Effects of Thyroid Hormone on Brain Development

Want create site? With you can do it easy.

Effects of Thyroid Hormone on Brain Development

find a primary research article on Effects of Thyroid Hormone on Brain Development then write the summary. the summary should include Author and Title of article (published in 2016 or later), a PDF copy of the paper and a 5 -10 sentence summary of the findings.

Don't use plagiarized sources. Get Your Custom Essay on
Effects of Thyroid Hormone on Brain Development
From $8/Page
Order Essay

ABSTRACT
Thyroid hormones are essential for normal brain development. They influence neurogenesis, neuronal and glial cell differentiation and migration, synaptogenesis, and myelination. Thyroid hormone deficiency may severely affect the brain during fetal and postnatal development, causing retarded maturation, intellectual deficits, and neurological impairment. Neural cells express the thyroid hormone nuclear receptors THRA and THRB, which mediate most actions of T3, the active hormone. Brain T3 derives in part from the circulation, and part from type-2 deiodinase-mediated 5’-deiodination of T4 in glial cells. Type 3 deiodinase inactivates T4 and T3 by 5-deiodination in neurons. Membrane transporters facilitate the passage of T4 and T3 across the brain barriers. The main transporters are the monocarboxylate transporter 8 (MCT8) and the organic anion transporter polypeptide 1C1 (OATP1C1). MCT8 facilitates T4 and T3 transport whereas OATP1C1 transports T4 but not T3. T3 regulates the expression of a large number of genes in the brain, mostly during developmental stages, but also in the adult. Rodent models of disease have provided most of our knowledge on thyroid hormone action in the brain. However, species-specific differences in brain maturation and organization make it difficult sometimes to extrapolate the data obtained in rodent models to the human. This review will present a summary of the main concepts developed from rodent studies, with a focus on the human brain.

For complete coverage of all related areas of Endocrinology, please visit our on-line FREE web-text, WWW.ENDOTEXT.ORG.

Go to:
INTRODUCTION
Thyroid hormones are crucial for brain development, and influence brain function throughout life. In adults, hypothyroidism causes lethargy, hyporeflexia, and poor motor coordination (1,2), is associated with bipolar affective disorders, depression, or loss of cognitive functions (3,4). Subclinical hypothyroidism is often associated with memory impairment. Conversely, hyperthyroidism causes hyperreflexia, irritability, and anxiety among other symptoms (5). Hypo- or hyperthyroidism can lead to mood disorders, dementia, confusion, and personality changes. Most of these disorders are usually reversible with proper treatment, indicating that adult-onset thyroid hormone alterations affect neural function but do not leave permanent structural defects.

Effects of Thyroid Hormone on Brain Development

Effects of Thyroid Hormone on Brain Development

The actions of thyroid hormones during mammalian brain maturation are qualitatively different. They influence many developmental processes, usually during limited time windows. They are required for the timely synchronization of independent events and facilitate the transition between fetal and postnatal stages (6,7), similarly to promoting amphibian metamorphosis (8,9). Thyroid hormone deficiency during critical transition periods may lead to irreversible brain damage, the consequences of which depend on the severity and duration of the deficiency, and most importantly its time of onset (10-14).

Until recently, the rat was the most widely used animal model in the study of thyroid physiology and the actions of thyroid hormones in the brain. However, for more than 20 years, the mouse is the preferred animal model, and the use of knockout and knockin mice has facilitated our understanding. However, it is important to be aware of species specificities which make it difficult to extrapolate the results to the human situation. The timing of development in relation to birth among mammals presents substantial differences, even if the sequence of events might be similar (15-17). The web resource www.translatingtime.org (18) provides tools to compare neurodevelopmental time across species. As an approximation, the newborn rat may be compared with a second-trimester human fetus, and the maturation of a newborn human cerebral cortex to that of a 12-13-day old rat pup (19). For integrative reviews on molecular and evolutionary aspects of the cerebral cortex and cerebellar development and the effects of thyroid hormones see (20-23).

Whenever possible, this chapter focuses on observations in humans. Gene and protein notations follow the HUGO nomenclature (http://www.genenames.org): for human genes, names are in italics and in capital letters, protein names are written in non-italic capital letters irrespective of species.

