第二型糖尿病(T2DM)與肥胖有密切關係，當營養過剩導致肥胖，此時脂肪細胞內的發炎訊息傳遞路徑活化，增加促發炎細胞激素的產生，造成胰島素阻抗。近年研究發現，細胞內的NLRs (nucleotide-binding and oligomerization domain (NOD)-like receptors)會辨識細胞質內與肥胖相關的危險信號分子，如體內脂質代謝產物，造成促發炎細胞激素IL-1β和IL-18的成熟和釋放，被認為干擾胰島素信號傳遞而導致胰島素阻抗。硫辛酸(Alpha-lipoic acid, ALA)是一個主要由粒線體合成的有機硫化合物，除了參與細胞能量代謝以外還具有抗氧化性質，被認為是發炎信號傳遞路徑的重要調節因子。本研究欲探討硫辛酸對高脂飲食及STZ (streptozotocin)誘發第二型糖尿病大鼠脂肪組織發炎反應、脂肪組織中NLRP3發炎體及其訊息傳遞路徑相關因子之影響。給予雄性Wistar大鼠高脂飲食(60%脂肪熱量)四周後腹腔注射STZ (30mg/kg)誘導T2DM，隨後繼續給予高脂飲食且投以ALA持續13周。結果顯示，T2DM大鼠連續13周給予ALA (200mg/kg BW)後可顯著降低其46.8%的內臟脂肪(副睪脂肪及副腎脂肪)重量(p<0.05)；給予PIO30mg/kg、ALA50mg/kg、ALA100mg/kg、ALA200mg/ kg BW組之總膽固醇(Total cholesterol, TC)、總三酸甘油酯(Total glyceride, TG)、游離脂肪酸(free fatty acid, FFA)濃度相較於DM顯著降低 (p<0.05)；高密度脂蛋白膽固醇(high density lipoprotein cholesterol, HDL-C)濃度則分別提升15.5%、19.2%、37.9%、68.2%。另外餵食ALA200mg/kg BW觀察到可減少T2DM大鼠47.9%之血中低密度脂蛋白膽固醇(low density lipoprotein cholesterol, LDL-C)濃度。西方墨點法結果顯示，DM+ALA200組的JNK1 (c-Jun N-terminal kinases)表現量與DM組相比下減少32.9%；DM+ALA50組、DM+ALA100組與DM+ALA200組之ASC蛋白表現量比DM組之表現量(1.35±0.29)分別減少37.6%、23.4%、35.1%；在Pro-caspase-1方面，DM+ALA200組顯著低於DM組47.6% (p<0.05)；在Active caspase-1表現量方面，與DM組相比則是DM+ALA100、DM+ALA200分別減少52.7%、36.1%；在IL-1β的表現量則是DM+ALA200組與DM組比較下，減少了29.4%。上述結果顯示，ALA可有效減少脂肪組織中JNK1生成，推測原因可能為降低促發炎細胞激素前驅物Pro-IL-1β之轉錄；另外，ALA可減少T2DM大鼠血中FFA、LDL-C、TC，因此降抑制NLRP3 inflammation危險因子的活化而減少下游之ASC、Pro-caspase-1、Active caspase-1、IL-1β表現量，因此減緩脂肪組織發炎反應。

Excess high calorie intake accelerates the development of obesity, which increases the risk of insulin resistance and pro-inflammatory cytokines production that attributed to the activation of inflammatory signaling pathway in adipocytes. In recent years, studies indicate that intracellular NLRs (nucleotide-binding and oligomerization domain (NOD)-like receptors) can identify obesity associated protein, resulting in maturation and release of IL-1β and IL-18, is considered to interfere with insulin signaling. Alpha-lipoic acid (ALA) is an organic sulfur compound ant it is considered an important regulatory factor of inflammatory signaling. We investigate the effects of ALA on the inflammation in adipose tissue, the expression of NLRP3 in the adipose tissue and the related factors of the inflammatory signaling pathway. Male Wistar rats were given HFD (60% fat of calorie) for 4 weeks followed by intraperitoneal (i.p.) injection of STZ (30mg/kg) to induce T2DM. These rats were continuously received HFD and then orally administered with 200 mg/kg ALA once a day for 13 weeks. After rats were sacrificed, the biochemistry analysis was conducted. T2DM rats significantly reduced the weight of visceral adipose tissue (epididymal adipose tissue and perirenal adipose tissue) by 46.8% after treated with ALA (200 mg / kg B.W.) for 13 weeks (p<0.05). The TC concentration of ALA 200mg / kg BW was significantly lower than DM group by 38.9% (p<0.05), the concentrations of TG was significantly decreased by 58.5%, (p<0.05); the concentration of FFA was significantly decreased by 51.8% (p<0.05), The HDL-C concentrations was significantly increased by 68.2%; In the ALA200 group, LDL-C concentration was reduced by 47.87%. The results of Western blotting shows that the expression of JNK1 in DM + ALA200 group was decreased 32.9% compared with DM group. The expression of ASC protein in DM + ALA50 group, DM + ALA100 group and DM + ALA200 group was decreased 37.6%, 23.4% and 35.1% compared with DM group (1.35 ± 0.29). Furthermore, the expressions of Pro-caspase-1 in DM+ALA200 group was significantly lower than DM group (p<0.05). Compared with DM group, the expressions of Active caspase-1 in DM + ALA100 and DM + ALA200 were decreased by 52.7% and 36.1%, respectively. Finally, the expression of IL-1β in DM + ALA200 group was decreased by 29.4% compared with DM group. In conclusion, we suppose that ALA decreases the expression of JNK1 via suppressing the transcription of the Pro-IL-1β in adipose tissue of T2DM rats. Moreover, ALA also decreases the expression of ASC, Pro-caspase-1 and Active caspase-1 as well as IL-1β level, thus inhibits the activation of NLRP3 inflammasome and alleviates the adipose tissue inflammation in adipose tissue of T2DM rats as consequence.

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