Effect of nicotinamide on proliferation, differentiation, and energy metabolism in bovine preadipocytes

This study examined the effects of nicotinamide on proliferation, differentiation, and energy metabolism in a primary culture of bovine adipocytes. After treatment of cells with 100-500 µM nicotinamide, cell growth was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and cellular lipid content was assessed by Oil Red O staining and a triglyceride (TG) assay. Several factors related to energy metabolism, namely adenosine triphosphatase (ATPase) activity, nitric oxide (NO) content, nitric oxide synthase (NOS) activity, the number of mitochondria and the relative expression of glyceraldehydes-3phosphate dehydrogenase (GAPDH), peroxisome proliferator-activated receptor-y (PPARy) and inducible NOS (iNOS), were also investigated. Results showed that nicotinamide induced both proliferation and differentiation in bovine preadipocytes. Nicotinamide decreased NO production by inhibiting NOS activity and iNOS mRNA expression, and controlled lipolytic activity by increasing ATPase activity and the number of mitochondria. The present study provides further evidence of the effects of nicotinamide on lipid and energy metabolism, and suggests that nicotinamide may play an important role in the development of bovine adipose tissue in vivo. This emphasizes the importance of investigating bovine adipose tissue to improve our understanding of dairy cow physiology. (Key Words : Nicotinamide, Bovine Preadipocytes, Nitric Oxide, Triglyceride, Lipolysis, Energy Balance)