Effect of Cichorium intybus L. on the expression of hepatic NF-κB and IKKβ and serum TNF-α in STZ− and STZ+ niacinamide-induced diabetes in rats

BACKGROUND: Inflammation is an early event in the development of diabetes type 2 (T2D). Cichorium intybus L. (chicory) possesses anti-inflammatory action. We compared the anti-inflammatory aspect of aqueous chicory seed extract (CSE) in early and late stage T2D in rats. METHODS: Wistar albino rats were divided into nine final groups (n = 6). Three main groups consisted of non-diabetic (Control), early stage diabetes (ET2D; niacinamide/streptozotocin, i.e., NIA/STZ), and late stage diabetes (LT2D; STZ). Within each main group, a subgroup was treated with CSE (125 mg/kg; i.p.); within each diabetic group (STZ and NIA/STZ) a subgroup received metformin (100 mg/kg; i.p.); another subgroup in STZ group received aspirin (120 mg/kg; oral). After 21 days, fasting blood glucose (FBS), insulin, and TNF-α level were measured in serum; IKKβ and NF-κB (p65) mRNA and protein expression were evaluated by real time PCR and Western blotting; p65 DNA binding activity was determined by ELISA, in liver tissue. RESULTS: The mRNA and protein expression levels of IKKβ, and P65 genes increased in both stages of T2D (p < 0.01); CSE decreased their expression (p < 0.001, mRNAs; p < 0.05, proteins). The increased DNA-binding capacity of NF-κB (p < 0.0001) in diabetes was lowered by CSE (p < 0.001). The effect of CSE was limited to ET2D requiring insulin. CONCLUSIONS: The anti-inflammatory action of CSE is due to a direct modulation of cytokine expression. The dependency of chicory action on the presence of insulin indicates its usefulness in the early stages of diabetes and for the purpose of preventing and delaying diabetes onset. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13098-016-0128-6) contains supplementary material, which is available to authorized users.