THE HISTOCHEMICAL DISTRIBUTION AND METABOLIC SIGNIFICANCE OF GLUCOSE-6-PHOSPHATE DEHYDROGENASE ACTIVITY, GLYCOGEN AND LIPID IN THE STIMULATED ADRENAL CORTEX1

Abstract

The adrenal cortices of normal and hypophysectomized rats subjected to cold stress of varying duration were studied using histochemical methods to determine the distribution of glucose-6-phosphate dehydrogenase activity, glycogen, and lipids. It was found that glucose-6-phosphate dehydrogenase activity did not vary in distribution or intensity in response to stress in either the normal or hypophysectomized animals, but remained concentrated in the reticular and fascicular zones. Glycogen in the normal animal, although distributed in the same areas as the enzyme, was depleted rapidly by stress, often disappearing from the cortex after only 30 minutes of stress. This was much more rapid than was the response of lipid to stress. Glycogen was usually well on its way to repletion before cortical lipid was at its lowest ebb. Neither glycogen nor fat responded to stress in the hypophysectomized animals. It is suggested that glycogenolysis initiated by ACTH provides substrate for the glucose-6-phosphate dehydrogenase, this setting into motion the initial steps in the pentose phosphate pathway of carbohydrate metabolism. This provides the energy and reduced triphosphopyridine nucleotide required for steroid synthesis and results in the utilization of cortical lipid stores. The histochemical method provides distributional data pertinent in the evaluation of a theory of ACTH function derived from the use of other technics.