“…Furthermore, endocannabinoids act as downstream effectors of D 2 R signaling in the inhibition of striatal synaptic transmission (Yin and Lovinger, 2006) and in the generation of corticostriatal long-term depression (Gerdeman et al, 2002(Gerdeman et al, , 2003. With respect to the interaction between DA and BDNF, it has been reported that acute administration of levodopa (Okazawa et al, 1992), dopamine, or direct D 1 R agonists (Kü ppers and Beyer, 2001;Williams and Undieh, 2009) upregulates BDNF signaling in the striatum. In contrast, other studies reported that both activation and inhibition of the DA system with, respectively, chronic cocaine (Fumagalli et al, 2007) and 6-OHDA treatment (Zhang et al, 2006) failed to affect striatal levels of BDNF.…”