Involvement of astroglial activation in trigeminal neuropathic pain

摘要

A significant increase occurred in GFAP-positive cells in ipsilateral Vc at postoperative day 7 in inferior alveolar nerve-transected (IANX) rats compared to sham-control rats, which was reversed following the astroglial inhibitor fluoroacetate (FA) administration. FA significantly increased the reduced head withdrawal latency to high-intensity heat stimulation of the maxillary whisker pad skin in IANX rats. FA also significantly reduced the increased number of phosphorylated extracellular signal-regulated kinase (pERK)-like immunoreactive cells in Vc and the enhanced Vc nociceptive neuronal responses following high-intensity skin stimulation that were documented in IANX rats, and glutamine administration restored the enhanced responses. Our results suggest that glutamine released from activated astroglia in Vc following trigeminal nerve injury is involved in the sensitization of nociceptive responses in Vc neurons and the enhanced nocifensive behavior induced by noxious stimulation.