Effects of (+)-pentazocine [(+)PTZ] on the expression of ERK1 (A), ERK2 (C), phosphorylated ERK1 (B), and phosphorylated ERK2 (D) protein in the spinal cords of diabetic and non-diabetic mice. Spinal samples were collected 30 min after the i.t. administration of (+)PTZ. Immunoblots are from an experiment that is representative of 4 similar experiments. Each column represents the mean ± S.E.M of 4 separate experiments. *P < 0.05 vs. non-diabetic mice; #P < 0.05 vs. respective vehicle-treated group.