OBJECTIVE: Alzheimer's disease (AD), also known as senile dementia, is a neurodegenerative disease associated with aging and with cognitive decline as the main clinical manifestation. We selected SAMP8 mice as the study subjects and SAMR1 mice as normal controls to explore the effects of rich rehabilitation training on SAMP8 learning and memory ability and mental behavior, and provide a theoretical basis for the application of enriched environment and rehabilitation training to prevent and delay the occurrence of AD. . METHODS: Forty male SAMP8 and SAMR1 were randomly divided into rich environmental group (EE), standard environmental group (SE), rich environment combined with running cage exercise group (ER-1), and rich environment combined with skill exercise group ( ER-2).
Behavioral evaluation after 2 months: learning and memory evaluation using Morris water maze (MWM) experiment and step down experiment, mental behavior evaluation using autonomous activity test and elevated cross maze (Elevated-plus maze, EPM )experiment. Immunohistochemistry was used to detect the positive expression of β-amyloid (Ap), synaptophysin (Syp), brain-derived neurotrophic factor (BDNF), neuronal nitric oxide and enzyme (nNOS) in hippocampus. RT-PCR was used to detect mRNA expression of β-amyloid precursor protein (APP) and brain-derived neurotrophic factor (BDNF) in hippocampus. Radioimmunoassay measures plasma adrenocorticotropic hormone (ACTH) and serum cortisol (Cor) levels. Beijing Zhongshi Di Chuang Technology Development Co., Ltd. produces an elevated cross maze instrument, model ZS-DSG
result:
1. Enriching rehabilitation training to enhance learning and memory ability of SAMP8 mice
1.1 SAMP8 and SAMRl mice SE group Moms water maze and platform test comparison: Moms water maze showed that the average escape latency of SAMP8 mice was significantly longer than SAMR1 (F=83.364, p<0.001), but from day 2, daily comparison There was progress in the previous day (F=129.79, P<0.001). The number of times SAMP8 traversed the platform was significantly lower than that of SAMR1 (Z=3.293, P<0.01). The platform test showed that the learning scores of SAMP8 on the first day were not significantly lower than those of SAMRl (Z=0.207, P>0.05), while the memory scores on the second day were significantly lower than those of SAMR1 (Z=2.796, P<0.01).
1.2 SAMP8 mouse ER group (ER-1, ER-2) compared with SE group Morris water maze and platform test: Morris water maze showed that the average escape latency of ER-1 and ER-2 groups was significantly shorter than that of SE group (P< 0.05); the number of crossing the platform was significantly increased in the ER-2 group (P<0.05), but there was no significant difference in the ER-1 group (P>0.05). The platform test showed that the first day of ER-1 group and the second day of memory performance were significantly improved compared with the SE group (P<0.05); while the ER-2 group had improved academic performance on the first day (P>0.05). ), the memory performance improved significantly on the second day (P<0.05).
1.3 SAMP8 mouse EE group and SE group Moms water maze and platform test comparison: Morris water maze showed: the average escape latency of EE group was significantly shorter than that of SE group (P<0.05); the number of crossing platforms increased compared with SE group (the average rank of EE group) The time was 56.95, the average rank of the SE group was 34.80) but not statistically significant (P>0.05). The platform test showed that the EE group had improved academic performance on the first day (P<0.05), and the second day did not improve the memory score (P>0.05).
2. Enrich rehabilitation training to improve mental behavior of SAMP8 mice
2.1 SAMP8 and SAMR1 mice SE group autonomic activity and elevated plus maze test comparison: Autonomic activity test showed that the number of spontaneous activities of SAMP8 mice was lower than that of SAMR1, but it was not statistically significant (SAMP8 average rank 47.34, SAMR1 average rank 53.66, Z = 1.089, p > 0.05). The elevated cross maze showed that the open arm residence time of SAMP8 mice was significantly shorter than that of SAMR1 (the average rank of SAMP8 was 40.76, the average rank of SAMR1 was 60.24, Z=3.358, P<0.05).
2.2 SAMP8 mouse ER group (ER-1, ER-2) compared with SE group autonomic activity and elevated plus maze test: Autonomic activity test showed that the number of spontaneous activity ER-1 group was significantly increased compared with SE group (P<0.05). The ER-2 group was more than the SE group but not statistically significant (P>0.05). The elevated cross maze showed that the open arm stay time ER-2 group was significantly longer than the SE group (P<0.05); the ER-1 group was compared with the SE group. Prolonged but not statistically significant (P>0.05).
2.3 SAMP8 mouse EE group and SE group autonomic activity and elevated plus maze test comparison: Autonomic activity test and elevated plus maze showed that the EE group had more autonomic activity and longer open arm stay time than the SE group, but there was no statistical significance ( P>0.05).
3. Enriched rehabilitation training to reduce the expression of Aβ, Syp protein and hippocampus APP mRNA in hippocampus of SAMP8 mice
3.1 HE staining and immunohistochemical staining of hippocampal neurons in SE group of SAMP8 and SAMR1 mice: HE staining showed degeneration and death of some neurons in hippocampus of SAMP8 mice, which showed nuclear condensation and vacuolar degeneration: hippocampal neurons of SAMR1 mice The shape is normal. Immunohistochemical staining showed that the Aβ and Syp positive reactions in the hippocampus of SAMP8 and SAMR1 mice were brownish-yellow particles distributed in the neuronal membrane and cytoplasm. Aβ immunopositive products were evident in hippocampal CA3 and CA1 regions, and Syp immunopositive products were evident in hippocampal CA3 and CA4 regions.
