Hormonal control of manganese transport in the mouse thyroid.
The present study deals with a possible mechanism controlling the transport of manganese (Mn), an essential trace element, from the circulation to the thyroid. Mice were pretreated with propylthiouracil (PTU) or triiodothyronine (T3), and a measurement of the thyroid:serum concentration ratio (T/S) of radioactive manganese (54Mn) was carried out. The T/S of 54Mn was greatly enhanced by PTU, but reduced by T3. Several methods were used to demonstrate that the T/S of 54Mn depends upon the level of thyroid-stimulating hormone (TSH) in the serum. First, bovine TSH was injected into mice; an increase in the T/S resulted. Secondly, serum thyroxine and T3 levels measured by radioimmunoassay (RIA) suggested that PTU produced an increase in serum TSH and T3 a decrease. However, direct measurement of mouse TSH by RIA for rat TSH failed to produce proof of any changes in TSH level, owing to poor cross-reactivity. Taking all the information into account, it is concluded that Mn-transport into the thyroid is controlled by the thyroid state.
Nishida
M
M
Faculty of Pharmaceutical Sciences, University of Tokushima, Japan.
Kawada
J
J
D000818:Animals; D005260:Female; D006728:Hormones / Q000502:physiology*; D008297:Male; D008345:Manganese / Q000378:metabolism*; D051379:Mice; D011441:Propylthiouracil / Q000494:pharmacology; D013961:Thyroid Gland / Q000378:metabolism* / Q000502:physiology; D013972:Thyrotropin / Q000502:physiology; D013974:Thyroxine / Q000502:physiology; D014284:Triiodothyronine / Q000502:physiology
D006728:Hormones; D014284:Triiodothyronine; D008345:Manganese; D011441:Propylthiouracil; D013972:Thyrotropin; D013974:Thyroxine