ACTH content of pituitary glands of arteriosclerotic breeder vs. non-arteriosclerotic virgin rats.

Acid extracts were made of the pituitary glands of non-arteriosclerotic male and female virgin rats and arteriosclerotic, male and female breeder rats. The ACTH content of these pituitary glands was determined by measuring the amount of corticosterone produced by the adrenal glands of healthy but hypophysectomized rats when challenged by the various ACTH acid extracts. The pituitary glands of the arteriosclerotic animals were significantly heavier than non-arteriosclerotic rats and contained decreased amounts of ACTH commensurate with the severity of the pituitary donor's arteriosclerosis. Similarly, arteriosclerotic donors had heavier adrenal glands but contained considerably less corticosterone than non-arteriosclerotic virgin rats. Male breeder rats developed microscopic aortic lesions involving intimal mesenchymal cell and ground substance alterations whereas the female breeder lesions progressed from intimal ground substance and connective tissue changes to medial elastolytic degeneration and eventual medial cartilaginous and osseous metaplasia. Histopathologic examination of the pituitary and adrenal glands demonstrated hyperplasia of basophil and other cytologic elements of the pituitary gland including colloid-filled cysts and lipid depletion of the zona glomerulosa as well as hemorrhage and thrombosis of the adrenal cortex of the arteriosclerotic breeder rats. The hypothesis is made that repeated breeding leads to abnormal hypothalamic regulation of pituitary gland synthesis and release of ACTH, which, in turn, contributes to abnormal adrenal glandular function conditioning the aortic wall toward abnormal changes in mesenchymal cell activity and metabolism of connective tissue ground substance.