| Obesity is considered a chronic and popular disease all over the world, which arise from the unbalance between the accumulation of adipose by intaking of food and the energy expenditure. Adipose tissue plays a crucial role in regulating energy metabolism and maintaining the homeostasis.Excess adipose result in the obesity, which increased the rate of the type 2 diabetes, cardiovascular disease. Mass of adipose tissue can be regulated by adipocyte and preasdipocyte apoptosis, as well as adipocyte differentiation. Therefore, in vivo and in vitro studies have indicated that apoptosis is a critical factor in adipocyte depletion during regulating adipose mass. Comparison with other cell models (e.g., mouse and rabbit), pig models provided many advantages including close similarity to human physiological characteristic, genetic modulation of growth and fat deposition, and pathologic reaction response to high-energy intake. Therefore, pigs were considered as optimal model animals in adipocyte research.Apoptosis, a form of the programme cell death, played a key role in the animal development and tissue homeostasis, as well as pathological states. Owing to the evidently ability of adipocyte to resist apoptosis, adipocyte apoptosis was not well studied and poorly understood. Amount of evidences indicated that adipocyte apoptosis was induced by adipocyte correlative factors, such as TNF-α, leptin. In addition, natural products have the potential for inducing apoptosis of adipocyte, preadipocyte and adipose tissue. Currently, most of the adipocyte apoptosis studies were more concentrated on the cell lines and the mouse model; the porcine preadipocyte apoptosis have not been reported. In this study, healthy 1~3 old pig were used as experimental animal, in vitro porcine preadipocytes were cultured, treated with resveratrol and nicotinamide respectively. Study the effect of both to preadipocytes apoptosis.1 Porcine primary preadipocyte was treated with different concentration of resveratrol (0μmol/L, 50μmol/L, 100μmol/L, 200μmol/L, and 400μmol/L). Morphological changes during apoptosis were observed by optical microscope and fluorescence microscope after staining by Hoechst 33258 Fluorescent dyes respertively. Expression of sirt1, caspase-3, bcl-2, bax, p53, NF-κB mRNA was measured by RT-PCR and protein by Western blotting. Here, we showed that primary preadipocyte apoptosis was apparent, accompanied by reduced cell volume, chromatin condensation, and nuclear shrinkage. Compared to the control and low concentration group, high dose group (200μmol/L) significantly increased the ratio of primary preadipocyte apoptosis. The expression of sirt1, caspase-3, bax mRNA and protein was up-regulated markedly in response to resveratrol; in contrast, apoptotic inhibitor bcl-2, p53, NF-κB down-regulated. We further proved fact that resveratrol can specifically promote the activity of sirt1; moreover, activated sirt1 modulates the activity of caspase-3 and bcl-2 family, involving in transcriptional regulation of p53 and NF-κB through antagonizing factor-induced acetylation. Taken together, our data established resveratrol as new regulator in porcine primary preadipocyte apoptosis via activating the expression of sirt1, modulating activity of apoptotic-associated factor.2 The use of Hoechst33258, Annexin-V-FITC staining and Flow Cytometry to study that effect of Sirt1 inhibitor -nicotinamide and rosiglitazone on porcine preadipocyte apoptosis. The results showed that comparision with low concentrations of group and control, 600μmol/L rosiglitazone for 48 hours after treatment significantly inhibited the proliferation of porcine preadipocytes, induced preadipocytes apoptosis (p <0.05), with emergence of typical characteristics of apoptosis. In contrast, treatment with different concentrations of (100,200,300μmol/L) nicotinamide significantly inhibited the rosiglitazone-induced preadipocyte apoptosis. These results show that, both Sirt1 inhibition and in the case of promotion, are able to affect the preadipocyte. The results suggested that, Sirt1 may be influence pporcine preadipocyte apoptosis through nuclear translocation and regulation of preasipocyte mass marker genes.
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