Hormonal effects on the acid mucopolysaccharide composition of the rat aorta

Both thyroidectomized and methimazole-treated rats had lower concentrations of the sulfated acid mucopolysaccharides in their aortas. This decrease could be prevented or reversed by the administration of thyroxine. The same observations were made in hypophysectomized rats, and it was concluded that the acid mucopolysaccharide (AMPS) changes were due to a lack of thyroid hormone rather than to any changes in thyroid stimulating hormone (TSH) concentration. On the other hand, growth hormone specifically increased the chondroitin sulfate concentration in hypophysectomized rats, and this proceeded independently from the action of thyroxine. Cortisone decreased the amounts of chondroitin sulfate in rat aorta, but it had no effect upon the other AMPS fractions. Estradiol and testosterone administration as well as adrenalectomy and gonadectomy had no effect upon the aortic AMPS, and it was concluded that the rat aorta is mainly dependent upon thyroid hormone for the maintenance of its AMPS composition. The administration of methimazole prevented the accumulation of chondroitin sulfate in the aortas of lathyritic rats. This suggests that hypothyroidism decreases the biosynthesis of aortic AMPS.