Investigação do efeito neuroprotetor da toxina tx3-4 da aranha phoneutria nigriventer na isquemia cerebral em ratos

Abstract

Stroke is the leading cause of death and disability in adults in South America and Brazil. Lots of research groups in the world try to find a neuroprotective drug that avoid neuronal death and consequent functional incapacity after stroke. The main objective of this study was investigating the neuroprotective effect of the toxin Tx3-4, antagonist of calcium channel voltage dependent, after cerebral ischemia in rats. The effect of central injection of toxin was studied using electroencephalographic, electrocardiographic and arterial pressure records to the doses 0.16g; 0.32g; 0.75g e 1.5g per animal. The focal and transient experimental ischemic model used was the middle cerebral artery occlusion (MCAo). Doses 0.16g; 0.32g; 0.75g were used to investigate the neuroprotective effect of the toxin Tx3-4 after cerebral ischemia in rats. Electroencephalographic records showed the interruption of blood to the left hemisphere after MCA left occlusion. Sensorial and motor tests were done to evaluating functional status of the animals after lesion. Magnetic resonance images were used to assessing infarct volume and functional status for 5 weeks. Different doses and time treatment were evaluated. Central injection of toxin did not change the heart rate of the animals. However, all studied doses changed mean arterial pressure and total energy of EEG, though these changes have not leaded the rats to death. All tested doses could protect cerebral tissue of death. Functional and structural protections were seen in all doses. Magnetic resonance images showed strutuctural protection by Tx3-4 injected 30 minutes e 2 hours after the beginning of xiv ischemia. Tx3-4 toxin showed low toxicity, functional and structural neuroprotective effect injected 30 minutes or 2 hours after beginning of cerebral ischemia.