Increased acridine orange uptake and lysosomal enzyme levels in rat liver after steroid administration

Abstract

A steroid which stabilizes lysosomes in vitro and a pyrogenic steroid which labilizes lysosomes in vitro were compared with respect to their ability to modify lysosomal uptake and lysosomal enzyme levels in vivo . Cortisone acetate increased the uptake of acridine orange by rat liver lysosomes when the dye was administered by intrathoracic injection. The steroid increased and accelerated the uptake of acridine orange so that, in liver lysosomes from treated rats, the maximum uptake was double that of controls and was reached at 2h, whereas in controls the maximum uptake was at 4h after the injection of the dye. This large elevation of uptake is specific to the lysosomal fraction and is not seen in other subcellular fractions of rat liver. The specific activities of a lysosomal enzyme β-N-acetylglucosaminidase were increased in lysosomal fractions from cortisone acetate-treated rats. Etiocholanolone, a steroid which labilizes lysosome in vitro , similarly accelerated and increased acridine orange uptake by lysosomes but had little effect on lysosomal β-N-acetylglucosaminidase levels. Thus the ability of steroids to stabilize or labilize lysosomes in vitro does not correlate with their effect on lysosomal uptake of injected substances in vivo , or with their ability to induce increased specific activities of lysosomal enzymes.