Published online Mar 21, 2006. doi: 10.3748/wjg.v12.i11.1718
Revised: November 21, 2005
Accepted: December 7, 2005
Published online: March 21, 2006
AIM: To evaluate the effects of betaine on the ethanol-induced secretion of IGF-I and IGFBP-1 using radioimmunoassay and Western blotting, respectively, in primary cultured rat hepatocytes.
METHODS: Hepatocytes isolated from male Sprague-Dawley rats were incubated with various concentrations of ethanol and PD98059 procedures. The hepatocytes were also treated with different doses of betaine (10-5, 10-4, and 10-3 mol/L). We measured IGF-I and IGFBP-1 using radioimmunoassay and Western blotting, respectively.
RESULTS: The ethanol-induced inhibition of IGF-I secretion was attenuated by betaine in a concentration-dependent manner in primary cultured rat hepatocytes. At 10-3 mol/L, betaine significantly increased IGF-I secretion but decreased IGFBP-1 secretion. In addition, p42/44 mitogen-activated protein kinase (MAPK) activity was accelerated significantly from 10 min to 5 h after treatment with 10-3 mol/L betaine. Furthermore, the changes in IGF-1 and IGFBP-1 secretion resulting from the increased betaine-induced p42/44 MAPK activity in primary cultured rat hepatocytes was blocked by treatment with the MAPK inhibitor PD98059. Betaine treatment blocked the ethanol-induced inhibition of IGF-I secretion and p42/44 MAPK activity, and the ethanol-induced increase in IGFBP-1 secretion.
CONCLUSION: Betaine modulates the secretion of IGF-I and IGFBP-1 via the activation of p42/44 MAPK in primary cultured rat hepatocytes. Betaine also alters the MAPK activations induced by ethanol.