Glycoprotein Hormones
2001; Humana Press; Linguagem: Inglês
10.1007/978-1-59259-102-2_13
Autores Tópico(s)Reproductive Physiology in Livestock
ResumoMembers of the glycoprotein hormone family include the gonadotropins: luteinizing hormone (LH), follicle-stimulating hormone (FSH), and chorionic gonadotropin (CG), and thyroid-stimulating hormone (TSH). These hormones are essential for the proper development and function of additional endocrine glands, and ultimately affect reproduction and metabolism. Each family member is comprised of a shared α-subunit that combines with unique β-subunits to form heterodimeric hormones. Thus, it is the β-subunit that confers biological specificity to each hormone (1). All mammals synthesize and secrete the three pituitary glycoprotein hormones (LH, FSH, and TSH). LH and FSH are produced in gonadotropes, while TSH is produced by thyrotropes of the anterior pituitary. In contrast, CG is synthesized and secreted from placental syncytiotrophoblasts only in primates and equids (2). LH and FSH act in concert to stimulate gonadal growth, gametogenesis, and steroidogenesis in males and females (3,4). Similarly, CG acts at the level of the ovary by binding to the same receptor as LH (5). This binding event is necessary for maintenance of the corpus luteum during early pregnancy in humans (6). In contrast to the gonadotropins, TSH stimulates thyroid growth as well as synthesis and secretion of thyroid hormone (7). Expression and secretion of the pituitary glycoprotein hormones are stimulated by trophic factors from the hypothalamus, and inhibited by hormones secreted from their respective end-organs. An overview of the glycoprotein hormone axes is presented in Fig. 1.
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