Effects of testosterone on the development of autoimmune thyroiditis in two strains of chicken

The effect of testosterone on organ-specific spontaneous autoimmune thyroiditis (SAT) was examined in two strains of chicken: the Obese (OS) strain, which develops SAT at several weeks of age and the control Special C (Sp. C) strain. Both were originally selected from the C strain and are homozygous for the B13 major histocompatibility haplotype. Testes development and testosterone levels in the OS strain were considerably less than those found in comparably aged birds of the Sp. C strain. Testosterone supplementation of the OS strain significantly decreased thyroid infiltration by lymphocytes while castration of the Sp. C strain significantly enhanced infiltration. These results suggest that testosterone reduces SAT and that the hormonal constitution in both strains of chicken affect the frequency of occurrence and severity of this disorder.