OXIDATIVE STRESS-INDUCED BY ADMINISTRATION OF THE NEUROLEPTIC DRUG HALOPERIDOL IS ATTENUATED BY HIGHER DOSES OF HALOPERIDOL

The effect of haloperidol administration on lipid peroxidation and glutathione/protein thiol homeostasis in the brain was examined 4 h following subcutaneous administration of a single dose of haloperidol; 1.0, 1.5, 2.0 or 2.5 mg/kg b.wt. Glutathione (GSH) levels decreased significantly in cortex, striatum and midbrain after haloperidol administration. Maximal decrease of GSH was observed in the striatum. The depleted GSH was recoverable as protein glutathione mixed disulfide (Pr-SSG) with concomitant loss of protein thiols (Pr-SH) in all the regions of the brain examined. Administration of 1.5 mg/kg b.wt. of haloperidol resulted in significant depletion of GSH in striatum and midbrain as compared to that after administration of the lower dose of 1.0 mg/kg b.wt. of haloperidol. However, administration of higher doses of haloperidol (2.0 and 2.5 mg/kg b.wt.) did not result in greater depletion of GSH; the GSH levels were not significantly different from that observed following the administration of 1.5 mg/kg b.wt. of haloperidol. However, Pr-SSG levels increased dose-dependently following haloperidol administration. The total GSH recovered as sum of GSH and Pr-SSG was significantly higher than controls in striatum and midbrain following administration of higher doses of haloperidol, namely, 2.0 and 2.5 mg/kg b.wt. The depleted GSH was not recoverable as glutathione disulfide (GSSG). GSSG levels were not significantly different from controls 4 h after administration of 1.5 mg/kg b.wt. of haloperidol. The levels of malondialdehyde (indicative of lipid peroxidation) increased significantly as compared to control levels (280-220%) following administration of 1.0 and 1.5 mg/kg b.wt. of haloperidol. Thereafter, the malondialdehyde levels in brain regions decreased and were only (186-150%) of control levels after administration of 2.0 and 2.5 mg/kg b.wt. of haloperidol, respectively. The present study demonstrates that administration of low doses of haloperidol results in depletion of GSH and increased levels of malondialdehyde. However, administration of higher doses of haloperidol results in attenuation of peroxidative damage with concomitant increase in the total GSH recovered as sum of free GSH and GSH bound to protein thiols (Pr-SSG).