Figure 7.
Cannabinoid inhibition of extrinsic GABAergic inputs onto PAG output neurons is presynaptic. Effect of WIN55212-2 (WIN) and AM251 on optically and electrically evoked IPSCs (oIPSCs, eIPSCs) in (A, C) RVM-retrolabeled and (B, D) unlabeled PAG neurons from (A, B) intra-CeA and (C, D) intra-PAG AAV-ChR2-injected animals. In panels A–D, (i) experiment configuration in animals with an intra-RVM retrograde tracer injection plus and intra-CeA, or PAG AAV-ChR2 injection, (ii) averaged traces of paired optically evoked IPSCs (blue arrows) normalized to the first IPSC, (iii) and electrically (black arrows) evoked IPSCs (from the corresponding neurons in Fig. 6A–D). Scatter plots of the effect of WIN55212-2 on (E) the paired-pulse ratio of oIPSCs and (F) the amplitude of eIPSCs in RVM-retrolabeled and unlabeled PAG neurons from intra-CeA and intra-PAG AAV-ChR2-injected animals. In E, F, **p < 0.01, ****p < 0.001 (pre vs WIN55212-2, paired t tests).