Effect of IGF-1 on cognitive function and the regulation of IGF-1/PI3K/Akt signal pathway in hippocampus of sleep deprived mice / 中华行为医学与脑科学杂志

ABSTRACT

Objective:To explore the effects of IGF-1 on cognitive function in REM sleep deprivation model mice and its possible mechanism.Methods:C57BL/6J mice aged 8 weeks were randomly divided into 4 groups with 6 mice in each group.They were Normal control group (CC group), REM sleep deprivation 5d group (SD group), REM sleep deprivation 5d+ Intraperitoneal injection of IGF-1 group (SD+ IGF-1 group), and REM sleep deprivation 5d+ Intraperitoneal injection of PBS group (SD+ PBS group). The Morris water maze was used to test the cognitive function of all mice.The content of IGF-1 in mice hippocampus was detected by Elisa, and the expression level of TNF-α, IL-1β and IL-6 mRNA in mice in hippocampus was determined by RT-qPCR.Western blot was used to detect the protein expression levels of p-GSK3β, GSK3 beta, p-Akt, Akt, Bcl-2 and Caspase-9 in mice hippocampus of each group.Results:The time in the target quadrant and the number of times across the platform of the SD group ((11.87±1.67)s, (12.50±5.54) times, respectively)was lower than that of the CC group((19.40±1.75)s, (22.17±8.21) times, respectively), the difference was statistically significant( t=8.71, 2.26, both P<0.05). The time in the target quadrant and the number of times across the platform of the SD+ IGF-1 group ((18.11±1.12)s, (21.83±10.26) times), which were higher than those in the SD+ PBS group ((10.60±1.36)s, (11.50±3.94) times). The difference was statistically significant( t=8.69, 2.42, both P<0.05). The expression of IGF-1 protein in the hippocampus of SD group ((579.38±55.95) pg/mg) was lower than that of CC group ((729.13±79.46)pg/mg), and the difference was statistically significant ( t=3.83, P<0.05). The expression of IGF1 protein in the hippocampus of SD+ IGF-1 group((665.50±55.21)pg/mg) was significantly higher than that of SD+ PBS group ((563.40±76.33)pg/mg), the difference was statistically significant ( t=2.61, P<0.05). The expression of p-GSK3 beta protein (1.51±0.02) in mice hippocampus of SD group was higher than that of CC group (1.47±0.03), and the expression of p-Akt (0.92±0.04) was lower than that of CC group (1.18±0.05), The difference was statistically significant ( t=3.07, t=10.85, both P<0.05). The expression of Caspase-9 in mice hippocampus of SD group(0.65±0.03)was higher than that of CC group (0.60±0.02). The expression of Bcl-2 in mice hippocampus of SD group (0.93±0.03) was lower than that of CC group (1.00±0.04), and the difference was statistically significant ( t=3.65, 3.98, both P<0.05). The expression of p-Akt and p-GSK3β protein in mice hippocamps of SD+ IGF-1 group( (1.20±0.04), (1.57±0.03)) was increased compared with those of SD+ PBS group ((0.92±0.05), (1.51±0.03)), and the difference was statistically significant ( t=3.98, 11.49, both P<0.05). The expression of Caspase-9 in mice hippocamps of SD+ IGF-1 group (0.60±0.03) was decreased compared with that of SD+ PBS group (0.67±0.02). The expression of Bcl-2 in mice hippocampus of SD+ IGF-1 group (1.00±0.03) was increased compared with SD+ PBS group (0.93±0.02), and the difference was statistically significant ( t=5.19, 3.83, both P<0.05). The expression level of TNF-α, IL-1β, and IL-6 mRNA in mice hippocampus of SD group ((3.36±0.67), (2.00±0.40), (4.63±0.72)) were increased compared with CC group with statistically significant differences ( t=8.58, 6.15, 2.37, all P<0.05). The expression level of TNF-α, IL-1β, and IL-6 mRNA in mice hippocampu of SD+ IGF-1 group ((1.21±0.25), (1.08±0.33), (0.98±0.47)) were lower than those of SD+ PBS group ((3.86±0.79), (2.11±0.30), (4.43±0.67)), with statistically significant differences ( t=7.81, 5.76, 10.39, all P<0.05). Conclusion:The cognitive function of mice decreased after REM sleep deprivation and improved after IGF-1 supplementation, which may be related to the activation of PI3K / Akt signal pathway by IGF-1, thus reducing apoptosis related signal transduction and inflammatory factor expression.