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Vrachnis N, Tsonis O, Vrachnis D, Antonakopoulos N, Paltoglou G, Barbounaki S, Mastorakos G, Paschopoulos M, Iliodromiti Z. The Effect of Thyrotropin-Releasing Hormone and Antithyroid Drugs on Fetal Thyroid Function. CHILDREN (BASEL, SWITZERLAND) 2021; 8:454. [PMID: 34071168 PMCID: PMC8228147 DOI: 10.3390/children8060454] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 05/21/2021] [Accepted: 05/25/2021] [Indexed: 01/06/2023]
Abstract
A euthyroid pregnant woman will normally have a fetus that displays normal fetal development. However, studies have long demonstrated the role of T3 (Triiodothyronine), T4 (Thyroxine), and TSH (Thyroid Stimulating Hormone) and their degree of penetrability into the fetal circulation. Maternal thyrotropin-releasing hormone (TRH) crosses the placental site and, from mid-gestation onward, is able to promote fetal TSH secretion. Its origin is not only hypothalamic, as was believed until recently. The maternal pancreas, and other extraneural and extrahypothalamic organs, can produce TRH variants, which are transported through the placenta affecting, to a degree, fetal thyroid function. Antithyroid drugs (ATDs) also cross the placenta and, because of their therapeutic actions, can affect fetal thyroid development, leading in some cases to adverse outcomes. Furthermore, there are a number of TRH analogues that share the same properties as the endogenous hormone. Thus, in this narrative review, we highlight the interaction of all the above with fetal growth in uncomplicated pregnancies.
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Affiliation(s)
- Nikolaos Vrachnis
- Third Department of Obstetrics and Gynecology, National and Kapodistrian University of Athens Medical School, Attikon Hospital, 157 72 Athens, Greece;
- Vascular Biology, Molecular and Clinical Sciences Research Institute, St George’s University of London, London SW17 0RE, UK
| | - Orestis Tsonis
- Department of Obstetrics and Gynecology, University of Ioannina Medical School, University Hospital of Ioannina, 455 00 Ioannina, Greece; (O.T.); (M.P.)
| | - Dionisios Vrachnis
- Department of Clinical Therapeutics, School of Medicine, National and Kapodistrian University of Athens, Alexandra Hospital, 157 72 Athens, Greece;
| | - Nikolaos Antonakopoulos
- Third Department of Obstetrics and Gynecology, National and Kapodistrian University of Athens Medical School, Attikon Hospital, 157 72 Athens, Greece;
| | - George Paltoglou
- Endocrinology Unit, 2nd Department of Obstetrics and Gynecology, National and Kapodistrian University of Athens Medical School, Aretaieio Hospital, 157 72 Athens, Greece; (G.P.); (G.M.)
| | | | - George Mastorakos
- Endocrinology Unit, 2nd Department of Obstetrics and Gynecology, National and Kapodistrian University of Athens Medical School, Aretaieio Hospital, 157 72 Athens, Greece; (G.P.); (G.M.)
| | - Minas Paschopoulos
- Department of Obstetrics and Gynecology, University of Ioannina Medical School, University Hospital of Ioannina, 455 00 Ioannina, Greece; (O.T.); (M.P.)
| | - Zoi Iliodromiti
- Department of Neonatology, National and Kapodistrian University of Athens Medical School, Aretaieio Hospital, 157 72 Athens, Greece;
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Abstract
Thyroid hormones (THs) are important in the development and maintenance of lipid and energy homeostasis. THs act through two closely related TH receptors (TRs α and β), which are conditional transcription factors. Recently, TH analogues or thyromimetics with varying degrees of TR subtype and liver uptake selectivity have been developed. These compounds exert beneficial effects of TH excess states without many undesirable TR-dependent side effects. Several selective TR modulators (STRMs) showed exceptionally promising results in lowering serum cholesterol in preclinical animal models and human clinical studies. Moreover, some first generation STRMs elicit other potentially beneficial effects on obesity, glucose metabolism, and nonalcoholic fatty liver disease (NAFLD). While it was initially thought that STRMs would be an effective long-term therapy to combat elevated cholesterol, possibly in conjunction with another cholesterol-lowering therapy, the statins, three major first generation STRMs failed to progress beyond early phase III human trials. The aim of this review is to discuss how STRMs work, their actions in preclinical animal models and human clinical trials, why they did not progress beyond clinical trials as cholesterol-lowering therapeutics, whether selective TR modulation continues to hold promise for dyslipidemias, and whether members of this drug class could be applied to the treatment of other aspects of metabolic syndrome and human genetic disease.
