Posted by raybakes on October 21, 2004, at 11:37:14
In reply to Re: Supplements for brain fog? » karaS, posted by raybakes on October 20, 2004, at 5:50:10
retinoic acid inhibiting TSH is interesting, particularly as hypothyroid people don't activate vitamin A easily.
Retinoic acid inhibits in vivo thyroid-stimulating hormone secretion.
Coya R, Carro E, Mallo F, Dieguez C.
Department of Physiology, Faculty of Medicine, University of Santiago de Compostela, Spain.
Retinoids are needed for normal growth and development. Retinoic acid (RA), an active metabolite of vitamin A, acts through nuclear receptors that belongs to the superfamily which also includes the T3 receptors and 1-25-dihydroxyvitamin D receptor. In order to assess whether RA is a regulator of in vivo thyroid-stimulating hormone (TSH) secretion, we studied the effect of RA administration on spontaneous basal TSH secretion and TSH responses to TRH in either euthyroid or hypothyroid rats. We found that rats treated with RA showed a decrease in spontaneous basal TSH levels and TSH responses to TRH. Similarly, RA administration to hypothyroid rats led to a decrease on TSH responses to TRH. Our data suggests that RA plays an important inhibitory role on in vivo secretion and this effect is unrelated to the thyroid status of the animals.
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