The effects of 18 alpha,beta-glycyrrhetinic acid on the hormonal induction of tyrosine aminotransferase in rat primary cultured hepatocytes.

The effects of 18 alpha,beta-glycyrrhetinic acid (18 alpha,beta-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 18 beta-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, 18 alpha-GA, which was the isomer of 18 beta-GA, exerted no influence on the hormonally mediated increase in enzyme activity. Moreover, 18 beta-GA reduced the glucose release induced by glucagon in a dose-dependent manner and 18 alpha-GA did not. These results suggested that 18 beta-GA reduced the glucagon-mediated cell response in rat hepatocytes.