Characteristic of glucose metabolism in myostatin deficient double muscled Japanese Shorthorn cattle

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 780-806-Determinants of Insulin Resistance & Associated Metabolic Disturbances
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-802
Katsuyoshi Sato*, Megumi Urakawa, Tatsuya Nakano, Hitoshi Watanabe, Yuya Nagasawa, Takahiro Sakurada, Kouichi Watanabe and Hisashi Aso
Tohoku University, Sendai, Japan
Myostatin is a member of the transforming growth factor-β superfamily, and functions as negative regulator of skeletal muscle development and growth. In mammals, myostatin deficient animals result in an increase of skeletal muscle mass with both hyperplasia and hypertrophy. In skeletal muscle, myostatin regulates energy metabolism. Myostatin deficient mice present with a significant reduction in adipose tissue, and the inhibition of myostatin increases the insulin sensitivity in skeletal muscle and white adipose tissue. The aim of this study was to investigate the characteristic of glucose metabolism in normal (NM) and myostatin deficient double muscled (DM) adult Japanese Shorthorn cattle.

 First, we investigated the expression levels of glucose uptake genes (GLUT1 and GLUT4 mRNA) in longissimus muscle of the NM and DM cattle by RT-PCR. There was no significant difference in the expression level of GLUT1 mRNA between the NM and DM cattle. However, in the DM cattle, GLUT4 mRNA level was significantly higher than the NM cattle.

 Secondly, we measured 2-deoxyglucose (2DG) uptake ability using the skeletal muscle cells isolated from the NM and DM cattle. The basal 2DG uptake was significantly increased in the DM cattle compared with the NM cattle. In addition, the treatment with a physiologic concentration of insulin significantly enhanced 2DG uptake in the skeletal muscle cells of myostatin deficient Japanese Shorthorn cattle.

 Finally, glucose tolerance test (GTT) was performed in the NM and DM cattle. Blood samples from jugular vein of fasted cattle were collected 0, 10, 20, 30, 45, 60, 90 and 120 min after the injection of 0.3 g/kg BW glucose for the measurement of plasma glucose and insulin. At 10 min after injection, the plasma glucose level of the DM cattle was significantly lower than that of the NM cattle. In addition, during 0 to 60 min after glucose injection, the plasma insulin levels of the DM cattle were significantly lower than that of the NM cattle. These results demonstrated that the DM cattle significantly improved GTT compared to the NM cattle, and that the improvement in the GTT of the DM cattle was due to response to insulin rather than to insulin secretions.

 In this study, we suggest that the myostatin deficient double muscled Japanese Shorthorn cattle may metabolize the glucose efficiently for maintaining big muscle.

Nothing to Disclose: KS, MU, TN, HW, YN, TS, KW, HA

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