scholarly journals The Biosynthesis, Signaling, and Neurological Functions of Bile Acids

Biomolecules ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 232 ◽  
Author(s):  
Yoshimitsu Kiriyama ◽  
Hiromi Nochi
Keyword(s):  
Bile Acids ◽  
Muscarinic Acetylcholine Receptor ◽  
Dietary Lipids ◽  
Farnesoid X Receptor ◽  
Na Channel ◽  
Peripheral Tissues ◽  
Surface Receptors ◽  
Glucose And Lipid Metabolism ◽  
Protein Receptor ◽  
The Central Nervous System

Bile acids (BA) are amphipathic steroid acids synthesized from cholesterol in the liver. They act as detergents to expedite the digestion and absorption of dietary lipids and lipophilic vitamins. BA are also considered to be signaling molecules, being ligands of nuclear and cell-surface receptors, including farnesoid X receptor and Takeda G-protein receptor 5. Moreover, BA also activate ion channels, including the bile acid-sensitive ion channel and epithelial Na+ channel. BA regulate glucose and lipid metabolism by activating these receptors in peripheral tissues, such as the liver and brown and white adipose tissue. Recently, 20 different BA have been identified in the central nervous system. Furthermore, BA affect the function of neurotransmitter receptors, such as the muscarinic acetylcholine receptor and γ-aminobutyric acid receptor. BA are also known to be protective against neurodegeneration. Here, we review recent findings regarding the biosynthesis, signaling, and neurological functions of BA.

scholarly journals Bile acids in glucose metabolism in health and disease

2018 ◽  
Vol 215 (2) ◽  
pp. 383-396 ◽  
Author(s):  
Hagit Shapiro ◽  
Aleksandra A. Kolodziejczyk ◽  
Daniel Halstuch ◽  
Eran Elinav
Keyword(s):  
Glucose Metabolism ◽  
Bile Acids ◽  
Glycogen Synthesis ◽  
Dietary Lipids ◽  
Farnesoid X Receptor ◽  
Morbidly Obese ◽  
Glycemic Response ◽  
Multiple Organs ◽  
Health And Disease ◽  
The Impact

Bile acids (BAs) are cholesterol-derived metabolites that facilitate the intestinal absorption and transport of dietary lipids. Recently, BAs also emerged as pivotal signaling molecules controlling glucose, lipid, and energy metabolism by binding to the nuclear hormone farnesoid X receptor (FXR) and Takeda G protein receptor 5 (TGR5) in multiple organs, leading to regulation of intestinal incretin secretion, hepatic gluconeogenesis, glycogen synthesis, energy expenditure, inflammation, and gut microbiome configuration. Alterations in BA metabolism and signaling are associated with obesity and type 2 diabetes mellitus (T2DM), whereas treatment of T2DM patients with BA sequestrants, or bariatric surgery in morbidly obese patients, results in a significant improvement in glycemic response that is associated with changes in the BA profile and signaling. Herein, we review the roles of BAs in glucose metabolism in health and disease; highlight the limitations, unknowns, and challenges in understanding the impact of BAs on the glycemic response; and discuss how this knowledge may be harnessed to develop innovative therapeutic approaches for the treatment of hyperglycemia and diabetes.

scholarly journals Bile Acid Signaling in Neurodegenerative and Neurological Disorders

2020 ◽  
Vol 21 (17) ◽  
pp. 5982
Author(s):  
Stephanie M. Grant ◽  
Sharon DeMorrow
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Neurological Diseases ◽  
Farnesoid X Receptor ◽  
Bile Acid Metabolism ◽  
Sphingosine 1 Phosphate ◽  
The Central Nervous System ◽  
Membrane Bound ◽  
Bile Acid Receptors ◽  
Cholestatic Diseases

Bile acids are commonly known as digestive agents for lipids. The mechanisms of bile acids in the gastrointestinal track during normal physiological conditions as well as hepatic and cholestatic diseases have been well studied. Bile acids additionally serve as ligands for signaling molecules such as nuclear receptor Farnesoid X receptor and membrane-bound receptors, Takeda G-protein-coupled bile acid receptor and sphingosine-1-phosphate receptor 2. Recent studies have shown that bile acid signaling may also have a prevalent role in the central nervous system. Some bile acids, such as tauroursodeoxycholic acid and ursodeoxycholic acid, have shown neuroprotective potential in experimental animal models and clinical studies of many neurological conditions. Alterations in bile acid metabolism have been discovered as potential biomarkers for prognosis tools as well as the expression of various bile acid receptors in multiple neurological ailments. This review explores the findings of recent studies highlighting bile acid-mediated therapies and bile acid-mediated signaling and the roles they play in neurodegenerative and neurological diseases.

