Pancreatic acinar cells (PAC) obtain thiamin from the circulation via carrier-mediated process that involves thiamin transporters 1 and 2 (THTR-1 and THTR-2; products of SLC19A2 and SLC19A3, respectively). Chronic alcohol exposure of PAC inhibits thiamin uptake, and based on in vitro studies this inhibition appears to be transcriptionally mediated. The aim of this study was to confirm the involvement of a transcriptional mechanism in mediating the chronic alcohol effect in in vivo settings, and to delineate the molecular mechanisms involved. Using transgenic mice carrying full-length SLC19A2 and SLC19A3 promoters, we found that chronic alcohol feeding lead to a significant reduction in the activity of SLC19A2 and SLC19A3 promoters (as well as in thiamin uptake and expression of THTR-1 and -2). Similar findings were seen in 266-6 cells chronically exposed to alcohol in vitro. In latter studies, the alcohol inhibitory effect was found to be mediated via the minimal SLC19A2 and SLC19A3 promoters, and involved the cis-regulatory elements SP1/GKLF and SP1-GG box and SP1/GC respectively. Chronic alcohol exposure of PAC also lead to a significant reduction in the expression of the SP1 transcription factor, which upon correction (via expression) not only led to the prevention of alcohol inhibitory effects on the activity of SLC19A2 and SLC19A3 promoters but also on the expression of THTR-1 and -2 mRNA and thiamin uptake. These results demonstrate that the inhibitory effect of chronic alcohol exposure on physiological/molecular parameters of thiamin uptake by PAC is mediated via specific cis-regulatory elements in SLC19A2 and SLC19A3 minimal promoters.