The flavonoid quercetin inhibits thyroid-restricted genes expression and thyroid function.
Quercetin is the most abundant flavonoid present in a broad range of fruit and vegetables. Furthermore, quercetin is available as dietary supplements that are based on its antioxidant, antiproliferative and anti-inflammatory properties. However, concerns have been raised about the potential toxic effects of excessive intake of quercetin, and several studies have demonstrated that flavonoids, included quercetin, can interfere with thyroid function. In a previous report, we showed that quercetin inhibits thyroid-cell growth and iodide uptake. The latter effect was associated with down-regulation of sodium/iodide symporter gene expression. In the present study, we have evaluated the effects of quercetin on the expression of other thyroid-restricted genes, and we show that quercetin decreases the expression of the thyrotropin receptor, thyroid peroxidase and thyroglobulin genes. We further investigated the inhibitory effects of quercetin on thyroid function in vivo through evaluation of radioiodine uptake in the Sprague-Dawley rat, which was significantly decreased after 14 days of quercetin treatment. These data confirm that quercetin can act as a thyroid disruptor, and they suggest that caution is needed in its supplemental and therapeutic use.
Unit of Endocrinology, Department of Medicine and Sciences of Aging, 'G. D'Annunzio' University of Chieti-Pescara, via dei Vestini, 66100 Chieti, Italy; Aging Research Center (Ce.S.I.), 'G. D'Annunzio' University Foundation, via L. Polacchi 11/17, 66100 Chieti, Italy. Electronic address: cgiulian@unich.it.
Cesidio
C
Giuliani
Unit of Endocrinology, Department of Medicine and Sciences of Aging, 'G. D'Annunzio' University of Chieti-Pescara, via dei Vestini, 66100 Chieti, Italy; Aging Research Center (Ce.S.I.), 'G. D'Annunzio' University Foundation, via L. Polacchi 11/17, 66100 Chieti, Italy. Electronic address: ibucci@unich.it.
Ines
I
Bucci
Aging Research Center (Ce.S.I.), 'G. D'Annunzio' University Foundation, via L. Polacchi 11/17, 66100 Chieti, Italy. Electronic address: serenadisanto@live.it.
Serena
S
Di Santo
Aging Research Center (Ce.S.I.), 'G. D'Annunzio' University Foundation, via L. Polacchi 11/17, 66100 Chieti, Italy. Electronic address: c.rossi@unich.it.
Cosmo
C
Rossi
Aging Research Center (Ce.S.I.), 'G. D'Annunzio' University Foundation, via L. Polacchi 11/17, 66100 Chieti, Italy; Department of Oncology and Neurosciences, 'G. D'Annunzio' University of Chieti-Pescara, via dei Vestini, 66100 Chieti, Italy. Electronic address: grassadonia@unich.it.
Antonino
A
Grassadonia
Aging Research Center (Ce.S.I.), 'G. D'Annunzio' University Foundation, via L. Polacchi 11/17, 66100 Chieti, Italy; Department of Oncology and Neurosciences, 'G. D'Annunzio' University of Chieti-Pescara, via dei Vestini, 66100 Chieti, Italy. Electronic address: mpiantel@unich.it.
Mauro
M
Piantelli
Unit of Endocrinology, Department of Medicine and Sciences of Aging, 'G. D'Annunzio' University of Chieti-Pescara, via dei Vestini, 66100 Chieti, Italy. Electronic address: fmonaco@unich.it.
Fabrizio
F
Monaco
Unit of Endocrinology, Department of Medicine and Sciences of Aging, 'G. D'Annunzio' University of Chieti-Pescara, via dei Vestini, 66100 Chieti, Italy; Aging Research Center (Ce.S.I.), 'G. D'Annunzio' University Foundation, via L. Polacchi 11/17, 66100 Chieti, Italy. Electronic address: gnapol@unich.it.
Giorgio
G
Napolitano
D000818:Animals; D002460:Cell Line; D015870:Gene Expression / Q000187:drug effects*; D011794:Quercetin / Q000494:pharmacology*; D012313:RNA / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology
D012313:RNA; D011794:Quercetin
Endocrine disruptor; FRTL-5; Quercetin; Radioiodide uptake; Rat; Thyroid