scholarly journals The role of bile acids in metabolic regulation

2016 ◽  
Vol 228 (3) ◽  
pp. R85-R96 ◽  
Author(s):  
Libor Vítek ◽  
Martin Haluzík
Keyword(s):  
Bile Acids ◽  
Metabolic Regulation ◽  
Energy Homeostasis ◽  
Farnesoid X Receptor ◽  
Therapeutic Effects ◽  
Cellular Targets ◽  
Glucose And Lipid Metabolism ◽  
Cell Compartments ◽  
Obesity And Diabetes ◽  
G Protein Coupled

Bile acids (BA), long believed to only have lipid-digestive functions, have emerged as novel metabolic modulators. They have important endocrine effects through multiple cytoplasmic as well as nuclear receptors in various organs and tissues. BA affect multiple functions to control energy homeostasis, as well as glucose and lipid metabolism, predominantly by activating the nuclear farnesoid X receptor and the cytoplasmic G protein-coupled BA receptor TGR5 in a variety of tissues. However, BA also are aimed at many other cellular targets in a wide array of organs and cell compartments. Their role in the pathogenesis of diabetes, obesity and other ‘diseases of civilization’ becomes even more clear. They also interact with the gut microbiome, with important clinical implications, further extending the complexity of their biological functions. Therefore, it is not surprising that BA metabolism is substantially modulated by bariatric surgery, a phenomenon contributing favorably to the therapeutic effects of these surgical procedures. Based on these data, several therapeutic approaches to ameliorate obesity and diabetes have been proposed to affect the cellular targets of BA.

scholarly journals ENDOCRINOLOGY IN PREGNANCY: Metabolic impact of bile acids in gestation

2021 ◽  
Vol 184 (3) ◽  
pp. R69-R83
Author(s):  
Hei Man Fan ◽  
Alice L Mitchell ◽  
Catherine Williamson
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Maternal Serum ◽  
Farnesoid X Receptor ◽  
Acid Uptake ◽  
Glucose And Lipid Metabolism ◽  
Bile Acid Uptake ◽  
In Pregnancy

Bile acids are lipid-solubilising molecules that also regulate metabolic processes. Farnesoid X receptor (FXR) and Takeda G-protein coupled receptor 5 (TGR5) are two bile acid receptors with key metabolic roles. FXR regulates bile acid synthesis in the liver and influences bile acid uptake in the intestine. TGR5 is mainly involved in regulation of signalling pathways in response to bile acid uptake in the gut and therefore prandial response. Both FXR and TGR5 have potential as therapeutic targets for disorders of glucose and/or lipid homeostasis. Gestation is also known to cause small increases in bile acid concentrations, but physiological hypercholanaemia of pregnancy is usually not sufficient to cause any clinically relevant effects. This review focuses on how gestation alters bile acid homeostasis, which can become pathological if the elevation of maternal serum bile acids is more marked than physiological hypercholanaemia, and on the influence of FXR and TGR5 function in pregnancy on glucose and lipid metabolism. This will be discussed with reference to two gestational disorders: intrahepatic cholestasis of pregnancy (ICP), a disease where bile acids are pathologically elevated, and gestational diabetes mellitus (GDM), characterised by hyperglycaemia during pregnancy.

scholarly journals Farnesoid X Receptor activation in brain alters brown adipose tissue function via the sympathetic system

2021 ◽  
Author(s):  
Benjamin Deckmyn ◽  
Dorothee Domenger ◽  
sarah ducatsel ◽  
emilie nicolas ◽  
emilie dorchies ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Energy Homeostasis ◽  
Receptor Activation ◽  
Farnesoid X Receptor ◽  
Metabolic Energy ◽  
Peripheral Organs ◽  
Glucose And Lipid Metabolism ◽  
Brown Adipose ◽  
The Central Nervous System

Background and Prupose: The nuclear bile acid (BA) receptor farnesoid X receptor (FXR) is a major regulator of metabolic/energy homeostasis in peripheral organs. Indeed, enterohepatic-expressed FXR controls metabolic processes (BA, glucose and lipid metabolism, fat mass, body weight). The central nervous system (CNS) regulates energy homeostasis in close interaction with peripheral organs. While FXR has been reported to be expressed in the brain, its function has not been studied so far. Experimental Approach: We studied the role of FXR in brain control of energy homeostasis by treating wild-type and FXR-deficient mice by intracerebroventricular (ICV) injection with the reference FXR agonist GW4064. Key Results: Here we show that pharmacological activation of brain FXR modifies energy homeostasis by affecting brown adipose tissue (BAT) function. Brain FXR activation decreases the rate-limiting enzyme in catecholamine synthesis, tyrosine hydroxylase (TH), and consequently the sympathetic tone. FXR activation acts by inhibiting hypothalamic PKA-CREB induction of TH expression. Conclusions and Implication: These findings identify a function of brain FXR in the control of energy homeostasis and shed new light on the complex control of energy homeostasis by BA through FXR.