3.2 SAMP8 and SAMR1 mice SE group were positive for Aβ and Syp expression in hippocampal CA3 region and hippocampus APP mRNA expression: Aβ immunopositive expression of SAMP8 (0.274±0.017) was significantly higher than SAMR1 (0.193±0.015) (P<0.01); The positive expression of SAMP8 (0.156±0.008) was significantly lower than that of SAMR1 (0.199±0.014) (P<0.01). The expression of APP mRNA SAMP8 (0.867±0.068) was significantly higher than that of SAMR1 (0.469±0.062) (p<0.05).
3.3 SAMP8 mouse ER group (ER-1, ER-2) and SE group hippocampal CA3 area Aβ, Syp immunopositive expression and hippocampal APP mRNA expression comparison: Aβ immunopositive expression of ER-1, ER-2 group (0.192 ± 0.018) , 0.198±0.014) was significantly lower than that of SE group (0.274±0.017) (P<0.05); Syp immunopositive expression of ER-1, ER-2 group (0.227±0.019, 0.225±0.019) compared with SE group (0.156±0.008) Significantly increased (P<0.05); APP mRNA expression in ER-1, ER-2 group (O.574±0.059, 0.692±0.031) was lower than that in SE group (0.867±0.068) but not statistically significant (P>0.05). The effect of rehabilitation training on learning memory and mental behavior
3.4 SAMP8 mouse EE group and SE group hippocampal CA3 area Aβ, Syp immunopositive expression and hippocampal APP mRNA expression comparison: Aβ immunopositive expression EE group (0.202±0.014) was significantly lower than SE group (0.274±0.017) (P<0.05) Syp immunopositive expression in EE group (0.202±0.004) was significantly higher than that in SE group (0.156±0.008) (P<0.05); APP mRNA expression in EE group (0.715±0.117) was lower than SE group (0.867±0.068) but no statistics. Academic significance (P>0.05).
4. Enriched rehabilitation training to enhance the expression of BDNF, nNOS protein and hippocampal BDNF mRNA in hippocampus of SAMP8 mice
4.1 Immunohistochemical staining of hippocampal neurons in SAMP8 and SAMR1 mice in the SE group.
4.2 SAMP8 and SAMR1 mice SE group were positive for nNOS immunoreactivity and BDNF mRNA expression in hippocampal CA1 region of BDNF and CA4 regions.
4.3 SAMP8 mouse ER group (ER-1, ER-2) and SE group hippocampal CA1 region BDNF, CA4 region nNOS immunopositive expression and hippocampal BDNF mRNA expression. 4.4 The positive expression of nNOS and the expression of BDNF mRNA in hippocampus of BDNF and CA4 in hippocampal CA1 region of EE group and SE group in SAMP8 mice.
5. Enriched rehabilitation training to increase plasma ACTH and serum Cor levels in SAMP8 mice
5.1 Comparison of plasma ACTH and serum Cor levels in SE group of SAMP8 and SAMR1 mice.
5.2 Comparison of plasma ACTH and serum Cor levels in SAMP8 mouse ER group (ER-1, ER-2) and SE group.
5.3 SAMP8 mouse EE group and SE group plasma ACTH and serum Cor levels.
in conclusion:
1. Five-month-old SAMP8 mice showed significant impairment of learning and memory, especially memory loss. Enriched rehabilitation training can significantly improve the learning and memory ability of SAMP8 to improve learning ability. The enrichment of SAMP8 spatial learning and memory ability after rehabilitation training is close to that of SAMR1 of the same age. The enriched environment combined with the running cage movement improved the SAMP8 spatial learning and memory ability better than the rich environment combined with skill movement. The effect of rehabilitation training on learning memory and mental behavior
2. SAMP8 mice at 5 months of age had depression and anxiety, which showed a significant decrease in the number of spontaneous activities and a significant shortening of the open arm stay time of the elevated cross maze. After enriching the rehabilitation training for 2 months, the number of spontaneous activities of SAMP8 mice increased significantly, and the staying time of open arms was significantly prolonged. We believe that enriched rehabilitation can improve the mental behavior of SAMP8 mice.
3. The neuronal cells of the hippocampus of SAMP8 mice at 5 months of age were degenerated and died. Increased expression of Aβ and APP in hippocampus and decreased expression of Syp may be the main reason for the decline of learning and memory ability in SAMP8 mice. Rich rehabilitation training can improve the learning and memory ability of SAMP8 by reducing Aβ deposition in hippocampus and increasing Syp expression.
4. The decline of learning and memory ability in SAMP8 mice may also be related to the decreased expression of BDNF and nNOS in hippocampus. Decreased expression of BDNF in hippocampus mediates a decrease in the expression of nNOS, which in turn affects the formation of LTP. Enriched rehabilitation training improves the learning and memory ability of SAMP8 by increasing the expression of BDNF and nNOS in hippocampus.
5. SAMP8 mouse plasma ACTH and serum cortisol levels are worthy of further discussion. We found that SALT8 plasma ACTH and serum cortisol levels were significantly lower than SAMR1 at 5 months of age. Enriched rehabilitation can improve the levels of ACTH and serum cortisol in SAMP8 plasma, improve the function of HPA axis, improve their learning and memory ability, and alleviate depression and anxiety. Beijing Zhongshi Di Chuang Technology Development Co., Ltd. produces an elevated cross maze instrument, model ZS-DSG
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