Mild Traumatic Brain Injury Contributes to the Development of Delayed Neuroinflammation

Abstract

Introduction: In recent years, according to the literature, the problem of mild traumatic brain injury (mTBI) has become more and more urgent. Compared to moderate to severe craniocerebral trauma, mTBI occurs in a far greater number of people. The delayed sequelae caused by a single mTBI or multiple mTBIs are a significant public health problem. Methods: A weight-drop model was used for the formation of mTBI. A metal rod weighing 337 g with a blunt tip of 3 mm diameter was uplifted at 8 cm height and held by a lever. The trauma was created by lowering the lever and the rod and free-dropping onto the rat skull. In the cerebral cortex of experimental animals, we analyzed the level of microglial activity (Iba-1-positive system) and the expression of pro-inflammatory markers (IL1β, IL6, and CD86). Also, the expression level of the endocannabinoid system receptor (cannabinoid receptor type 1 [CB1]) was assessed in brain samples. Results: Experiments have shown that mTBI increases (1) the amount of microglia (iba-1) activated by the pro-inflammatory pathway (CD86); (2) the level of pro-inflammatory cytokines IL1β and IL6; and (3) CB1R activity. Conclusion: Overall, the results of this study indicate that mTBI induces a sustained neuroinflammatory response.