scholarly journals Broadening the role of osteocalcin in hypothalamic-pituitary-gonadal axis

2021 ◽  
Author(s):  
Chang Shan ◽  
Jiang Yue ◽  
Wei Liu
Keyword(s):  
Developmental Disorders ◽  
Active Form ◽  
Peripheral Tissues ◽  
Glucose And Lipid Metabolism ◽  
Reproductive Endocrine ◽  
The Central Nervous System ◽  
Testosterone Biosynthesis ◽  
Increase Insulin Secretion ◽  
Functional Mechanisms

Bone is emerging as a versatile endocrine organ and its interactions with apparently unrelated organs are being more widely recognized. Osteocalcin (OCN), a polypeptide hormone secreted by osteoblasts, has been found to exert multiple endocrine functions through its metabolically active form, uncarboxylated OCN (uOCN). Mounting evidence has shown that following its binding to G-protein coupled receptor 6a (Gprc6a) in the peripheral tissues, uOCN acts on pancreatic β cells to increase insulin secretion, and on muscle and white adipose tissue to promote glucose and lipid metabolism. More strikingly, researchers have found a surprising role of uOCN in testicular function to facilitating testosterone biosynthesis and regulating male fertility via a pancreas-bone-gonadal axis. However, the detailed functional mechanisms of uOCN on the hypothalamic-pituitary-gonadal axis or the pancreas-bone-gonadal axis are not fully understood. Besides highlighting the regulatory mechanisms of uOCN in the central nervous system, hypothalamus and pituitary, we also discuss its role in male as well as female fertility and its potential clinical implications in some reproductive endocrine diseases and pubertal developmental disorders.

scholarly journals Farnesoid X Receptor Activation in Brain Alters Brown Adipose Tissue Function via the Sympathetic System

2022 ◽  
Vol 14 ◽  
Author(s):  
Benjamin Deckmyn ◽  
Dorothée Domenger ◽  
Chloé Blondel ◽  
Sarah Ducastel ◽  
Emilie Nicolas ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Energy Homeostasis ◽  
Receptor Activation ◽  
Farnesoid X Receptor ◽  
Metabolic Energy ◽  
Peripheral Organs ◽  
Glucose And Lipid Metabolism ◽  
Brown Adipose ◽  
The Central Nervous System

The nuclear bile acid (BA) receptor farnesoid X receptor (FXR) is a major regulator of metabolic/energy homeostasis in peripheral organs. Indeed, enterohepatic-expressed FXR controls metabolic processes (BA, glucose and lipid metabolism, fat mass, body weight). The central nervous system (CNS) regulates energy homeostasis in close interaction with peripheral organs. While FXR has been reported to be expressed in the brain, its function has not been studied so far. We studied the role of FXR in brain control of energy homeostasis by treating wild-type and FXR-deficient mice by intracerebroventricular (ICV) injection with the reference FXR agonist GW4064. Here we show that pharmacological activation of brain FXR modifies energy homeostasis by affecting brown adipose tissue (BAT) function. Brain FXR activation decreases the rate-limiting enzyme in catecholamine synthesis, tyrosine hydroxylase (TH), and consequently the sympathetic tone. FXR activation acts by inhibiting hypothalamic PKA-CREB induction of TH expression. These findings identify a function of brain FXR in the control of energy homeostasis and shed new light on the complex control of energy homeostasis by BA through FXR.

scholarly journals Potential of therapeutic bile acids in the treatment of neonatal Hyperbilirubinemia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lori W. E. van der Schoor ◽  
Henkjan J. Verkade ◽  
Anna Bertolini ◽  
Sanne de Wit ◽  
Elvira Mennillo ◽  
...  
Keyword(s):  
Bile Acids ◽  
Treatment Options ◽  
Preventive Treatment ◽  
Neonatal Hyperbilirubinemia ◽  
Farnesoid X Receptor ◽  
Neurological Damage ◽  
Obeticholic Acid ◽  
Protein Levels ◽  
Gunn Rats ◽  
Plasma Bilirubin

