This study was conducted to assess the effects of specific oxysterols on the adipogenic differentiation and expression of adipogenic transcripts in C3H10T1/2 mouse stem cells. In the first study, four oxysterols namely; 20S, 22R, 22S and 25 hydroxycholesterol (25-HC) were tested to determine which one best inhibits adipogenesis in C3H10T1/2 mouse stem cells. Adipogenic differentiation was induced using an adipogenic media (DMITro) consisting of dexamethasone (DEX), 3-isobutyl-1-methyl-xanthine (IBMX), insulin and troglitazone (Tro). Inhibition of adipogenesis was assessed by treatment of cells with DMITro+20S, 22R, 22S or 25-HC for six days. Oil red O pictures and gene expression analysis showed that 25-HC was more effective in inhibiting the expression of adipogenic genes compared to the other oxysterols. Further investigation of the mechanisms of action of 25-HC showed that the inhibitory effects of 25-HC on adipogenesis are not mediated by hedgehog signalling. / October 2015

Growth hormone (GH) has growth-stimulating effects on skeletal muscle and liver but a growth-inhibitory effect on adipose tissue. The mechanisms underlying these actions of GH are not fully understood. Two studies were conducted to achieve the following objectives: 1) to determine the cellular mechanism by which GH stimulates liver growth; 2) to determine the effects of GH on the commitment of mesenchymal stem cells (MSCs) to myogenic and adipogenic lineages. In the first study, the GH-deficient lit/lit male mice were injected (s.c.) daily with rbGH or vehicle for two weeks. GH-injected lit/lit mice tended to have a greater liver/body weight percentage than lit/lit control mice. GH injection did not alter the percentage of proliferating cells in the liver. However, GH-injected lit/lit mice had 18% larger hepatocytes and 16% less DNA per unit liver weight than those of lit/lit control mice. These data together indicate that GH stimulates liver growth in mice by increasing the size, not by increasing the number of hepatocytes. In the second study, we treated the MSC cell line C3H10T1/2 cells with or without 5'-azacytidine and rbGH for 4 days. We assessed the myogenic or adipogenic potential by determining the ability of these cells to differentiate into myotubes or adipocytes, respectively. C3H10T1/2 cells treated with 5'-azacytidine and GH formed more myotubes, myoblasts, and fewer adipocytes compared to cells treated with 5'-azacytidine alone. Taken together, these results suggest that GH enhances 5'-azacytidine-induced myogenic commitment but inhibits 5'-azacytidine-induced adipogenic commitment in C3H10T1/2 cells. / Master of Science

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