Effects of discontinuous drug administration on the development of dopamine receptor supersensitivity during chronic trifluoperazine or cis-flupenthixol administration to rats.

Rats received continuous or discontinuous administration of trifluoperazine or cis-flupenthixol in drinking water for up to 12 months. Continuous and discontinuous trifluoperazine administration had no consistent effect on apomorphine-induced stereotyped behaviour and there was no difference between drug treatments. Continuous and discontinuous cis-flupenthixol administration enhanced apomorphine-induced stereotypy, but there was no difference in the effect of the two drug treatments. Both continuous and discontinuous administration of trifluoperazine increased the number of specific striatal 3H-spiperone binding sites (Bmax). Over the period of treatment there was no difference in the effects of the different treatments. Continuous or discontinuous cis-flupenthixol intake did not increase Bmax after 6 or 12 months intake. Continuous or discontinuous neuroleptic treatment produced no difference in functional striatal dopamine receptor activity as judged by apomorphine-induced stereotyped behaviour. Ligand binding studies also suggest that the overall change in striatal receptor function is not affected by the use of a discontinuous drug regime.