Effects of Middle Cerebral Artery Occlusion on Cardiac Autonomic Function and Sleep Pattern in Freely Moving Male, Female and Ovariectomized Rats

• Main Authors: Hsing-Hui Su, 蘇倖慧
• Other Authors: Cheryl C. H. Yang
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/72945378615433457827

碩士 === 國立陽明大學 === 腦科學研究所 === 99 === Background and Purpose－The Chronic autonomic function and sleep architecture changes in patients post-stroke were not fully conclusion. Using a well-controlled middle cerebral artery occlusion (MCAO) model, together with wireless polysomongraphic recordings and the techniques of sleep and heart rate variability analysis, this study aimed to investigate the long-term effects on sleep patterns and autonomic function in free moving rats after MCAO. As Estrogen to cardiovascular disease, there are different results of positive effects on autonomic system and sleeping respectively. Therefore when looking into second part, we will discuss whether there will be any improvement effect on autonomic system or sleeping of estrogen on post-stroke female ovariectomized rat. Methods－Male and female Wistar-Kyoto rats (WKY) were usesd in this study. And the female rats were divided into three groups: sham-ovariectomized (Female), ovariectomized (OVX), and ovarian removed with estrogen therapy (OVX+E). First, all animals were implanted with electrodes to wirelessly record electroencephalogram (EEG), electromyogram (EMG) and electrocardiogram (ECG) information, which then were used to analyze sleep patterns and heart rate variability (HRV). After 7-10 days, the rats were divided into two groups; one group underwent MCAO surgery, while the other group underwent sham surgery. Then, the HRV, sleep patterns and EEG frequency power of these groups were compared over the following 4 weeks. Results－Compared with sham-MCAO group, the MCAO significantly decreased accumulated quiet sleep (QS) time over 24 h during the third week. The percentage of QS time, average duration of the QS stage and the delta power of the EEG were also significantly decreased in MCAO group during the dark period. In addition, the high frequency power of the HRV (an index of cardiac vagal activity) during active waking and paradoxical sleep were significantly suppressed during the first to third weeks after MCAO. The female, OVX, and OVX+E got the significant brain infarction after MCAO, and the infarction volume of OVX+E seems smaller than the others. Hoever, the sleep time% of female, OVX, and OVX+E were not influenced significantly between each other. HF of HRV after MCAO was higher in the OVX+E group than in OVX. And the EEG performance in OVX+E group was also better than the other two groups. Conclusions－This study showed that the long-term effects of ischemic stroke injury involve significant changes to the rats’ sleep/wake patterns, including decreased QS time and changed autonomic functioning so that there is impaired cardiac vagal activity after MCAO. The second part experiment, suggest that estrogen could partially improving vagal function and neuron function after MCAO. But it still needs more researches to confirm.