Our previous studies have demonstrated that glial activation may contribute to central sensitization induced in Vc nociceptive neurons by application of the inflammatory irritant mustard oil (MO) to the tooth pulp (Chiang et al. SfN Abst 518.10, 2004; Zhang et al. SfN Abst 285.2, 2004). Since numerous noradrenergic terminals contact neurons, glia, and blood vessels in the rat spinal dorsal horn, the aim of the present study was to test for the possible involvement of central adrenergic receptor activation in Vc central sensitization. Extracellular recordings were made from nociceptive-specific (NS) neurons in the deep laminae of Vc in urethane/α-chloralose-anesthetized adult male rats. The mechanoreceptive field (RF), mechanical activation threshold and responses to graded pinch or pressure of each neuron were assessed at baseline. Then 2 assessments were made at 5 and 15 min after superfusion (0.6 ml/h throughout the experiment) onto Vc of guanethidine (sympathetic release blocker; 100 µM) or phentolamine...