Inhibition effects of di(2-ethylhexyl)phthalate on mouse-liver lysosomal vacuolar H(+)-ATPase

Abstract

We investigated the effects of di(2-ethylhexyl)phthalate (DEHP) on mouse-liver lysosomes. After 2 weeks of oral administration in mice, a reduction in vacuolar H(+)-ATPase (V-ATPase) was observed, and after 3 weeks, the liver lysosomal compartment was completely negative for V-ATPase, as determined by immunocytochemical analysis. When the mice were subsequently fed a normal diet for 1 week, V-ATPase levels recovered to normal values. According to Northern blot analysis, V-ATPase subunit A mRNA decreased gradually with DEHP treatment. Enzyme cytochemical staining showed acid phosphatase (AcPase) to be present in lysosomes and late autophagosomes (autolysosomes) in normal animals as well as in DEHP-treated animals. But the number of late autophagosomes containing AcPase increased clearly after DEHP treatment. These results suggest that: (1) DEHP causes marked V-ATPase reduction in the liver lysosomal compartment and the effect of DEHP is reversible; and (2) the effect of DEHP on protein expression is likely to be exerted at the transcriptional level.