Fig. 2. Effects of intrathecal idazoxan on oral, intrathecal, and intracerebroventricular gabapentin analgesia after spinal nerve ligation (SNL) in rats. The mechanical withdrawal threshold is presented over time. ( A ) Intrathecal idazoxan or saline was injected 90 min after oral gabapentin (100 mg/kg, n = 6–7). ( B and C ) Intrathecal idazoxan or saline was coadministered with intracerebroventricular (30 μg/rat, n = 6; B ) and intrathecal (100 μg/rat, n = 6; C ) gabapentin. ( D ) Intrathecal idazoxan or saline was injected alone (n = 6). * P < 0.05 versus time 0 by one-way analysis of variance. Groups differ by two-way analysis of variance in A , B , and C but not in D . # P < 0.05 versus saline by two-way analysis of variance followed by Student-Newman-Keuls test.