1
|
Sympathetic blockage attenuates fasting-induced hepatic steatosis. Neuroreport 2022; 33:763-770. [PMID: 36250432 DOI: 10.1097/wnr.0000000000001844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Although the central nervous system coordinates whole-body metabolism, the neural mechanism for hepatic steatosis remains unclear. This study is aimed to explore the neural mechanism of fasting-induced hepatic steatosis. Mice were pretreated with 6-hydroxydopamine to block sympathetic nerve activity before fasting, and to explore the potential effects of chemical sympathectomy on fasting-induced hepatic steatosis and transcriptional changes. Twenty-four hours fasting led to obvious hepatic steatosis, low-core temperature, and similar effects to cold-induced white adipose lipolysis. The alterations in hepatic mRNA expression revealed that the hepatic lipid accumulation did not result from an increase in hepatic lipogenesis or a decrease in fatty acid oxidation but from enhanced fatty acid uptake as indicated by upregulation of CD36. Blockage of the sympathetic nervous system via chemical sympathectomy attenuated fasting-induced hepatic steatosis and suppressed CD36 upregulation in the liver, but did not obviously alter the expression of genes associated with lipogenesis or fatty acid oxidation. These findings indicate that the sympathetic nervous system orchestrates the mechanism for fasting-induced hepatic steatosis via modulating CD36 expression and adipose fat trafficking into the liver, which provides clues to reveal new targets for fatty liver diseases.
Collapse
|
2
|
Zhou Q, Wang Y, Han X, Fu S, Zhu C, Chen Q. Efficacy of Resveratrol Supplementation on Glucose and Lipid Metabolism: A Meta-Analysis and Systematic Review. Front Physiol 2022; 13:795980. [PMID: 35431994 PMCID: PMC9009313 DOI: 10.3389/fphys.2022.795980] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 02/25/2022] [Indexed: 02/05/2023] Open
Abstract
Background Lipids are ubiquitous metabolites with diverse functions. Excessive lipid accumulation can trigger lipid redistribution among metabolic organs such as adipose, liver and muscle, thus altering the lipid metabolism. It has been revealed that disturbed lipid metabolism would cause multiple disease complications and is highly correlated with human morbidity. Resveratrol (RSV), a phytoestrogen with antioxidant, can modulate insulin resistance and lipid profile. Recently, research on RSV supplementation to improve glucose and lipid metabolism has been controversial. A meta-analysis may provide a scientific reference for the relationship between lipid metabolism and RSV supplementation. Methods and Analysis We searched the PubMed, Cochrane Library, Web of Science, and Embase databases from inception to October 2021 using relevant keywords. A comprehensive search for randomized controlled trials (RCTs) was performed. For calculating pooled effects, continuous data were pooled by mean difference (MD) and 95% confidence interval (CI). Adopting the method of inverse-variance with a random-effect, all related statistical analyses were performed using the Rev Man V.5.3 and STATA V.15 software. Results A total of 25 articles were incorporated into the final meta-analysis after removal of duplicates by checking titles and abstracts and excluding non-relevant articles. The selected articles had a total of 1,171 participants, including 578 in the placebo group and 593 in the intervention group. According to the current meta-analysis, which demonstrated that there was a significant decrease in waist circumference (SMD = –0.36; 95% CI: –0.59, –0.14; P = 0.002; I2 = 88%), hemoglobin A1c (–0.48; –0.69, –0.27; P ≤ 0.001; I2 = 94%), total cholesterol (–0.15; –0.3, –0.01; P = 0.003; I2 = 94%), low density lipoprotein cholesterol (–0.42; –0.57, –0.27; P ≤ 0.001; I2 = 92%), high density lipoprotein cholesterol (0.16; –0.31, –0.02; P = 0.03; I2 = 81%) following resveratrol administration. Conclusion These results suggest that RSV has a dramatic impact on regulating lipid and glucose metabolism, and the major clinical value of resveratrol intake is for obese and diabetic patients. We hope that this study could provide more options for clinicians using RSV. Furthermore, in the future, large-scale and well-designed trials will be warranted to confirm these results. Systematic Review Registration Website [https://www.crd.york.ac.uk/prospero/#recordDetails], identifier [CRD42021244904].
