Evaluation of the effect of tranilast on rats with spinal cord injury

Glial and fibrotic scars inhibit neural regeneration after spinal cord injury (SCI). N-[3,4-dimethoxycinnamoyl]-anthranilic acid (tranilast) inhibits transforming growth factor β, alleviates allergic reactions, and decreases hypertrophic skin scars. We evaluated its ability to improve motor function and inhibit the spread of tissue damage in rats with SCI.

Rats with SCI were divided into groups that received tranilast (30 mg/[kg · day]) by intravenous administration (group IV), tranilast (200mg/[kg · day]) by oral administration (group OR), and saline injections (control). Motor functions were assessed by determining Basso, Beattie, and Bresnahan (BBB) scores and %grip tests for 8 weeks after SCI. Histological evaluation of ionized calcium binding adaptor molecule 1 (Iba1) at 1 week after SCI and glial fibrillary acidic protein (GFAP), fibronectin, and chondroitin sulfate (CS) at week 8 was performed.

Motor function recovery, BBB score, and the %grip test were significantly higher in the tranilast-treated groups than in the control group. At week 1 after SCI, inflammatory-cell invasion was more severe and Iba1 expression was significantly higher in the control group. At week 8, although the number of GFAP-positive cells increased greatly from the impaction site to the proximal and distal sites in the control group, these cells were confined around a cavity in the tranilast-treated groups. GFAP distribution coincided with that of fibronectin. Anti-CS antibody level in the tranilast-treated groups was significantly lower than that in the control group.

Tranilast inhibits inflammation in the acute phase of SCI and reduces glial and fibrotic scars and could present a new method for treating SCI.