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Affiliation(s)
- Sunitha Meruvu
- Center for Genomic Medicine, Houston Methodist Research Institute , Houston, Texas
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Nyaradi A, Li J, Hickling S, Foster J, Oddy WH. The role of nutrition in children's neurocognitive development, from pregnancy through childhood. Front Hum Neurosci 2013; 7:97. [PMID: 23532379 PMCID: PMC3607807 DOI: 10.3389/fnhum.2013.00097] [Citation(s) in RCA: 259] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 03/07/2013] [Indexed: 12/20/2022] Open
Abstract
This review examines the current evidence for a possible connection between nutritional intake (including micronutrients and whole diet) and neurocognitive development in childhood. Earlier studies which have investigated the association between nutrition and cognitive development have focused on individual micronutrients, including omega-3 fatty acids, vitamin B12, folic acid, choline, iron, iodine, and zinc, and single aspects of diet. The research evidence from observational studies suggests that micronutrients may play an important role in the cognitive development of children. However, the results of intervention trials utilizing single micronutrients are inconclusive. More generally, there is evidence that malnutrition can impair cognitive development, whilst breastfeeding appears to be beneficial for cognition. Eating breakfast is also beneficial for cognition. In contrast, there is currently inconclusive evidence regarding the association between obesity and cognition. Since individuals consume combinations of foods, more recently researchers have become interested in the cognitive impact of diet as a composite measure. Only a few studies to date have investigated the associations between dietary patterns and cognitive development. In future research, more well designed intervention trials are needed, with special consideration given to the interactive effects of nutrients.
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Affiliation(s)
- Anett Nyaradi
- Centre for Child Health Research, Telethon Institute for Child Health Research, The University of Western AustraliaPerth, WA, Australia
- School of Population Health, The University of Western AustraliaPerth, WA, Australia
| | - Jianghong Li
- Centre for Child Health Research, Telethon Institute for Child Health Research, The University of Western AustraliaPerth, WA, Australia
- Centre for Population Health Research, Curtin Health Innovation Research Institute, Curtin UniversityPerth, WA, Australia
- Social Science Research CenterBerlin, Germany
| | - Siobhan Hickling
- Centre for Child Health Research, Telethon Institute for Child Health Research, The University of Western AustraliaPerth, WA, Australia
- School of Population Health, The University of Western AustraliaPerth, WA, Australia
| | - Jonathan Foster
- Centre for Child Health Research, Telethon Institute for Child Health Research, The University of Western AustraliaPerth, WA, Australia
- School of Psychology and Speech Pathology, Curtin UniversityPerth, WA, Australia
- Neurosciences Unit, Health Department of Western AustraliaPerth, WA, Australia
- School of Paediatrics and Child Health, The University of Western AustraliaPerth, WA, Australia
| | - Wendy H. Oddy
- Centre for Child Health Research, Telethon Institute for Child Health Research, The University of Western AustraliaPerth, WA, Australia
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Zhou YD, Teng YC, Jiang RZ, Huang YJ. A case of a naturally conceived pregnancy associated with multiple ovarian cysts in a patient with severe untreated primary hypothyroidism. Gynecol Endocrinol 2012; 28:686-7. [PMID: 22309686 DOI: 10.3109/09513590.2011.652246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
There are few reports of multiple ovarian cysts secondary to hypothyroidism, and multiple ovarian cysts associated with pregnancy most commonly occur in association with assisted reproductive technologies. Herein, we report a case of a naturally conceived pregnancy occurring 2 years after stopping treatment for primary hypothyroidism. The patient developed multiple ovarian cysts in the first trimester, and laboratory studies and ultrasonography were consistent with hypothyroidism. Herein, we present the case and discuss the importance of prenatal screening for hypothyroidism.
