Effects of foraging exercise on depressive-like behaviors and expression of transforming growth factor-β1 in hippocampus of rats with ischemic stroke after chronic stress / 中华行为医学与脑科学杂志

ABSTRACT

Objective:To explore the effects of foraging exercise (FE) on depressive-like behaviors and expression of transforming growth factor-β1 (TGF-β1) in hippocampus of rats with ischemic stroke after chronic stress.Methods:The right middle cerebral artery occlusion (MCAO) model was used in 30 male adult clean grade SD rats by suture method.According to the body weight, rats were evenly divided into stroke group ( n=10) and chronic unpredictable mild stimulation (CUMS) group ( n=20). Rats of CUMS group received stress induction 1 week after operation and lasted for 3 weeks. Then, according to random number generator of SPSS 24.0 software, the depression rats were divided into post-stroke depression (PSD) group( n=10) and FE groups ( n=10). The FE group received free FE intervention for 4 weeks. Body weight, water maze test, novelty inhibition feeding test (NSFT) and sucrose preference test (SPT) were performed at the end of the 1st, 4th and 8th week, respectively. The expression of TGF-β1 in hippocampus was detected by Immunohistochemistry (IHC) and Western blot (WB), and the levels of TGF-β1 and TNF-α in serum were detected by ELISA. SPSS 24.0 software was used for statistical analysis. The behavioral data were compared by two factor repeated measurement analysis of variance. One way ANOVA was used for comparison among groups, and LSD test was used for further pairwise comparison. Results:(1) The interaction between group and time had statistical significance on body weight, latency and food intake of NSFT and sucrose preference index(SPI) ( F=2.936-12.098, all P<0.05). After 4 weeks, compared with the stroke group((343.80±19.34)g, (12.10±6.97)s, (0.75±0.09)%), the body weight((307.80±17.23)g, (305.30±24.39)g), and SPI((0.52±0.06)%, (0.53±0.07)%) of PSD group and FE group were lower and the NSFT latency((21.70±7.02)s, (22.40±0.84)s) was longer (all P<0.05). After 8 weeks, SPI in FE group was higher than that in PSD group ( P=0.045). There were significant differences in body weight of three groups, NSFT latency and SPI of PSD group and FE group, and food intake of stroke and FE group ( F=8.478-196.548, all P<0.05). There was no interaction between group and time in the water maze test. Main effect of time ( P=0.034) and main effect of group ( P<0.01) had statistical significance on escape latency. The escape latency after 4 weeks was longer than that after 1 week ( P=0.003). The latency of PSD group was longer than that of stroke group ( P=0.005), and latency of FE group was shorter than that of the PSD group ( P<0.01). The main effect of group had statistical significance in the number of crossing quadrant ( P<0.01). The number of crossing quadrant of FE group was less than that of PSD group ( P<0.01). (2) Immunohistoche mistry staining showed that compared with the stroke group, the expression of TGF-β1 was down-regulated in 3 areas of hippocampus of PSD group (CA1, CA3 and DG) ( t=5.449-9.353, all P<0.01). Compared with stroke group, the expression of TGF-β1 of CA1 ( t=7.433, P<0.01) in FE group was down-regulated, but was up-regulated in CA3 ( t=3.342, P<0.05) of FE group. Compared with the PSD group, the expression of TGF-β1 was up-regulated in CA3 and DG of FE group ( t=7.811, 8.790, both P<0.01). (3) Western blot results: Compared with stroke group, the expression of TGF-β1 in hippocampus of PSD group was down-regulated ( t=3.255, P<0.01). Compared with the PSD group, the expression of TGF-β1 in hippocampus of FE group was up-regulated ( t=2.906, P<0.05). (4) ELISA detection showed that compared with the stroke group, the levels of TGF-β1 decreased ( t=2.224, P<0.05), but TNF-α increased ( t=6.127, P<0.01) in PSD group.Compared with the PSD group, the expression of TGF-β1 in FE group increased significantly ( t=4.417, P<0.01). Conclusion:Foraging exercise can improve the depressive behavior symptoms of ischemic stroke rats after chronic stress, and its mechanism may be related to the increasing expression of TGF-β1, which can alleviate the inflammatory reaction in hippocampus.