Background: Neurological effects of microwave radiation remain uncertain. Although RKIP is known as a metastasis suppressor in various carcinomas, its function in nervous system is limited. This study investigated whether RKIP is important for neural cell apoptosis and explored its mechanism. Methods: 48 male Wistar rats aged 8 weeks and differentiated PC12 cells cultured in vitro were randomly divided into control group and microwave group. Animals and PC12 cells were exposed to 2.856GHz for 5min and 15min, respectively, at an average power density of 30 mW/cm2. Transmission electron microscopy was used to observe chromatin ultrastructure of hippocampal neurons and PC12 cells. JC-1, TUNEL and Annexin V-FITC/PI staining detected the important apoptotic events in PC12 cells. RKIP sense and anti-sense recombinant plasmids were constructed and transfected into PC12 cells. Results: After microwave radiation, chromatin condensation and apoptotic body formation were observed in both hippocampus and PC12 cells. Moreover, the mitochondria membrane potential decreased, the ratio of Bcl-2/Bax decreased, the activity of caspase-3 increased, and thus DNA fragmentation and the apoptotic cell percentage increased. Furthermore, RKIP was downregulated, while the Raf/MEK/ERK and NFκB pathway were both activated excessively. RKIP overexpression significantly inhibited the activation of ERK pathway and cell apoptosis, while RKIP downregulation had the reverse effect. Conclusion: RKIP plays an important role in the neural cell apoptosis induced by microwave radiation. The regulation of cell apoptosis by RKIP refered to the ERK and NFκB pathway, and the crosstalk between them may be involved.
This work was supported by the National Natural Science Foundation of China (81102101, 30770527)