Gabapentin attenuates intestinal inflammation: Role of PPAR-gamma receptor

Gabapentin is an anticonvulsant drug that is also used for post-herpetic neuralgia and neuropathic pain. Recently, gabapentin showed anti-inflammatory effect. Nuclear factor kappa B (NFκB) is a regulator of the inflammatory process, and Peroxisome Proliferator-activated Receptor gamma (PPAR-gamma) is an important receptor involved in NFκB regulation. The aim of the present work was to study the potential role of PPAR-gamma receptor in gabapentin-mediated anti-inflammatory effects in a colitis experimental model. We induced colitis in rats using trinitrobenzenosulfonic acid and treated them with gabapentin and bisphenol A dicyldidyl ether (PPAR-gamma inhibitor). Macroscopic lesion scores, wet weight, histopathological analysis, mast cell count, myeloperoxidase, malondialdehyde acid, glutathione, nitrate/nitrite, and interleukin levels in the intestinal mucosa were determined. In addition, western blots were performed to determine the expression of Cyclooxygenase-2 (COX-2) and NFκB; Nitric Oxide Inducible Synthase (iNOS) and Interleukin 1 beta (IL-1β) levels were also determined. Gabapentin was able to decrease all inflammatory parameters macroscopic and microscopic in addition to reducing markers of oxidative stress and cytokines such as IL-1β and Tumor Necrosis Factor alpha (TNF-α) as well as enzymes inducible nitric oxide synthase and cyclooxygenase 2 and inflammatory genic regulator (NFκB). These effect attributed to gabapentin was observed to be lost in the presence of the specific inhibitor of PPAR-gamma. Gabapentin inhibits bowel inflammation by regulating mast cell signaling. Furthermore, it activates the PPAR-gamma receptor, which in turn inhibits the activation of NFκB, and consequently results in reduced activation of inflammatory genes involved in inflammatory bowel diseases.