Taurine supplementation does not decrease homocysteine levels and liver injury induced by a choline-deficient diet

Abstract

AimsThe aim of this study is to examine the effects of taurine supplementation on homocysteine (Hcy) metabolism and liver injury in rats fed a choline-deficient diet. Main methodsThirty rats were divided into three groups (n=10), to receive one of the following diets for 4weeks: control diet (C), choline-deficient diet (CDD), or choline-deficient diet supplemented with taurine (CDDT). The CDD and the CDDT consisted of AIN-93 without the recommended choline content of 2.5%, and the CDDT was supplemented by the addition of 2.5% taurine. Key findingsFour weeks of ingesting a CDD resulted in a significant increase in plasma Hcy (50%) as well as a decrease in liver S-adenosylmethionine (SAM) concentration and S-adenosylmethionine/S-adenosylhomocysteine ratio. No changes were found in plasma methionine and cysteine plasma levels compared to control group. Four weeks of ingesting a CDD also caused a significant (P<0.05) increase in hepatic total fat, hepatic malondialdehyde (MDA), and plasma alanine aminotransferase (ALT) levels. In addition, reduced hepatic glutathione (GSH) levels and reduced/oxidized glutathione ratios (GSH/GSSG) were found in rats fed a CDD compared to controls. Taurine supplementation of the CDD normalized genes involved in the remethylation pathway, BHMT and CHDH, which were impaired by CDD alone. However, taurine supplementation failed to prevent CDD-induced Hcy metabolism disturbances and hepatic injury. Also, taurine added to CDD caused decreased expression of PEMT, CHKa, and CHKb, key genes involved in phosphatidylcholine (PC) synthesis and liver fat accumulation. SignificanceTaurine supplementation failed to ameliorate impaired Hcy metabolism and liver injury caused by CDD intake.