The present invention relates to a therapeutic agent for neuropathic pain containing, as an active ingredient, a compound represented by general formula (I) or a pharmacologically acceptable acid addition salt thereof:(wherein R1, R2, R3, R4, R5, R6, R7, R8, A, and B have the same definitions as those described in the specification), and an animal model produced by administering (+)-4a-(3-hydroxyphenyl)-2-methyl-1,2,3,4,4a,5,12,12a-octohydro-trans-quinolino[2,3-g]isoquinoline. The present invention makes it possible to perform drug treatment for neuropathic pain. The therapeutic effect of a compound against neuropathic pain can also be evaluated.
