Figure 4.

Spinothalamic tract lesions induce subjective pain that is reversed by ethosuximide. a, Rats receiving an electrolytic spinothalamic tract lesion (eSTTx) 14 d earlier (n = 5) displayed significantly reduced locomotion, quantified as the number of crossings of the outer quadrants during a 5 min trial, comparing with sham animals (one-way ANOVA, n = 5 lesioned, 8 sham, F = 6.27, *p < 0.05 for lesioned vs sham). Intraperitoneal administration of ethosuximide (50 mg/kg) had no effect on locomotion in sham animals (n = 8), but prevented the decrease in locomotion in lesioned animals (n = 7). b, There were no significant differences in the percentage of crossings into the inner quadrants, an assay of anxiety, between lesioned and sham animals, either with or without ethosuximide (one-way ANOVA, n = 5 lesioned, 8 sham, F = 1.26).