The Effect Of Low Sound Pressure Infrasound On Cognitive Function In Rats With Vascular Dementia And Its Related Mechanism

BACKGROUND:Vascular dementia is a severe cognitive disorder caused by cerebral vascular injury.It has a high incidence and is the second largest cause of dementia in the world.Patients with vascular dementia often lose their ability to live independently and become a heavy burden for families and society.In severe cases,they can even endanger life.Vascular disease is the root cause of vascular dementia.It can be divided into pathological types such as subcortical ischemic vascular dementia,multiple infarction cerebral infarction dementia,post-stroke dementia,mixed dementia and hypoperfusion dementia.Management of risk factors related to cerebrovascular disease is a fundamental measure to prevent vascular dementia.Some patients with vascular dementia can be benefit from Cholinesterase inhibitors and non-competitive N-methyl-D-aspartate receptor antagonists.As a non-invasive treatment,physical factors can produce a variety of beneficial biological effects on the human body.The infrasound is a sound wave with a frequency less than 20 Hz,which can stimulate the human body to generate resonance.Appropriate application of infrasound can play a beneficial and positive role.Sound pressure level is the key factor of infrasound effect.There are studys from different fields confirm that the infrasound with sound pressure less than 90dB can relieve symptoms and promote functional recovery.OBJECTIVE:To investigate whether low sound pressure infrasound can improve cognitive impairment and its related mechanisms in rats with vascular dementiaMETHODS:Twenty-four SD rats were randomly divided into three groups:sham group,dementia group and infrasound group,with an average of 8 rats in each group.In the dementia group and the infrasound group,a stepwise bilateral common carotid artery occlusion model was established.The sham group only separated the common carotid artery.The rats In the infrasound group were treated with low-sound pressure infrasound for 1 hour/time,once a day for 7 consecutive days.On the 7th day,passive avoidance experiments were performed to evaluate the cognitive function of each group of rats.Magnetic resonance T2 weighted scan was performed to observe the presence or absence of ischemic lesions.Arterial spin labelling scan was performed to obtain cerebral blood flow in both hippocampus.??-tublin immunofluorescence staining was performed to observe the differentiation of the neural stem cells in the subgranular zone of hippocampal dentate gyrus.RESULTS:The step-through latency of rats in the dementia group is significantly shorter than that in the sham group(P<0.05).The step-through latency of the rats in the infrasound group is longer than that in the dementia group(P<0.05).There is no significant difference im the step-through latency between infrasound group and sham group(P>0.05).There are no obvious infarcts in each layer of T2-weighted coronal scan of each group.The mean cerebral blood flow of bilateral hippocampus in dementia group and infrasound group is lower than that in sham group(P<0.05).The mean cerebral blood flow of bilateral hippocampus in infrasound group is higher than that in dementia group(P<0.05).The expression of ??-tublin in the subgranular zone of the hippocampal dentate gyrus of the dementia group is higher than that of the sham group(P<0.05).The expression of ??-tublin in the subgranulation zone of the hippocampal dentate gyrus of the infrasound group is higher than that of the dementia group.<0.05).Conclusion:This study found that low sound pressure has the effect of improving the cognitive function of rats with vascular dementia.At the same time,we also found that low sound pressure infrasound can also improve hippocampal perfusion and promote endogenous neural stem cell differentiation,which may be the underlying mechanism behind the improvement of cognitive function in rats with vascular dementia by low sound pressure infrasound,but it needs further research to confirm.