Sensory satellite glial Gq-GPCR activation alleviates inflammatory pain via peripheral adenosine 1 receptor activation

Abstract

Glial fibrillary acidic protein expressing (GFAP ⁺) glia modulate nociceptive neuronal activity in both the peripheral nervous system (PNS) and the central nervous system (CNS). Resident GFAP ⁺ glia in dorsal root ganglia (DRG) known as satellite glial cells (SGCs) potentiate neuronal activity by releasing pro-inflammatory cytokines and neuroactive compounds. In this study, we tested the hypothesis that SGC Gq-coupled receptor (Gq-GPCR) signaling modulates pain sensitivity in vivo using Gfap-hM3Dq mice. Complete Freund’s adjuvant (CFA) was used to induce inflammatory pain, and mechanical sensitivity and thermal sensitivity were used to assess the neuromodulatory effect of glial Gq-GPCR activation in awake mice. Pharmacogenetic activation of Gq-GPCR signaling in sensory SGCs decreased heat-induced nociceptive responses and reversed inflammation-induced mechanical allodynia via peripheral adenosine A1 receptor activation. These data reveal a previously unexplored role of sensory SGCs in decreasing afferent excitability. The identified molecular mechanism underlying the analgesic role of SGCs offers new approaches for reversing peripheral nociceptive sensitization.