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Affiliation(s)
- Yue-Di Zhou
- Department of Obstetrics and Gynecology, Shanghai Sixth People's Hospital, Shanghai Jiaotong University, Shanghai, China
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Nucera C, Muzzi P, Tiveron C, Farsetti A, La Regina F, Foglio B, Shih SC, Moretti F, Della Pietra L, Mancini F, Sacchi A, Trimarchi F, Vercelli A, Pontecorvi A. Maternal thyroid hormones are transcriptionally active during embryo-foetal development: results from a novel transgenic mouse model. J Cell Mol Med 2011; 14:2417-35. [PMID: 19863697 PMCID: PMC3823160 DOI: 10.1111/j.1582-4934.2009.00947.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Even though several studies highlighted the role of maternal thyroid hormones (THs) during embryo-foetal development, direct evidence of their interaction with embryonic thyroid receptors (TRs) is still lacking. We generated a transgenic mouse model ubiquitously expressing a reporter gene tracing TH action during development. We engineered a construct (TRE2×) containing two TH-responsive elements controlling the expression of the LacZ reporter gene, which encodes β-galactosidase (β-gal). The specificity of the TRE2× activation by TH was evaluated in NIH3T3 cells by cotransfecting TRE2× along with TRs, retinoic or oestrogen receptors in the presence of their specific ligands. TRE2× transgene was microinjected into the zygotes, implanted in pseudopregnant BDF1 (a first-generation (F1) hybrid from a cross of C57BL/6 female and a DBA/2 male) mice and transgenic mouse models were developed. β-gal expression was assayed in tissue sections of transgenic mouse embryos at different stages of development. In vitro, TRE2× transactivation was observed only following physiological T3 stimulation, mediated exclusively by TRs. In vivo, β-gal staining, absent until embryonic day 9.5-10.5 (E9.5-E10.5), was observed as early as E11.5-E12.5 in different primordia (i.e. central nervous system, sense organs, intestine, etc.) of the TRE2× transgenic embryos, while the foetal thyroid function (FTF) was still inactive. Immunohistochemistry for TRs essentially colocalized with β-gal staining. No β-gal staining was detected in embryos of hypothyroid transgenic mice. Importantly, treatment with T3 in hypothyroid TRE2× transgenic mice rescued β-gal expression. Our results provide in vivo direct evidence that during embryonic life and before the onset of FTF, maternal THs are transcriptionally active through the action of embryonic TRs. This model may have clinical relevance and may be employed to design end-point assays for new molecules affecting THs action.
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Affiliation(s)
- Carmelo Nucera
- Endocrinology Unit, Molecular Endocrinology and Endocrine Cancers laboratory, Department of Internal Medicine, Medical School A. Gemelli, Catholic University, Roma, Italy
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Maternal Thyroid Hormones in Early Pregnancy and Risk of Breech Presentation. JOURNAL OF OBSTETRICS AND GYNAECOLOGY CANADA 2010; 32:948-55. [DOI: 10.1016/s1701-2163(16)34682-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Dong J, Liu W, Wang Y, Hou Y, Xi Q, Chen J. Developmental iodine deficiency resulting in hypothyroidism reduces hippocampal ERK1/2 and CREB in lactational and adolescent rats. BMC Neurosci 2009; 10:149. [PMID: 20021662 PMCID: PMC2804698 DOI: 10.1186/1471-2202-10-149] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 12/18/2009] [Indexed: 11/10/2022] Open
Abstract
Background Developmental iodine deficiency (ID) leads to inadequate thyroid hormone that impairs learning and memory with an unclear mechanism. Here, we show that hippocampal extracellular signal-regulated kinase (ERK1/2) and cAMP response element-binding protein (CREB) are implicated in the impaired learning and memory in lactational and adolescent rat hippocampus following developmental ID and hypothyroidism. Methods Three developmental rat models were created by administrating dam rats with either iodine-deficient diet or propylthiouracil (PTU, 5 ppm or 15 ppm)-added drinking water from gestational day (GD) 6 till postnatal day (PN) 28. Then, the total and phorsporylated ERK1/2 and total and phorsporylated CREB in the hippocampus were detected with western blot on PN14, PN21, PN28 and PN42. Results The iodine-deficient and hypothyroid pups showed lower serum FT3 and FT4 levels, smaller body size, and delayed eyes opening. The mean number of surviving cells in the hippocampus of the iodine-deficient and 15 ppm PTU-treated rats was significantly reduced compared to controls (P < 0.05). Iodine-deficient and 15 ppm PTU-treatment groups demonstrated significantly lower level of total and phosphorylated ERK1/2 and CREB than the controls on PN14, PN21 and PN28 (P < 0.05, respectively). The reduction of ERK1/2 and CREB was not reversible with the restoration of serum thyroid hormone concentrations on PN42. Conclusions Developmental ID and hypothyroidism down-regulate hippocampal ERK1/2 and CREB in lactational and adolescent rats.
