Endocrine Abstracts

Neuromedin B (NB) is a peptide highly expressed in adipose tissue (AT) but its function remains unclear. We showed that NB receptor (NB) knockout mice (NBR-KO) are resistant to diet-induced obesity compared to wild type (WT) and now we aimed to analyze NBR influence in adipocytes. Mesenchimal cells from perigonadal AT of WT and NBR-KO mice were isolated and maintained in growth medium (GM) as control group or in differentiation medium (DM) as induced group. After 2 weeks cells were fixed and lipid accumulation was evaluated by Oil Red O staining. NBR-KO cells accumulated 56% less lipids than WT cells in DM. To analyze NBR antagonist intervention during adipogenesis 3T3-L1 cells were cultured in GM (GMC), or in DM in the absence (DMC) or presence of 3 μM of NBR antagonist (DMA), during 21 days. In parallel NBR antagonist was added to DMC group for 6 days after 21 days in culture to verify its influence after differentiation. Cells were fixed and stained with Dapi and Bodipy for cell and lipid measurements. After 21 days DMC group exhibited 2.7 times more cells number than GMC but DMA group presented similar cell number as GMC. DMC group reached 83% of well area as lipid while DMA did only 7% although it was corrected by cells area. When NBR antagonist was added for 6 days to DMC it decreased cells number by 40% and lipid accumulation diminished 10%. In conclusion NBR-KO AT cells have impaired induced-adipogenesis and NBR antagonist promoted less adipogenesis, reduced adipocytes number and decreased lipid accumulation. Data demonstrate, for the first time, a role for NBR in adipocyte differentiation, suggesting it is a possible target for obesity treatment. Presently, we are analyzing hormones and factors involved in adipogenesis, lipogenesis and cell death to clarify mechanisms.