The Effects of 18 α,β-Glycyrrhetinic Acid on the Hormonal Induction of Tyrosine Aminotransferase in Rat Primary Cultured Hepatocytes

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