Protective effect of rapamycin on cognitive function in lupus mice by regulating Cysteine rich 61 and autophagy in hippocampus / 中华风湿病学杂志

ABSTRACT

Objective:To investigate the effects of rapamycin (RAPA) on the cognitive function of lupus mice by regulating Cysteine rich 61 (Cyr61) and autophagy.Methods:MRL/lpr lupus mice were randomly divided into lupus group and rapamycin + lupus group, wild-type C57BL/6 mice were randomly divided into normal control group and rapamycin group with six mice in each group, RAPA + lupus group and rapamycin group were intraperitoneally injected with RAPA (2.0 mg/kg). The lupus group and the normal control group were injected with equal amounts of dimethyl sulfoxide (DMSO). Morris water maze was used to observe the cognitive function of mice. Western blotting was used to detect the expression of Cyr61, Programmed cell death-1 (Beclin-1), Microtubule associated protein 1 light chain3B (LC3B). Hematoxylin-eosin (HE) staining was used to observe the pathological changes in the hippocampus. The changes of neurons and bodies in hippocampus were observed by Nissl staining. The localization and expression of Cyr61 and LC3B in hippocampus were detected by immunofluorescence staining. One-way analysis of variance (ANOVA) was used between groups, and LSD-T test was used for pairwise comparison.Results:Western blotting results showed thatthe protein expression of Cyr61 (0.99±0.15) was significantly increased ( P=0.011), and the protein expression of Beclin-1 (0.64±0.04) and LC3B(0.54±0.05) was significantly decreased in lupus group ( P=0.025, P= 0.008) when compared with normal control group (0.73±0.08, 0.81±0.12, 0.80±0.03). The expressions of Cyr61 (0.75±0.05, 0.75±0.08), Beclin-1 (0.84±0.08, 0.92±0.04) and LC3B (0.93±0.16, 0.76±0.08) in rapamycin group and rapamycin + lupus group were not significantly changed ( P>0.05). Compared with rapamycin group, the protein expression of Cyr61 (0.99±0.15) was significantly increased ( P=0.016), and Beclin-1 (0.64±0.04), LC3B (0.54±0.05) was significantly decreased in lupus group ( P=0.013, P=0.001). The expressions of Cyr61 (0.75± 0.08), Beclin-1 (0.92±0.04) and LC3B (0.76±0.08) were not significantly changed in rapamycin+lupus group ( P=0.999, P=0.241, P=0.062). Compared with lupus group, the expression of Cyr61 (0.75±0.08) protein in rapamycin+lupus group was significantly decreased ( P=0.016), and the expression of Beclin-1 (0.92±0.04) and LC3B(0.76±0.08) protein were significantly increased ( P=0.002, P=0.017). Immunofluorescence results showed that Cyr61 and LC3B were mainly expressed in the cytoplasm of hippocampal neurons, and the quantitative detection results were consistent with western blot results, the differences were statistically significant ( P=0.025, P=0.032). HE staining showed that the levels and number of cells in the hippocampus of mice with lupus were reduced, and the arrangement was sparse, and the nuclei were hyperchromatic, showing nuclear pyknosis and migration. The results of Nissl staining showed that there were relatively fewer Nissl bodies, loose arrangement of neurons and vacuolar areas in some cells, which were improved after RAPA treatment in lupus mice. Conclusion:RAPA can protect the cognitive function of lupus mice by inhibiting the expression of Cyr61 in hippocampus and promoting autophagy.