Effects Of Aging And Hypertension On Brain Alff And Spatial Cognitive Ability

Objective: Using Amplitude of low-frequency(ALFF),an analysis method of Resting-state function MRI(Rs-f MRI),and Morris Water Maze investigate changes in brain activity and spatial cognitive ability in elderly spontaneously hypertensive rats(SHR).Methods: In this study,SHR and its control group Wistar-Kyoto rats(WKY)were divided into four week-old groups : 10-week-group(SHR,n=5;WKY,n=6),20-week-group(SHR,n=6;WKY,n=6),40-week-group(SHR,n=4;WKY,n=5),60-week-group(SHR,n=9;WKY,n=7).T2 WI and BOLD data were collected by 7.0T MRI after anesthesia in all rats.MATLAB and software packages such as SPM12 were used to process the functional data,calculate the ALFF value of each brain region of rats,and conduct statistical analysis.All rats used Morris Water Maze for positioning navigation experiment and space exploration experiment,and the results were analyzed and counted to evaluate the cognitive function of rats.Results:1.The ALFF value of 60-week SHR in the left Cingulate cortex 1 area(Cg1)at the bilateral anterior cingulate cortex(ACC)was decreased compared with that of SHR at other weeks.2.The ALFF value of SHR at 10,20 and 40 weeks increased compared with that of the same-week WKY in Cg1 at the bilateral ACC,while the ALFF value of the 60-week SHR in the left ACC was lower than that of the same-week WKY.3.The ALFF value of 10-week SHR at left Retrosplenial granular b cortex(RSGb)was higher than that of the same-week WKY.4.The results of SHR Water Maze at 10,20 and 40 weeks had no significant statistical difference and were significantly better than that at 60-week-group.There was no significant statistical difference between WKY Water Maze results at 40 and 60 weeks.5.The results of 40-week SHR were significantly better than 40-week WKY,but there was no significant statistical difference between Water Maze scores at 60-week SHR and WKY.Conclusions:1.The combined effect of long-term hypertension damage and aging will lead to a function decrease in the Cg1 at ACC of SHR.Only short-term hypertension or aging may not cause this change,and the reduction of the function of this ACC may be one of the reasons leading to the decline of spatial cognition in rats.2.Early hypertension may reduce the function of RSGb at the posterior cingulate cortex of SHR,but the persistent state of hypertension may not further impair its function.