OBJECTIVETo investigate the effects of microwave irradiation on the expression and regulation of heat shock proteins (HSPs) in primary cultured rat hippocampal neurons.

METHODSNeurons were exposed to 90 mW/cm(2) microwave irradiation for 10 minutes. Western blot was used to determine the expression of HSP27, HSP70, HSP90 and heat shock factor 1 (HSF1) at 0, 3, 6, 12 and 24 hour respectively. Real-time RT-PCR was used to determine the mRNA expression of HSF1. DNA-binding activity of HSF1 was measured by electrophoretic mobility shift assay (EMSA).

RESULTSThe protein expression of HSP27 was significantly increased by 22%, 36%, 18% at 3, 6, 12 h, respectively (P < 0.05). The protein expression of HSP70 was significantly increased by 23%, 32%, 26% at 3, 6, 12 h, respectively (P < 0.05, P < 0.01). The protein expression of HSP90 was significantly increased by 27%, 33% at 6, 12 h, respectively (P < 0.05, P < 0.01). The DNA-binding activity of HSF1 was stimulated, however, no significant change of the expression of HSF1 was observed on both the mRNA and protein levels.

CONCLUSIONThe transcriptional activity of HSF1 is activated by microwave irradiation, which promotes the expression of HSPs. Heat shock response which contributes to establish a cytoprotective state is induced by microwave irradiation in primary cultured rat hippocampal neurons.