Figure 2.

eCB and mGluR5 involvement in VTA GABA cell plasticity. The eCBs are signaling molecules often involved in presynaptic plasticity mechanisms. A, A nonhydrolysable form of an eCB, R(+)methanandamide, induces depression of glutamatergic neurotransmission (n = 6, p ≪ 0.05). B, The Type 1 mGluR agonist DHPG also induced depression, similar to HFS-LTD (n = 7, p ≪ 0.05). C, The specific mGluR5 antagonist MPEP blocked HFS-LTD (n = 6; p < 0.05; compared to control LTD). D, To further test for the necessity of a postsynaptic GPCR (such as an mGluR) involvement in LTD, the GDP analog GDPβS, which inhibits G-proteins, was added to the internal solution and resulted in blocked HFS-LTD (n = 7; p > 0.05; compared to its baseline).