The CB₁ receptor-mediated endocannabinoid signaling and NGF: the novel targets of curcumin.

Increasing interest has recently been attracted towards the identification of natural compounds including those with antidepressant properties. Curcumin has shown promising antidepressant effect, however, its molecular target(s) have not been well defined. Based on the interaction between the neurotrophins and endocannabinoid system as well as their contribution to the emotional reactivity and antidepressant action, here we show that 4-week treatment with curcumin, similar to the classical antidepressant amitriptyline, results in the sustained elevation of brain nerve growth factor (NGF) and endocannabinoids in dose-dependent and brain region-specific fashion. Pretreatment with cannabinoid CB(1) receptor neutral antagonist AM4113, but not the CB(2) antagonist SR144528, prevents the enhancement of brain NGF contents. AM4113 exerts no effect by itself. Our findings by presenting the CB(1) receptor-mediated endocannabinoid signaling and NGF as novel targets for curcumin, suggest that more attention should be focused on the therapeutic potential of herbal medicines including curcumin.