The effects of dexmedetomidine and halothane on Fos expression in the spinal dorsal horn using a rat postoperative pain model

Abstract

We investigated the effect of an intrathecal injection of a selective α2 adrenergic receptor agonist, dexmedetomidine (Dex), and halothane anesthesia on Fos expression in the lumbar spinal dorsal horn after skin incision of the planter surface of the hind paw, a postoperative pain model using rats. Fos immunoreactivity was induced particularly in the superficial layers of the spinal cord 2 h after surgery. Halothane anesthesia (0.5–1.5%) partially reversed Fos induction, but not in a dose-dependent manner. Preoperative spinal Dex (0.1–10 μg) dose-dependently reduced Fos immunoreactivity, while a relatively high dose of Dex (10 μg) was necessary to produce a profound effect. When used with halothane anesthesia, relatively low doses of Dex (1–3 μg) completely suppressed Fos induction in the superficial spinal layers. These findings indicate that preoperative Dex treatment may provide anesthesia that does not induce stress on spinal neurons.