Collapse
|
3
|
DHA reduces hypothalamic inflammation and improves central leptin signaling in mice. Life Sci 2020; 257:118036. [PMID: 32622949 DOI: 10.1016/j.lfs.2020.118036] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/17/2020] [Accepted: 06/29/2020] [Indexed: 01/09/2023]
Abstract
AIMS Anti-obesity effects and improved leptin sensitivity from n-3 polyunsaturated fatty acids (n-3 PUFAs) have been reported in diet-induced obese animals. This study sought to determine the beneficial central effects and mechanism of docosahexaenoic acid (DHA, 22:6 n-3) in high-fat (HF) diet fed mice. MAIN METHODS Male C57BL/6J mice were given HF diet with or without intracerebroventricular (icv) injection of docosahexaenoic acid (DHA, 22:6 n-3) for two days. Central leptin sensitivity, hypothalamic inflammation, leptin signaling molecules and tyrosine hydroxylase (TH) were examined by central leptin sensitivity test and Western blot. Furthermore, the expression of hepatic genes involved in lipid metabolism was examined by RT-PCR. KEY FINDINGS We found that icv administration of DHA not only reduced energy intake and body weight gain but also corrected the HF diet-induced hypothalamic inflammation. DHA decreased leptin signaling inhibitor SOCS3 and improved the leptin JAK2-Akt signaling pathways in the hypothalamus. Furthermore, icv administration of DHA improved the effects of leptin in the regulation of mRNA expression of enzymes related to lipogenesis, fatty acid β-oxidation, and cholesterol synthesis in the liver. DHA increased leptin-induced activation of TH in the hypothalamus. SIGNIFICANCE Therefore, increasing central DHA concentration may prevent the deficit of hypothalamic regulation, which is associated with disorders of energy homeostasis in the liver as a result of a high-fat diet.
Collapse
|
4
|
Zhu Z, Cao F, Li X. Epigenetic Programming and Fetal Metabolic Programming. Front Endocrinol (Lausanne) 2019; 10:764. [PMID: 31849831 PMCID: PMC6901800 DOI: 10.3389/fendo.2019.00764] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 10/21/2019] [Indexed: 12/30/2022] Open
Abstract
Fetal metabolic programming caused by the adverse intrauterine environment can induce metabolic syndrome in adult offspring. Adverse intrauterine environment introduces fetal long-term relatively irreversible changes in organs and metabolism, and thus causes fetal metabolic programming leading metabolic syndrome in adult offspring. Fetal metabolic programming of obesity and insulin resistance plays a key role in this process. The mechanism of fetal metabolic programming is still not very clear. It is suggested that epigenetic programming, also induced by the adverse intrauterine environment, is a critical underlying mechanism of fetal metabolic programming. Fetal epigenetic programming affects gene expression changes and cellular function through epigenetic modifications without DNA nucleotide sequence changes. Epigenetic modifications can be relatively stably retained and transmitted through mitosis and generations, and thereby induce the development of metabolic syndrome in adult offspring. This manuscript provides an overview of the critical role of epigenetic programming in fetal metabolic programming.
Collapse
Affiliation(s)
- Ziqiang Zhu
- Children's Hospital of Soochow University, Suzhou, China
- Changzhou Maternity and Child Health Care Hospital affiliated to Nanjing Medical University, Changzhou, China
| | - Fang Cao
- Changzhou Maternity and Child Health Care Hospital affiliated to Nanjing Medical University, Changzhou, China
| | - Xiaozhong Li
- Children's Hospital of Soochow University, Suzhou, China
| |
Collapse
|
5
|
Mirzahosseini-pourranjbar A, Karimabad MN, Hajizadeh MR, Khoshdel A, Fahmidehkar MA, Mohammad-Sadeghipour M, Afshari-Nesab M, Mahmoodi M. The effect of Prosopis farcta extract on the expression of some key genes of the glycolysis pathway and the genes involved in insulin signaling in HepG2 cells. GENE REPORTS 2019. [DOI: 10.1016/j.genrep.2019.100494] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
|
6
|
Pierce AA, Duwaerts CC, Siao K, Mattis AN, Goodsell A, Baron JL, Maher JJ. CD18 deficiency improves liver injury in the MCD model of steatohepatitis. PLoS One 2017; 12:e0183912. [PMID: 28873429 PMCID: PMC5584926 DOI: 10.1371/journal.pone.0183912] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Accepted: 08/14/2017] [Indexed: 02/06/2023] Open
Abstract
Neutrophils and macrophages are important constituents of the hepatic inflammatory infiltrate in non-alcoholic steatohepatitis. These innate immune cells express CD18, an adhesion molecule that facilitates leukocyte activation. In the context of fatty liver, activation of infiltrated leukocytes is believed to enhance hepatocellular injury. The objective of this study was to determine the degree to which activated innate immune cells promote steatohepatitis by comparing hepatic outcomes in wild-type and CD18-mutant mice fed a methionine-choline-deficient (MCD) diet. After 3 weeks of MCD feeding, hepatocyte injury, based on serum ALT elevation, was 40% lower in CD18-mutant than wild-type mice. Leukocyte infiltration into the liver was not impaired in CD18-mutant mice, but leukocyte activation was markedly reduced, as shown by the lack of evidence of oxidant production. Despite having reduced hepatocellular injury, CD18-mutant mice developed significantly more hepatic steatosis than wild-type mice after MCD feeding. This coincided with greater hepatic induction of pro-inflammatory and lipogenic genes as well as a modest reduction in hepatic expression of adipose triglyceride lipase. Overall, the data indicate that CD18 deficiency curbs MCD-mediated liver injury by limiting the activation of innate immune cells in the liver without compromising intrahepatic cytokine activation. Reduced liver injury occurs at the expense of increased hepatic steatosis, which suggests that in addition to damaging hepatocytes, infiltrating leukocytes may influence lipid homeostasis in the liver.
