects*
  • Remoxipride / pharmacology
  • Serotonin Antagonists / pharmacology
  • Serotonin Receptor Agonists / pharmacology*
  • Thiazoles / pharmacology
  • Tropanes / pharmacology


  • (3-exo)-8-benzoyl-N-(((2S)7-chloro-2,3-dihydro-1,4-benzodioxin-1-yl)methyl)-8-azabicyclo(3.2.1)octane-3-methanamine monohydrochloride
  • Antipsychotic Agents
  • Dioxanes
  • Dopamine Antagonists
  • Dopamine D2 Receptor Antagonists
  • Excitatory Amino Acid Antagonists
  • Piperazines
  • Pyridines
  • Quinolones
  • Serotonin Antagonists
  • Serotonin Receptor Agonists
  • Thiazoles
  • Tropanes
  • Remoxipride
  • Receptor, Serotonin, 5-HT1A
  • ziprasidone
  • N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide
  • 8-Hydroxy-2-(di-n-propylamino)tetralin
  • Aripiprazole
  • Phencyclidine
  • Clozapine
  • Haloperidol