AbstractNeonatal hyperbilirubinemia or jaundice is associated with kernicterus, resulting in permanent neurological damage or even death. Conventional phototherapy does not prevent hyperbilirubinemia or eliminate the need for exchange transfusion. Here we investigated the potential of therapeutic bile acids ursodeoxycholic acid (UDCA) and obeticholic acid (OCA, 6-α-ethyl-CDCA), a farnesoid-X-receptor (FXR) agonist, as preventive treatment options for neonatal hyperbilirubinemia using the hUGT1*1 humanized mice and Ugt1a-deficient Gunn rats. Treatment of hUGT1*1 mice with UDCA or OCA at postnatal days 10–14 effectively decreased bilirubin in plasma (by 82% and 62%) and brain (by 72% and 69%), respectively. Mechanistically, our findings indicate that these effects are mediated through induction of protein levels of hUGT1A1 in the intestine, but not in liver. We further demonstrate that in Ugt1a-deficient Gunn rats, UDCA but not OCA significantly decreases plasma bilirubin, indicating that at least some of the hypobilirubinemic effects of UDCA are independent of UGT1A1. Finally, using the synthetic, non-bile acid, FXR-agonist GW4064, we show that some of these effects are mediated through direct or indirect activation of FXR. Together, our study shows that therapeutic bile acids UDCA and OCA effectively reduce both plasma and brain bilirubin, highlighting their potential in the treatment of neonatal hyperbilirubinemia.

scholarly journals Role of Bile Acids in the Regulation of Food Intake, and Their Dysregulation in Metabolic Disease

Nutrients ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 1104
Author(s):  
Cong Xie ◽  
Weikun Huang ◽  
Richard L. Young ◽  
Karen L. Jones ◽  
Michael Horowitz ◽  
...  
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Peptide Yy ◽  
Glycogen Synthesis ◽  
Hormone Secretion ◽  
Gastrointestinal Hormones ◽  
Farnesoid X Receptor ◽  
Gastrointestinal Hormone ◽  
Bile Acid Sequestrants

Bile acids are cholesterol-derived metabolites with a well-established role in the digestion and absorption of dietary fat. More recently, the discovery of bile acids as natural ligands for the nuclear farnesoid X receptor (FXR) and membrane Takeda G-protein-coupled receptor 5 (TGR5), and the recognition of the effects of FXR and TGR5 signaling have led to a paradigm shift in knowledge regarding bile acid physiology and metabolic health. Bile acids are now recognized as signaling molecules that orchestrate blood glucose, lipid and energy metabolism. Changes in FXR and/or TGR5 signaling modulates the secretion of gastrointestinal hormones including glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), hepatic gluconeogenesis, glycogen synthesis, energy expenditure, and the composition of the gut microbiome. These effects may contribute to the metabolic benefits of bile acid sequestrants, metformin, and bariatric surgery. This review focuses on the role of bile acids in energy intake and body weight, particularly their effects on gastrointestinal hormone secretion, the changes in obesity and T2D, and their potential relevance to the management of metabolic disorders.

Isolated premature menarche in two siblings with Neurofibromatosis type 1

2020 ◽  
Vol 33 (6) ◽  
pp. 813-816
Author(s):  
James Blackburn ◽  
Mohammed Didi ◽  
Shivaram Avula ◽  
Senthil Senniappan
Keyword(s):  
Neurofibromatosis Type 1 ◽  
Pubertal Timing ◽  
Genetic Disorder ◽  
Pubertal Development ◽  
Neurofibromatosis Type ◽  
Malignant Tumours ◽  
Peripheral Tissues ◽  
Paediatric Endocrinology ◽  
The Central Nervous System

AbstractObjectivesNeurofibromatosis type 1 (NF1) is an autosomal dominant genetic disorder, caused by mutation in NF1. The condition is typified by the development of benign and malignant tumours in both the central nervous system and peripheral tissues. Isolated menarche is a sub-classification of incomplete isosexual precocious puberty typified by menarche in girls with no other features of pubertal development. The effects of NF1 on pubertal timing are poorly understood, we report two siblings with NF1 and apparent abnormal pubertal development.Case PresentationTwo siblings were referred to the tertiary paediatric endocrinology clinic at 6 and 7 years of age with recurrent, cyclical vaginal bleeding. There was a strong family history of NF1, the mother of the siblings and two brothers were also diagnosed at a young age. On examination both patients were prepubertal at presentation. Both siblings underwent a gonadotrophin releasing hormone test, which revealed a follicle-stimulating hormone dominant (prepubertal) response. The features were suggestive of isolated premature menarche as no other cause was identified. The elder sibling established menarche and developed signs of consonant pubertal development at 12 years of age. The younger sibling remains under regular follow-up.ConclusionsNF1 has previously been associated with alterations in pubertal timing. We report, for the first time, two siblings with NF1 who presented with isolated menarche.

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