Possible involvement of iNOS and TNF-α in nutritional intervention against nicotine-induced pancreatic islet cell damage

Abstract

Nicotine is the more abundant and most significant components of cigarette smoke. Epidemiological evidence strongly suggests an association between cigarette smoking and pancreatic injury. Although effects of smoking on endocrine pancreas are still controversial Here, we examined the impact and underlying mechanisms of action of folic acid and vitamin B12 on nicotine induced damage in pancreatic islets of rats. Male Wistar rats were treated with nicotine (3mg/kg body weight/day, intraperitonealy) with or without folic acid (36μg/kg body weight/day, orally) and vitamin B₁₂ (0.63μg/kg body weight/day, orally) for 21days. Supplementation with folic acid and vitamin B₁₂ suppressed the nicotine induced changes in HbA1c, insulin, TNF-α, IL-6, generation of reactive oxygen species, and attenuated the changes in markers of oxidative stress. Moreover, folic acid and vitamin B₁₂ also counteracted the increased expression of protein and mRNA contents of TNF-α and iNOS produced by nicotine. Further, folic acid and vitamin B₁₂ in combination limits the nicotine induced changes in cell cycle and excessive apoptosis of the pancreatic β-cells and also successfully blunted the nicotine induced alteration in loss of mitochondrial membrane potential. In conclusion, data demonstrate that folic acid and vitamin B₁₂ may be possible nutritional intervention against cellular oxidative stress, which is a critical step in nicotine-mediated islet injury, and improves islet cell functional status by scavenging free radicals and by inhibiting the generation of pro-inflammatory mediators.

Keywords: Apoptosis; Islet cells; Oxidative stress; Pro-inflammatory mediators.