味觉感知的人体肠-脑轴信号传导机制研究进展

味觉是人类感知生物摄取能的重要环节,胃肠道亦存在味觉感知现象。本文从胃肠道味觉受体、胃肠道味觉感知通路及肠-脑轴味觉信号传导机制等方面进行了分析,胃肠道中味觉感知表明胃肠道中存在味觉受体第一家族亚型（taste receptor type 1 member,T1R）1、T1R2、T1R3、味觉受体第二家族亚型（taste receptors type 2,T2Rs）等味觉受体,且肠道味觉物质刺激肠内分泌细胞分泌胆囊收缩素（cholecystokinin,CCK）、肽YY（peptide YY,PYY）等脑肠肽激素,与味觉信号在神经元的传递有关;肠道中鲜味物质谷氨酸钠显著激活大脑缰核、杏仁核和下丘脑亚核的神经网络,表明肠-脑轴味觉感知是基于胃肠道受体及脑肠肽、神经元和大脑中枢神经系统之间的共同调控,从而提出肠-脑轴味觉信号传导机制假说,认为甜味受体T1R2/T1R3和鲜味受体T1R1/T1R3具有相似的信号传导通路,味觉物质作用于肠道后,与肠道中相应的味觉受体结合,激活磷脂酶-β2（phospholipase C-β2,PLC-β2）,释放Ca2＋,引起肠道内环境的变化,刺激肠内分泌细胞分泌PYY、CCK等激素,被肠神经元突触特异性识别,将味觉信号传导至大脑神经中枢;而谷氨酸代谢型受体4（metabotropic glutamate receptor 4,mGluR4）和苦味受体T2Rs信号传导通路则是通过激活磷酸二酯酶（phosphodiesterase,PDE）,使细胞质内3’,5’-环腺苷酸（3’,5’-cyclic adenylic acid,cAMP）浓度降低,从而解除环核苷酸（cyclic nucleotide,cNMP）的抑制作用,从而释放Ca2＋。基于肠-脑轴味觉偏好,为味觉发生改变的患者开发治疗新药物、寻找新的药物靶点提供了新的方向。对肠-脑轴味觉信号传导机制的研究将为胃肠道生理的神经控制提供分子框架、精准控制人体对味觉营养物质的生理反应,并对味觉物质在肠-脑轴中的摄入、代谢、调节等及开发新的味觉感知途径提供新的理论依据。     

Evaluation of hypolipidemic effects of peanut skin-derived polyphenols in rats on Western-diet

The effect of water soluble polyphenolic extract of peanut skin (PE) was investigated for its hypolipidemic properties in rats on Western diet. Seven-weeks old Wistar rats received control diet (AIN-93G), Western diet with and without a bolus of PE five times a week for 10weeks. Group which received 300mg/kg body weight showed significantly reduced body weight and epididymal fat. Plasma and liver triglyceride (TG) and cholesterol (TC) levels were significantly reduced while faecal secretion of TG and TC was greatly increased upon PE administration. Liver mRNA expression of enzymes involved in fatty acid synthesis, such as fatty acid synthase (FAS), sterol receptor element binding protein (SREBP)-1c, acetyl-CoA carboxylase (ACC1) and lipid uptake genes, such as PPARγ, were decreased, while PPARα was up-regulated by administration of PE. These data suggest that administration of PE may contribute to the improved lipid homoeostasis in rats on diets high in cholesterol and lipids.     

Lemon balm extract causes potent antihyperglycemic and antihyperlipidemic effects in insulin‐resistant obese mice

Over the last decades polyetiological metabolic diseases such as obesity and type 2 diabetes have emerged as a global epidemic. Efficient strategies for prevention and treatment include dietary intervention and the development of validated nutraceuticals. Safe extracts of edible plants provide a resource of structurally diverse molecules that can effectively interfere with multifactorial diseases. In this study, we describe the application of ethanolic lemon balm (Melissa officinalis) leaves extract for the treatment of insulin‐resistance and dyslipidemia in mice. We show that lemon balm extract (LBE) activates the peroxisome proliferator‐activated receptors (PPARs), which have key roles in the regulation of whole body glucose and lipid metabolism. Application of LBE (0.6 mg/mL) to human primary adipocytes resulted in specific peroxisome proliferator‐activated receptor target gene expression. LBE treatment of insulin‐resistant high‐fat diet‐fed C57BL/6 mice (200 mg/kg/day) for 6 weeks considerably reduced hyperglycemia and insulin resistance, plasma triacylglycerol, nonesterified fatty acids and LDL/VLDL cholesterol levels. Taken together, ethanolic lemon balm extract can potentially be used to prevent or concomitantly treat type 2 diabetes and associated disorders such as dyslipidemia and hypercholesterolemia.     

miR-126对小鼠乳腺上皮细胞增殖及泌乳功能的影响

应用脂质体转染技术,改变miR-126在小鼠乳腺上皮细胞中的表达量,采用qRT-PCR、HPLC、Western印迹等技术检测miR-126对小鼠乳腺上皮细胞的影响。结果显示,miR-126沉寂后,细胞增殖能力提高,β-酪蛋白表达增加,乳糖质量浓度增加,孕酮受体(PGR)表达增强。研究表明,miR-126可能通过抑制靶蛋白PGR表达,进而抑制乳腺上皮细胞增殖和泌乳量变化。