Effect of chronic alcohol feeding on vitamin B1 (thiamine) transport in rat kidneys

Abstract

Renal uptake of thiamine plays an important role in regulating the vitamin body homeostasis and is mediated by thiamine transporters1 and 2 (THTR1 and THTR2). Little is known about the effect of chronic alcohol consumption on renal thiamine transport. We addressed this issue in this investigation using purified renal brush border membrane vesicles (BBMV) and basolateral membrane vesicles (BLMV) isolated from rats fed alcohol liquid diet (36% calories) for 2, 4 and 6 weeks and compared the findings to those of pair‐fed controls (alcohol free liquid diet). Results showed that chronic ethanol feeding significantly inhibits carrier mediated thiamine uptake in renal BBMV and the effect was evident as early as 2 weeks after the start of alcohol feeding. Uptake of thiamine by renal BLMV was similarly inhibited. This decrease in thiamine transport was associated with parallel decrease in mRNA level of THTR1 and 2 (detected by real‐time PCR) as well as in level of transcription of their respective genes [established from level of expression of heterogeneous nuclear RNA (hnRNA)]. These studies show for the first time that chronic alcohol consumption leads to inhibition in renal thiamine uptake and the effect appears to be mediated (at least in part) via transcriptional mechanism(s). (Supported by grants from DVA and NIH).