monoiodotyrosine and Dwarfism

Age related changes in the levels of circulating thyroid hormones as well as the type of hormones synthesized in the thyroid glands from normal and sex-linked recessive dwarf, female chickens were studied. The impact of the presence of the dwarf gene on the parameters measured was minimal but significant alterations in the types of hormones produced in the thyroid gland with increasing age were observed. As the birds approached sexual maturity, the synthesis of triiodothyronine increased sharply such that the ratio of triiodothyronine (T3): tetraiodothyronine (T4) was approximately 15:1. This was in contrast to the T3:T4 ratio of younger birds which was approximately 0.7:1.0. This shift in hormone synthesis was reflected in relatively more circulating T3 in laying hens when compared with younger birds. It was also noted that four week old dwarf birds had higher circulating T3 values than those found for the normals.

Topics: Age Factors; Animals; Chickens; Diiodotyrosine; Dwarfism; Female; Genes, Recessive; Monoiodotyrosine; Poultry Diseases; Sex Chromosomes; Thyroid Gland; Thyroid Hormones; Thyroxine; Triiodothyronine