Figure 1.
Effects of CUMS and escitalopram treatment on sucrose preference (A), sucrose and water total intake (B) and immobility time in forced swimming test (C) Data are presented as mean ± S.D. (n = 6 per group).
* P<0.05, ** P<0.01 vs. control+saline group, # P<0.01 vs. CUMS+saline group.
Figure 2.
Effects of CUMS and escitalopram treatment on acquisition and consolidation in the Morris water maze test.
(A) In the acquisition trials, CUMS rats showed longer escape latency during training days 2–4, while escitalopram treatment restored the CUMS-induced longer latencies to control levels. In the probe trial, CUMS impaired memory retrieval as indicated by fewer crossing times of the platform position (B) and less time spent in the target quadrant (C), while escitalopram treatment restored the CUMS-induced impairment of memory retrieval to levels seen in controls. There was no significant difference of swim distance (D) and swim speed (E) among groups. Data are presented as mean ± S.D. (n = 6 per group). * P<0.05, ** P<0.01 vs. control+saline group. # P<0.05, # # P<0.01, vs. CUMS+saline group.
Table 1.
Effects of CUMS and escitalopram treatment on normalized hippocampal volume.
Table 2.
Effects of CUMS and escitalopram treatment on hippocampal 1H-MRS measurements.
Figure 3.
Correlation analysis between NAA/Cr of the right hippocampus and the learning and memory test.
(A–D) In the acquisition trials, a significant negative correlation was found between NAA/Cr of right hippocampus and the latency to find platform on day 1 (r = −0.478, P = 0.018), day 3 (r = −0.539, P = 0.007) and day 4 (r = −0.450, P = 0.027), although the correlation of day 2 (r = −0.348, P = 0.096) was not significant. (E) A significant positive correlation was shown between NAA/Cr of right hippocampus and the crossing number of platform (r = 0.654, P = 0.001). (F) There is a strong positive correlation between NAA/Cr of right hippocampus and the time spent in the target quadrant (r = 0.627, p = 0.001).
Figure 4.
Schematic representation of animal group assignments and behavioural tests.
Rats were randomly divided into 4 groups: control+saline, control+escitalopram, CUMS+saline and CUMS+escitalopram (n = 6 per group). Two weeks after the beginning of the CUMS regimen, rats received escitalopram (10 mg/kg, i.p.) or saline treatment once a day for another 4 weeks while the CUMS procedure was continued. Sucrose preference test and forced swimming test were measured before stress (0 week), before drug administration (2 week) and at the end of the experiment (6 week). Morris water maze and MRI scan were carried out at the end of the experiment.
Figure 5.
Illustration of the voxel to the site of hippocampus for 1H-MRS was presented, with associated magnetic resonance spectrographic imaging spectrum.
(A) Left and right hippocampi are indicated by the white rectangles in coronal T2-weighted imaging of rat brain. (B) Typical hippocampal 1H-MRS with marked Myo-inositol (MI), choline-containing compounds (Cho), creatine and phosphocreatine (Cr), glutamate (Glu) and N-acetylaspartate (NAA) peaks.