Down-regulation of liver RNA breakdown by turpentine administration in the starved rat: autophagy and relevant factors.

OBJECTIVE AND DESIGN

To determine whether the inhibition of RNA breakdown observed in ad libitum fed rats 24 h after turpentine administration still occurs in inflamed rats fasted for 24 h and to examine the mechanism and factors involved.

METHODS

RNA breakdown was measured during cyclic in situ perfusion of livers by the accumulation of [14C] cytidine after in vivo RNA labelling. Autophagic activity was determined by the morphometric analysis of lysosomal structures.

RESULTS

The decrease in RNA breakdown (53%) observed in the inflamed rats was accompanied by a 38% drop in the fractional cytoplasmic volume of initial and digestive autophagic vacuoles. Among amino acids, only the portal levels of glutamate were significantly enhanced by 83%. In vivo suppression of glucocorticoid activity using RU 38486 in inflamed rats did not affect the inhibition of RNA breakdown.

CONCLUSIONS

The results show that turpentine-induced inflammation in fasted rats inhibits RNA degradation as well as autophagy and that glucocorticoids do not seem to be involved.