Modulation of peroxisome proliferator-activated receptor-α activity by bile acids causes circadian changes in the intestinal expression of Octn1/Slc22a4 in mice.

In addition to their digestive actions, bile acids modulate gene expression by altering the activity of peroxisome proliferator-activated receptor-α (PPARα). The modulatory effects of bile acids have been shown to affect the expression of genes responsible for lipid metabolism as well as membrane transporters. Bile acids are secreted in response to food intake and accumulate in intestinal epithelial cells.

Comparison of protein phosphatase inhibitory activity and apparent toxicity of microcystins and related compounds.

Two metabolites of microcystin-LR glutathione conjugate and, microcystin-cysteine conjugate, as well as microcystin-RR (MCRR) are less toxic than microcystin-LR (MCLR). In the present study, we investigated why these compounds are weakly toxic in comparison with MCLR, as the reason is still unknown and no systematic study has so far been carried out for a clarification of this issue. Although they showed almost the same inhibitory activity against protein phosphatases 1 and 2A as MCLR in vitro, the apparent toxicity of these three compounds by intratracheal administration to mice decreased to about 1/12 the level of MCLR at 100microg/kg.