Effects Of Hypothermia Environment On Local Field Potential And Memory In Hippocampal CA1 Region Of Rats

Hemorrhagic shock can cause inadequate perfusion of various organ tissues as well as a series of pathophysiological changes such as brain injury.In this study,biochemical tests,and in vivo multi-channel recording techniques were used to record changes in field potentials of hippocampal CA1 neurons in live rats during 5℃hypovolemic shock.The study was aimed to investigate the effect of 5℃hypothermic hemorrhagic shock on memory in the rats.ObjectiveTo investigate the effects of 5℃ low-temperature environment on local field potential in the hippocampal CA1 region and memory in rats with hemorrhagic shock.Methods1.Healthy male SD rats,weighting 350 ~ 400 g were selected and divided into three groups.In group A,24 rats were used for biochemical detection and electrophysiological monitoring with multi-channel in vivo recording technique,and in group B,24 rats were used for behavioral detection.2.In this study,Morris water maze method was mainly used to further evaluate the spatial learning ability of animals.Each rat was trained four times a day with an interval of 15 minutes,with a view to training rats to find the hidden platform and recording the escape latency.On the sixth day,the space probe test was mainly carried out,during which the number of animals crossing the platform in one minute was recorded in realtime.3.The multi-channel recording technique was applied to monitor the localfield potentials(LFPs)of rats with hemorrhagic shock under different temperatures.The CA1 area on the back of the animal’s hippocampus was put into the CA1 area of the animal’s hippocampus,and after 7 days of recovery,hemorrhagic shock models were constructed at different temperatures.The latest version of Matlab software was used for real-time recording and further completion of lfp analysis..4.Hemorrhagic shock models at different temperatures were resuscitated using both volume and temperature resuscitation methods.On the third day after operation,the animals were euthanized.Then their brain tissues were extracted according to the research needs.The hippocampal tissue was isolated for relevant biochemical tests,and the accuracy of electrode implantation in the CA1 area was confirmed.5.Tissue samples were determined by HE staining,and neuronal apoptosis was measured based on TUNEL method.Plasma S100β expression level was measured by enzyme-linked immunoassay.6.In this study,the powerful Graph Pad Prism 9 software was mainly to process and analyze the data obtained from the study.Mean±standard error was adopted to represent quantitative data,and one-way analysis of variance was used for within-group and between-group comparisons.P<0.05 indicated statistical significance,and LFPs were analyzed using Matlab 2022 b.Results1.Morris water maze results of different rat groupsResults of place navigation experiments showed that the increase in escap e latency was significantly greater in the Nhs group than in the Sham(control)group(P<0.05),whereas the increase in escape latency was less pronounced in the Lsh group than in the Sham group(P>0.05).In spatial probe tests,the Lsh group showed no significant difference compared to the Sham group(P>0.05),whereas the number of crossings over the platform was significantly decreas ed in the Nhs group compared to the Lsh group(P<0.05).2.Histopathological changes in the hippocampus of rat groupsHE staining showed that the normal cell number was decreased in Nhs group compared to Sham and Lsh groups,accompanied by higher degree of nucl ear condensation,and more severe damage to the hippocampal CA1 region.By contrast,the extent of damage in the Lsh group was relatively mild.3.ELISA assay resultsCompared to the Sham group,levels of S100β expression in the plasma in creased significantly in the Nhs group(P<0.05),and were also significantly highe r in the Nhs group compared to the Lsh group(P<0.05),whereas the increase was not significant in the Lsh group(P>0.05).4.TUNEL assay resultsCompared to the Sham group,both the Nhs and Lsh groups had significa ntly higher apoptosis index(AI)values(P<0.05).5.EEG measurement resultsCompared to the Sham group,the amplitude was significantly increased w hereas the frequency was significantly decreased in the Nhs group(P<0.05).Meanwhile,the amplitude in the Lsh group was slightly increased and the frequency was not significantly decreased(P>0.05).Compared to the Sham group,the energy of both theta and gamma frequency bands decreased significantly in the other two groups(P<0.05).Conclusion1.Hypovolemic shock at normal temperature can trigger brain injury,cause apoptosis of neuronal cells and induce a decrease in memory abilities.2.A low temperature environment of 5℃ can reduce the degree of brain injury.