Fig. 6. Intra-locus coeruleus (LC)–injected gabapentin (GBP) reduced mechanical hypersensitivity after spinal nerve ligation (SNL) surgery. (  A ) Normal (n = 6) and SNL rats (n = 7 or 8) received intra-LC injection of vehicle or GBP (0.1–3 μg). The mechanical withdrawal threshold to pressure to the paw in normal rats or ipsilateral to SNL is presented over time. *  P < 0.05  versus time 0. In SNL rats, 0.3–3 μg GBP groups differ significantly from the vehicle group by two-way repeated-measures analysis of variance (  P < 0.05). (  B ) Intrathecal (IT) saline or idazoxan (Ida, 30 μg) was administered followed in 30 min by vehicle or 1 μg GBP injection in the LC, and the postdrug measurement (Post) was obtained 15 min later in SNL rats (n = 7). *  P < 0.05  versus predrug (Pre). (  C ) 1 μg GBP, 0.3 μg CNQX, or their mixture was injected in the LC 15 min before the measurement (Post) in SNL rats (n = 8). *  P < 0.05  versus predrug (Pre).