Neuroprotective effects of Tempol (4-hidroxi tempo) after sciatic nerve transection in neonatal rats

Author(s)

Gabriela Bortolança Chiarotto

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2013-08-14

Examining board members

Alexandre Leite Rodrigues de Oliveira; Valéria Paula Sassoli Fazan; Fábio Rogério

• Advisor: Alexandre Leite Rodrigues de Oliveira

Abstract

The peripheral nerve injury in newborn animals results in extensive neuronal death in the spinal cord and dorsal root ganglia. Since most neuronal loss is due to oxidative stress and apoptotic mechanisms, several studies have been conducted to investigate the effect of neuroprotective substances. Among these drugs, the antioxidant Tempol has shown promising results as it is capable of chelating reactive oxygen species (ROS) and to minimize or even prevent, tissue damage. In this sense, the present study aimed to evaluate the neuroprotective effects of Tempol on neuronal death induced by sciatic nerve section in newborn rats. For this purpose, two days old (P2) Wistar rats underwent left sciatic nerve section and were divided into two groups: (1) Tempol-treated group (24mg/kg) - 10 minutes and 6 hours, and every 24 hours after injury for up to 1 week; (2) Group Vehicle - Vehicle treated with the same dilution of Tempol. The animals of both groups were sacrificed at survival times of 8, 12, 24, 72 hours and one week after the lesion. The contralateral side of the spinal cord was used as internal control. After the respective days of survival, the animals were anesthetized and underwent thoracotomy for transcardial perfusion with saline and fixative. The assembly containing the lumbar intumescence and nerve roots were processed for subsequent preparation of histological sections. Cross sections of 12 ?m were used for evaluation of neuronal survival and TUNEL for the detection and quantification of apoptotic cells. The results showed that Tempol treatment increased the survival of motoneurons in the spinal cord 15% after 8 hours, 19% after 12 hours, 13% after 24 hours, 15% after 72 hours and 21% after one week post-lesion ( p <0.0001). Likewise, Tempol treated animals showed a decrease in the number of TUNEL positive cells, indicating reduction in apoptotic events. To further investigate the apoptotic events observed herein, we have performed qRT-PCR evaluation of bax, caspase3 and bcl2 transcript levels, 12 and 24 after injury. The results showed an increase in gene expression of 13, 3 and 28 times for bax, caspase 3 and bcl2, respectively, after 12 hours of axotomy and treatment with Tempol. After 24 hours no differences were observed relative to the control. As a whole, these results showed that Tempol is neuroprotective, leading to improved survival of motor neurons after peripheral nerve injury, minimizing the occurrence of apoptotic events (AU)

• FAPESP's process: 11/12857-8 - Neuroprotective effects of tempol (4 - hydroxy - Tempo) after sciatic nerve transection in neonatal rats
• Grantee: Gabriela Bortolança Chiarotto
• Support Opportunities: Scholarships in Brazil - Master