Anti-edema effect of Aloe vera leaf extract following traumatic brain injury: Role of pro-inflammatory cytokines

OBJECTIVE: Based on anti-inflammatory effects of Aloe vera, the effect of aqueous extract of this plant on brain edema and changes in some pro-inflammatory cytokines was investigated after traumatic brain injury (TBI). MATERIALS AND METHODS: In this study, adult male Wistar rats were divided into 5 groups: Sham, TBI, vehicle (Veh), and low dose (LA) and high dose (HA) Aloe vera. The vehicle and aqueous extract of Aloe vera were injected intraperitoneally 30 min after induction of diffuse TBI by Marmarou’s method. Brain edema (brain water content), and transforming growth factor beta (TGF-β), tumor necrosis factor alpha (TNFα), interleukin 6 (IL-6) and IL-1β levels in serum and brain were measured 24 hr after TBI induction. RESULTS: Increased brain edema by TBI was reduced by both LA and HA (p<0.01 and p<0.05, respectively). IL-6 increased in the brain of TBI group compared to sham, and which was inhibited by both Aloe vera doses compared to Veh (p<0.001). The differences in the IL-6 serum levels among Veh, LA and HA groups were not significant. Increases in serum and brain IL-1β levels were reduced only in the HA group (p<0.001). Although only in the brain, TNF-α level increased after trauma, but both LA and HA inhibited it in a dose-dependent manner (p<0.01 and p<0.05, respectively) . The amount of TGF-β in the brain was reduced by both doses of the extract (p<0.001). CONCLUSION: These results indicated that Aloe vera has a neuroprotective effect induced by reducing brain edema. The probable mechanism particularly for HA is decreasing levels of pro-inflammatory cytokines such as TGF-β, TNF-α, IL-6 and IL-1β.