Figure 8.

Inhibition of GABAergic neurons and excitation of glutamatergic neurons in the vlPAG participate in EA analgesia. (A) Under pain conditions, GABAergic neurons are excited, resulting in glutamatergic, and serotoninergic neuron inhibition. (B) Chemogenetic inhibition of GABAergic neurons results in activation of glutamatergic neurons and serotoninergic neurons, and the descending inhibitory pain pathway would be activated to relieve the pain. (C) EA synchronously inhibits GABAergic neurons and activates glutamatergic neurons, thereby allowing serotoninergic neurons to be excited sufficiently. (D) With chemogenetic inhibition of GABAergic neurons, glutamatergic neurons are still activated by EA, and serotoninergic neurons in the descending inhibitory pain pathway remained partially activated. Chemogenetic activation of GABAergic neurons and inhibition of glutamatergic neurons is sufficient to attenuate the effects of EA.