| Abstract: | 隨著生活水準不斷提高及醫療衛生的進步，國人平均壽命逐漸延長，老年人口持續增加，慢性疾病遂成威脅國人健康的重要疾病。近年來，糖尿病便開始進入國人十大死因排行榜上。針對糖尿病之保健食品不斷推陳出新，其中有許多天然物所含的多醣類物質，經動物實驗證實是具有降血糖的效用。在天然生成的冬蟲夏草中，由於含有高含量之多醣物質，可能有助於減緩高血糖之症狀。之前研究證實，採用 streptozotocin (STZ) 能成功運用在 Wistar 大鼠誘發糖尿病，餵食冬蟲夏草子實體之實驗組，發現有降低高血糖之顯著效果。本研究嘗試探究大鼠模式中，冬蟲夏草如何在不影響胰島素分泌量之下，達成降血糖之作用，分別針對葡萄糖的恆定機制與代謝路徑進行追蹤。 Wistar 大鼠經由 STZ 誘發糖尿病後，分別口服冬蟲夏草之子實體、蟲體，以及兩者之混合物；經分析肝臟中葡萄糖轉運蛋白 GLUT2 、葡萄糖激? GK 與胰島素受器 InR 表現量、GK 酵素活化性等參數。初步結果顯示，除 GK 外，口服冬蟲夏草的各組，其肝臟細胞 GLUT2 與 InR 表現均較未食用 STZ 控制組為高。GK 基因表現在蟲體或子實體分食時略降，而於合併給於時則增加，其意義有待探討。推測冬蟲夏草經由口服，可能藉更多的血糖轉運蛋白與胰島素接受器，以及更有效率的葡萄糖磷酸化以達成降低血糖之效應。
Diabetes mellitus is one of the life-threatening chronic diseases and has become a top-four killer in Taiwan(Department of health, 2004). Cordyceps sinensis is one of the most precious Chinese herbs and may play various physiological roles in restoring the body’s homeostasis. In addition to those well-known functions, recent evidences suggested that extracts of Cordyceps, most probably polysaccharide fractions, may have help to alleviate hyperglycemia in diabetic animals. However the underlying molecular mechanisms have not been addressed. In this study, we attempted to clarify how Cordyceps affect the hepatic glucose homeostasis in diabetic rats. Male Wistar rats were injected with streptozotocin for diabetes induction of diabetes and then were fed with carcass of Cordyceps, fruiting body, mixture of the fruiting body and carcass, and starch; that is, the CC, FB, CF and STZ groups, respectively. Hepatic glucokinase activities were determined from enzyme kinetics, whereas the expression levels of glucokinase, glucose transporter 2 and insulin receptor were accessed by real-time quantitative RT-PCR. Preliminary results revealed that the Cordyceps-treated groups（the CC, FB and CF groups）showed higher glucose transporter 2 and insulin receptor, than the STZ group. These trends are in accordance to the glycermic status of these groups. For currently unknown reason, expression level of glucose kinase was lower in diabetic rats fed with carcass or fruiting body. Presumably, Cordyceps might exert its anti-hyperglycermic activities through more robust glucose transportation to livers, more effective phosphorylation of glucose, which is the key step for glycolysis, glycogen synthesis, and pentose phosphate pathway, and perhaps more efficient insulin signaling for control glucose homeostasis. |
