The anti-apoptotic, antioxidant and anti-inflammatory effects of curcumin on acrylamide-induced neurotoxicity in rats
Abstract Background: As a chemical extensively used in industrial areas as well as formed during heating of carbohydrate-rich food and tobacco, acrylamide (ACR) has been known as well-established neurotoxic pollutant. Although the precise mechanism is unclear, enhanced apoptosis, oxidative stress and inflammation have been demonstrated to contribute to the ACR-induced neurotoxicity. In this study, we assessed the possible anti-apoptotic, antioxidant and anti-inflammatory effects of curcumin, the most active component in a popular spice known as turmeric, on the neurotoxicity caused by ACR in rats. Methods: Curcumin at the dose of 50 and 100 mg/kg was orally given to ACR- intoxicated Sprague-Dawley rats exposed by ACR at 40mg/kg for 4 weeks. All rats were subjected to behavioral analysis. The HE staining and terminal deoxynucleotidyl transferase mediated dUTP nick end labelling (TUNEL) staining were used to detect histopathological changes and apoptotic cells, respectively. The mRNA and protein expressions of apoptosis-related molecule telomerase reverse transcriptase (TERT) were detected using real-time PCR and immunohistochemistry, respectively. The contents of malondialdehyde (MDA) and glutathione (GSH) as well as the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were measured as the indicators for evaluating the level of oxidative stress in brain. The levels of pro-inflammatory cytokinestumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in cerebral homogenates were detected using ELISA assay. Results: Concurrent administration of curcumin at the oral doses of 50 and 100 mg/kg with ACR significantly protected the rats from ACR-induced weigh loss and motor function deficits, and improved the pathological alterations in the ACR-intoxicated brains. Curcumin treatment especially at a high dose enhanced the TERT mRNA expression level and increased the number of TERT-positive nerve cells in cortex tissues of ACR intoxicated rats. The levels of MDA, TNF-α and IL-1β in the cerebral homogenates were reduced, the contents of GSH as well as the activities of SOD and GSH-Px were increased by curcumin treatment, compared to ACR control group. Conclusions: These data suggested the anti-apoptotic, antioxidant and anti-inflammatory effects of curcumin on ACR-induced neurotoxicity in rats. And maintaining TERT-related anti-apoptotic function might be one mechanism underlying the protective effect of curcumin on ACR-intoxicated brains.