Perspectives in the Study of Thyroid Hormone Action on Brain Development and Function

Bernal, Juan; Guadaño-Ferraz, Ana; Morte, Beatriz

doi:10.1089/105072503770867174

Cited by 265 publications

(174 citation statements)

References 66 publications

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“…El iodo es indispensable en la síntesis de hormonas tiroideas, necesarias para el correcto desarrollo cerebral y mental, así como en la maduración ósea, pulmonar y cardiaca a lo largo de la vida fetal y neonatal (6). El feto depende del suministro de hormonas tiroideas maternas, siendo la etapa más crítica del desarrollo cerebral las primeras 10-12 semanas.…”

Section: Iodounclassified

Suplementos en gestación: últimas recomendaciones

2016

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Pregnancy is a challenge from the nutritional point of view, because nutrient requirements are increased and alter its intake can affect maternal and fetal health. Micronutrient defi ciency states are related to preeclampsia, intrauterine growth restriction, abortion and congenital anomalies. Currently, the diet of many expectant mothers is insuffi cient in micronutrients, in this cases supplementation is necessary. It is recommended supplementation with folic acid in doses of 400 mcg / day and 5 mg/day in risk pregnant, and should begin at least one month before conception and during the fi rst 12 weeks gestation, and extend it throughout pregnancy in mothers with nutritional risk. It is important to keep watch the proper dose of folic acid to prevent possible adverse effects of unmetabolized accumulation in plasma. A high percentage of pregnant women presented iron defi ciency anemia, being recommended intermittent use of iron supplements (with lower gastrointestinal alteration and oxidative stress); not recommended for mothers without anemia (hemoglobin> 13.5 g / L). Since calcium absorption is increased up to 40% in gestation, its supplementation is not recommended for mothers with adequate intakes (3 dairy / day), and its use must be reserved to women with inadequate intakes and / or high risk of preeclampsia. Regarding the iodine, there are confl icting positions by different working groups established potassium iodide supplementation in women who do not reach their recommended intake (3 servings of milk and dairy products + 2 g of iodized salt), with their diets. Given that vitamin A and D can be toxic to mother and fetus, it is not recommended its supplementation except in cases of defi ciency. Although the use of multiple micronutrients supplements may favorably impact the outcome of pregnancy, more scientifi c evidence is needed to establish the replacement of iron and folic acid with a multiple micronutrient supplement. Suplementos en gestación: últimas recomendaciones ResumenEl embarazo representa un desafío desde el punto de vista nutricional, debido a que las necesidades de nutrientes están aumentadas y una alteración en su ingesta puede afectar la salud materno-fetal. Estados defi citarios en micronutrientes están relacionados con preeclampsia, retraso del crecimiento intrauterino, aborto y anomalías congénitas. Actualmente, la dieta de muchas madres gestantes es insufi ciente en micronutrientes, siendo necesaria su suplementación. Se recomienda la suplementación con ácido fólico en dosis de 400 μg/día, y de 5 mg en embarazadas de riesgo, debiendo comenzar al menos 1 mes antes de la concepción y durante las primeras 12 semanas de gestación, y prolongarla durante todo el embarazo en madres con riesgo nutricional. Es importante vigilar la dosis adecuada de ácido fólico para prevenir los posibles efectos adversos derivados de su acumulación plasmática no metabolizada. Un elevado porcentaje de gestantes presenta anemia ferropénica, estando recomendado el uso intermitente de suplementos con hi...

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Section: Iodounclassified

Suplementos en gestación: últimas recomendaciones

2016

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“…Although less common, TH excess is also detrimental to brain development (Kempers et al 2003(Kempers et al , 2005. Rodent cerebellum development is highly sensitive to hypothyroidism and appears to be a suitable experimental model to study congenital hypothyroidism (Lauder 1977, Bernal et al 2003, Bernal 2005. It takes place mainly during the first post-natal weeks, a developmental stage which coincides with a peak in the circulating level of T 3 (Hadj-Sahraoui et al 2000).…”

Section: Introductionmentioning

confidence: 99%

A combined approach identifies a limited number of new thyroid hormone target genes in post-natal mouse cerebellum

Quignodon¹,

Grijota-Martínez²,

Compe³

et al. 2007

Journal of Molecular Endocrinology

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Thyroid hormones act directly on gene transcription in the post-natal developing cerebellum, controlling neuronal, and glial cell differentiation. We have combined three experimental approaches to identify the target genes that are underlying this phenomenon: 1) a microarray analysis of gene expression to identify hormone responsive genes in the cerebellum of Pax8 K/K mice, a transgenic mouse model of congenital hypothyroidism; 2) a similar microarray analysis on primary culture of cerebellum neurons; and 3) a bioinformatics screen of conserved putative-binding sites in the mouse genome. This identifies surprisingly a small set of target genes, which, for some of them, might be key regulators of cerebellum development and neuronal differentiation.

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“…The impact of thyroid hormones (THS) on the development of the central nervous system is shown in situations of clinical or induced TH deficit or excess. Under these circumstances, processes of cell migration and formation of cortical layers are affected in particular, as well as neuronal and glial cell differentiation (Bernal et al 2003). Thyroxine (T 4 ), the prohormone produced by the thyroid gland, is considered to be inactive and needs to be converted into the active 3,5,3 -triiodothyronine (T 3 ).…”

Section: Introductionmentioning

confidence: 99%

Type II iodothyronine deiodinase protein in chicken choroid plexus: additional perspectives on T3 supply in the avian brain

Verhoelst¹,

Darras²,

Roelens³

et al. 2004

Journal of Endocrinology

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It is widely accepted that type II iodothyronine deiodinase (D2) is mostly present in the brain, where it maintains the homeostasis of thyroid hormone (TH) levels. Although intensive studies have been performed on activity and mRNA levels of the deiodinases, very little is known about their expression at the protein level due to the lack of specific antisera. The current study reports the production of a specific D2 polyclonal antiserum and its use in the comparison of D2 protein distribution with that of type I (D1) and type III (D3) deiodinase protein in the choroid plexus at the blood-brain barrier level. Immunocytochemistry showed very high D2 protein expression in the choroid plexus, especially in the epithelial cells, whereas the D1 and D3 proteins were absent. Furthermore, dexamethasone treatment led to an up-regulation of the D2 protein in the choroid plexus. The expression of D2 protein in the choroid plexus led to a novel insight into the working mechanism of the uptake and transport of thyroid hormones along the blood-brain barrier in birds. It is hypothesized that D2 allows the prohormone thyroxine (T 4 ) to be converted into the active 3,5,3 -triiodothyronine (T 3 ). Within the choroidal epithelial cells. T 3 is subsequently bound to its carrier protein, transthyretin (TTR), to allow transport through the cerebrospinal fluid. Neurons can thus not only be provided with a sufficient T 3 level via the aid of the astrocytes, as was hypothesized previously based on in situ hybridization data, but also by means of T 4 deiodination by D2, directly at the blood-brain barrier level.

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Perspectives in the Study of Thyroid Hormone Action on Brain Development and Function

Cited by 265 publications

References 66 publications

Suplementos en gestación: últimas recomendaciones

Suplementos en gestación: últimas recomendaciones

A combined approach identifies a limited number of new thyroid hormone target genes in post-natal mouse cerebellum

Type II iodothyronine deiodinase protein in chicken choroid plexus: additional perspectives on T3 supply in the avian brain

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