Neuroprotective effect of peroxynitrite decomposition catalyst and poly(adenosine diphosphate-ribose) polymerase inhibitor alone and in combination in rats with focal cerebral ischemia

Abstract

Object: The authors evaluated the neuroprotective effect of 5,10,15,20-tetrakis(N-methyl-4'-pyridyl)porphyrinato-iron(III) (FeTMPyP), a peroxynitrite decomposition catalyst, and 1,5-isoquinolinediol (ISO), a poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitor, alone and in combination in rats with focal cerebral ischemia induced by middle cerebral artery occlusion (MCAO).

Methods: Male Sprague-Dawley rats were subjected to 2 hours of MCAO followed by 22 hours of reperfusion. Cerebral infarction and neurological deficits were estimated after ischemia. Intraperitoneal injections of FeTMPyP (1 and 2 mg/kg) and ISO (0.05 and 0.1 mg/kg) were administered alone or in combination in ischemic animals. The PARP activity in vehicle- and drug-treated groups was estimated using anti-poly(ADP-ribose) antibody in immunofluorescence and immunoblotting studies. Two hours of MCAO and 22 hours of reperfusion produced significant cerebral infarction and neurological deficits. Treatment with FeTMPyP (1 and 2 mg/kg) and ISO (0.05 and 0.1 mg/kg) produced a significant reduction in cerebral infarction and neurological deficits. Combination therapy (2 mg/kg FeTMPyP and 0.1 mg/kg ISO) enhanced the inhibition of ischemic volume (77.81+/-0.86%) compared with monotherapies (FeTMPyP 54.07+/-5.6% and ISO 53.06+/-3.88%). Immunoblotting and immunofluorescence studies showed PARP activation after ischemia, which was reduced by drug treatment.

Conclusions: Neuroprotection observed with FeTMPyP and ISO alone and in combination may be attributed to inhibition of the peroxynitrite-PARP cascade of cerebral ischemia/reperfusion injury.