- 學位論文
飲食中添加精胺酸對第2型糖尿病大鼠體內發炎反應及腎損傷之影響
Effects of dietary arginine on inflammation and renal injury in rats with streptozotocin-induced type 2 diabetes
摘要
近年來，許多研究指出，精胺酸(Arginine, Arg)在代謝壓力下具有免疫調節的功用；體外研究亦顯示，Arg對糖化終產物(advanced glycation end products; AGEs)之合成有抑制的效果。本研究從飲食中添加Arg，探討其對第2型糖尿病大鼠體內促發炎物質產生及腎臟AGEs接受器(RAGE)表現之影響。實驗選用雄性Wistar大鼠，將大鼠分成控制組 (NC)及兩組糖尿病組。實驗為期八週，實驗期間NC組餵食標準飼料，一組糖尿病組(diabetes mellitus, DM)餵食半純化之標準飼料，而另一糖尿病組餵食以Arg (DM-Arg，佔總熱量2%)取代部分酪蛋白的飼料。以腹腔注射nicotinamide及streptozotocin的方式誘發大鼠第2型糖尿病。當禁食血糖 ?d 180 mg/dl即判定為糖尿病。分別在基準點、4週及8週時收集血液樣本，並在犧牲時收集腎臟進行分析。研究結果顯示，在8週時血漿C-反應蛋白(C-reactive protein, CRP)、單核球趨化蛋白(monocyte chemotactic protein, MCP)-1、前列腺素(prostaglandin, PG) E2 及果糖胺(fructosamine)濃度，DM及DM-Arg組皆顯著高於NC組 (p < 0.05)，且MCP-1、PGE2在DM組與DM-Arg組間無統計差異。而血漿CRP及fructosamine濃度DM-Arg組皆顯著低於DM組 (CRP: 33.2 ± 4.7 vs. 37.6 ± 4.2 mg/dl, p < 0.05; fructosamine: 0.16 ± 0.02 vs. 0.19 ± 0.02 ΔA/3min, p < 0.001)。在腎臟硝基酪胺酸(nitrotyrosine)及核轉錄因子(nuclear factor-kappa B, NF-κB)次單元p65蛋白質表現結果顯示，DM-Arg組顯著低於DM 組 (nitrotyrosine: 176 ± 26.7 vs. 199 ± 21 nM, p < 0.05)，此外，免疫組織染色法得知腎臟RAGE表現量，DM-Arg組亦顯著低於DM組 (33.6 ± 0.4 vs. 42.3 ± 0.4 μm2, p < 0.05)。綜合上述研究結果顯示，飲食中添加Arg對第2型糖尿病大鼠可降低血中發炎反應介質，減少體內AGEs之合成並改善腎臟損傷之情形。
並列摘要
Arginine (Arg) has been shown to have immunomodulatory effect and inhibits advanced glycation end products (AGEs) formation in in vitro and in vivo studies. However, the effects of dietary Arg supplementation on the expression of inflammatory mediators and renal receptor of AGE (RAGE) in diabetic rats are still unclear. In the present study, normal control (NC) group and two diabetic groups are involved. Rats in NC groups were fed with chow diet. One diabetic group (DM) was fed a common semipurified diet whereas the other diabetic group received an identical diet except that part of the casein was replaced by Arg (DM-Arg), which provided 2% of the total energy intake. Diabetes was induced by intraperitoneal injection of nicotinamide followed by streptozotocin. Rats with blood glucose levels exceeding 180 mg/dl were considered diabetic. Blood samples were collected at baseline, 4 wk, and 8 wk. Rats were sacrificed at the end of 8 wk. The kidneys of the animals were harvested at the end of the study for further analysis. The results showed that plasma C-reactive protein (CRP), monocyte chemotactic protein (MCP)-1, prostaglandin (PG)E2 and fructosamine levels were significantly higher in the diabetic groups than those in the NC group (p < 0.05). No differences in plasma MCP-1 and PGE2 levels were found between the DM and DM-Arg groups. However, CRP, fructosamine were significantly lower in DM-Arg group than in DM group (CRP: 33.2 ± 4.7 vs. 37.6 ± 4.2 mg/dl, p < 0.05; fructosamine: 0.16 ± 0.02 vs. 0.19 ± 0.02 ΔA/3min, p < 0.001). Kidney nitrotyrosine concentrations and nuclear factor-kappa B p65 protein expressions were significantly lower in DM-Arg group than in DM group (Nitrotyrosine: 176 ± 26 vs. 199 ± 21 nM, p < 0.05). The result of immunohistochemistry stain also showed that the expressions of RAGE in kidney were significantly lower in DM-Arg group than in DM group (33.6 ± 0.4 vs. 42.3 ± 0.4 μm2, p < 0.05). These results suggest that dietary Arg supplementation may decrease AGE formation and ameliorate renal damage in rats with type 2 diabetes.