Thiamine as a peripheral neuro-protective agent in comparison with N-acetyl cysteine in axotomized rats

In this study, the impact of thiamine (Thi), N-acetyl cysteine (NAC), and dexamethasone (DEX) were investigated in axotomized rats, as a model for neural injury.

Sixty-five axotomized rats were divided into two different experimental approaches, the first experiments included five study groups (n=5): intrathecal Thi (Thi.it), intraperitoneal (Thi), NAC, DEX, and control. Cell survival was assessed in L5DRG in the 4^th week by histological assessment. In the second study, 40 animals were engaged to assess Bcl-2, Bax, IL-6, and TNF-α expression in L4-L5DRG in the 1^st and 2^nd weeks after sural nerve axotomy under treatment of these agents (n=10).

Ghost cells were observed in morphological assessment of L5DRG sections, and following stereological analysis, the volume and neuronal cell counts significantly were improved in the NAC and Thi.it groups in the 4^th week (P<0.05). Although Bcl-2 expression did not show significant differences, Bax was reduced in the Thi group (P=0.01); and the Bcl-2/Bax ratio increased in the NAC group (1^st week, P<0.01). Furthermore, the IL-6 and TNF-α expression decreased in the Thi and NAC groups, on the 1^st week of treatment (P≤0.05 and P<0.01). However, in the 2^nd week, the IL-6 expression in both Thi and NAC groups (P<0.01), and the TNF-α expression in the DEX group (P=0.05) were significantly decreased.

The findings may classify Thi in the category of peripheral neuroprotective agents, in combination with routine medications. Furthermore, it had strong cell survival effects as it could interfere with the destructive effects of TNF-α by increasing Bax.