Effects Of Cold On Local Field Potentials In The Primary Auditory Cortex Of Rats

In this study,multi-channel in vivo recording(MIVR)was used to record spontaneous and evoked local field potentials(LFP)of the autidory cortex(AC)in rats after cold exposure.To explore the effect of low temperature on the LFP in the AC region of rats.In this study,the rats were divided stochastically into normal temperature control group,-10℃ cold exposure group,-15℃ cold exposure group and-20℃ cold exposure group.Electrodes were placed in the AC region of the rats,and after adaptive feeding,the rats in each group were placed in a low temperature climate chamber for 4 hours per day,last for 7 days.On the 7th day,LFP was collected from rats without stimulation and under sound stimulation.The sound stimulus was a click-train pure tone stimulus with 70 d B and 40 Hz,and the Raw power spectra density(PSD)was obtained.Blood was collected,and rats were sacrificed and brain tissues were extracted by cold perfusion.The tissue in AC region was observed by HE staining.Terminal deoxynucleotidyl transferase-mediated dut P Nick end labeling(TUNEL)was used to detect neuronal apoptosis in the auditory cortex.The brain injury related protein S100β concentration in serum was detected by enzyme linked immunosorbent assay(ELISA).The electrophysiological results showed that the energies of spontaneous LFPs in-10℃,-15℃ and-20℃ groups were significantly lower than those in the control group(P<0.05).Compared with the normal temperature control group,the energy of the evoked LFPs at 35-45 Hz in the-10℃,-15℃ and-20℃ groups was significantly decreased(P<0.05).HE staining showed that compared with the control group,a small amount of karyopyknosis,were observed in the AC region of the low temperature exposure group,but there was no significant difference among the three low temperature exposure groups.TUNEL results showed that compared with the normal temperature control group,the-10℃,-15℃ and-20℃ cold exposure groups had a significant increase in neuronal apoptosis(P<0.05).ELISA results showed that compared with the normal temperature control group,the serum levels of S100β of the-10℃,-15℃ and-20℃cold exposure groups were significantly increased(P<0.05),suggesting that there was central nerve cell damage.Based on this study,it can be concluded that there are changes in spontaneous and evoked LFP in the AC region of rats after low temperature exposure,which is manifested as a decrease in the power spectral density of LFPs.Increased apoptosis in the AC region may be responsible for the changes in LFPs.The results of this experiment are helpful to understand the adverse effects of low temperature environment on human physiology more deeply.It is of practical significance for the officers and soldiers in cold areas to make more reasonable operational plans and ensure work efficiency.