臺灣博碩士論文加值系統

不同海拔其環境因子如溫度和氧氣等會隨之改變。同種間的不同個體通常會因生存環境的不同而在形態、行為、生殖或生理上產生相應性變化，以符合生存的需要。本研究從分子生物學角度，對其心血管系統生理機制在海拔適應過程扮演之角色進行研究，藉由探討各海拔族群一氧化氮合成酶與血管緊縮素接受器基因表現變化，進一步瞭解此等物質參與動物在不同海拔心血管功能適應之角色。
本實驗以台灣本島垂直分佈較廣的嚙齒動物刺鼠(Niviventer coxingi)作為研究對象。並且在天然的情況下進行研究，希望藉此來提供一個具生態背景的個體不同海拔生理適應，並藉由低海拔馴養，進一步瞭解此生理適應之意義。不同海拔和馴養期間刺鼠的體重、血壓、心跳和各採樣組織中(大腦皮層、下視丘、延腦、肺、心、主動脈、腎上腺及腎)神經性(nNOS)、內皮細胞性(eNOS)或誘發性(iNOS)一氧化氮合成酶與第一型或第二型血管緊縮素接受器(ATI or ATII receptor) mRNA含量被測量並進行分析。結果顯示：1.體重在不同海拔族群有顯著差異(750 m: 178.6±35.8 g and 1600 m: 122.3±29.3 g)，海拔越高體重顯著下降。原棲息於海拔750公尺族群於馴養期間體重有下降趨勢，而原棲息於海拔1600公尺族群則並無統計差異。2.血壓與心跳方面，不同海拔族群及馴養期間並無統計差異。3.ATII receptor mRNA 表現量在各組織中皆少（在可測量範圍之下），因此在以下部分不再敘述。各組織中一氧化氮合成酶與第一型血管緊縮素接受器基因表現，在不同海拔族群間並無顯著差異。但各組織中一氧化氮合成酶與第一型血管緊縮素接受器基因表現在馴養後有顯著差異，其中原棲息於750公尺族群nNOS在心臟之基因表現有逐漸減少趨勢，ATI接受器在腎臟基因表現在馴養三個月時先減少但馴養五個月後回到野外的表現量。在原棲息於1600公尺族群iNOS在心臟之基因表現有逐漸減少趨勢。
綜合上述結果，刺鼠的血壓、心跳和組織中第一型血管緊縮素接受器與不同亞型一氧化氮合成酶基因表現，並不因其棲息海拔不同而有差異。若無其他補償機制，較高海拔個體對氧氣的利用勢必受到低氧環境的限制，而高海拔個體體重偏低可能與低氧環境的適應有關。

Environmental factors such as ambient temperature and oxygen availability are variation in different altitude. Individuals within a species, living in variable environments often display phenotypic plasticity by changing morphology, behavior, reproduction, and physiology to meet the individual’s ability to survive demanding conditions. This study was aimed to investigate the expression of angiotensin receptor and nitric oxide synthase genes of individuals resided at differential altitude, in an attempt to find the role of these molecules in cardiovascular adaptation to altitude.
Spiny rats (Niviventer coxingi) are widely elevational distributed in Taiwan. They were studied under more natural conditions to provide an ecological context data on physiological plasticity between the different altitudes. I examined the body weight, blood pressure, heart rate and the expression of angiotensin type 1 or type 2 (ATI or ATII) receptor and nitric oxide synthase (NOS) genes in tissues (cortex, hypothalamus, medulla, lung, heart, aorta, adrenal gland and kidney) of spiny rats resided at differential altitude and during the domesticated period. The results of the study showed that spiny rats resided at higher altitudes were lighter than that at lower altitudes (750 m: 178.6±35.8 g and 1600 m: 122.3±29.3 g). Spiny rats resided at 1600 m did not change their body weight during the domesticated period, but rats resided at 750 m gradually reduced their body weight. Blood pressure and heart rate were similar between rats resided at different altitudes, and did not change during the domesticated period. ATI receptor, endothelelial NOS (eNOS), inducible NOS (iNOS) and neuronal NOS (nNOS) mRNA expression in these tissues were similar between rats resided at different altitudes. ATII receptor mRNA expressed in these tissues under our detection limit. Rats resided at 750 m declined the level of nNOS in heart, when they were domesticated at 100 m. ATI receptor in kidney reduced at first, but subsequently increase to same level like native. Moreover, rats resided at 1600 m declined the level of iNOS in heart, when they were domesticated at 100 m.
Together, these results indicate that heart rate, blood pressure, ATI receptor, eNOS, iNOS and nNOS mRNA expressions in these tissues were similar between rats resided at different altitudes. If there was no other compensatory mechanism, individuals resided at higher altitude were limited in low available oxygen. A reduced body weight could help in adaptation to high-altitude.

ABSTRACT (IN CHINESE)…………………………………………………………………………...2
ABSTRACT (IN ENGLISH)…………………………………………………………………………...4
INTRODUCTION………………………………………………………………………………………6
THE PURPOSE OF THIS STUDY…………………………………………………………………..10
MATERIALS AND METHODS……………………………………………………………………...12
STUDY AREA ………………………………………………………………………………………12
EXPERIMENTAL ANIMALS……………………………………………………………………..12
EXPERIMENTAL MEASUREMENTS…………………………………………………………...13
RT-PCR (REVERSE TRANSCRIPIPTION-POLYMERASE CHAIN REACTION)……… 13
1.TOTAL RNA EXTRACTION FROM TISSUE SAMPLES ………………………………13
2.REVERSE TRANSCRIPTASE REACTION………………………………………………14
3.POLYMERASE CHAIN REACTION……………………………………………………...15
BLOOD PRESSURE AND HEART RATE …………………………………………………… 15
STATISTICAL ANALYSES………………………………………………………………………..16
RESULTS………………………………………………………………………………………………18
BODY WEIGHT…………………………………………………………………………………….18
BLOOD PRESSURE AND HEART RATE……………………………………………………….19
EXPRESSION OF NITRIC OXIDE SYNTHASE AND ANGIOTENSIN RECEPTOR GENES………………………………………………………………………………………………20
DISCUSSION………………………………………………………………………………………….24
BODY WEIGHT…………………………………………………………………………………….24
BLOOD PRESSURE AND HEART RATE……………………………………………………….25
EXPRESSION OF NITRIC OXIDE SYNTHASE AND ANGIOTENSIN RECEPTOR
GENES………………………………………………………………………………………………25
CONCLUSION………………………………………………………………………………………..28
REFERENCES………………………………………………………………………………………..29
APPENDICES AND FIGURES ……………………………………………………………………..33

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