Abstract:

Objective To discuss the effect of nucleoredoxin （NXN） in medial prefrontal cortex （mPFC） region of the mice with post-stroke depression （PSD）， and to clarify its possible mechanism. Methods A total of 42 mice among 80 C57BL/6 mice were randomly divided into NXN over-expression adeno-associated virus infection group （AAV-NXN-OE group， n=21） and negative control adeno-associated virus infection group （AAV-NC group， n=21）. The remaining mice were divided into sham operation group （n=20） and PSD group （n=18）. After injectied with NXN over-expression adeno-associated virus， the remaining mice in AAV-NXN-OE group and AAV-NC group were further divided into PSD+AAV-NC group （n=18） and PSD+AAV-NXN-OE group （n=18）. Three weeks before surgery， NXN over-expression adeno-associated virus was injected into the mPFC region of brain tissue of the mice by stereotaxic method， and the expression of the virus in mPFC region of the mice was observed under microscope. Western blotting method was used to detect the expression levels of NXN protein in brain tissue of the mice in various groups； middle cerebral artery occlusion （MCAO） model was established by thread embolism method， followed one week post-surgery by three weeks of chronic unpredictable moderate stress （CUMS） combined with isolation feeding to construct the PSD mice model. During modeling， the body weight changes of the mice were monitored. After modeling， sucrose preference test， tail suspension test， and forced swim test were used to observe the depressive-like behavioral changes of the mice in various groups； biochemical method was used to detect the levels of malondialdehyde （MDA） and reduced glutathione （GSH）， and superoxide dismutase （SOD） activities in mPFC region of brain tissue of the mice in various groups； DCFH-DA fluorescence probe labeling method was used to detect the reactive oxygen species （ROS） levels in mPFC region of brain tissue of the mice in various groups； Western blotting method was used to detect expression levels of NXN protein in mPFC region， amygdala， and hippocampus tissues of the mice in various groups. Results A large amount of green fluorescence was observed in the mPFC region in brain tissue of the PSD mice， indicating successful infection and expression of AAVs virus labeled with ZsGreen green fluorescent protein in mPFC region in brain tissue of the PSD mice. Compared with AAV-NC group， the expression level of NXN protein in mPFC region in brain tissue of the mice in AAV-NXN-OE group was significantly increased （P<0.05）. Compared with sham operation group， the body weight of the mice in PSD group was increased slowly （P<0.05）， the sucrose preference rate was significantly decreased （P<0.05）， and the immobility time of the mice in the tail suspension test and forced swim test was significantly increased （P<0.05）. Compared with sham operation group， the sucrose preference rate of the mice in PSD+AAV-NC group was significantly decreased （P<0.05）， and the immobility time in tail suspension test and forced swim test was significantly increased （P<0.05）. Compared with PSD+AAV-NC group， the sucrose preference rate of the mice in PSD+AAV-NXN-OE group was significantly increased （P<0.05）， and the immobility time of the mice in tail suspension test and forced swim test was significantly decreased （P<0.05）. Compared with sham operation group， the MDA and ROS levels in mPFC region in brain tissue of the mice in PSD+AAV-NC group were significantly increased （P<0.05）， while the GSH level and SOD activity were significantly decreased （P<0.05）. Compared with PSD+AAV-NC group， the levels of MDA and ROS in mPFC region in brain tissue of the mice in PSD+AAV-NXN-OE group were significantly decreased （P<0.05）， while the GSH level and SOD activity were significantly increased （P<0.05）. Compared with sham operation group， the expression level of NXN protein in the mPFC region of brain tissue of the mice in PSD group was significantly decreased （P<0.05）， the expression levels of NXN protein in amygdala and hippocampus tissue had no statistically significant difference （P>0.05）. Conclusion Over-expression of NXN in mPFC region of brain tissue of the mice can improve the depressive-like behavior in the PSD mice， and its mechanism is possibly related to regulating the redox balance.

Key words: Post-stroke depression, Nucleoredoxin, Medial prefrontal cortex, Redox balance