Fig. 2. Effects of intrathecal idazoxan on oral and intracerebroventricular gabapentin analgesia. The mechanical withdrawal threshold is presented over time. (  A )  Arrows indicate oral gabapentin (100 mg/kg) or vehicle, and intrathecal idazoxan (30 μg/rat, 1.5 h after gabapentin administration) or saline. (  B ) The  arrow indicates coadministration of intrathecal idazoxan (3–30 μg/rat) or saline with intracerebroventricular gabapentin (100 μg/rat). *  P < 0.05  versus time 0 by one-way analysis of variance. Groups differ by two-way analysis of variance with gabapentin + saline > gabapentin + idazoxan > vehicle + idazoxan in  A and with gabapentin + saline > gabapentin + idazoxan 30 μg = gabapentin + idazoxan 3 μg in  B .