Nicotine aggravates many chronic inflammatory disorders in females under the protein-malnourished conditions because women are more susceptible to nicotine-induced diseases due to their low innate immunity. Although curcumin have been found to obliterate the nicotine-induced disorders through its anti-nicotinic activity under the protein-malnourished condition, the exact mechanism of protective action of curcumin is still unclear. Female Wister rats maintained under the normal and protein-restricted diets in two separate groups were injected with the effective dose of nicotine-tartrate (2.5 mg/kg body weight/day, subcutaneously) and supplemented with the effective dose of curcumin (80 mg/kg body weight/day, orally) for 21 days. The morphology of red blood cells (RBCs), molecular docking, lipid profile and activities of antioxidant enzymes in tissues, cytokines profiling (T helper cell type 1; and T helper cell type 2), mRNA and protein expression of cytokines, transcription factors (activator protein 1), regulatory molecule (P(53)), growth factors (Granulocyte-macrophage colony-stimulating factor; Transforming growth factor beta) were determined to establish the mechanism of actions of curcumin against the nicotine-mediated stress in the protein-malnourished rats. This study revealed that curcumin bound to the Histidine 87 residues of haemoglobin with a greater binding affinity and significantly protected the RBCs against nicotine-induced damage. Furthermore, the nicotine-mediated disruption of Th1/Th2 balance through upregulation and downregulation of different factors was effectively restored by curcumin under the protein-malnourished conditions. The study demonstrated that curcumin was a potent protective compound against the nicotine-induced stress and offered a probable biochemical and immunomodulatory mechanism of protective action of curcumin.
Keywords: Curcumin; Cytokines; Nicotine; Protein-malnourished; Th1/Th2 balance.