[Effects of recurrent laryngeal nerve on thyroid hormone secretion in rats]

The effects of recurrent laryngeal never (RLN) on serum thyroid hormones and thyroidal radioiodide uptake were examined in rats. The results are (1) Serum thyroxine (T4) level increased significantly after section of unilateral RLN. When the sectioned peripheral end was stimulated immediately after section, the serum T4 level went even significantly lower than the control within 30 minutes. (2) Radioiodide uptake by homolateral thyroid increased significantly after section of unilateral RLN. These results indicate that RLN normally exerts an inhibitory effect on thyroxine secretion possibly mediated by muscarinic receptors.