Collapse
Affiliation(s)
- Andrew A. Pierce
- Department of Medicine, University of California, San Francisco, San Francisco, California, United States of America
- Liver Center, University of California, San Francisco, San Francisco, California, United States of America
| | - Caroline C. Duwaerts
- Department of Medicine, University of California, San Francisco, San Francisco, California, United States of America
- Liver Center, University of California, San Francisco, San Francisco, California, United States of America
| | - Kevin Siao
- Department of Medicine, University of California, San Francisco, San Francisco, California, United States of America
- Liver Center, University of California, San Francisco, San Francisco, California, United States of America
| | - Aras N. Mattis
- Liver Center, University of California, San Francisco, San Francisco, California, United States of America
- Department of Pathology, University of California, San Francisco, San Francisco, California, United States of America
| | - Amanda Goodsell
- Department of Medicine, University of California, San Francisco, San Francisco, California, United States of America
- Liver Center, University of California, San Francisco, San Francisco, California, United States of America
| | - Jody L. Baron
- Department of Medicine, University of California, San Francisco, San Francisco, California, United States of America
- Liver Center, University of California, San Francisco, San Francisco, California, United States of America
| | - Jacquelyn J. Maher
- Department of Medicine, University of California, San Francisco, San Francisco, California, United States of America
- Liver Center, University of California, San Francisco, San Francisco, California, United States of America
- * E-mail:
| |
Collapse
|
7
|
Huang Z, Huang S, Cong H, Li Z, Li J, Keller KL, Shearer GC, Kris-Etherton PM, Wu S, Gao X. Smell and Taste Dysfunction Is Associated with Higher Serum Total Cholesterol Concentrations in Chinese Adults. J Nutr 2017; 147:1546-1551. [PMID: 28615376 PMCID: PMC5525109 DOI: 10.3945/jn.117.250480] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 04/11/2017] [Accepted: 05/15/2017] [Indexed: 01/09/2023] Open
Abstract
Background: Several lipid-related hormones and peptides, such as glucagon-like peptide-1 and leptin, are involved in the regulation of taste and smell function. However, to our knowledge, it remains unknown whether these chemosensory functions are associated with lipid profiles.Objective: We examined the cross-sectional association between taste and smell dysfunction and blood cholesterol concentrations.Methods: With the use of a questionnaire, we assessed chronic smell and taste dysfunction in 12,627 Chinese participants (10,418 men and 2209 women; mean age: 54.4 y) who did not take hypolipidemic agents. Participants were categorized into 3 groups based on the number of smell and taste dysfunctions, ranging from 0 (best) to 2 (worst). A general linear model was used to test differences in serum concentrations of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides (TGs) across groups with different smell and taste status after adjusting for age, sex, education, occupation, smoking, drinking, obesity, and history of cardiovascular disease, cancer, and head injury.Results: The prevalence of smell and taste dysfunction was 2.4% and 1.2%, respectively. Worse smell and taste dysfunction was associated with higher total cholesterol concentrations (P-trend = 0.005). No significant differences were observed in LDL cholesterol, HDL cholesterol, and TG concentrations across groups with different numbers of chemosensory dysfunctions (P-trend > 0.1 for all). The associations between chemosensory dysfunction and total cholesterol concentrations were more pronounced in participants aged ≤60 y and in those who were nonsmokers relative to their counterparts (P-interaction < 0.05 for all).Conclusions: In this large cross-sectional study, chemosensory dysfunction was associated with higher serum total cholesterol concentrations among Chinese adults. Prospective studies are needed to investigate the temporal relation between these chemosensory dysfunctions and hypercholesterolemia.
