Development of tactile allodynia after L5/L6 spinal nerve ligation and the effects of intrathecal gabapentin infusion on established allodynia. Left L5/L6 spinal nerve tight ligation was performed in Harlan Sprague Dawley rats, and the PWT to mechanical stimulation was tested daily as indicated. Allodynic rats (1 week after nerve ligation) were treated with saline or gabapentin for 1 week through an intrathecal (i.t.) pump. Data are presented as the means ± SEM from at least 5 treated to 20 nontreated rats in each group.