Dose-dependent effect of TRH on plasma oleic acid in man.

Administered to normal subjects of either sex, the TRH enhances the plasma oleic acid after 60 minutes without any significantly marked modification in the blood concentration of total FFA. The oleic acid increase is significantly dependent on the amount of administered TRH (200 microgram and greater than or equal to 400 microgram). It is accompanied by 1) a more or less pronounced but acute release of TSH, and 2) a rise in circulating T3 but a submaximal value within the time-course of the experiment (1 h). This elevation is presumably due to a preferential liberation of oleic acid by the adipose tissue, through a direct action of TSH and/or under the permissive influence of the thyroid hormone, among other factors that may intervene in the process.