Subfração PnTx 3-6 do veneno da aranha armadeira (Phoneutria nigriventer) no tratamento de ratos wistar (Rattus novergicus) submetidos ao trauma compressivo agudo à medula espinhal

Abstract

The aim of this study was to evaluate the effect of the PnTx3-6 sub fraction, derived from Phoneutria nigriventer toxin, on acute spinal trauma in Wistar rats. Eighteen male animals, approximately three months old, weighting an average of 350g were used. All animals underwent laminectomy (Group G1 negative control) on 12th thoracic vertebrae, and 12 of them (Groups G2 and G3) were also submitted to compressive spinal injury by a weight drop model (70g for five minutes) applying pressure directly over the duramater. After 30 minutes, treatment was administered to the traumatized animals by intra medullar injection at the lesion site. Animals from group G2 (positive control) received 2l of PBS, while animals from group G3 received 200pMol of PnTx3-6 diluted in 2 l of PBS. Neurological function evaluations were performed 24 hours after trauma and daily for eight days in order to analyze and graduate motor and sensitive functions over post surgical period, as well as recovery when applicable. On the eighth day post surgery, animals were euthanized and had their spinal tissue collected for microscopic morphological and neuronal integrity evaluation by immunohistochemistry with anti-NeuN monoclonal antibody. No significant statistical differences were found between groups G2 and G3 in all behavioral tests. Descriptive evaluations of the spinal segments analyzed outpointed to milder lesions in animals treated with PnTx3-6, when compared to animals treated only with PBS, where larger areas of degeneration were observed. Nevertheless, this observation was not seen on immunohistochemistry labeled slides, where no relevant statistical difference between treatments was observed. We suggest, this way, that the PnTx3-6 sub fraction, on the dose of 200pMol, administered by intralesional injection 30 minutes after trauma, was not able to promote neuroprotection, not reducing the gravity of secondary lesions due to spinal injury primary lesions. Still, further studies using different doses, periods of treatment, observation and trauma intensity should be carried out to elucidate the real efficacy or inefficacy of this toxin.