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Affiliation(s)
- Jing Dong
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, Shenyang, PR China.
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Van Wijk N, Rijntjes E, Van De Heijning BJM. Perinatal and chronic hypothyroidism impair behavioural development in male and female rats. Exp Physiol 2008; 93:1199-209. [DOI: 10.1113/expphysiol.2008.042416] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
An inadequate supply of iodine during gestation results in damage to the foetal brain that is irreversible by mid-gestation unless timely interventions can correct the accompanying maternal hypothyroxinemia. Even mild to moderate maternal hypothyroxinemia may result in suboptimal neurodevelopment. This review mainly focuses on iodine and thyroid hormone economy up to mid-gestation, a period during which the mother is the only source for the developing brain of the foetus. The cerebral cortex of the foetus depends on maternal thyroxine (T4) for the production of the 3',3,5-tri-iodothyronine (T3) for nuclear receptor-binding and biological effectiveness. Maternal hypothyroxinemia early in pregnancy is potentially damaging for foetal brain development. Direct evidence has been obtained from experiments on animals: even a relatively mild and transient hypothyroxinemia during corticogenesis, which takes place mostly before mid-gestation in humans, affects the migration of radial neurons, which settle permanently in heterotopic locations within the cortex and hippocampus. Behavioural defects have also been detected. The conceptus imposes important early changes on maternal thyroid hormone economy that practically doubles the amount of T4 secreted something that requires a concordant increase in the availability of iodine, from 150 to 250-300 microg I day- 1. Women who are unable to increase their production of T4 early in pregnancy constitute a population at risk for having children with neurological disabilities. As a mild to moderate iodine deficiency is still the most widespread cause of maternal hypothyroxinemia, the birth of many children with learning disabilities may be prevented by advising women to take iodine supplements as soon as pregnancy starts, or earlier if possible, in order to ensure that their requirements for iodine are met.
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Ahmed OM, El‐Gareib A, El‐bakry A, Abd El‐Tawab S, Ahmed R. Thyroid hormones states and brain development interactions. Int J Dev Neurosci 2007; 26:147-209. [DOI: 10.1016/j.ijdevneu.2007.09.011] [Citation(s) in RCA: 202] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2007] [Revised: 09/17/2007] [Accepted: 09/26/2007] [Indexed: 12/20/2022] Open
Affiliation(s)
- Osama M. Ahmed
- Zoology Department, Faculty of ScienceBeni Suef UniversityEgypt
| | - A.W. El‐Gareib
- Zoology Department, Faculty of ScienceCairo UniversityEgypt
| | - A.M. El‐bakry
- Zoology Department, Faculty of ScienceBeni Suef UniversityEgypt
| | | | - R.G. Ahmed
- Zoology Department, Faculty of ScienceBeni Suef UniversityEgypt
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Saunier B. How low can maternal thyroxin go? Endocrinology 2007; 148:2591-2. [PMID: 17507577 DOI: 10.1210/en.2007-0320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Gilbert ME, Sui L, Walker MJ, Anderson W, Thomas S, Smoller SN, Schon JP, Phani S, Goodman JH. Thyroid hormone insufficiency during brain development reduces parvalbumin immunoreactivity and inhibitory function in the hippocampus. Endocrinology 2007; 148:92-102. [PMID: 17008398 DOI: 10.1210/en.2006-0164] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Thyroid hormones are necessary for brain development. gamma-Amino-butyric acid (GABA)ergic interneurons comprise the bulk of local inhibitory circuitry in brain, many of which contain the calcium binding protein, parvalbumin (PV). A previous report indicated that severe postnatal hypothyroidism reduces PV immunoreactivity (IR) in rat neocortex. We examined PV-IR and GABA-mediated synaptic inhibition in the hippocampus of rats deprived of thyroid hormone from gestational d 6 until weaning on postnatal d 30. Pregnant dams were exposed to propylthiouracil (0, 3, 10 ppm) via the drinking water, which decreased maternal serum T(4) by approximately 50-75% and increased TSH. At weaning, T(4) was reduced by approximately 70% in offspring in the low-dose group and fell below detectable levels in high-dose animals. PV-IR was diminished in the hippocampus and neocortex of offspring killed on postnatal d 21, an effect that could be reversed by postnatal administration of T(4). Dose-dependent decreases in the density of PV-IR neurons were observed in neocortex and hippocampus, with the dentate gyrus showing the most severe reductions (50-75% below control counts). Altered staining persisted to adulthood despite the return of thyroid hormones to control levels. Developmental cross-fostering and adult-onset deprivation studies revealed that early postnatal hormone insufficiency was required for an alteration in PV-IR. Synaptic inhibition of the perforant path-dentate gyrus synapse evaluated in adult offspring, in vivo, revealed dose-dependent reductions in paired pulse depression indicative of a suppression of GABA-mediated inhibition. These data demonstrate that moderate degrees of thyroid hormone insufficiency during the early postnatal period permanently alters interneuron expression of PV and compromises inhibitory function in the hippocampus.
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Affiliation(s)
- M E Gilbert
- Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA.
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Wilcoxon JS, Nadolski GJ, Samarut J, Chassande O, Redei EE. Behavioral inhibition and impaired spatial learning and memory in hypothyroid mice lacking thyroid hormone receptor alpha. Behav Brain Res 2006; 177:109-16. [PMID: 17129617 PMCID: PMC1819397 DOI: 10.1016/j.bbr.2006.10.030] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Revised: 10/26/2006] [Accepted: 10/30/2006] [Indexed: 11/28/2022]
Abstract
Thyroid hormone insufficiency leads to impaired neurogenesis, behavioral alterations and cognitive deficits. Thyroid hormone receptors, expressed in brain regions involved in these behaviors, mediate the effects of thyroid hormone deficiency or excess. To determine the contribution of thyroid hormone receptor alpha (TRalpha) in these behaviors, we examined the behavior of euthyroid as well as hypo- and hyperthyroid mice lacking all isoforms of the TRalpha (TRalpha(o/o)). The hypothyroxinemic TRalpha(o/o) mice demonstrated behavioral inhibition, manifested in decreased activity and increased anxiety/fear in the open field test (OFT) and increased immobility in the forced swim test (FST) compared to C57BL/6J mice. TRalpha(o/o) mice also showed learning and recall impairments in the Morris water maze (MWM), which were exaggerated by hypothyroidism in TRalpha(o/o) mice. These impairments were concurrent with increased thigmotaxis, suggesting an increased anxiety-like state of the TRalpha(o/o) mice in the MWM. Expression of genes, known to be involved in processes modulating learning and memory, such as glucocorticoid receptor (GR), growth-associated protein 43 (GAP-43) and neurogranin (RC3), were significantly decreased in the hippocampus of TRalpha(o/o) mice. GR expression was also decreased in the frontal cortex and amygdala of TRalpha(o/o) mice, indicating that expression of GR is regulated, probably developmentally, by one or more isoforms of TRalpha in the mouse brain. Taken together these data demonstrate behavioral alterations in the TRalpha(o/o) mice, indicating the functional role of TRalpha, and a delicate interaction between TRalpha and TRbeta-regulated genes in these behaviors. Thyroid hormone-regulated genes potentially responsible for the learning deficit found in TRalpha(o/o) mice include GR, RC3 and GAP-43.
