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 .