Effects of leptin and adiponectin on proliferation and protein metabolism of porcine myoblasts.

The aim of this study was to show the abundance of leptin and adiponectin receptors (LEPR, ADIPOR1, ADIPOR2) and to determine the direct effects of leptin and adiponectin on the in vitro growth of porcine skeletal muscle cells. ADIPOR1 and ADIPOR2 were abundant at mRNA and protein level in proliferating and differentiating myoblast cultures derived from semimembranosus and semitendinosus muscles of newborn piglets, whereas LEPR expression was close to the detection limit. Adiponectin (10, 20, 40 μg/ml) attenuated the proliferation of porcine myoblasts, measured as [(3)H]-thymidine incorporation and real-time monitoring of the cells in response to 24- and 48-h exposure, in a dose-dependent manner. This effect resulted from suppressed basic fibroblast growth factor (bFGF)-mediated stimulation of DNA synthesis in serum-free medium (SFM) containing bFGF. No effects of leptin (5, 10, 20, 40, 80 ng/ml) on myoblast proliferation in SFM were detectable. Neither leptin nor adiponectin altered protein synthesis and degradation in differentiating porcine myoblasts cultured in SFM. The results on receptor abundance suggest that porcine skeletal muscle cells may be sensitive to adiponectin and leptin. However, except via inhibitory interaction of adiponectin with bFGF, these adipokines appear not to affect in vitro proliferation and protein metabolism of porcine muscle cells directly under serum-free culture conditions.