Aims: 

Acute administration of antipsychotics induces peripheral release of OXY. This motivated us to reveal how intensively may respond the OXY-ergic neurons in the PVN to pharmacologically differently acting antipsychotic drugs and whether the activated OXY neurons exhibit spatial distribution differences in the PVN.

Methods: 

Wistar male rats received a single injection (i.p.) of haloperidol (1mg/kg), clozapine (30mg/kg), olanzapine (30mg/kg), risperidone (2mg/kg), vehicle (5% chremophor), and saline. Sixty min later, the animals were perfused with fixative. Fos/OXY co-stainings were analyzed by dual immunohistochemistry in 4 PVN subdivisions: anterior (Ant), middle (Mid), dorsal cap (Dc), and periventricular (Pev) ones, using computerized light microscope. Results:

Most apparent activation of OXY cells was induced by clozapine, i.e. 27.4%, 23.9%, 34.7%, and 26.7% of in Ant, Mid, Dc, and Pev, respectively. The second most effective drug was olanzapine indicating for 12.1%, 10.4%, 18.7%, and 25.3% of co-localizations in Ant, Mid, Dc, and Pev, respectively. Around 2% of Fos/OXY cells were stimulated by haloperidol and risperidone treatments. Naive controls and vehicle treated rats did not show Fos/OXY colocalisations.

Conclusion: 

The present data indicate for the existence of substantial differences in the stimulatory effect of the tested antipsychotics on the quantity of PVN oxytocinergic cells with the preferential action of the atypicals clozapine over olanzapine and little effects of haloperidol and risperidone. Spatial distribution distinctions of activated OXY cells in the PVN were less pronounced. Supported by VEGA 2/7003/7.