The neuroprotective effect of lithium in cannabinoid dependence is mediated through modulation of cyclic AMP,ERK1/2 and GSK-3β phosphorylation in cerebellar granular neurons of rat

Lithium (li),a glycogen synthase kinase-3β (gsk-3β) inhibitor,has used to attenuate the cannabinoid-induced dependence/withdrawal signs,but molecular mechanisms related to this are unclear. recent studies indicate the involvement of upstream extracellular signal kinase1/2 (erk1/2) and downstream gsk-3β pathways in the development of cannabinoid-induced dependence. this is mediated through cannabinoid receptor 1 (cb1) enriched in cerebellar granular neurons (cgns). accordingly,the present study aimed to investigate the mechanism of modulatory/neuroprotective effects of li on a cannabinoid agonist (win 55,212-2 (win))-induced dependence,through quantitative analysis of some involved proteins such as erk1/2,gsk-3β and related signaling pathways including their phosphorylated forms; and camp level as the other molecular mechanisms leading to dependence,in cgns model. the cgns were prepared from 7-day-old wistar rat pup in a 12-well plate,pretreated with li (1mm) and an erk1/2 inhibitor sl327 (sl,10 μm). the win (1 μm) was added 30 minutes prior to treatment and am251 (am,1 μm),as a cannabinoid antagonist was co-treated with win. the camp level,as an indicator of cannabinoid-induced dependence,was measured by elisa following forskolin (fsk) stimulation. western blot analyses determined the phosphorylated forms of erk1/2 (p-erk1/2),gsk-3β (p-gsk-3β) as well as their total expressions in various treatment times and doses in cgns. win alone could down regulate the camp/p-erk1/2 cascade compared to am treatment. however,p-gsk-3β was up-regulated with li and win or with sl and li pretreatment to am-induced cellular response,which was the highest 60 minutes after cgns exposure. results further suggested the potential role of li pretreatment to diminish the development of cannabinoid-induced dependence/neuronal injury through possible mechanisms of modulating the camp/p-erk1/2 cascade independent of p-gsk-3β signaling pathway in-vitro. © 2015 by school of pharmacy shaheed beheshti university of medical sciences and health services.