Serine dehydratase expression decreases in rat livers injured by chronic thioacetamide ingestion.

Serine dehydratase (SerDH) is a gluconeogenic enzyme involved in the catabolism of serine, which is regulated by the composition of their diet and their hormonal status in rats. This study examines how chronic injury caused to the liver of rats by the ingestion of thioacetamide (TAA) affects SerDH protein, mRNA levels, enzyme kinetics and its tissue location. After 97 days' oral intake of TAA, the activity of SerDH at all substrate concentrations assayed was about 60% lower than in controls. No significant differences in Km values were found between the treated group and controls. Immunoblotting and immunohistochemistry revealed a significant reduction in the level of SerDH protein in the livers of the treated rats. SerDH was detected specifically in the periportal zone of the hepatic acinus and this location did not change in response to TAA treatment. The level of SerDH mRNA, quantified by reverse transcription and polymerase chain reaction, was significantly lower in treated rats than in the controls. The present findings suggest that the SerDH expression is rendered to be down regulatory during chronic liver injury induced by TAA. These results enhance our understanding about the biochemical mechanisms implied in the control and integration of serine catabolism during liver injury in rat.