Project description:Perchlorate, which is a ubiquitous and persistent ion, competitively interferes with iodide accumulation in the thyroid, causing iodine deficiency, which may result in reduced thyroid hormone synthesis and secretion. Human studies suggest that perchlorate presents very little risk in healthy individuals; however, the precautionary principle demands that the sensitive populations of iodine deficient adults and mothers require extra consideration. In an attempt to determine if the effects on gene expression were similar, we compared the thyroidal effects of perchlorate (10 mg/kg) treatment for 14 days in drinking water with those caused by 8 weeks of Iodine-deficiency in rats. The thyroids were collected (N=3 each group) and total mRNA was analyzed using the Affymetrix Rat Genome 230 2.0 GeneChip®. Changes in gene expression were compared with appropriate control groups. We compared the 2-fold gene changes due to I-deficiency with changes due to perchlorate treatment. 189 transcripts were changed by the Iodine-deficient diet and 722 transcripts were changed by the perchlorate treatment. 34% of the transcripts changed by the I-deficient diet were also changed by perchlorate and generally in the same direction. three specific transporter genes, AQP1, NIS, & SLC22A3 were changed by both treatments, indicating that the membrane specific changes were similar. Iodine-deficiency primarily caused changes in retinol and calcium signaling pathways and perchlorate primarily caused changes related to the accumulation of extracellular matrix proteins. This study provides evidence that perchlorate, at least at this dose level, changes more genes and changes different genes compared to iodine deficiency. Changes in gene expression due to I-deficiency compared to normal diet for 2 months. Changes in gene expression due to perchlorate in the drinking water compared to normal drinking water for 1 or 14 days. Feeding study in rats.
Project description:Perchlorate, which is a ubiquitous and persistent ion, competitively interferes with iodide accumulation in the thyroid, causing iodine deficiency, which may result in reduced thyroid hormone synthesis and secretion. Human studies suggest that perchlorate presents very little risk in healthy individuals; however, the precautionary principle demands that the sensitive populations of iodine deficient adults and mothers require extra consideration. In an attempt to determine if the effects on gene expression were similar, we compared the thyroidal effects of perchlorate (10 mg/kg) treatment for 14 days in drinking water with those caused by 8 weeks of Iodine-deficiency in rats. The thyroids were collected (N=3 each group) and total mRNA was analyzed using the Affymetrix Rat Genome 230 2.0 GeneChip®. Changes in gene expression were compared with appropriate control groups. We compared the 2-fold gene changes due to I-deficiency with changes due to perchlorate treatment. 189 transcripts were changed by the Iodine-deficient diet and 722 transcripts were changed by the perchlorate treatment. 34% of the transcripts changed by the I-deficient diet were also changed by perchlorate and generally in the same direction. three specific transporter genes, AQP1, NIS, & SLC22A3 were changed by both treatments, indicating that the membrane specific changes were similar. Iodine-deficiency primarily caused changes in retinol and calcium signaling pathways and perchlorate primarily caused changes related to the accumulation of extracellular matrix proteins. This study provides evidence that perchlorate, at least at this dose level, changes more genes and changes different genes compared to iodine deficiency.
Project description:The excessive perchlorate utilization as an oxidizer in rocket propellants and blasting agents had led to the contamination of surface and ground waters. This chemical is known to compete with iodine for binding to the thyroid membrane receptors potentially causing hypothyroidism and fetal retardation in pregnant women. Nevertheless, to date, its biological effects are not completely understood. We have investigated the molecular mechanisms responsive to perchlorate in the nematode C. elegans to nominate a candidate gene for further peruse in the development of a C.elegans perchlorate biosensor. Perchlorate (1 mg/mL) affected the transcriptional response of Regulation of developmental process, growth, defense mechanisms and stress response, among other biological processes.
Project description:Thyroid autonomy is a frequent cause of thyrotoxicosis in regions with iodine deficiency. Epidemiological data suggest that the prevalence of thyroid autonomy is not only inversely correlated with the ambient iodine supply, but that iodide may also influence the course of pre-existing thyroid autonomy with possibly different effects on thyroid growth and function. Iodine slows TSH effects on thyroid growth stimulation and this effect is more pronounced in thyrocytes with constitutive cAMP activation i.e. in thyroid autonomy. Iodine induced growth alteration in early stage thyroid autonomy is conferred by induction of apoptosis and G2/M arrest. Transcriptome analysis revealed significant modulation of gene networks relevant to cell adhesion, cadherin signalling and ion binding with more pronounced effects in constitutively active FRTL-5 cells compared to normal FRTL-5 cells.
Project description:Thyroid autonomy is a frequent cause of thyrotoxicosis in regions with iodine deficiency. Epidemiological data suggest that the prevalence of thyroid autonomy is not only inversely correlated with the ambient iodine supply, but that iodide may also influence the course of pre-existing thyroid autonomy with possibly different effects on thyroid growth and function. Iodine slows TSH effects on thyroid growth stimulation and this effect is more pronounced in thyrocytes with constitutive cAMP activation i.e. in thyroid autonomy. Iodine induced growth alteration in early stage thyroid autonomy is conferred by induction of apoptosis and G2/M arrest. Transcriptome analysis revealed significant modulation of gene networks relevant to cell adhesion, cadherin signalling and ion binding with more pronounced effects in constitutively active FRTL-5 cells compared to normal FRTL-5 cells. The aim was to study iodide-induced changes in global gene expression in an in vitro model of thyroid autonomy. This model makes use of FRTL-5 cells with stable expression of a constitutively activating TSH receptor mutation or wild type TSHR as a control.
Project description:We investigated the effects of thyroid hormone disruptions on gene expression in juvenile mice liver to develop a stronger understanding of the mechanisms by which thyroid disrupting chemicals impair development. Gene expression was examined by hybridization of hepatic RNA to Agilent mouse microarrays for hyper-, hypo-, hypo-replacement (hypo+) and euthyroid animals. Keywords: Toxicogenomics, biomarkers of thyroid disruptors Hypothyroidism was induced from post natal day (PND) 13 to 15 by adding model thyroid toxicants methimazole and sodium perchlorate to drinking water of pregnant females. Hyperthyroidism was induced by intraperitoneal injections (i.p.) of THs at PND 15, 4 hours before decapitation and tissue collection. For the hypothyroid/replacement group; dams were provided with drinking water for 3 days (PND 13 to 15), containing a mixture of methimazole/sodium perchlorate. Pups then received intraperitoneal injections of thyoid hormones on PND 15, 4 hours before decapitation and tissue collection.