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Affiliation(s)
- Jennifer Slone Wilcoxon
- Northwestern University Feinberg School of Medicine, The Asher Center Department of Psychiatry and Behavioral Sciences, Chicago, IL 60611, USA
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Gilbert ME, Sui L. Dose-dependent reductions in spatial learning and synaptic function in the dentate gyrus of adult rats following developmental thyroid hormone insufficiency. Brain Res 2006; 1069:10-22. [PMID: 16406011 DOI: 10.1016/j.brainres.2005.10.049] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Revised: 10/07/2005] [Accepted: 10/10/2005] [Indexed: 01/18/2023]
Abstract
Thyroid hormones are critical for the development and maturation of the central nervous system. Although somatic and neurological effects are well documented following severe thyroid hormone deprivation, much less is known of the functional consequences of moderate levels of hormone insufficiency. We have previously demonstrated that severe thyroid hormone reductions in the postnatal period are associated with impairments in synaptic transmission in the dentate gyrus. The present study was performed to examine the dose-response relationships of moderate levels of hormone disruption on synaptic function in the dentate gyrus in an in vivo preparation and to determine the effects on spatial learning. Pre- and postnatal thyroid hormone insufficiency was induced by administration of 3 or 10 ppm propylthiouracil (PTU) to pregnant and lactating dams via the drinking water from gestation day (GD) 6 until postnatal day (PN) 30. This regimen produced a 47% and 65% reduction in serum T4, in the dams of the low and high-dose groups, respectively. At the time of testing of adult offspring, hormone status had returned to control levels. In littermates, field potentials evoked in the dentate gyrus in response to stimulation of the perforant path were assessed under urethane anesthesia. The data reveal dose-dependent reductions in synaptic transmission and impairments in long-term potentiation (LTP) of the EPSP component of the compound field potential. In contrast, LTP of the population spike measure was paradoxically enhanced. Spatial learning in the Morris water maze was profoundly impaired in high-dose animals. Although the majority of subjects in the low-dose group eventually acquired the task, their acquisition rate lagged behind control values. Reversal learning was assessed in all animals reaching criterion performance and found to be impaired in PTU-exposed animals relative to controls. These data support previous findings in area CA1 in vitro, extend observations associated with dentate gyrus synaptic function to a lower dose range, and provide correlative evidence of behavioral disruption in a hippocampal-dependent learning task following developmental thyroid hormone insufficiency.
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Affiliation(s)
- M E Gilbert
- Neurotoxicology Division (MD-B105-05), National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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Sui L, Anderson WL, Gilbert ME. Impairment in short-term but enhanced long-term synaptic potentiation and ERK activation in adult hippocampal area CA1 following developmental thyroid hormone insufficiency. Toxicol Sci 2005; 85:647-56. [PMID: 15673845 DOI: 10.1093/toxsci/kfi095] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Thyroid hormones are critical for the development and maturation of the central nervous system. Insufficiency of thyroid hormones during development impairs performance on tasks of learning and memory that rely upon the hippocampus and impairs synaptic function in young hypothyroid animals. The present study was designed to determine if perturbations in synaptic function persist in adult euthyroid animals exposed developmentally to insufficient levels of hormone. Pre- and postnatal thyroid hormone insufficiency was induced by administration of 3 or 10 ppm propylthiouracil (PTU) to pregnant and lactating dams via the drinking water from gestation day (GD) 6 until postnatal day (PN) 30. This regimen produced a graded level of hormonal insufficiency in the dam and the offspring. Population spike and population excitatory postsynaptic potentials (EPSP) were recorded at the pyramidal cell layer and the stratum radiatum, respectively, in area CA1 of hippocampal slices from adult male offspring. PTU exposure increased baseline synaptic transmission, reduced paired-pulse facilitation, and increased the magnitude of the population spike long-term potentiation (LTP). Phosphorylation of the extracellular signal-regulated kinases (ERK1 and ERK2) was increased as a function of LTP stimulation in slices from PTU-exposed adult animals. On the other hand, no differences in the basal levels of synaptic proteins implicated in synaptic plasticity (total ERK, synapsin, growth-associated protein-43, and neurogranin) were detected. These results reinforce previous findings of persistent changes in synaptic function and, importantly extend these observations to moderate levels of thyroid hormone insufficiency that do not induce significant toxicity to the dams or the offspring. Such alterations in hippocampal synaptic function may contribute to persistent behavioral deficits associated with developmental hypothyroidism.
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Affiliation(s)
- L Sui
- National Research Council, Washington, DC 20001, USA
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