Neurofilaments in Thyrotrophs of Hypothyroid Rats: An Immunohistochemical Study

We examined by immunohistochemistry the expression of 200-kDa (NF-H) neurofilaments in pituitary thyrotrophs of rats, made hypothyroid by propylthiouracil (PTU) administration. Rats were sacrificed at 3, 7, 14, and 28 d of PTU administration as well as at 3, 7, and 14 d after interruption of a 14-d PTU treatment. The pituitaries were fixed, dehydrated, and embedded in paraffin. Consecutive sections were prepared for the immunohistochemical demonstration of thyroid-stimulation hormone and NF-H. NF-H were found in some thyrotrophs of the adenohypophysis of control rats. NF-H were expressed in thyroidectomy cells of hypothyroid rats. Discontinuation of PTU treatment led to recovery from cytologic alterations in the thyroidectomy cells expressing NF-H.