碩士 / 中國醫藥大學 / 醫學研究所碩士班 / 96 / Severe hypoxia would alter nitric oxide synthase activity to cause neuronal degeneration or cell death via the overproduction of nitric oxide and impingement on metabolic pathways of related neurochemicals. Fortunately, the anti-oxidative enzymes and calcium buffering system in normal organism attenuate the free radical molecule that produced in cell metabolic process, suggesting it sustains an important role on the oxidative stress and cell protection. Furthermore, recent studies have shown that melatonin and coenzyme Q10 (CoQ10) could attenuate hypoxia or ischemia-induced nerve injuries by decreasing the production of free radicals. The present study, by using immunohistochemical and western blotting methods, aimed to explore whether melatonin and CoQ10 pre-treatment following hypobaric hypoxia might affect the diversion in nitric oxide system, Mn SOD and Cu/Zn SOD of anti-oxidative enzymes and calbindin-D28K/parvabulmin of calcium buffering system in hippocampal neurons of young albino rats. At the same time, we hope to understand that damaged neurons might have protective effect through regulating anti-oxidative enzymes and calcium buffering system.
Firstly, the high altitude chamber with 48 Torr of the partial oxygen concentration (pO2) (i.e., 0.303 atm at 9000 m in height) for 7 h as hypobaric hypoxic exposure was selected as the experimental paradigm to determine the effect of hypoxic exposure on the expression patterns of related neurochemicals of hippocampal neurons. The results revealed that after hypoxic exposure, the immunoreactivities of neuronal nitric oxide synthase (nNOS), endothelial nitric oxide synthase (eNOS), nitrotyrosine (Ntyr), and NMDA receptor-1 (NR-1) of nitric oxide system, Mn SOD and Cu/Zn SOD of anti-oxidative enzymes as well as calbindin-D28K/parvabulmin of calcium buffering system in the hippocampus were up-regulated. The neuronal loss was detected in the hippocampus 3 days following hypoxic exposure. The extent of NOS up-regulation was positively correlated with the severity of neuronal damage.
Furthermore, the melatonin and CoQ10 pre-treatment coupled with hypobaric hypoxic exposure model to determine the related neurochemical expression in the hippocampus. Prior to hypoxic treatment, adult rats were pretreated with melatonin (100 mg/kg, i.p.) and CoQ10 (10 mg/kg, i.p. for 10 days) before they were exposed to the altitude chamber for 7 h, and sacrificed after 0 h, 4 h, 1, 3 and 7 days of reoxygenation. The results showed that the immunohistochemistry and immunoblotting densitometry of the nNOS, eNOS, Ntyr, and NR-1 in the nitric oxide system increased from 0 h to 3 days of reoxygenation, so are the immunoreactivity of anti-oxidative enzymes (Mn SOD and Cu/Zn SOD) and the immunoreactivity of calcium buffering protein (calbindin and parvalbuminin) in the hippocampus. However, the hypoxic-induced increase in nNOS, eNOS, Ntyr, and NR-1 protein expression were significantly depressed in the hypoxic rats treated with melatonin or CoQ10. The expression patterns of related neurochemicals and the numbers of neuronal survival were all more significant in the melatonin and CoQ10 pre-treatment coupled with hypobaric hypoxic treated rats as compared with those of hypobaric hypoxic exposure only ones.
In summary, by the use of melatonin and CoQ10 pre-treatment coupled with hypoxic exposure as experimental models, the present study was clearly demonstrated the relationship between the related neurochemical expression and neuronal damage in the hippocampal neurons. The results obtained from the present study will not only help us to better understand the physiological significance of melatonin and CoQ10 pre-treatment on the hypoxic exposure, but also document the possible functional roles of related neurochemicals i.e. free radical, anti-oxidative enzymes and calcium buffering system for during the process of neuronal degeneration.
| Identifer | oai:union.ndltd.org:TW/096CMCH5534019 |
| Date | January 2008 |
| Creators | Chia-Jou Lai, 賴佳柔 |
| Contributors | I-Hua Wei, 魏一華 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 243 |
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