Basic Research
Copyright ©2006 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Mar 21, 2006; 12(11): 1718-1722
Published online Mar 21, 2006. doi: 10.3748/wjg.v12.i11.1718
Effects of betaine on ethanol-stimulated secretion of IGF-I and IGFBP-1 in rat primary hepatocytes: Involvement of p42/44 MAPK activation
Myeong Soo Lee, Myung-Sunny Kim, Soo Young Park, Chang-Won Kang
Myeong Soo Lee, Complementary Medicine, Peninsula Medical School, Universities of Exeter and Plymouth, Exeter, EX2 4NT, United Kingdom
Myung-Sunny Kim, Korea Food Research Institute, Kyongki-do, 463-746, Republic of Korea
Soo Young Park, Department of Animal Resources and Biotechnology, Chonbuk National University, Jeonju 561-756, Republic of Korea
Chang-Won Kang, Department of Physiology, College of Veterinary Medicine, Chonbuk National University, Jeonju 561-756, Republic of Korea
Supported by KOSEF, project R0-2003-99-101340-0
Correspondence to: Chang-Won Kang, VMD, PhD, Department of Physiology, College of Veterinary Medicine, Chonbuk National University, Jeonju 561-756, Republic of Korea. cwkang@chonbuk.ac.kr
Telephone: +82-63-2703715
Received: November 10, 2005
Revised: November 21, 2005
Accepted: December 7, 2005
Published online: March 21, 2006
Abstract

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.

Keywords: Betaine; IGF-I; IGFBP-1; p42/44 MAPK; Hepatocytes; Ethanol