| Objective:Some studies have shown that chronic stress have a certain impact on spatial cognition function, and the possible wayis that chronic stress affects hippocampal glutamic neurotransmission, regulating hippocampal synaptic plasticity by glucocorticoids. This research established the chronic unpredictable mild stress rats and its restoration model, through the space cognitive function,, serum corticosterone, glucocorticoid receptor content, glutamic acid(AMPA receptor subunits) neurotransmission, and related protein(PICK1, PSD- 95), to discuss the influences of chronic stress on hippocampus glutamic neurotransmission.Methods: Male Sprague-Dawley rats, randomized to the control group(n = 16), chronic stress group(n = 16) and recovery group(n = 8). Gived the rats with fiveweeks chronic unpredictable mild stress(CUMS), to set up chronic stress model is. By open field test experimental to observe rats anxiety levels, activity and exploring ability, etc., as indicators of behavior, and Elisa test of content of serum corticosterone looked as physiological indicators, to inspect that chronic stress and recovery model was set up successfully. Testing space cognitive function in hippocampus by Barnes maze test, To discuss the effect of chronic stress on the spatial memory of rats. After the behavior experiment, studied the effect of chronic stress on hippocampus glutamic neurotransmission, mainly by Western blotting method measuring the hippocampus glucocorticoid receptor protein expression levels of change, and immunohistochemical method inspection of glutamate AMPA receptor subunits Glu A1, Glu A2, Glu A3 expressed in hippocampus of the different distribution, and by exploring the expression of its related proteins PICK1 and PSD-95 to explore the regulating mechanism in the distribution of change.Results:①From the behavioral results of open field test and physiology result of corticosterone testing, chronic stress model was successfully established, and in the recovery period which had been restored.②Behavioral result from Barnes maze shows that chronic stress leads to falling in obtain, maintain, extraction ability of spatial memory of rats. Control and recovery group on the third day of the Barnes maze learning phase compared to the model group were significantly reduced; In the testing phase, in the control and recovery group, the number of looking for hole had significant more than model group; And the model group was significantly higher than other two groups to repeat to find the target hole area.③From corticosterone Elisa experiment result shows that chronic stress evoked serum corticosterone levels rised the modek group,and significantly higher than the control group and recovery group.④Impact of chronic stress on rat hippocampal glutamate AMPA receptor subunits: Expression of protein Glu A1 Glu A2,Glu A3 in the model group hippocampus were significantly higher than the control group and recovery group; In different in the model group hippocampal partition, expression of protein Glu A2 and Glu A3 were significantly higher than the control group and recovery group. In the model group expression of protein Glu A1 in the DG was not higher than the control group and recovery group.⑤Impact of chronic stress on rat hippocampal glutamate AMPA receptor subunits related proteins: In the model group hippocampal partition, expression of protein PICK1 was significantly higher than the control group and recovery group and expression of protein PSD-95 was not higher than the control group and recovery group. Conlusion:① Chronic stress caused spatial cognitive function injury in rats, which might reversible changes in the hippocampal glutamate AMPA receptor. ② The raised corticosterone content suggested that corticosterone plays an important role in chronic stress process, The effects of chronic stress on memory and behavior and.related to the level of glucocorticoid.③. In the condition of chronic stress, rat hippocampal glutamate AMPA receptors and their subunits changes, showed that this changes, were important mechanisms of chronic stress impact hippocampal function by changing the hippocampal structure. ④ Chronic stress not only adjust the hippocampus AMPA receptor expression, also influence its related protein PICK1 expression level at the same time, rather thanregulating the expression of PSD- 95. ⑤ Chronic stress might through the glucocorticoid pathway, effected hippocampal neurons postsynaptic AMPA receptors and related protein expression and function, changed hippocampal spatial cognitive function reversiblely. |
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