Diphenylhydantoin stimulates the intrapituitary conversion of thyroxine to triiodothyronine in the rat.

Treatment of normal rats with diphenylhydantoin (DPH) decreases serum thyroxine (T4) and triiodothyronine (T3) levels without the anticipated rise in serum thyrotropin (TSH). The present work has studied the intrapituitary conversion of T4 to T3 in male Wistar rats, 200-250 g body weight (BW), treated with DPH 5 mg/100 g BW/day for 8 days. A tracer dose of 3',5'-[125I]T4 (150 microCi) was injected intravenously, and 2 h later hypophyses were removed and homogenized individually at 4 degrees C in ice-cold PBS buffer (pH 7.

Effects of amiodarone on 5'-deiodination of thyroxine to tri-iodothyronine in rat myocardium.

The present work studied the effects of amiodarone (AMD) and iopanoic acid (IA) on the conversion of thyroxine (T4) to tri-iodothyronine (T3) by rat myocardium. In vivo: male Wistar rats weighing 200-250 g were injected i.p.

Effects of thyroxine on oestrogen receptor concentrations in anterior pituitary and hypothalamus of hypothyroid rats.

The effects of thyroxine (T4) were studied on the concentration of oestrogen receptors in the anterior pituitary gland and hypothalamus of ovariectomized euthyroid and hypothyroid rats. A group of rats was made hypothyroid by the administration of 131I. Seven days after ovariectomy, animals were separated into five groups: I, euthyroid controls; II, hypothyroid controls; III, hypothyroid and injected with oestradiol benzoate (10 micrograms/day for 10 days); IV, hypothyroid and injected with T4 (4 micrograms/day for 10 days) and V, hypothyroid and injected with both oestradiol and T4 as described above.

Effect of inferior laryngeal nerve section on thyroid function in rats.

To examine the role of thyroid parasympathetic innervation in organ's function, rats subjected to inferior laryngeal nerve (ILN) section were employed. This procedure decreased thyroid [3H]choline uptake by about half. Bilaterally ILN-sectioned rats treated with methylmercaptoimidazole for 4 days exhibited a significant impairment of the methylmercaptoimidazole-induced goitrogenic response.