HORMONE-MODULATED AND ENDOTOXIN-MODULATED GENE-EXPRESSION OF A LONG-TERM ORGAN-CULTURE SYSTEM OF ADULT-RAT LIVER

Precision-cut slices of normal adult rat liver maintained in serum-fre e medium remain hormone- and endotoxin-responsive for at least 48 h. T hey respond to glucocorticoid (dexamethasone) with the induction of th e gluconeogenic enzyme tyrosine aminotransferase (TAT), as determined by enzymatic activity and by the increase in enzyme protein. Furthermo re, endotoxin (LPS) induced nitric oxide synthase II (i-NOS), and this induction is repressed, similarly to the in vivo situation, by dexame thasone (DEX). All increases are inhibited by cycloheximide (CHX). The length of the period of responsiveness suggests that this organ cultu re system might be generally useful for studying the modulation of liv er gene expression by physiological and pathological influences.