Maintenance and Restoration of Growth in Thyroidectomized Rats

The document summarizes a study on the impact of thyroidectomy on rat growth and the effectiveness of thyroid hormone treatments in restoring growth. Thyroidectomy was shown to significantly retard growth, but administering thyroid preparations like desiccated thyroid, thyroxine, or artificial thyroprotein could maintain or restore normal growth rates. The study involved young male rats with an average initial weight of 40-50 g. The most effective treatment was thyroid gland preparation, with treated rats gaining an average of 50 g. Other treatments, such as ox pituitary gland extracts and gonadotrophins, had limited effects on body weight but caused reproductive organ hypertrophy. Daily thyroxine injections or thyroxine tablet implantation were also effective in maintaining growth, with implanted rats reaching an average weight of 174 g after 100 days. The study concludes that thyroid preparations can effectively maintain or restore growth in thyroidectomized rats and highlights a complex, possibly synergistic relationship between thyroid and pituitary glands in growth regulation.