Intracellular mechanisms coupled to NPY Y2 and Y5 receptor activation and lipid accumulation in murine adipocytes

The formation of adipose tissue is a process that includes the pre-adipocyte proliferation and differentiation to adipocytes that are cells specialized in lipid accumulation. The adipocyte differentiation is a process driven by the coordinated expression of various transcription factors, such as peroxisome proliferator-activated receptor (PPAR-c). Neuropeptide Y (NPY) induces adipocyte proliferation and differentiation but the NPY receptors and the intracellular pathways involved in these processes are still not clear. In the present work we studied the role of NPY receptors and the intracellular pathways involved in the stimulatory effect of NPY on lipid accumulation. The murine pre-adipocyte cell line, 3T3-L1, was used as a cell model. Adipogenesis was evaluated by quantifying lipid accumulation by Oil red-O assay and by analyzing PPAR-c expression using the Western blotting assay. Adipocytes were incubated with NPY (100 nM) and a decrease on lipid accumulation and PPAR-c expression was observed in the presence of NPY Y2 receptor antagonist (BIIE0246, 1 lM) or NPY Y5 antagonist. Furthermore, NPY Y2 (NPY3–36, 100 nM) or NPY Y5 (NPY19–23(GLY 1 , Ser 3 , Gln 4 , Thr 6 , Ala 31 , Aib 32 , Gln 34 ) PP, 100 nM) receptor agonists increased lipid accumulation and PPAR-c expression. We further investigate the intracellular pathways associated with NPY Y2 and NPY Y5 receptor activation. Our results show NPY induces PPAR-c expression and lipid accumulation through NPY Y2 and NPY Y5 receptors activation. PKC and PLC inhibitors inhibit lipid accumulation induced by NPY Y5 receptor agonist. Moreover, our results suggest that lipid accumulation induced by NPY Y2 receptor activation occurs through PKA, MAPK and PI3K pathways. In conclusion, this study contributes to a step forward on the knowledge of intracellular mechanisms associated with NPY receptors activation on adipocytes and contributes to a better understanding and the development of new therapeutic targets for obesity treatment.