Go to:
STRUCTURAL DEFECTS CAUSED BY THYROID HORMONE DEFICIENCY
As an approach to understanding how thyroid hormones influence brain development, the changes caused by thyroid hormone deprivation are informative. In rats, perinatal hypothyroidism causes reduced myelination and diverse structural defects (for a classical review on this topic see (24). A reduction of the neuropil causes increased cell density in the cerebral cortex (25,26). Reduction in total cell numbers of regions with significant neurogenesis during the postnatal period, such as the olfactory bulb and the granular layers of the hippocampus and cerebellum (26-28). Transient structures show retarded disappearance. An important example is the subplate, a transient structure of the cortex involved in the organization of thalamic afferents to the cortex (29). In the cerebellum, regression of the external granular, or germinal layer, is retarded by a few days (30). The Cajal-Retzius cells, formed early during cortical development and involved in the regulation of the inside-out migration of neurons have delayed appearance (Fig. 1 left panel) (31). The GABAergic interneurons have altered distribution and connectivity, and the parvalbumin subclass is reduced in number (32-35). The maturation of several types of neurons is compromised, with stunted dendritic and/or axonal growth and maturation, for example cholinergic cells (36), cerebellar Purkinje cells (Fig. 1 central panel) (37,38), and cortex layer V pyramidal cells (39,40). Changes in dendritic spine number are also observed in the cortex and hippocampus after adult-onset hypothyroidism and are reversible with thyroxine treatment (41,42). Hypothyroidism also causes delayed and poor deposition of myelin (43-46) whereas hyperthyroidism accelerates myelination (47).

Did you find apk for android? You can find new and apps.

Full satisfaction or return your money back

Our experts will write you a top-quality paper and revise it an unlimited number of times until you're 100% satisfied - or offer a refund.

Check Prices
Get the best discount and better grades here
Pages (550 words)
$0.00
*Price with a welcome 15% discount applied.
Pro tip: If you want to save more money and pay the lowest price, you need to set a more extended deadline.
We know that being a student these days is hard. Because of this, our prices are some of the lowest on the market.

Instead, we offer perks, discounts, and free services to enhance your experience.
Sign up, place your order, and leave the rest to our professional paper writers in less than 2 minutes.
step 1
Upload assignment instructions
Fill out the order form and provide paper details. You can even attach screenshots or add additional instructions later. If something is not clear or missing, the writer will contact you for clarification.
How to get the most out of your experience with Toptutor4me
One writer throughout the entire course
If you like the writer, you can hire them again. Just copy & paste their ID on the order form ("Preferred Writer's ID" field). This way, your vocabulary will be uniform, and the writer will be aware of your needs.
The same paper from different writers
You can order essay or any other work from two different writers to choose the best one or give another version to a friend. This can be done through the add-on "Same paper from another writer."
Copy of sources used by the writer
Our college essay writers work with ScienceDirect and other databases. They can send you articles or materials used in PDF or through screenshots. Just tick the "Copy of sources" field on the order form.
Here is what our happy clients say about us.
Receiving customer feedback and reviews from legit students who have utilized our services is one of our favorite part of the job. We love seeing testimonials from happy students whom we have helped to succeed. Read through the below review page to see what our partners think.
Sociology
Perfect! Appreciate all of your help! Thank you so much!
Customer 452483, November 14th, 2021
English 101
Great work! Thanks!
Customer 452567, August 2nd, 2022
Microbiology
Perfect! Thank you guys for all of your great help! :)
Customer 452483, August 23rd, 2021
Mathematics
Thank you so much!
Customer 452483, July 26th, 2021
Introduction to Sociology
Thank you very much for all of your hard work!
Customer 452483, October 15th, 2021
Psychology
On point! Appreciate all the hard work!!
Customer 452483, August 16th, 2021
English 101
na
Customer 452547, March 22nd, 2022
Introduction to Sociology
Amazing! Thank you so much for your hard work, appreciate it!!
Customer 452483, October 24th, 2021
Other
I appreciate the help.
Customer 452567, March 18th, 2022
Communications
Thank you! It was great :)
Customer 452483, July 26th, 2021
Education
Thank you for your help
Customer 452555, February 16th, 2022
Nursing
Good job!! Thank you!!!
Customer 452487, September 9th, 2021
11,595
Total Reviews
98%
Satsfaction rate
6 pages
Average paper length
40%
Customers referred by a friend
Enjoy the best prices and lifetime 15% discount
Use a coupon TOP15 and enjoy expert help with any task at the most affordable price.
Order Now Order in Chat