Carbon nanotube-anandamide complex exhibits sustained protective effects in an in vitro model of stroke

Introduction: The therapeutic potential of anandamide (AEA) for the neurological disorders may be negatively affected by its short half-life or poor solubility. The superior properties of carbon nanotubes (CNTs) for controlled drug delivery, prompted us to design AEA-CNTs complex and assess its effect in in vitro model of ischemic stroke. Methods: In this experimental study, a multi-walled CNTs (MWCNTs)-AEA complex was prepared using amino-functionalized COOH-MWCNTs and characterized by Fourier transform infrared spectroscopy and transmission electron microscopy. PC12 cells in the presence of AEA (0.5, 1, 2 &mu;g/ml), acid- or amine-modified MWCNTs, or MWCNTs-AEA complex (2, 5, 8 &mu;g/ml) were exposed to 1 and 3 h oxygen-glucose deprivation (OGD) followed by 24 h re-oxygenation. In vitro cytotoxicity and oxidative stress were evaluated using three-way ANOVA. Results: AEA immobilization on the aminated MWCNTs was confirmed. OGD significantly reduced cell viability (P<0.001). After 3 h of OGD induction, COOH-MWCNTs showed higher cytotoxicity than other MWCNTs (P<0.05, P<0.01, P<0.001) and MWCNTs-AEA was more protective than AEA alone (P<0.05, P<0.01). OGD increased malondialdehyde (MDA) and decreased glutathione (GSH) and superoxide dismutase (SOD) (P<0.001). Following 1-h OGD, AEA dose-dependently reduced MDA (P<0.001), and elevated GSH (P<0.05, P<0.01) and SOD (P<0.05, P<0.01), but AEA was ineffective following 3-h OGD (P>0.05). MWCNTs-AEA complex was effective at both time points (MDA and GSH: P<0.01, P<0.001, SOD: P<0.05, P<0.01, P<0.001). This nanostructure was more effective than AEA following longer exposure periods to OGD insult (P<0.05, P<0.01, P<0.001). Conclusion: Aminated MWCNTs are suitable carriers for AEA and provide longer- lasting effects against OGD insult.