Open Access Medical Books

TEXTBOOK : GONADOTROPIN

GONADOTROPIN

Edited by Jorge Vizcarra .

190 pages . 
Open Access .

It is widely recognized that proper gonadal function depends on the coordinated action of multiple factors influencing the synthesis and secretion of gonadotropin hormones. The term gonadotropin derives from the combination of gonas (from Greek gonos or “seed”) and tropin (from Greek trepein or “to change”). Thus, gonadotropins are protein hormones that have the ability to change gonadal function. Although the word gonadotrophin is also used in scientific literature, the etymological derivation of  this alternative spelling is different. Trophic (from Greek trophe or “nutrition”) implies a nurturing action, a function that is not consistent with the nature these protein hormones. Thus, from a physiological point of view, the term gonadotropin better describes the main emphasis of this book.
The gonadotropin family includes luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secreted from the pituitary gland. These hormones are composed of two dissimilar subunits: an alpha subunit and a beta subunit. Within species, the alpha subunits are nearly identical; however, the beta subunits are specific for each hormone. When the subunits are combined, to form a noncovalently associated heterodimer, the beta subunit provides a unique spatial conformation that ensures a high affinity interaction with their membrane receptors; thus, the biological specificity of each hormone. Each subunit is the product of separate genes. Genes are translated and subsequently glycosylated before packaging and secretion from the Golgi  apparatus. Glycosylation is an enzymatic process that attaches poly- or oligosaccharides (glycans) to the different subunits. Thus, gonadotropins are also part of the glycoprotein hormone family that includes other hormones such as thyroidstimulation hormone (TSH). In addition, some species also secrete chorionic  gonadotropins during pregnancy. Chorionic gonadotropins are also heterodimeric glycoprotein than can have different degrees of LH and FSH biological activity in horses (eCG), humans (hCG), and other primates.
Synthesis and secretion of LH and FSH takes place in the gonadotropes of the pituitary gland (adenohypophysis). The hypothalamus, in turn, controls the secretion of gonadotropins by the pulsatile secretion of gonadotropin releasing hormone (GnRH).
Therefore, the neuroendocrine linkage of the hypothalamic-pituitary-gonadal axis provides an integrated system responsible for proper reproductive performance, including gamete development and sex steroids secretion.
The scope and objective of this book is to provide researchers and graduate students with an updated review of the control mechanisms associated with the synthesis and secretion of gonadotropins. From a practical point of view, the book also provides relevant information that integrates reproductive performance of domestic species. A dedicated panel of authors was assembled to address these topics, aiming to provide a cutting edge platform to those interested in reproductive physiology and endocrinology.
The book is organized in eight chapters. The first four chapters are dedicated to the control of gonadotropin secretion via GnRH and GnRH isoforms, Kisspeptin, Endocannabinoids and neuropeptide–glutamic acid-isoleucine. A series of three interrelated chapters summarize the regulation of gonadotropin secretion in cattle, and an additional chapter is devoted to the functions of gonadotropin-related structural
features.
Putting this book together has been an enjoyable task. I would like to thank all the authors for their patience throughout the editorial process, and most importantly for their valuable contribution.



Dr. Jorge Vizcarra
Department of Food and Animal Science, Alabama A&M University,
USA
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CONTENTS OF THE TEXTBOOK :


1 Contribution of Chicken GnRH-II 
and Lamprey GnRH-III on Gonadotropin Secretion 1
Jorge Vizcarra

2 Role of Adipose Secreted Factors and Kisspeptin in the Metabolic Control of Gonadotropin Secretion and Puberty 25
Clay A. Lents, C. Richard Barb and Gary J. Hausman

3 Endocannabinoids and Kisspeptins: Two Modulators in Fight for the Regulation of GnRH Activity 57
Rosaria Meccariello, Rosanna Chianese, Silvia Fasano and Riccardo Pierantoni

4 Influence of Neuropeptide – Glutamic Acid-Isoleucine (NEI) on LH Regulation 89
María Ester Celis

5 Regulation and Differential Secretion of Gonadotropins During Post Partum Recovery of Reproductive Function in Beef and Dairy Cows 107
Mark A. Crowe and Michael P. Mullen

6 Relative Roles of FSH and LH in Stimulation of Effective Follicular Responses in Cattle 125
Mark A. Crowe and Michael P. Mullen

7 Regulation and Function of Gonadotropins 
Throughout the Bovine Oestrous Cycle 143
Mark A. Crowe and Michael P. Mullen

8 Structural and Functional 
Roles of FSH and LH as Glycoproteins Regulating Reproduction in Mammalian Species 155
Michael P. Mullen, Dara J. Cooke and Mark A. Crow .


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