Catalpol Ameliorates Oxidative Stress and Neuroinflammation after Traumatic Brain Injury in Rats

Oxidative stress and neuroinflammation are deemed the prime causes of neurological damage after traumatic brain injury (TBI). Catalpol, an active ingredient of Rehmannia glutinosa, has been suggested to possess antioxidant and anti-inflammatory properties. This study was designed to investigate the protective effects of catalpol against TBI and the underlying mechanisms of action of catalpol. A rat model of TBI was induced by controlled cortical impact. Catalpol (10 mg/kg) or vehicle was administered via intravenous injection 1 h post trauma and then once daily for 3 consecutive days. Following behavioural tests performed 72 h after TBI, the animals were sacrificed and pericontusional areas of the brain were collected for neuropathological experiments and analysis. Treatment with catalpol significantly ameliorated neurological impairment, blood-brain barrier disruption, cerebral oedema, and neuronal apoptosis after TBI (P < 0.05). Catalpol also attenuated TBI-induced oxidative insults, as evidenced by reduced reactive oxygen species generation; decreased malondialdehyde levels; and enhanced superoxide dismutase, catalase and glutathione peroxidase activity (P < 0.05). Catalpol promoted the nuclear translocation of nuclear factor erythroid 2-related factor 2 and the expression of its downstream antioxidant enzyme HO-1 following TBI (P < 0.05). Moreover, catalpol treatment markedly inhibited posttraumatic microglial activation and neutrophil infiltration, suppressed NLRP3 inflammasome activation and reduced the production of the proinflammatory cytokine IL-1β (P < 0.05). Taken together, these findings reveal that catalpol provides neuroprotection against oxidative stress and neuroinflammation after TBI in rats. Therefore, catalpol may be a novel treatment strategy for TBI patients.