Structure of the adrenal glands in mice with the obese-hyperglycaemic syndrome (gene symbol ob).

Quantitative histological methods were used to study the adrenal glands of obese-hyperglycaemic mice and their lean litter mates of various ages. Five weeks old obese mice had significantly enlarged adrenals, due to increased volumes of the zona fasciculata and a persistent cortical X-zone. The enlarged zona fasciculata persisted also in the 5- and 18-month-old obese mice whereas the X-zone had disappeared at these ages. Further, the adrenals of 18-month-old obese mice showed deposits of amyloid in the juxtamedullary cortical zone. It is apparent that the adrenal cortical enlargement coincides in time with the appearance of the other manifestations of the obese-hyperglycaemic syndrome. This further emphasizes that also the adrenal cortical enlargement is an integral part of the syndrome and may contribute to the insulin resistance already at an early stage in the development of the syndrome. The more pronouced weight gain of the adrenal glands of the obese mice together with the morphological changes of the adrenal cortex further suggest an increased ACTH stimulation in these animals. The delayed disappearance of the adrenal X-zone probably reflects the hypogonadism previously demonstrated in these animals.