Regulation of the Growth Hormone Receptor, Insulin-like Growth Factor (IGF) I and IGF Binding Protein 2 in Reproductive Tissues of Dairy Cattle During Lactation and Associated Effects on Fertility PDF Download
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Author: Michelle Lynn Bode-Rhoads Publisher: ISBN: Category : Somatomedin Languages : en Pages : 376
Book Description
The components of the growth hormone (GH)/insulin-like growth factor (IGF) system play critical reproductive and metabolic roles in dairy cattle. In liver, GH receptor (GHR) and IGF-I are dynamically regulated by lactation and energy balance. Less is known about the regulation of GHR and IGF-I mRNA in reproductive tissues. The objective of these studies was to measure the expression of total GHR (tGHR), IGF-I and IGF binding protein (IGFBP) 2 mRNA in reproductive tissues during several stages of lactation and around the time of artificial insemination. Changes in gene expression were then evaluated for potential effects on fertility. The expression of tGHR, IGF-I and IGFBP-2 was measured in uterine, luteal, follicular and hepatic tissue three times during the early postpartum period. Expression of tGHR and IGFBP-2 mRNA in the reproductive tissues did not change during early lactation. Luteal and follicular expression of IGF-I changed in an inverse manner from the second sample collection to the third (luteal expression decreased and follicular expression increased). Further research is needed to elucidate the implications these changes have for fertility in dairy cattle. The expression of tGHR, IGF-I and IGFBP-2 was also measured in uterine and hepatic tissue at several stages of lactation around the time of insemination. Uterine tGHR mRNA, uterine IGF-I mRNA and plasma IGF-I concentrations increased at estrus. The timing of these changes suggests that uterine IGF-I does not directly affect early embryonic development, but may enhance the uterine environment for early embryonic development. The cows that became pregnant had higher liver tGHR and IGFBP-2 mRNA concentrations. The cows that became pregnant may have been metabolically distinct from the cows that did not become pregnant, resulting in different levels of hepatic gene expression and providing a reproductive advantage.
Author: Michelle Lynn Bode-Rhoads Publisher: ISBN: Category : Somatomedin Languages : en Pages : 376
Book Description
The components of the growth hormone (GH)/insulin-like growth factor (IGF) system play critical reproductive and metabolic roles in dairy cattle. In liver, GH receptor (GHR) and IGF-I are dynamically regulated by lactation and energy balance. Less is known about the regulation of GHR and IGF-I mRNA in reproductive tissues. The objective of these studies was to measure the expression of total GHR (tGHR), IGF-I and IGF binding protein (IGFBP) 2 mRNA in reproductive tissues during several stages of lactation and around the time of artificial insemination. Changes in gene expression were then evaluated for potential effects on fertility. The expression of tGHR, IGF-I and IGFBP-2 was measured in uterine, luteal, follicular and hepatic tissue three times during the early postpartum period. Expression of tGHR and IGFBP-2 mRNA in the reproductive tissues did not change during early lactation. Luteal and follicular expression of IGF-I changed in an inverse manner from the second sample collection to the third (luteal expression decreased and follicular expression increased). Further research is needed to elucidate the implications these changes have for fertility in dairy cattle. The expression of tGHR, IGF-I and IGFBP-2 was also measured in uterine and hepatic tissue at several stages of lactation around the time of insemination. Uterine tGHR mRNA, uterine IGF-I mRNA and plasma IGF-I concentrations increased at estrus. The timing of these changes suggests that uterine IGF-I does not directly affect early embryonic development, but may enhance the uterine environment for early embryonic development. The cows that became pregnant had higher liver tGHR and IGFBP-2 mRNA concentrations. The cows that became pregnant may have been metabolically distinct from the cows that did not become pregnant, resulting in different levels of hepatic gene expression and providing a reproductive advantage.
Author: Isabel Varela-Nieto Publisher: Springer Science & Business Media ISBN: 0387262741 Category : Medical Languages : en Pages : 420
Book Description
Insulin-like growth factor (IGF)-I is a widely expressed growth factor with diverse effects on many tissues throughout development and in adult life. The purpose of this work is to provide detailed and updated information on the role of the growth hormone (GH)-IGF axis in fetal and postnatal development, as well as its physiological functions and implications in pathology.
Author: Derek LeRoith Publisher: Springer Science & Business Media ISBN: 146845949X Category : Science Languages : en Pages : 528
Book Description
This volume addresses a fundamental puzzle in biology and medicine, namely, how does tissue develop, repair and replace itself. The answer appears to lie in growth factors and their regulation. To thrive and survive we need growth factors and this book concentrates on two factors that are related to growth hormone. Growth hormone does not act directly on all tissues, but mediates many of its actions through the release of insulin-like growth factors from the liver. The growth factors were originally called somatomedins by McConaghey and Sledge (1), who discovered that they mediated growth-like effects of growth hormone. However, the factors were purified on the basis of their insulinomimetic actions on fat and muscle and it is their relationship to the insulin family of pep tides that now gives them their name (2,3) of insulin-like growth factors (IGFs). They mediate the actions of. growth hormone on the proteoglycan synthesis of cartilage and produce mitogenic effects in fibroblast cultures.
