| 摘要: | 更年期的發生源於卵母細胞數量和雌激素濃度的下降，因此導致月經永久停止，此時期體內促發炎細胞激素和活性氧物質(reactive oxygen substances, ROS) 增加，進而導致腹部肥胖，血脂異常、胰島素抵抗、肌肉萎縮和腸道菌相失衡等現象。米糠含有蛋白質、脂質、膳食纖維和植化素等，已被證明可以改善某些健康狀況，但對於停經後的肌肉萎縮的影響機制尚未得到充分的研究與解釋。本研究旨在評估不同劑量台灣的台農81號全脂米糠對高脂誘導的卵巢切除小鼠肌肉萎縮之影響。本研究以雌性ICR小鼠為實驗動物，共36隻，隨機分為6 組，其中一組年輕控制組以AIN-93M餵食，其他五組卵巢切除組餵食如：AIN-93M、高脂飲食、高脂飲食含5% (w/w) 米糠 、高脂飲食含10% (w/w) 米糠和高脂飲食含20% (w/w) 米糠，介入12週，收集血液、肝臟、肌肉、子宮、內臟脂肪、大腸、盲腸內容物及糞便進行分析。本研究結果顯示20% (w/w) 米糠介入可改善高油餵食卵巢切除小鼠之胰島素阻抗、前肢抓力上調肌肉合成蛋白基因mTOR、eIF-4EBP1和Myog並下調之肌肉萎縮因子FoxO1和MuRF-1之表現量，並還可透過增加產生短鏈脂肪酸的菌株Muribaculum 來增強高油餵食卵巢切除小鼠之腸道緊密連接蛋白 (Occludin和ZO-1) 以調節腸道菌分布。而10% (w/w) 米糠介入可下調 FoxO1 基因表現量並增加菌株 Lachnospiraceae_UCG-001 的豐富度。不同劑量的米糠介入具有改善以高脂飲食餵食之卵巢切除小鼠其肌肉萎縮、胰島素阻抗及腸道菌相，且以20% (w/w) 米糠劑量效果較佳。
Menopause, characterized by the permanent cessation of menstruation resulting from declining oocyte count and estrogen levels, leads to heightened levels of pro-inflammatory cytokines and reactive oxygen species. This contributes to abdominal fat accumulation, abnormal lipid levels, insulin resistance, muscle loss, and imbalance in gut microbiota. Rice bran (RB), which contains proteins, lipids, dietary fiber, and phytochemicals, has shown beneficial effects on various health conditions. However, its impact on muscle atrophy in post-menopausal individuals has not been extensively researched. The aim of this study was to investigate the impact of varying doses of full-fat RB (Tainung No. 81, Taiwan) on muscle atrophy in ovariectomized (OVX) mice that were induced with a high-fat diet. Thirty-six female ICR mice were randomly divided into six groups for a 12-week study. One group consisted of young sham-operated mice fed with an AIN-93M diet. The remaining five groups were OVX and were fed different diets: AIN-93M diet, high-fat diet (HFD) comprising 45% of calories from fat, HFD supplemented with 5% (w/w) RB, HFD supplemented with 10% (w/w) RB, and HFD supplemented with 20% (w/w) RB. The blood, liver, muscle, uterus, visceral fat, colon, cecal contents, and feces were collected for analysis. This study showed that 20% (w/w) RB could enhance the insulin resistance in OVX-HFD mice, upregulating the muscle protein synthesis gene mTOR, eIF-4EBP1, and Myog, while downregulated the muscle atrophy markers FoxO1 and MuRF-1. Moreover, supplementation with 20% (w/w) RB was observed to enhance colonic tight junction Occludin and ZO-1, and regulate the gut microbiome in OVX-HFD mice by increasing the abundance of SCFAs-producing bacteria Muribaculum genus. 10% (w/w) RB was found to downregulate the gene expression FoxO1 and increase the abundance of Lachnospiraceae_UCG-001 genus. In conclusion, intervention with different doses of RB improved muscle atrophy, insulin resistance, and the gut microbiome in HFD-fed OVX mice, with the 20% (w/w) RB dosage proving most effective. |
