Liver Glycogenesis, Glycogen Synthetase and Adrenal Responsiveness of Rats Exposed to Acceleration Stress1

To investigate further the mechanism (s) of stress-induced stimulation of liver glycogenesis, overnight fasted female rats, 14, 40, 70 and 90 days old, were centrifuged at 4.7 g for 0.5, 1.0, 2.5 and 5.0 hr. Changes in plasma glucose, plasma corticosterone, liver glycogen, G-6-P and glycogen synthetase activity were determined. Increased liver glycogenesis in stressed rats was always preceded by an increase in total synthetase activity due to an increase in the G-6-P independent form of the enzyme. No increase in liver glycogenesis or synthetase activity occurred in 14-day-old rats, in rats treated with actinomycin D or Metopirone, or in adrenalectomized rats. The 14-day-old rats which showed no marked increase in plasma corticosterone when stressed had significantly smaller concentrations of adrenal corticosterone and a lower rate of steroidogenesis in vitro than mature rats. (Endocrinology 80: 707, 1967)