A second site of vasopressin action on [1-14C]oleate metabolism in isolated rat hepatocytes: increased formation of 14CO2.

White-adipose-tissue lipogenesis showed a similar response to that of brown fat after glucose and insulin treatment in the three conditions, though the rates were severalfold lower in white adipose tissue. The differences in the basal lipogenesis in brown fat in the virgin, lactating and weaned states may be related to the plasma insulin concentration. Plasma insulin decreases during lactation (Robinson et al., 1978), but increases on weaning (Agius et af., 1979), and brown-adipose-tissue lipogenesis shows a similar pattern. The failure of glucose to elicit the same increase in lipogenesis during lactation as insulin suggests either that the insulin response to a glucose load may be decreased during lactation and weaning or that brown fat has a decreased sensitivity to insulin. The fate of the newly synthesized fatty acids in brown adipose tissue after a glucose load is not known. However, if the newly synthesized lipids are catabolized within the tissue, the decreased rate of lipogenesis during lactation may be important in the direction of substrates to the mammary gland by preventing the ultimate oxidation of lipogenic precursors in brown fat.