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