Studies were made in rats bearing the growth hormone secreting tumor (MtTW15). There was (a) a generalized depletion of depot fat with a decrease of its total fatty acidcontent, and increased rate of lipolysis, (b) a rise in the fasting levels of serum FFA detectable only during theearly period of tumor development, and (c) a severe depression of the in vitro metabolism in adipose tissue of glucose to CO2 and fatty acids. The addition of insulin could not restore the lowered values to the basal level of the controls.
These findings indicate that chronically elevated levels of GH decrease the glucose utilization and insulin responsivenessof rat adipose tissue and suggest that rats bearing this particular tumor constitute a suitable experimental model for studies on the metabolic effect of hypersommatotropism