Author: Robert Paul Rhoads Publisher: ISBN: 9780496620098 Category : Languages : en Pages : 193
Book Description
In transition dairy cows, plasma insulin-like growth factor (IGF)-I declines near parturition despite elevated growth hormone (GH). Furthermore, GH administration cannot restore plasma IGF-I suggesting impaired hepatic GH-dependent IGF-I production. In contrast, the metabolic effects of GH on adipose tissue are believed to persist. Objectives of this thesis were: (1) To determine the role of insulin in the regulation of hepatic IGF-I production during early lactation and (2) To examine the GH responsiveness of liver and adipose tissue during undernutrition. The first study showed that hepatic cyclophilin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA abundance was regulated during the transition period, periods of hyperinsulinemia and poor nutrition. In the second study, a reduction in plasma insulin paralleled exactly the deteriorating energy balance during the periparturient period. To test the role of insulin, we performed hyperinsulinemic-euglycemic clamps in late pregnant and early lactating dairy cows. Hyperinsulinemia increased plasma IGF-I irrespective of physiological state. This effect was associated with increased abundance of hepatic IGF-I mRNA. Furthermore, insulin increased hepatic GH receptor (GHR) abundance by stimulating GHR1A mRNA. Finally, insulin increased the abundance of the GHR in adipose tissue without altering total GHR mRNA indicating that the regulation of GHR synthesis differs between tissues. In the third study, late lactating dairy cows were treated for 4 days with saline or bovine somatotropin (bST) when well-fed (120% of total requirements) or underfed (30% of maintenance requirements). Underfed cows approximated early lactating cows in their degree of negative energy balance, elevations in plasma GH and reductions in plasma IGF-I and insulin. Underfed cows had decreased GHR abundance in liver and adipose tissue without a reduction in GHR mRNA. In well-fed cows, both tissues responded in a robust manner to GH (parameters were plasma IGF-I concentration for liver, epinephrine-stimulated plasma NEFA for adipose tissue, and IGF-I mRNA for both tissues). In underfed cows, these responses were reduced in liver and lost completely in adipose tissue. In conclusion, an adequate level of insulin is needed for hepatic IGF-I production. Lower GHR abundance cannot completely account for reduced GH responsiveness of liver and adipose tissue in underfed cows.
Author: Haim Werner Publisher: MDPI ISBN: 3036507701 Category : Science Languages : en Pages : 196
Book Description
This Special Issue of Cells on “Insulin-Like Growth Factors in Development, Cancers and Aging” provides a collection of modern articles dealing with the role of insulin-like growth factors (IGF1) in cancer biology, aging and development. Featured articles explore basic and clinical aspects of the IGF1 system, including post-genomic analyses as well as novel approaches to target the IGF1 receptor (IGF1R) in oncology.
Author: Ron G. Rosenfeld Publisher: Springer Science & Business Media ISBN: 1592597122 Category : Medical Languages : en Pages : 883
Book Description
It has been over 40 years since the original report by Salmon and Daughaday demon strating that the ability of GH to stimulate sulfation of cartilage was mediated by a "sulfation factor. " In the ensuing decades, it has become apparent that this "sulfation factor activity" encompasses a complex system ofligands (IGFs), receptors, and carrier proteins that are, in tum, responsible for a wide array of cellular actions. The IGF system has been demonstrated to be critically involved in both intrauterine and postnatal growth, and to have important implications in cancer biology as well, owing to the ability of the IGFs to function in endocrine, paracrine, and autocrine modes and given the wide distri bution of IGFs in virtually every organ system. The contributions to The /GF System reflect the wide span of interest in the IGF system and its implications for normal and abnormal growth and metabolism. The chapters have been divided into four broad sections: I. Molecular biology of the IGF system; II. Bio logical actions of the IGFs; III. IGF physiology; and IV. Clinical aspects of the IGFs. We have made every effort to highlight the major contemporary themes in IGF biology, but as is inevitable in such a fast-moving field, perspectives will continue to change as new information is accumulated.
Author: L. Matera Publisher: Elsevier ISBN: 0080507662 Category : Medical Languages : en Pages : 332
Book Description
For more than seventy years evidence has accumulated documenting the existence of a bi-directional communication network between growth hormone and the immune system. In the past twenty years there has been a tremendous proliferation of information detailing the workings of the growth hormone and insulin-like growth factor axis. A multitude of growth factors and binding proteins have been identified. More and more evidence supporting the important role of the growth hormone IGF network in the well functioning of the normal immune system has been documented. Clearly the challenge today is not to prove, but to understand, the neuroimmune regulatory role of GLH in its entire complexity.The ultimate goal of this volume and of all the other volumes of this series is to promote the understanding of the science and to ease human suffering.
Author: Michelle Lynn Bode-Rhoads
Author: Michelle Lynn Bode-Rhoads
Author: Isabel Varela-Nieto
Author: Mark A. McGuire
Author: Derek LeRoith
Author: Robert Paul Rhoads
Author: Jesse Cheng-lin Chow
Author: Haim Werner
Author: Ron G. Rosenfeld
Author: Maria Eudoxia Zavala
Author: L. Matera