It has been previously found that the blockade of metabotropic glutamate receptor type 5 (mGluR5) protects against hepatic ischemia/reperfusion injury and acetaminophen toxicity. The role of mGluR5 in NAFLD has not yet been elucidated. Here, we evaluated the effects of mGluR5 blockade in an in vitro model of steatosis. HepG2 cells were pre-incubated for 12 h with an mGluR5 agonist, a negative allosteric modulator (DHPG and MPEP, respectively) or vehicle, then treated with 1.5 mM oleate/palmitate (O/P) for another 12 h. Cell viability was evaluated with the MTT assay; fat accumulation was measured using the fluorescent dye nile red; SREBP-1, PPAR-α, iNOS and Caspase-3 protein expression were evaluated by Western blot; NFkB activity was evaluated as pNFkB/NFkB ratio. mGluR5 modulation did not alter cell viability in O/P-incubated cells; MPEP prevented intracellular lipid accumulation in O/P treated cells; MPEP administration was also associated with a reversion of O/P-induced changes in SREBP-1 and PPAR-α expression, involved in free fatty acid (FFA) metabolism and uptake. No changes were observed in iNOS and Caspase-3 expression, or in NFkB activity. In conclusion, mGluR5 pharmacological blockade reduced fat accumulation in HepG2 cells incubated with O/P, probably by modulating the expression of SREBP-1 and PPAR-α.

先前已经发现，对5型代谢型谷氨酸受体（mGluR5）的阻断可防止肝缺血/再灌注损伤和对乙酰氨基酚毒性。mGluR5在NAFLD中的作用尚未阐明。在这里，我们评估了mGluR5阻断剂在体外的作用脂肪变性模型。将HepG2细胞与mGluR5激动剂，负变构调节剂（分别为DHPG和MPEP）或赋形剂预孵育12小时，然后再用1.5 mM油酸盐/棕榈酸酯（O / P）处理12小时。用MTT测定法评估细胞活力；使用荧光染料尼罗红测量脂肪堆积；Western blot检测SREBP-1，PPAR-α，iNOS和Caspase-3蛋白的表达。以pNFkB / NFkB比评估NFkB活性。mGluR5调节不会改变O / P孵育细胞的细胞活力；MPEP阻止了O / P处理细胞中的细胞内脂质蓄积；MPEP给药还与O / P诱导的SREBP-1和PPAR-α表达变化的逆转有关，这涉及游离脂肪酸（FFA）的代谢和摄取。iNOS和Caspase-3表达未见变化，或NFkB活动。总之，mGluR5药理学阻断作用可能是通过调节SREBP-1和PPAR-α的表达来减少与O / P孵育的HepG2细胞中的脂肪积累。