Objective: The aim of this study was to survey whether plumbagin (PLB), a naturally occurring naphthoquinone found in the plants of Plumbago genus, can protect rat primary cortical neurons against mechanical injury which classically mimics traumatic brain injury (TBI) in vitro.
Materials and Methods: Rat primary cortical neurons were isolated from time-mated pregnant Sprague-Dawley rats and cultured in vitro, and then, randomly divided into control group，trauma group，trauma+GKT137831 (50 μM) group，trauma+PLB (5 μM) group, trauma+PLB (10 μM) group and trauma+PLB (20 μM) group．The influence of PLB on rat primary cortical neuron viability and morphology was evaluated after mechanical injury. Flow cytometry was applied to examine neuron apoptotic rate and intracellular production of reactive oxygen species (ROS) after the pretreatment of PLB. The expression of NOX4/p38 MAPK pathway-related proteins was determined by Western blotting.
Results: Our results indicated that PLB pretreatment significantly alleviated trauma induced-neuronal injury by restoring cell viability and reducing lactate dehydrogenase (LDH) leakage compared with the trauma group (p<0.01). The morphology of injured neurons was improved by PLB pretreatment. Also, PLB notably reduced ROS production in cultured rat primary cortical neurons compared with the trauma group (p<0.01). Furthermore, PLB counteracted the mechanical injury-mediated apoptosis (p<0.01) and inhibited the expression of NOX4 protein and p38 MAPK phosphorylation in cortical neurons compared with the trauma group (p<0.01).
Conclusion: The present findings illustrate that PLB can alleviate mechanical trauma injury-induced apoptosis by inhibiting the NOX4/ROS/p38 MAPK pathway in primary cortical neurons.