Thesis (M.Sc.)--Chulalongkorn University, 2015

Degenerative mitral valve disease (DMVD) is the most common cause of acquired cardiac diseases in adult small and medium sized dogs. Transforming growth factor beta 1 (TGF-β1), a cytokine controlling extracellular matrix homeostasis within valves is thought to be involved in valve degenerative process. The expression of TGF-β1 protein was reported markedly increase in the DMVD valves. The first objective of this study was to measure the concentration of TGF-β1 in plasma of normal and DMVD dogs by ELISA technique. The second objective was to compare TGF-β1 mRNA expression between normal and DMVD dogs from mitral valve (MV) samples by RT-PCR. Comparison of plasma TGF-β1 concentrations was performed with Mann Whitney U test. P-value less than 0.05 was considered statistically significant. The result showed no statistical difference in median of plasma TGF-β1 concentrations between 22 normal (1.14(0.94-1.33) ng/mL) and 27 DMVD (1.21(0.92-1.32) ng/mL) dogs. The expression of TGF-β1 mRNA from 10 MV (normal = 5, DMVD = 5) samples showed positive band. For positive bands, the mean ± SD of TGF-β1 and GAPDH band intensity ratio was compared between normal and DMVD dogs assessed by independent t-test. The result between normal (0.55 ± 0.07) and DMVD (0.95 ± 0.06) valves were significantly different (p < 0.05). In conclusion, the concentration of TGF-β1 protein is very low in circulation. It is possible that cells within mitral valves are the major source of TGF-β1 in dogs affected with DMVD.