Microglial Inhibitory Effect of Ginseng Ameliorates Cognitive Deficits and Neuroinflammation Following Traumatic Head Injury in Rats

Traumatic brain injury produces several neuropathological alterations, some of them are analogous to patients suffering from memory disorders. Role of neuroinflammation and oxidative stress has been suggested in the pathophysiology of brain injury-induced cognitive dysfunction. Therefore, the present study was designed to explore the possible role of ginseng and its interaction with minocycline (microglial inhibitor) against experimental brain trauma-induced behavioral, biochemical and molecular alterations. Wistar rats were exposed to brain traumatic injury using weight-drop method. Following injury and a post-injury rehabilitation period of 2 weeks, animals were administered vehicle/drugs for another 2 weeks. Brain injury caused significant memory impairment in Morris water maze task as evident from increase in escape latency and total distance travelled to reach the hidden platform. This was followed by a significant decrease in time spent in target quadrant and frequency of appearance in target quadrant. Further, there was a significant increase in oxidative stress markers, neuroinflammation (TNF-α and IL-6) and acetylcholinesterase levels in both cortex and hippocampal regions of traumatized rat brain. Ginseng (100 and 200 mg/kg) and minocycline (50 mg/kg) treatment for 2 weeks significantly attenuated all these behavioral, biochemical and molecular alterations. Further, combination of sub-effective doses of ginseng (50 and 100 mg/kg) and minocycline (25 mg/kg) potentiated their protective effects which was significant as compared to their effects alone. The results of the present study suggest that the therapeutic effects of ginseng might involve inhibition of microglial pathway against head trauma-induced cognitive impairment and neuroinflammation in rats.