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Updated: Jul 14, 2026
Colorimetric Assessment of Deiodinase 1 Activity in Human Liver Microsomes Using the Sandell-Kolthoff Reaction
Published on: April 10, 2026
Methylmercury inhibition of type II 5'-deiodinase activity resulting in a decrease in growth hormone production in
Kouki Mori1, Katsumi Yoshida2, Yoshinori Nakagawa1
1Division of Nephrology, Endocrinology and Vascular Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan.
Abstract:
We have recently reported that methylmercury (MeHg) inhibits type II iodothyronine 5'-deiodinase (D2) activity in mouse neuroblastoma NB41A3 cells. In the present study, we determined the biological significance of D2 inhibition by MeHg. GH3 rat pituitary tumor cells were treated with MeHg and D2 activity and production of a thyroid hormone-responsive gene product, growth hormone (GH) were analyzed. MeHg inhibited D2 activity and decreased thyroxine (T4)-induced, but not 3,3',5-triiodothyronine (T3)-induced GH secretion in GH3 cells. Our results suggest that MeHg inhibition of D2 activity might be involved in the inhibition of GH production in GH3 cells. Thus, D2 inhibition could be a novel mechanism involved in MeHg toxicity.
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