不同油脂種類之高脂高果糖飲食對於大鼠認知功能及 staroyl-coA desaturase 之影響

脂質生合成酵素---Stearoyl-CoA desaturase (SCD) 於體內長期高血糖狀況扮演重要角色，其可被體內胰島素直接刺激增加表現。在 AD 過逝病患腦中發現有 SCD 表現顯著增加情形，且與認知功能測試分數呈現顯著負相關，顯示腦中 SCD 對於認知功能退化應扮演重要角色。本次實驗以高脂高果糖飲食誘發大鼠產生胰島素抗性及腦部認知功能障礙，並探討肝臟及腦中 SCD表現。本研究選用32隻6週齡大之 Wistar 大鼠，經分組後分為控制組、大豆油組及椰子油組。大豆油及椰子油組皆給予含大豆油或椰子油 39% 總熱量之脂質及含48% 總熱量之高果糖飲食。經誘發 20 週後以莫氏水迷宮給予認知功能測試並予以犧牲。由20週之血液生化數值顯示椰子油組血糖、果糖胺及胰島素均顯著高於控制組。莫氏水迷宮測試方面，第四天結果顯示椰子油組認知功能結果顯著低於控制組。進一步分析腦部皮質及肝臟中脂肪酸組成，結果顯示椰子油組於肝臟及大腦皮質中油酸含量及腦部皮質、海馬迴 SCD mRNA 表現均顯著高於控制組。故本次實驗結論大鼠肝及腦部 SCD 表現可被高飽和脂肪酸飲食誘發上升，且大鼠具高胰島素、血糖長期調控不良及認知功能障礙情形，而推測大鼠認知功能障礙與腦中 SCD 表現增加有關。

關鍵字

Stearoyl coA desaturase ；高脂高果糖飲食；飽和脂肪酸；認知功能障礙

並列摘要

Stearoyl-CoA desaturase (SCD), one of the lipid synthesizing enzymes, plays an important role in hyperglycemia. Previous studies found that SCD expression increased in the brains of Alzheimer’s disease patients, and the expression of SCD was negatively correlated with cognitive score. The purpose of the present study was to investigate the effect of high fat high fructose diet (HFHF) on blood insulin resistance, brain cognitive impairment, SCD expression in rats. Wistar rats were 32 male, 6 weeks old and divided into 3 groups: control group (n=8), soybean oil group (n=12) and coconut oil group (n=12). Soybean oil group and coconut oil group were fed high fat (39% kcal) high fructose (48% kcal) diets with soybean oil or coconut oil separately for 20 weeks to induce blood insulin resistance. After 20 weeks, rats were given cognitive tests and sacrificed. Serum analysis at week 20 showed that compared with control group coconut oil group had higher blood glucose, insulin and fructosamine, which indicated hyperglycemia and insulin resistance. Day-4 Morris water maze result showed coconut oil group had lowest cognitive function compared with control groups. Western results showed that coconut oil group and soybean oil group had higher β-amyloid accumulation in brain cortex. In fatty acid composition, both cortex and liver had higher oleic acid contents in coconut group which indicated that the rats had higher SCD activity. In RT-PCR results, coconut oil groups had higher SCD mRNA expression in brain cortex and hippocampus compare with control group.In conclusion, SCD activity could be activated by a 20-week high saturated fatty acid high fructose diet, SCD metabolism related fatty acid content could also be changed. We also found cognitive impairment in rat brain, which may relevant with brain SCD activity.

並列關鍵字

Stearoyl coA desaturase, high fat high sugar diets, saturated fatty acid, cognitive impaired

參考文獻

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不同油脂種類之高脂高果糖飲食對於大鼠認知功能及 staroyl-coA desaturase 之影響

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