Effect of Emotional Stress and TSH on Thyroid Vein Hormone Level in Sheep with Exteriorized Thyroids

Abstract

The development of an exteriorized thyroid gland preparation in the sheep allowed thyroid vein blood to be collected from an undisturbed conscious animal. Thyroid exteriorization was carried out on 6 Merino ewes at 18 months of age. The right lobe of the thyroid was transferred with its blood supply to a carotid artery jugular vein loop; the left lobe was removed at a subsequent operation. Observations were made 6- 18 months after operation, a week after a dose of 50 μc of carrier-free ¹³¹I. Sampling was carried out through a cannula in the jugular vein. Rises in plasma PB¹³¹I and PBI were noted 15–30 min after insertion of the cannula into the jugular vein. Subsequently, after these changes had subsided, similar rises were demonstrable after a series of firework explosions, and (most consistently) after exposure to a barking dog. These rises lasted up to 2 hr. Restraint was followed by an increase in PBl31I, but after training no effect was observed. Similar but larger rises in PB¹³¹I, PBI and also free ¹³¹I were noted following TSH, both intramuscularly and intravenously. (Endocrinology75: 42, 1964)