Collapse
Affiliation(s)
- Zhe Huang
- Department of Cardiology, Tianjin Medical University, Tianjin, China;,Department of Cardiology, Kailuan Hospital, Tangshan, China
| | - Shue Huang
- Department of Nutritional Sciences, Pennsylvania State University, University Park, PA; and
| | - Hongliang Cong
- Department of Cardiology, Tianjin Medical University, Tianjin, China
| | - Zheng Li
- Department of Cardiology, Tianjin Medical University, Tianjin, China;,Department of Cardiology, Tangshan Chinese Medicine Hospital, Tangshan, China
| | - Junjuan Li
- Department of Cardiology, Kailuan Hospital, Tangshan, China
| | - Kathleen L Keller
- Department of Nutritional Sciences, Pennsylvania State University, University Park, PA; and
| | - Gregory C Shearer
- Department of Nutritional Sciences, Pennsylvania State University, University Park, PA; and
| | - Penny M Kris-Etherton
- Department of Nutritional Sciences, Pennsylvania State University, University Park, PA; and
| | - Shouling Wu
- Department of Cardiology, Kailuan Hospital, Tangshan, China;
| | - Xiang Gao
- Department of Nutritional Sciences, Pennsylvania State University, University Park, PA; and
| |
Collapse
|
8
|
Chardonnay Grape Seed Flour Ameliorates Hepatic Steatosis and Insulin Resistance via Altered Hepatic Gene Expression for Oxidative Stress, Inflammation, and Lipid and Ceramide Synthesis in Diet-Induced Obese Mice. PLoS One 2016; 11:e0167680. [PMID: 27977712 PMCID: PMC5157984 DOI: 10.1371/journal.pone.0167680] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 11/18/2016] [Indexed: 01/04/2023] Open
Abstract
To identify differentially expressed hepatic genes contributing to the improvement of high-fat (HF) diet-induced hepatic steatosis and insulin resistance following supplementation of partially defatted flavonoid-rich Chardonnay grape seed flour (ChrSd), diet-induced obese (DIO) mice were fed HF diets containing either ChrSd or microcrystalline cellulose (MCC, control) for 5 weeks. The 2-h insulin area under the curve was significantly lowered by ChrSd, indicating that ChrSd improved insulin sensitivity. ChrSd intake also significantly reduced body weight gain, liver and adipose tissue weight, hepatic lipid content, and plasma low-density lipoprotein (LDL)-cholesterol, despite a significant increase in food intake. Exon microarray analysis of hepatic gene expression revealed down-regulation of genes related to triglyceride and ceramide synthesis, immune response, oxidative stress, and inflammation and upregulation of genes related to fatty acid oxidation, cholesterol, and bile acid synthesis. In conclusion, the effects of ChrSd supplementation in a HF diet on weight gain, insulin resistance, and progression of hepatic steatosis in DIO mice were associated with modulation of hepatic genes related to oxidative stress, inflammation, ceramide synthesis, and lipid and cholesterol metabolism.
Collapse
|
9
|
Yamashita Y, Yamada-Goto N, Katsuura G, Ochi Y, Kanai Y, Miyazaki Y, Kuwahara K, Kanamoto N, Miura M, Yasoda A, Ohinata K, Inagaki N, Nakao K. Brain-specific natriuretic peptide receptor-B deletion attenuates high-fat diet-induced visceral and hepatic lipid deposition in mice. Peptides 2016; 81:38-50. [PMID: 27020246 DOI: 10.1016/j.peptides.2016.03.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 03/16/2016] [Accepted: 03/23/2016] [Indexed: 12/19/2022]
Abstract
C-type natriuretic peptide (CNP) and its receptor, natriuretic peptide receptor-B (NPR-B), are abundantly distributed in the hypothalamus. To explore the role of central CNP/NPR-B signaling in energy regulation, we generated mice with brain-specific NPR-B deletion (BND mice) by crossing Nestin-Cre transgenic mice and mice with a loxP-flanked NPR-B locus. Brain-specific NPR-B deletion prevented body weight gain induced by a high-fat diet (HFD), and the mesenteric fat and liver weights were significantly decreased in BND mice fed an HFD. The decreased liver weight in BND mice was attributed to decreased lipid accumulation in the liver, which was confirmed by histologic findings and lipid content. Gene expression analysis revealed a significant decrease in the mRNA expression levels of CD36, Fsp27, and Mogat1 in the liver of BND mice, and uncoupling protein 2 mRNA expression was significantly lower in the mesenteric fat of BND mice fed an HFD than in that of control mice. This difference was not observed in the epididymal or subcutaneous fat. Although previous studies reported that CNP/NPR-B signaling inhibits SNS activity in rodents, SNS is unlikely to be the underlying mechanism of the metabolic phenotype observed in BND mice. Taken together, CNP/NPR-B signaling in the brain could be a central factor that regulates visceral lipid accumulation and hepatic steatosis under HFD conditions. Further analyses of the precise mechanisms will enhance our understanding of the contribution of the CNP/NPR-B system to energy regulation.
