Effects of 2,4-dichlorophenoxyacetic acid butyl ester on chick liver.

Fertilized hen eggs were externally treated with 3.1 mg 2,4-dichlorophenoxyacetic acid butyl ester (2,4-D ester) before starting incubation. Liver lipid composition, (14C)2,4-dichlorophenoxyacetic acid (14C-2,4-D) subcellular distribution and covalent binding to proteins and lipids of chicks hatched from these eggs were studied. Furthermore, catalase, glutathione S-transferase and glucose 6-phosphatase activities as well as reduced glutathione content were determined. The herbicide produced a significant decrease on the total lipids, specially on phospholipids, both in total liver and microsomes. (14C-2,4-D) subcellular distribution in liver demonstrated that the herbicide passed through the plasmatic membrane and it was present in all the studied fractions. Herbicide bound covalently to hepatic proteins and lipids, being the binding to proteins tenfold higher than to lipids. Because these results might be of potential relevance to the understanding of the 2,4-D toxicity, further studies on the mechanisms of these reactions are necessary. On the other hand, the microsomal and cytosolic glutathione S-transferases activities remained unchanged, even though in vitro studies 2,4-D ester caused a decrease of the enzyme activities with an I50 value of 0.2 mM. No significant change in reduced glutathione content between control and treated livers was observed. The catalase activity increased two-fold whereas glucose 6-phosphatase activity decreased 46% with respect to the corresponding control values. These results indicate that 2,4-D ester may have effects on the metabolism of xenobiotics.