Morphological Study On Hippocampus Subfields Under Psychological Stress

Objective1.Using an automatic morphometric analysis software with good test-retest reliability to measure the volumetric atrophy in hippocampal subfields of patients with psychological stress.To Observe the relationship between volume of subfields and the Clinician-Administered PTSD Scale(CAPS)score as well as the exposure time of stress to provides clues for finding specific hippocampal subfields that are sensitive to psychological stress.2.Two stress rats models were established(psychological stress model and physical stress model).By comparing with each other,we showed the properties of psychological stress in GR leave and morphology of hippocampus subfields and behavioral dynamic changing.Method1.68 parents who lost their only children and could not be pregnant were collected as psychological stress group.According to CAPS score,they were divided into PTSD+ group(57 cases)and PTSD-(11 cases),and 39 healthy volunteers were recruited as control group.The hippocampal subfields volume of all subjects was measured and analyzed,and the volume of each subfields differences between the groups were observed,the relationship with the CAPS score and the time course of trauma exposure as well.2.60 male Wistar rats.Thirty rats were randomly selected to prepare a physiological stress group by foot electroporation,and another 30 rats were randomly selected to be exposed to emotional stimuli in compartmentss adjacent to the rats underwent electric shock group,such as visual,auditory,and olfactory sensations of from the physical stress group with electric foot shaking were defined as the psychological stress group in this study.These rats were observed at 0,2,4,and 6 weeks.The observations are as follows:(1)Behavior.(2)Volume of the hippocampus subregion.(3)Evaluation of the GR in the hippocampus.At the fourth and sixth weeks,6 rats randomly selected from the physiological stress group and the psychological stress group were kept in the normal environment for 6 weeks,and the changes in the above contents were observed.Result1.Compared with the healthy control group,the left hippocampus CA2-3,CA4-DG and right CA2-3,CA4-DG subfields in the psychological stress group showed significant atrophy.Post-hoc analysis showed that the above subfields of the PTSD+/-group showed significant atrophy compared with healthy controls,but there was no significant difference in the volume of the above subfiels between the PTSD+/-groups.2.The percentage reduction of CA2-3 and CA4-DG on the left side is greater than that on the right side,and the left side(three subfields)is significantly affected by the subfields more than the right side(two subfields).3.Multiple linear regression showed that the total volume of bilateral CA4-DG subfields in the psychological stress group decreased with increasing traumatic exposure time(r=0.82).4.Multiple comparisons showed that,first,under physiological stress,hippocampal atrophy and behavioral abnormalities were found at 2 weeks,but did not change until 4 weeks under psychological stress.Second,the effects of psychological stress were more pronounced in the fourth week than in the physiology,but were reversed in the sixth week.That is to say,the effects of physiological stress appear earlier,but mild,while the effects of psychological stress appear late,but rapidly increase.In addition,the most significant difference between the two groups was that DG volume was still decreasing at 6 weeks under psychological stress,and the final volume was significantly smaller than the physiological stress group.5.After 6 weeks of feeding in a normal environment,rats subjected to physiological stress at 4 weeks and 6 weeks showed recovery of DG area volume and behavioral abnormalities,but rats subjected to 6 weeks of psychological stress were irreversible,and interestingly Recovery of DG area volume and behavioral abnormalities was also observed in rats subjected to 4 weeks of psychological stress..Conclusion1.Psychological stress has cumulative effects on hippocampal injury,and hippocampal CA2-3 and CA40-DG subfields play an important role in psychological stress.2.By comparing with physiologically stressed rats,it is found that:(1)The psychological stress effect appears later,but it is more intense.It suggests that the damage mechanism is different from physiological stress.(2)The sensitivity of the hippocampus subfields from high to low is CA1,CA3 and DG.(3)The long-term(6 weeks in this experiment)psychological stress can lead to irreversible damage in the DG area,and this phenomenon does not appear in physiological stress,suggesting that the psychological stress area may participate in the neuroplasticity of the injured DG area.Stimulating reaction.