Comparison of intraperitoneal and local thiamine administration on the neuronal death of dorsal root ganglion after sciatic nerve transection in rat

The retrograde neuronal death in the dorsal root ganglia (DRG) can be the main factor in poor regeneration of injured peripheral nerves occurring by increased activity of oxidant agents. The present study investigated the effect of thiamine treatment, as an antioxidant, on neuronal death after sciatic nerve transection.

Twenty-five male Wistar rats were allocated in 5 experimental groups (n = 5). Group 1 was considered as intact. The sciatic nerve was transected in groups 2 to 5. Then rats were treated daily with physiological saline (control group), thiamine (50 and 100 mg/kg; i.p.) and thiamine (1.7 mg/kg locally). After four weeks, animals were sacrificed and L5DRG was removed for histological assessment.

Morphological analysis showed some no cell areas in L5DRG sections, which may be related to apoptotic cells in axotomized animals. L5DRG volume measurement showed no significant difference between intact and local thiamine treated group, while its volume was significantly reduced in other experimental groups (p < 0.001). This parameter was also significantly reduced in control group compared with local thiamine treated group (p < 0.001). Although the difference of L5DRG cell number in local thiamine treated group was not significant, its reduction was significant in control and intraperitoneal groups compared with intact group (p < 0.01). The L5DRG cell count in local thiamine treated group was significantly higher than that in control group (p < 0.01).

These findings may indicate that thiamine if is administered in sufficient doses can be classified as neuroprotective agent.