Abstract
The effects of 18α,β-glycyrrhetinic acid (18α,β-GA) on the hormonal induction of tyrosine
aminotransferase (TAT) in rat primary cultured hepatocytes were investigated. Dexamethassone
or glucagon used alone caused an increase in enzyme activity, and in combination their
effects were additive. In the 18β-GA hepatocytes pretreated for 6 h, the dexamethasone-induced
increase in the enzyme activity was slightly reduced in a dose-independent manner,
and the glucagon-induced increase and the combined effects of these two inducers were
significantly reduced in a dose-dependent manner. On the other hand, 18α-GA, which
was the isomer of 18β-GA, exerted no influence on the hormonally mediated increase
in enzyme activity. Moreover, 18β-GA reduced the glucose release induced by glucagon
in a dose-dependent manner and 18α-GA did not. These results suggested that 18β-GA
reduced the glucagon-mediated cell response in rat hepatocytes.
Key words
18α,β-Glycyrrhetinic acid - tyrosine aminotransferase (TAT) - glucagon - dexamethasone
- glucose release - hepatocytes
