Difference in the Pathological Mechanisms of Intermittent Hypoxia-Induced Cognitive Impairments in Normotensive and Hypertensive Rat Strains

• Main Authors: Man-Ting Hsu, 徐曼婷
• Other Authors: Cheryl C.H. Yang
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/e8d2f8

碩士 === 國立陽明大學 === 腦科學研究所 === 107 === Background: Sleep apnea causes intermittent hypoxia (IH) and sleep fragmentation, and induces autonomic dysfunction and hypertension, all of which are the risks of dementia. However, the interaction between those physiological parameter during IH and cognitive function after IH are difficult to explore clearly due to a lack of successive study. Hypothesis: WKYs and SHRs during IH are associated with increased blood pressure (BP), autonomic dysregulation and sleep fragmentation that result in cognitive impairments, which are different in WKYs and SHRs. Materials and Methods: To simulate human sever sleep apnea that WKYs and SHRs were exposed to 30 IH/hour for 8 hours during the light cycle daily for 2 weeks, and simultaneously measured physiological signals, and then examined cognition-related behaviors in the 8-arm radial maze. Result: Compared with WKYs, IH group in SHRs had a more increase in mean arterial pressure (MAP) than room air (RA) control group. The IH group had a lower R-R interval than RA group during sleep in WKYs and SHRs. In both WKYs and SHRs, high frequency power (HF) in wakefulness, low frequency power to high frequency power ratio (LF/HF) and normalized low frequency power (LF%) during sleep was higher in IH group than RA group. Compared with WKYs, SHRs had a lower baroreflex sensitivity. Additionally, the IH group of WKYs and SHRs spent less time in sleep, more time in wakefulness and that had more interruptions and less delta power% of quiet sleep (QS) during the light period than did RA group. Compared with WKYs, SHRs spent more time in paradoxical sleep and had more interruptions of QS. In the 8-arm radial maze test, IH group of WKYs had more numbers of error and less correct% than did RA group. And there were no difference between WKYs and SHRs. Correlated analysis revealed that MAP was correlated with numbers of correct in WKYs. And LF/HF, LF% and interruptions of QS were correlated with numbers of error in WKYs. Conclusions: During IH intervention, SHRs had a significant increase in BP, and both WKYs and SHRs had autonomic dysfunction, changed sleep structure and decreased sleep quality. Moreover, the intervention of IH resulted in cognitive impairments in WKYs. It might have poor cognitive function in SHRs, so there is no difference between IH and RA. Furthermore, BP, sympathetic activity and interruptions of QS during IH were correlated with cognitive function in WKYs. But cardiovascular variables did not appear to be related to cognitive function in SHRs.