Vince
Super Moderator
Undercarboxylated osteocalcin crosses the BBB and has positive effects on cognition
Osteocalcin actively promotes increases in muscle mass with exercise.
Osteocalcin is involved in cross talk with leptin. Energy metabolism is affected such that osteocalcin promotes lean body mass.
Lack of osteocalcin is associated with a decrease in male fertility.
Abstract and Introduction
Abstract
Osteocalcin is involved in cross talk with leptin. Energy metabolism is affected such that osteocalcin promotes lean body mass.
Lack of osteocalcin is associated with a decrease in male fertility.
Abstract and Introduction
Abstract
A genetics approach has uncovered that bone has more functions than expected. In particular, bone is an endocrine organ that secretes a growing number of hormones. In that context, the discovery of the osteoblast-derived hormone osteocalcin has significantly broadened the field of bone biology because of the number of physiologic processes regulated by this hormone. At present, osteocalcin has been shown to enhance several aspects of energy metabolism, brain development, and cognition. These discoveries shed light on the cross-talk between multiple organs and provide credence to the search for additional endocrine functions of bone.
IntroductionBone fulfills several physiologic functions that are essential for vertebrate survival. First and foremost, bone modeling allows bone to grow, and bone remodeling allows constant renewal. The nature of the cell biology events involved in this process strongly suggests that bone modeling and remodeling are energy-consuming processes. This appreciation of bone biology, together with clinical observations mentioned below, underlies the hypothesis that there must be a coordinated control of bone growth, energy metabolism, and reproductive functions. One implication of this hypothesis is that bone should be an endocrine organ regulating aspects of energy metabolism and reproduction.
Bone is the only tissue in the bodies of bony vertebrates that contains a cell type, the osteoclast, whose main function is to actively destroy the host tissue.[SUP][1][/SUP] In a sense, it is as if bone had invented autoimmunity except that in that case it is a much-needed physiological process. This destruction, or resorption of bone as it is called, occurs daily in multiple locations in an organ that covers a large surface in the body of vertebrates. To make matters worse, bone resorption is only one aspect of bone remodeling.[SUP][2][/SUP] Bone formation, another energy demanding event since it entails the constant synthesis and secretion of protein, follows bone resorption. This reading of bone physiology suggesting a close link with energy metabolism is fully supported by clinical observations. Indeed, longitudinal bone growth stops in children and bone mass decreases in adults with severely limited access to food (i.e., energy).[SUP][3,4][/SUP] Besides this link between bone remodeling and energy metabolism, another well established and apparently unrelated clinical observation is that bone mass invariably declines in both sexes when gonadal functions end.[SUP][5,6][/SUP] Considering these observations as a whole led to the hypothesis that there should be a coordinated regulation of bone growth/mass, energy metabolism, and reproduction.Beyond its appearance of vagueness, this hypothesis is in fact quite far reaching. For instance, what justifies it in the first place, is the existence of bone and the peculiar mechanism whereby it constantly renews itself. This necessarily implies that if hormones coordinating these 3 physiologic functions exist, they most likely appear during evolution with bone, since it is the physiology of this tissue that requires their existence. In agreement with this constraint of the working hypothesis, leptin, a powerful endocrine regulator of bone mass that also controls fertility and energy metabolism, appears during evolution with bone. More to the point, the study of a mouse model of a partial gain of function of the leptin receptor showed that the amount of leptin signaling needed to influence bone mass is lower than that needed to affect appetite, energy expenditure, or fertility.[SUP][7,8][/SUP] But the most original and far reaching implication of the working hypothesis was not to identify a new hormone regulating bone mass, but rather that bone should be an endocrine organ regulating energy metabolism and reproduction if not other physiologic functions. It is the testing of this particular aspect of the working hypothesis that eventually significantly broadened the field of bone endocrinology.
​https://www.medscape.com/viewarticle/888856_1Bone is the only tissue in the bodies of bony vertebrates that contains a cell type, the osteoclast, whose main function is to actively destroy the host tissue.[SUP][1][/SUP] In a sense, it is as if bone had invented autoimmunity except that in that case it is a much-needed physiological process. This destruction, or resorption of bone as it is called, occurs daily in multiple locations in an organ that covers a large surface in the body of vertebrates. To make matters worse, bone resorption is only one aspect of bone remodeling.[SUP][2][/SUP] Bone formation, another energy demanding event since it entails the constant synthesis and secretion of protein, follows bone resorption. This reading of bone physiology suggesting a close link with energy metabolism is fully supported by clinical observations. Indeed, longitudinal bone growth stops in children and bone mass decreases in adults with severely limited access to food (i.e., energy).[SUP][3,4][/SUP] Besides this link between bone remodeling and energy metabolism, another well established and apparently unrelated clinical observation is that bone mass invariably declines in both sexes when gonadal functions end.[SUP][5,6][/SUP] Considering these observations as a whole led to the hypothesis that there should be a coordinated regulation of bone growth/mass, energy metabolism, and reproduction.Beyond its appearance of vagueness, this hypothesis is in fact quite far reaching. For instance, what justifies it in the first place, is the existence of bone and the peculiar mechanism whereby it constantly renews itself. This necessarily implies that if hormones coordinating these 3 physiologic functions exist, they most likely appear during evolution with bone, since it is the physiology of this tissue that requires their existence. In agreement with this constraint of the working hypothesis, leptin, a powerful endocrine regulator of bone mass that also controls fertility and energy metabolism, appears during evolution with bone. More to the point, the study of a mouse model of a partial gain of function of the leptin receptor showed that the amount of leptin signaling needed to influence bone mass is lower than that needed to affect appetite, energy expenditure, or fertility.[SUP][7,8][/SUP] But the most original and far reaching implication of the working hypothesis was not to identify a new hormone regulating bone mass, but rather that bone should be an endocrine organ regulating energy metabolism and reproduction if not other physiologic functions. It is the testing of this particular aspect of the working hypothesis that eventually significantly broadened the field of bone endocrinology.
