Nonreactive Strains Research Articles

Thyroid function in rats selectively bred for emotional elimination. III. Behavioural and physiological changes after treatment with drugs acting on the thyroid.

SUMMARY 1. The effect has been studied of propylthiouracil, thyrotrophic hormone (TSH) and potassium iodide on the behaviour of rats from the Maudsley Reactive and Non-reactive strains bred for emotional defecation. 2. In Reactive, high defecating rats treated with propylthiouracil, the defecation scores increased significantly, and the ambulation score decreased slightly; in the Non-reactive, low defecating rats, no significant change occurred in the defecation score. 3. After the injection of TSH, the behavioural scores did not change significantly, although the defecation scores were decreased and the ambulation scores increased in the majority of cases. 4. No significant changes were found in response to the administration of potassium iodide. 5. Differences in adrenal weight were found between the two strains, the gland being significantly larger in the high defecating strain than in the low defecating one. 6. The ovaries of the high defecating females were significantly smaller than those of the low defecating ones. 7. No marked difference was found in the weight of the pituitary and testes. 8. The weight of the kidneys was significantly lower in the high defecating than in the low defecating strain. 9. Treatment with propylthiouracil and TSH altered the size of the thyroids, the serum protein bound iodine and the weight of the adrenals. Injections of pituitary extracts containing TSH also affected the weight of the kidneys.

Thyroid function in rats selectively bred for emotional elimination. II. Differences in thyroid activity.

SUMMARY 1. The incorporation of 131I into the thyroid and the secretion of labelled thyroid hormones from the gland have been studied in living animals and in vitro in rats of both sexes from the Maudsley Reactive and Non-reactive strains, selectively bred for emotional defecation. 2. The rate of uptake of 131I in living animals differed significantly in the two strains, being slower in the high defecating strain than in the low defecating one. 3. The rate of excretion of thyroid hormones from the gland was also different in these rats both in vivo and in vitro; it was slower in the high defecating than in the low defecating strain. 4. The size of the thyroids differed significantly; the wet weights of the gland of the rats of the high defecating strain were higher than those of the low defecating strain. 5. The water content of the thyroids of the high defecating strain was higher than in the low defecating strain. 6. Histology of the thyroids showed that the glands of the high defecating rats contained proportionately less secretory epithelium and more colloid and intercellular tissue than the glands of the low defecating rats. 7. The thyrotrophic hormone (TSH) content of the serum and the pituitary differed in the two strains. In the high defecating strain the level of TSH in the serum was lower and in the pituitary higher than that in the low defecating animals.

Thyroid function in rats selectively bred for emotional elimination. I. Differences in thyroid hormones.

SUMMARY 1. The amount and distribution of thyroid hormones have been studied in the blood and thyroid gland of rats of both sexes from the Maudsley Reactive and Non-reactive strains, selectively bred for emotional defecation. 2. The amount of thyroid hormones in the thyroid gland was significantly lower in the animals from the high-defecating strain than in those from the low-defecating strain. 3. The quantity of protein-bound iodine in the serum was significantly lower in the high-defecating strain than in the low-defecating strain. 4. From the thyroid gland and from the serum the thyroid hormones were extracted with butanol and quantitatively determined. The ratio of the thyroid hormones was different in the two strains, thyroxine being lower and triiodothyronine (with other iodine-containing compounds) higher in the high-defecating strain.