Effect of amino acids and cycloheximide on changes caused by vinblastine, leupeptin and methylamine in the autophagic/lysosomal system of mouse hepatocytes in vivo

Abstract

The number of autophagic vacuoles in hepatocytes of 24 h fasted mice in vivo increased manyfold following the administration of vinblastine, leupeptin and methylamine. The effect of each chemical is characterized by the predominance of a certain kind of vacuole. Vinblastine treatment is accompanied by a large proportion of vacuoles containing morphologically unaltered organelles, leupeptin causes preferential accumulation of dense and complex vacuoles, methylamine administration produces mostly large, electron-lucent, swollen vacuoles. The amounts of segregated and accumulated cytoplasmic material, expressed as percentage cytoplasm per hour, were 0.84%, 2.08% and 0.74% following vinblastine, leupeptin and methylamine treatment respectively. The actual rate of segregation was probably higher than this. Inhibition of degradation of the sequestered cytoplasmic material is proposed to be a main factor in the increase in the size of the autophagic/lysosomal compartment. Treatment with cycloheximide or exogenously added mixture of amino acids cut down the size of the autophagic/lysosomal system in control cells and strongly inhibited the accumulation caused by vinblastine, leupeptin and methylamine.