Seung-Won Park, Jae-Hyuk Yi, Guruwattan Miranpuri, Irawan Satriotomo, Kellie Bowen, Daniel K. Resnick and Raghu Vemuganti
Department of Neurological Surgery (S.-W.P., J.-H.Y., G.M., I.S., K.B., D.K.R., R.V.), Neuroscience Training Program (R.V.), Cardiovascular Research Center (R.V.), and Regenerative Medicine Program (R.V.), University of Wisconsin, Madison, Wisconsin; and Department of Neurological Surgery, Chung-Ang University, Seoul, Korea (S.-W.P.)
Address correspondence to : Dr. Raghu Vemuganti, Department of Neurological Surgery, University of Wisconsin, K4/8 (Mail stop code CSC-8660), 600 Highland Ave., Madison WI 53792.
S.-W.P. and J.-H.Y. contributed equally to this work.
Abstract
Thiazolidinediones (TZDs) are potent synthetic agonists of the ligand-activated transcription factor peroxisome proliferator-activated receptor-γ (PPARγ). TZDs were shown to induce neuroprotection after cerebral ischemia by blocking inflammation. As spinal cord injury (SCI) induces massive inflammation that precipitates secondary neuronal death, we currently analyzed the therapeutic efficacy of TZDs pioglitazone and rosiglitazone after SCI in adult rats. Both pioglitazone and rosiglitazone (1.5 mg/kg i.p.; four doses at 5 min and 12, 24, and 48 h) significantly decreased the lesion size (by 57 to 68%, p < 0.05), motor neuron loss (by 3- to 10-fold, p < 0.05), myelin loss (by 66 to 75%, p < 0.05), astrogliosis (by 46 to 61%, p < 0.05), and microglial activation (by 59 to 78%, p< 0.05) after SCI. TZDs significantly enhanced the motor function recovery (at 7 days after SCI, the motor scores were 37 to 45% higher in the TZD groups over the vehicle group; p< 0.05), but the treatment was effective only when the first injection was given by 2 h after SCI. At 28 days after SCI, chronic thermal hyperalgesia was decreased significantly (by 31 to 39%; p< 0.05) in the pioglitazone group compared with the vehicle group. At 6 h after SCI, the pioglitazone group showed significantly less induction of inflammatory genes [interleukin (IL)-6 by 83%, IL-1β by 87%, monocyte chemoattractant protein-1 by 75%, intracellular adhesion molecule-1 by 84%, and early growth response-1 by 67%] compared with the vehicle group (p< 0.05 in all cases). Pioglitazone also significantly enhanced the post-SCI induction of neuroprotective heat shock proteins and antioxidant enzymes. Pretreatment with a PPARγ antagonist, 2-chloro-5-nitro-N-phenyl-benzamide (GW9662), prevented the neuroprotection induced by pioglitazone.