Classical as well as novel antipsychotic drugs increase self-stimulation threshold in the rat--similar mechanism of action?

Eur J Pharmacol. 2006 Aug 21;544(1-3):69-76. doi: 10.1016/j.ejphar.2006.06.051. Epub 2006 Jun 28.

Abstract

Antipsychotic drugs given acutely increase the threshold for intracranial self-stimulation elicited from the ventral tegmental area. As all the antipsychotic drugs share the dopamine D2-receptor antagonism it is reasonable to believe that this is the cause for suppression of intracranial self-stimulation behaviour. The objective of this investigation was to examine the effect of classical (haloperidol) as well as novel antipsychotic drugs (clozapine, olanzapine and sertindole) on intracranial self-stimulation behaviour. Furthermore, the effects of different specific receptor antagonists on intracranial self-stimulation behaviour were examined. Our results showed that both the classical (haloperidol) and the three novel antipsychotic drugs increase the threshold for intracranial self-stimulation. The results obtained with the receptor specific antagonists showed that dopamine D2, alpha1-adrenoceptor and serotonin 5-HT2A receptor antagonisms inhibit intracranial self-stimulation behaviour and that muscarinic receptor antagonism is without effect. Even though all the tested antipsychotic drugs inhibited intracranial self-stimulation behaviour, there seems to be a difference in their ratio between doses that inhibits intracranial self-stimulation behaviour and those that produce antipsychotic effect in a preclinical model (amphetamine hyperactivity). Sertindole was the only antipsychotic drug able to produce antipsychotic effect without significant inhibition of intracranial self-stimulation behaviour at a narrow dose interval. The remaining antipsychotic drugs all inhibited intracranial self-stimulation behaviour at equal or lower doses than those producing antipsychotic effect.

MeSH terms

  • Animals
  • Antipsychotic Agents / pharmacology*
  • Behavior, Animal / drug effects*
  • Dose-Response Relationship, Drug
  • Haloperidol / pharmacology
  • Male
  • Motivation
  • Rats
  • Rats, Wistar
  • Receptors, Adrenergic, alpha-1 / metabolism
  • Receptors, Dopamine D2 / metabolism
  • Receptors, Serotonin / metabolism
  • Self Stimulation

Substances

  • Antipsychotic Agents
  • Receptors, Adrenergic, alpha-1
  • Receptors, Dopamine D2
  • Receptors, Serotonin
  • serotonin 5 receptor
  • Haloperidol