The antidepressant action of cannabis as well as the interaction between antidepressants and the endocannabinoid system has been reported. This study was conducted to assess the antidepressantlike activity of Δ 9 -THC and other cannabinoids. Cannabinoids were initially evaluated in the mouse tetrad assay to determine doses that do not induce hypothermia or catalepsy. The automated mouse forced swim (FST) and tail suspension (TST) tests were used to determine antidepressant action. At doses lacking hypothermic and cataleptic effects (1.25, 2.5, and 5 mg/kg, i.p.), both Δ 9 -THC and Δ 8 -THC showed a U-shaped dose response with only Δ 9 -THC showing significant...

The hippocampal dentate gyrus in the adult mammalian brain contains neural stem/progenitor cells (NS/PCs) capable of generating new neurons, i.e., neurogenesis. Most drugs of abuse examined to date decrease adult hippocampal neurogenesis, but the effects of cannabis (marijuana or cannabinoids) on hippocampal neurogenesis remain unknown. This study aimed atinvestigating the potential regulatory capacity ofthe potent synthetic cannabinoid HU210 on hippocampal neurogenesis and its possible correlation with behavioral change. We show that both embryonic and adult rat hippocampal NS/PCs are immunoreactive for CB1 cannabinoid receptors, indicating that cannabinoids could act onCB1 receptors to regulate neurogenesis.This hypothesis is supported by further findings that HU210 promotes proliferation,...