Subchronic treatment of rats with remoxipride fails to modify sigma binding sites in the brain.

The effects of 14 days' treatment of rats with haloperidol, remoxipride or both combined on the sigma binding sites in whole brain and liver were determined. The compounds were given subcutaneously via osmotic minipumps at a dose of 0.25 mg/rat/day (corresponding to about 1 mg/kg body weight/day at start) for haloperidol and 2.5 mg/rat/day (10 mg/kg/day) for remoxipride hydrochloride. The sigma recognition sites were determined after a washout period of 2 days with the radioligand 3H-N-propyl-3-(3-hydroxyphenyl)piperidine (3H-3-PPP). It was found that the haloperidol treatment but not the remoxipride treatment decreased the density of the sigma sites in the brain, without any effect on the affinities of the ligands. Haloperidol had no effect on the binding of 3H-3-PPP to the sigma recognition sites in the liver.