Melanin-concentrating hormone receptor 2 affects 3T3-L1 preadipocyte differentiation

To investigate the influence of melanin-concentrating hormone receptor 2 (MCHR2) on preadipocyte proliferation and differentiation, a 3T3-L1-MCHR2 cell line stably expressing human MCHR2 was established. The expression level and biological activity of MCHR2 were evaluated by immunofluorescence and radioligand binding assays. A 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay and cell cycle analysis showed that MCH did not affect 3T3-L1-MCHR2 and 3T3-L1-mock cell proliferation. MCH accelerated preadipocyte differentiation of the two cell lines when they were administered various doses of standard adipogenic inducers. The rate and degree of differentiation of the 3T3-L1-MCHR2 cells were higher than those of the 3T3-L1-mock cells. The expression levels of adipocyte-specific marker genes, including peroxisome proliferator-activated receptorγ2 (PPARγ2), CCAAT enhancer-binding proteinα (C/EBPα), adipocyte-specific fatty acid-binding protein (aP2) and leptin were significantly up-regulated, especially in 3T3-L1-MCHR2 cells. These findings suggest that MCHR2 positively mediates the regulation of MCH during preadipocyte differentiation and is involved in energy balance regulation without affecting preadipocyte proliferation.