Osmoregulatory element binding protein and osmoprotective genes as molecular biomarkers for discriminate patterns of drowning

The expression levels of osmoregulatory element binding protein (OREBP) and the genes it transactivates are up-regulated by hypertonicity; thus, this study aims to determine the usefulness of these gene expression levels, as well as inflammatory cytokine levels, as biomarkers to elucidate whether drowning occurred in sea water or fresh water. Fifteen male rats were allocated into three different groups, the cervical dislocation group, a fresh water drowning group, and a salt water drowning group. The levels of inflammatory cytokines in bronchoalveolar lavage fluid were significantly raised in the sea water drowning rats compared with the fresh water drowning and control groups. Moreover, the transcriptional levels of OREBP, sodium/chloride/betaine cotransporter (BGT1), sodium/myoinositol transporter (SMIT), aldose reductase (AR), HSP70 and NF-κB/p65 were highly expressed in the salt water drowning animals in relation to the fresh water drowning and control groups. These results imply that OREBP and osmoprotective genes are up-regulated by hypertonic water, and an analysis of these genes might be a serious forensic tool for discriminating the pattern of drowning.