Effect of chlorpromazine treatment on nitric oxide and oxyradical production by brain mitochondria

LORES ARNAIZ, SILVIA; D’AMICO, GABRIELA; BUSTAMANTE, JOANITA; CARDILLO, ALEJANDRA BEATRIZ; BOVERIS, ALBERTO

Mar del Plata, Argentina

Congreso; South American Group For Free Radical Reaserch II Congress; 2001

An altered mitochondrial production of NO and oxygen free radicals and dysfunctional mitochondria have been suggested to be involved in chlorpromazine neurotoxicity. In this study, mice were subjected to chlorpromazine acute toxicity (10 mg/Kg, i.p., single dose), and sacrificed one hour after injection. Westernblot analysis of nitric oxide synthases was performed with brain mitochondrial membranes from control and treated animals. Nitric oxide (NO) and superoxide (O2-) production rates were measured in submitochondrial particles (SMP), and oxygen consumption and hydrogen peroxide (H2O2) production rate were determined in isolated brain mitochondria. The in vitro effect of chlorpromazine on NO production by mtNOS was also analyzed. Westernblot analysis showed that the NOS present in mouse brain mitochondrial membranes (mtNOS) reacts mainly with the n-NOS antibody. Chlorpromazine treatment produced a marked inhibition of mitochondrial NO production of 48% (control value 0.48 ± 0.05 nmol/min.mg protein). Direct supplementation of brain mitochondria (SMP) with 1-4 µM chlorpromazine inhibited NO production by 72% in a concentration-dependent manner (IC50= 0.4 µM). Chlorpromazine treatment produced an increase of 30-40% in malate-glutamate and in succinate-dependent oxygen uptake, both in states 4 and state 3. O2- production rate was significantly decreased in brain SMP after chlorpromazine treatment, in the presence of succinate and succinate-antimycin (control values: 0.9 ± 0.1 and 1.3 ± 0.1 nmol/min.mg protein respectively. Mitochondrial H2O2 production rate was increased by 49% in the presence of succinate-antimycin, after chlorpromazine treatment (control value: 0.45 ± 0.07 nmol/min.mg protein). Our results indicate that chlorpromazine acute toxicity leads to a state of brain mitochondrial dysfunction with decreased NO and O2- production and with an increase in oxygen uptake and in H2O2 production.