Change in Triacylglycerol Hydrolase Activity in Hen Liver with Age, and by Estradiol Administration to Male Chicks

Most of the triacylglycerol hydrolase activity in the hen liver showed its maximum activity at pH 6.0 and at 40°C. The hydrolase activity was markedly inhibited by serum of the laying hen. At 145 and 167 days of age, the activity was markedly decreased to less than one half that in the young hen. The hydrolase activity in cockerel was monitored to compare with that of hen. In cockerels, the hydrolase activity tended to increase with age of days. On estrogenization of the male chicks, the hydrolase activity in the liver was significantly decreased in contrast to an increase in lipid content in the liver. These observations suggest that the degradation of triacylglycerol in the liver is regulated by estradiol with the increase in lipogenesis for egg production.