TRPV4Is Expressed In Different Cells In Rat Brain And Involed In Oxidative Stress Injury Caused By Infrasound

Background: Infrasound is a special kind of soundwave with thefrequency of less than20Hz. It has been shown that infrasound exposure canlead to lesions of various tissues and organs. Due to its extensive existence andstrong penetrability, it is difficulty to protect from infrasound injury. So, toreduce the leisions caused by infrasound, it is necessary to further investigate themechanism of infrasound injury..Objectives: The frequency of infrasound is just coincident with theintrinsic frequency of several organs, so resonance is considered to be the initialfactor of the infrasound injury. But the mechanism that transform mechanicalvibration to biology signal is still unclear. These years, it has been reported thatsome members of TRP family are potential mechanosensitive channels and playvarious roles related to mechanical stimulation. So, we hypothesized thatinfrasound injury may be mediated by some mechanosensitive channels likeTRPs. To finding some clues that indicate the link between infrasound and mechanosensitive channels, we designed this experiment to learn more about themechanism of infrasound injury.Methods:(1) Treat rats with16Hz/130dB infrasound for2h, then extracttotal RNA of cortex. Measure the ralative transcription level of trpv1-trpv4mRNA with RT-PCR method, and compare the different effect of infrasound totrpvs transcription.(2) Detect the expression of TRPV4with WB method atdifferent time after infrasound exposure.(3) Collect primary cultured corticalneuron, astrocyte and microglial, and determine the distribution of TRPV4in thethree kinds of cells with immunofluorescence staining, WB and RT-PCTmethods in vitro.(4) Construct RNAi plasmid vector that specificallydownregulate the expression of TRPV4, and transfect U87cells to identify itsRNAi efficiency.(5) Treat U87cells with16Hz/130dB infrasound for2h, andmeasure MDA content in supernatant, SOD activities and GSH content in lysateof U87cells at different time after infrasound exprosure to investigate theoxidative stress injury caused by infrasound.(6) Transfect U87cells with trpv4specific RNAi vectors, and measure the indicators above again to identify thatwhether RNAi has protective effect on oxidative stress injury caused byinfrasound.Results:(1) trpv4mRNA levels was significantly increased after16Hz/130dB infrasound exprosure, compared with the other three trpvs.(2)Treating rats with16Hz/130dB infrasound, the highest expression of TRPV4was observed0.5h after infrasound exprosure, later TRPV4expression slightlydecreased, but was still higher than the level of control group until2h.(3)TRPV4was widely expressed in cortical neuron, astrocyte and microglial cell,and in astrocytes the expression level was much higher than the other two celltypes.(4) TRPV4expression can be effectively down regulated in U87cells by TRPV4specific RNAi vector.(5)16Hz/130dB infrasound exprosuresignificantly increased the MDA level in supernatant and decreased SODactivities as well as GSH content in lysate, indicating the oxidative stress injuryof infrasound to U87cells.(6)Down-regulate the expression of TRPV4in U87cells have some protective effect on oxidative stress injury of infrasound.Conclusions: TRPV4, as a mechano-receptive molecules, is widelyexpressed in rat cortical neurons, astrocytes and microglial cells, and theexpression level in astrocytes is much higher than the other two cell types.16Hz/130dB infrasound can cause oxidative stress injury in U87cells, anddown-regulation of TRPV4have some protective effects. These data suggestthat TRPV4may play some roles in infrasound injury.