Cannabidiol inhibits inducible nitric oxide synthase protein expression and nitric oxide production in β-amyloid stimulated PC12 neurons through p38 MAP kinase and NF-κB involvement

In view of the pro-inflammatory scenario observed in Alzheimer's disease, in the recent years anti-inflammatory drugs have been proposed as potential therapeutic agents. We have previously shown that cannabidiol, the main non-psychotropic component from Cannabis sativa, possess a variegate combination of anti-oxidant and anti-apoptotic effects that protect PC12 cells from Aβ toxicity. In parallel, cannabidiol has been described to have anti-inflammatory properties in acute models of inflammation but the possible inhibitory effect of cannabidiol on iNOS protein expression and nitrite production in the nitrosative stress induced by Aβ in neuronal cell-line is un-investigated. Stimulation of differentiated PC12 cells with Aβ (1–42) (1 μg/mL) for 36 h caused a significant increase of nitrite production, compared to un-stimulated cells, that was inhibited in a concentration-dependent manner by both the non-selective iNOS inhibitor, l-NAME (0.3–30 μM), and, at higher extent, by the selective iNOS inhibitor SMT (0.3–30 μM). CBD (10−6 to 10−4 M) inhibited both nitrite production and iNOS protein expression induced by Aβ (1–42). Cannabidiol effect was mediated through the inhibition of phosphorylated form of p38 MAP kinase and transcription factor nuclear factor-κB activation in a concentration-dependent manner. The here reported data increases our knowledge about the possible neuroprotective mechanism of cannabidiol, highlighting the importance of this compound to inhibit β-amyloid induced neurodegeneration, in view of its low toxicity in humans.