Hepatic gluconeogenesis in rats treated with cortisol

A single subcutaneous injection of cortisol into starved rats increased liver glycogen after a short lag period, and radioactivity derived from glucose- 14C injected at the same time as cortisol appeared in blood glucose and glycogen. At the time corresponding to the onset of glycogen deposition there was an increased rate of incorporation of 14C into glycogen but a fall in the specific activity of the glycogen that was not paralleled by a drop in the specific activity of blood glucose. In contrast to these results, there was very little incorporation of radioactivity derived from injected lactate or glycerol. Using labelled alanine, it was concluded that there was no large influx of amino acids into the plasma from peripheral tissues. In order to explain the fall in the specific activity of glycogen it is suggested that one of the initial effects of cortisol on liver results in an increased rate of gluconeogenesis from liver protein.