Preface

Thyroid hormone is important for controlling metabolism and many other body functions. Changes in thyroid hormone physiology, its regulation and diseases thereof have been a concern for the mankind.

Understanding of thyroid hormone(s) has been continuously updated and revised. The contributions from different authors have been incorporated in this book for this purpose. The original work of these contributors will be especially useful in furthering the knowledge on thyroid and help in creating new vistas of research.

The book incorporates physiology of thyroid hormone in maternal-fetal axis, and regulation of thyroid hormone synthesis in health and disease. The controversy in the cut-off for delineating normal from abnormal thyroid function has also been dealt with. Thyroid hormone deficiency and excess states have been highlighted through elaborate review to encompass the present understanding and management of such problems. A separate section on thyroid hormone changes in special situation has been incorporated.

#### **Dr Neeraj Kumar Agrawal**

Associate Professor and Head of Department of Endocrinology and Metabolism Institute of Medical Sciences, Banaras Hindu University, Varanasi, India

**Section 1** 

**Thyroid Hormone Physiology** 

**Section 1** 

**Thyroid Hormone Physiology** 

**Chapter 1** 

© 2012 Sarkar, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

© 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

**"Quo Vadis?" Deciphering the Code of** 

**Mature Mammalian Brain** 

Additional information is available at the end of the chapter

regulation of the functions of THs at the subcellular level [1,2].

Pradip K. Sarkar

**1. Introduction** 

http://dx.doi.org/10.5772/46206

**Nongenomic Action of Thyroid Hormones in** 

Thyroid hormones (TH) have major well-known actions on the growth and development of the maturing tissues including mammalian brain via activation of specific nuclear receptors leading to gene expression and subsequent target protein synthesis. Deficiency of THs has serious issues on the development on all types of tissues including brain leading to severe thyroid disorders and as a result imposes overall metabolic malfunctioning of all system organs. Endemic goiter was probably first described with cretinism by Paracelsus (1493 -1541) and by other physicians of the Alps and Central Europe. However, the relationship between cretinism and involvement of thyroid gland was lacking over centuries. Thyroid gland was literally described by Wharton in 1656. Since then the progress of research on thyroid gland gained attention particularly for its most observed pleiotypic action in number of species from aquatic animals to humans. Developments of new scientific technologies and the progress in the area of molecular biology from time to time are continually changing our concepts of the

Immunocytochemical localization studies revealed that TH receptors (TR) in adult vertebrates are highly concentrated within choroids plexus, dentate gyrus, hippocampus, amygdaloid complex, pyriform cortex, granular layer of cerebellum, mammillary bodies and medial geniculate bodies. Although specific nuclear receptors for THs in adult brain have been identified, their functions are unclear about target gene expression. Imunohistochemical mapping further documented that locus coeruleus norepinephrine stimulates active conversion of L-tetraiodothyronine (L-T4) to L-triiodothyronine (L-T3). A morphologic linking between central thyronergic and noradrenergic systems has been established. This changes in TH ontogeny gradually started drawing attention that possible
