Analgesic and Neuroprotective Effects of Electroacupuncture in a Dental Pulp Injury Model—A Basic Research

Irreversible pulpitis is an extremely painful condition and its consequence in the central nervous system (CNS) remains unclear. A mouse model of dental pulp injury (DPI) resembles the irreversible pulpitis profile in humans. This study sought to determine whether pain induced by DPI activates microglia and astrocytes in the trigeminal subnucleus caudalis (Vc), as well as increases levels of proinflammatory cytokines, and whether electroacupuncture (EA) can be a potential analgesic and neuroprotective therapy following DPI. Pain behavior was measured via head-withdrawal threshold (HWT) and burrowing behavior at days 1, 3, 7, 14 and 21 after DPI. A marked decrease in HWT and burrowing activity was observed from day 1 to 14 after DPI and no changes were seen on day 21. Microglial and astrocytes activation; along with high cytokine (TNFα, IL-1β, and IL-6) levels, were observed in the Vc at 21 days after DPI. These effects were attenuated by verum (local and distal) EA, as well as oral ibuprofen administration. The results suggest that DPI-induced pain and glial activations in the Vc and EA exert analgesic efficacy at both local and distal acupoints. Furthermore, verum (local and distal) EA might be associated with the modulations of microglial and astrocytes activation.