Free and nanoencapsulated curcumin prevents cigarette smoke-induced cognitive impairment and redox imbalance

Cigarette smoke-exposure promotes neurobiological changes associated with neurocognitive abnormalities. Curcumin, a natural polyphenol, have shown to be able to prevent cigarette smoke-induced cognitive impairment. Here, we investigated possible mechanisms involved in curcumin protection against cigarette smoke-induced cognitive impairment and, due to its poor bioavailability, we investigated the potential of using curcumin-loaded lipid-core nanocapsules (C-LNC) suspension. Rats were treated with curcumin and cigarette smoke, once a day, 5 days each week, for 30 days. Animals were divided into ten groups: I, control (vehicle/corn oil); II, curcumin 12.5 mg/kg; III, curcumin 25 mg/kg; IV, curcumin 50 mg/ kg; V, C-LNC 4 mg/kg; VI, tobacco exposed; VII, curcumin 12.5 mg/kg along with tobacco exposure; VIII, curcumin 25 mg/kg along with tobacco exposure; IX, curcumin 50 mg/kg along with tobacco exposure; X, C-LNC 4 mg/kg along with tobacco exposure. Cigarette smoke-exposure impaired object recognition memory (P < 0.001), indicated by the low recognition index, increased biomarkers of oxidative/nitrosative stress such as TBARS (P < 0.05) and NOx (P < 0.01), decreased antioxidant defenses such as NPSH content (P<0.01) and SOD activity (P<0.01) and inhibited the activities of enzymes involved in ion homeostasis such as Na+,K+-ATPase and Ca2+-ATPase. Both curcumin formulations (free and nanoencapsulated) prevented the memory impairment, the redox imbalance and the alterations observed in the ATPases activities. Maintenance of ion homeostasis and redox balance is involved in the protective mechanism of curcumin against tobacco-induced cognitive impairment. Our results suggest that curcumin is a potential therapeutic agent for neurocognition and that C-LNC may be an alternative to its poor bioavailability.