Figure 6.

Microglia facilitate the transmission of pain to the brain through an inflammatory-driven mechanism. Mice were provided ad libitum diets of PLX5622 (PLX) or vehicle (Veh) chow for 14 days and then exposed to repeated social defeat (RSD; Stress) or left undisturbed as controls. (A) Mice were tested for mechanical allodynia before exposure to RSD and 12 hours after the first, third, and sixth day of stress. Before stress, each of the four treatment groups had comparable baseline withdrawal thresholds of mechanical stimulation to the hindpaw using the von Frey behavior test. Microglial depletion by PLX5622 prevented RSD-induced allodynia after three and six days of RSD. (B–D) The gene expression of critical inflammatory markers involved in nociceptive signaling were increased in the spinal cord with RSD, and induction of these genes was attenuated by microglial elimination with PLX5622. Modified from Sawicki and others (2019).