Biochemical evidence on positive effects of rolipram a phosphodiesterase-4 inhibitor in malathion-induced toxic stress in rat blood and brain mitochondria

Malathion is an organophosphate (OP) pesticide that has been shown to induce oxidative stress in brain through the generation of free radicals and alteration of the cellular antioxidant defense system independent of its anticholinesterase effects. The aim of this study was to investigate the possible protective role of rolipram as a selective phosphodiesterase (PDE) type 4 inhibitor, on toxicity of malathion, by measuring the activities of brain mitochondrial and plasma peroxynitrite (ONOO⁻), glutathione peroxidase (GPx), superoxide dismutase (SOD), Mn-SOD, catalase (CAT), and lipid peroxidation (LPO) in rats. Effective doses of malathion (200 mg/kg/day) and rolipram (200 μg/kg/day) were administered alone or in combination for 7 days by intraperitoneal injection. At the end of the experiment, the brain mitochondria and plasma of the animals were separated. In the brain cells mitochondria and blood plasma, the LPO, ONOO⁻, and GPx were higher in the malathion group as compared with controls. Rolipram ameliorated all of malathion-induced changes. Plasma CAT decreased in malathion-treated animals while it increased in brain mitochondria comparing with controls. Co-administration of rolipram with malathion improved CAT in both brain mitochondria and plasma. Malathion and rolipram did not alter total SOD or Mn-SOD in the plasma while both caused a significant elevation in brain mitochondria. In conclusion, this model of study that we employed, in a large extent, characterized the relationships among malathion-induced neurotoxicity, mitochondrial dysfunction, and significant increase in systemic and local oxidative/nitrosative stress in plasma and brain, respectively. Intracellular cAMP-elevating agents like rolipram, may be considered beneficial for the protection or recovery of malathion-induced toxic damage in brain mitochondria and blood.