[Lipogenesis, aging and hormonal regulation]

Thyroid hormones stimulate hepatic synthesis of fatty acids as well as activities of lipogenic enzymes. According to the present study, there also partially exists an age dependency. In livers of 3- and 18-month-old rats of the Wistar strain both the velocity of fatty acid synthesis and the activities of lipogenic enzymes were measured in dependence on thyroid function. An impaired stimulation of malic enzyme activity under hyperthyreosis conditions was found in the older animals. The velocity of fatty acid synthesis was diminished in the group of 18-month-old rats, but there was no age dependence with respect of the effect of a variation in thyroid status. In the adipose tissue of the older animals, the activities of lipogenic enzymes were lowered. In this tissue no effects of thyreohormones in either young or old rats were observed.