عنوان المقالة:Stijn L.J. Van Herck, Stijn Geysens, Edward Bald, Grazyna Chwatko, Evelyne Delezie, Elham Dianati, R.G. Ahmed, Veerle M. Darras, 2013. Maternal transfer of methimazole and effects on thyroid hormone availability in embryonic tissues. Journal of Endocrinology 218, 105–115.
Stijn L.J. Van Herck, Stijn Geysens, Edward Bald, Grazyna Chwatko, Evelyne Delezie, Elham Dianati, R.G. Ahmed, Veerle M. Darras,
الملخص العربي
Methimazole (MMI) is an anti-thyroid drug used in the treatment of chronic hyperthyroidism.
There is, however, some debate about its use during pregnancy as MMI is known to
cross the mammalian placenta and reach the developing foetus. A similar problem occurs in
birds, whereMMIis deposited in the egg and taken up by the developing embryo. To investigate
whether maternally derived MMI can have detrimental effects on embryonic development, we
treated laying hens with MMI (0.03% in drinking water) and measured total and reduced MMI
contents in the tissues of hens and embryos at different stagesof development. In hens,MMIwas
selectively increased in the thyroid gland, while its levels in the liver and especially brain
remained relatively low. Long-term MMI treatment induced a pronounced goitre with a
decrease in thyroxine (T4) content but an increase in thyroidal 3,5,30-triiodothyronine (T3)
content. This resulted in normal T3 levels in tissues except in the brain. In chicken embryos, MMI
levels were similar in the liver and brain. They gradually decreased during development but
always remained above those in the corresponding maternal tissues. Contrary to the situation in
hens, T4 availability was onlymoderately affected in embryos. Peripheral T3 levels were reduced
in 14-day-old embryos but normal in 18-day-old embryos, while brain T3 content was decreased
at all embryonic stages tested.We conclude that all embryonic tissues are exposed to relatively
high doses of MMI and its oxidised metabolites. The effect of maternal MMI treatment on
embryonic thyroid hormone availability is most pronounced for brain T3 content, which is
reduced throughout the embryonic development period.
Ahmed R. G. | Ahmed R. G. | 2259