Search

Purpose: To determine hippocampal subfields volume loss in depression, which was simulated by a rat chronic unpredictable mild stress (CUMS) model. As different cellular and molecular characteristics in hippocampal subfields, these subfields are regarded as differentially vulnerable to processes associated with stress.Materials and Methods: Twenty male Wistar rats were exposed to various stressors until the model was successfully established. The effects of physical exercise on recovery of hippocampal volume in depressed rats were simulated using the wheel running test (WRT). These rats hippocampal volumes were dynamically measured using T2 -weighted images (T2 WIs) at 7T structural magnetic resonance imaging (MRI).Results: After 4 weeks of CUMS (CUMS-4W), the behavioral tests showed that the rat model of depression was successfully established (P < 0.001). In this process, the bilateral CA1 volume was significantly atrophic after 2 weeks of CUMS (CUMS-2W) compared with controls (left: 21.09 ± 2.31 vs. 26.16 ± 3.83 mm3 , P < 0.001; right: 21.05 ± 2.36 vs. 26.12 ± 3.78 mm3 , P < 0.001), whereas the other subfields did not show a similar change (all P > 0.05). The volume of CA3, dentate gyrus (DG), and subiculum displayed atrophy after CUMS-4W (CA3: left:12.23 ± 1.10 mm3 , right: 12.20 ± 1.14 mm3 ; DG: left:8.16 ± 0.58 mm3 , right: 8.18 ± 0.92 mm3 ; subiculum: left: 4.30 ± 0.52 mm3 , right: 4.29 ± 0.44 mm3 ; all P < 0.05). The rats' (CUMS-4W) hippocampal DG volume was restored (left: 10.67 ± 1.60 mm3 , right: 10.71 ± 1.58 mm3 ), and the depression-like behaviors of these rats improved after WRT-4W (P < 0.05).Conclusion: In general, volume loss was demonstrated in various rat hippocampal subfields during the development and recovery from depression, which were detected by ultrahigh-field MRI.Level Of Evidence: 3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1456-1463. [ABSTRACT FROM AUTHOR]

The occurrences of dilated Virchow-Robin spaces (dVRSs) and inflammatory factors were closely related with development of depression and antidepressants. The present study indicated accumulation of inflammatory factors in dVRSs played a practical role in behaviors and the treatment-resistant in rats with depression. Eighty-one male Wistar rats were exposed to chronic unpredictable mild stress (CUMS) until the model was successfully established. According to the detection of dVRSs on 7 T structural magnetic resonance imaging (MRI), rats were divided into two groups (45 CUMSnon-dVRSs rats and 36 CUMSdVRSs rats). Subsequently, different antidepressant treatment (nontreat, aspirin, fluoxetine, fluoxetine+aspirin) was given to the two groups, respectively. Sucrose preference test (SPT), forced swim test (FST) and morris water maze (MWM) was used to test the behaviors of rats. ELISA and Western blot was used to determine the levels of inflammatory factors. Compared with the negative control (NC) group, there were obvious behavioral abnormalities and increased inflammatory factors in the CUMSnon-dVRSs rats. Interestingly, these changes were more significant in the CUMSdVRSs rats. In addition, the efficacy of fluoxetine was only found in CUMSnon-dVRSs rats rather than CUMSdVRSs rats. Meanwhile, behaviors and levels of inflammatory factor in hippocampus were ameliorated in the aspirin group of CUMSdVRSs rats, and these effects were significantly enhanced in the fluoxetine+aspirin group. The dVRSs in the hippocampus might exacerbate depression-like behaviors and the effects of antidepressant treatment in depressed rats by increasing the levels of inflammatory factors. [ABSTRACT FROM AUTHOR]

The reduction of hippocampal volume remains controversial in depression because of the variability among individuals in clinical studies. Here, a reliable experimental rat model of depression, established by chronic unpredictable mild stress (CUMS), was used. Thirty rats were randomly divided into two groups (CUMS group and control group). Hippocampal volume was dynamically measured every 2 weeks in a 56-day chronic stress procedure using structural magnetic resonance imaging, and the correlation between the hippocampal volume and the learning and memory changes was investigated. Our results demonstrated that CUMS rats showed significantly smaller volumes of the bilateral hippocampus compared to that of the controls, changing dramatically with the development of CUMS procedure. The left hippocampal volume was reduced earlier and more markedly than the right one from the 2nd week to the 8th week of the CUMS procedure (on the 8th week: left: approximately 15.3 %; right: approximately 8.4 % reduction). Additionally, the hippocampal volume of CUMS rats was significantly negatively correlated with the learning and memory changes. Of note, it showed that the more obviously the hippocampal volume reduced, the more severely the learning and memory damaged. In conclusion, the hippocampal volume decreased gradually and dynamically and was correlated with the impairment of the learning and memory in depression. [ABSTRACT FROM AUTHOR]