Collapse
Affiliation(s)
- Yui Yamashita
- Department of Diabetes, Endocrinology and Nutrition, Kyoto University Graduate School of Medicine, 54, Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
| | - Nobuko Yamada-Goto
- Division of Endocrinology, Metabolism and Nephrology, Department of Internal Medicine, Keio University, School of Medicine, 35, Shinano-machi, Shinjyuku-ku, Tokyo 160-8582, Japan.
| | - Goro Katsuura
- Department of Diabetes, Endocrinology and Nutrition, Kyoto University Graduate School of Medicine, 54, Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Yukari Ochi
- Department of Diabetes, Endocrinology and Nutrition, Kyoto University Graduate School of Medicine, 54, Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Yugo Kanai
- Department of Diabetes, Endocrinology and Nutrition, Kyoto University Graduate School of Medicine, 54, Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Yuri Miyazaki
- Division of Food Science and Biotechnology, Kyoto University Graduate School of Agriculture, Gokasyo, Uji-shi, Kyoto 611-0011, Japan
| | - Koichiro Kuwahara
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Naotetsu Kanamoto
- Department of Diabetes, Endocrinology and Nutrition, Kyoto University Graduate School of Medicine, 54, Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Masako Miura
- Department of Diabetes, Endocrinology and Nutrition, Kyoto University Graduate School of Medicine, 54, Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Akihiro Yasoda
- Department of Diabetes, Endocrinology and Nutrition, Kyoto University Graduate School of Medicine, 54, Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Kousaku Ohinata
- Division of Food Science and Biotechnology, Kyoto University Graduate School of Agriculture, Gokasyo, Uji-shi, Kyoto 611-0011, Japan
| | - Nobuya Inagaki
- Department of Diabetes, Endocrinology and Nutrition, Kyoto University Graduate School of Medicine, 54, Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Kazuwa Nakao
- Kyoto University Graduate School of Medicine Medical Innovation Center, 53, Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| |
Collapse
|
10
|
Cheng L, Yu Y, Zhang Q, Szabo A, Wang H, Huang XF. Arachidonic acid impairs hypothalamic leptin signaling and hepatic energy homeostasis in mice. Mol Cell Endocrinol 2015; 412:12-8. [PMID: 25986657 DOI: 10.1016/j.mce.2015.04.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 04/15/2015] [Accepted: 04/28/2015] [Indexed: 11/30/2022]
Abstract
Epidemiological evidence suggests that the consumption of a diet high in n-6 polyunsaturated fatty acids (PUFA) is associated with the development of leptin resistance and obesity. We aim to examine the central effect of n-6 PUFA, arachidonic acid (ARA) on leptin sensitivity and leptin-regulated hepatic glucose and lipid metabolism. We found that intracerebroventricular injection of ARA (25 nmol/day) for 2.5 days reversed the effect of central leptin on hypothalamic JAK2, pSTAT3, pAkt, and pFOXO1 protein levels, which was concomitant with a pro-inflammatory response in the hypothalamus. ARA also attenuated the effect of central leptin on hepatic glucose and lipid metabolism by reversing the mRNA expression of the genes involved in gluconeogenesis (G6Pase, PEPCK), glucose transportation (GLUT2), lipogenesis (FAS, SCD1), and cholesterol synthesis (HMG-CoA reductase). These results indicate that an increased exposure to central n-6 PUFA induces central cellular leptin resistance with concomitant defective JAK2-STAT3 and PI3K-Akt signaling.
Collapse
Affiliation(s)
- Licai Cheng
- School of Medicine, Illawarra Health and Medical Research Institute, University of Wollongong, NSW 2522, Australia
| | - Yinghua Yu
- School of Medicine, Illawarra Health and Medical Research Institute, University of Wollongong, NSW 2522, Australia; Schizophrenia Research Institute (SRI), 405 Liverpool St, Sydney, NSW 2010, Australia.
| | - Qingsheng Zhang
- School of Medicine, Illawarra Health and Medical Research Institute, University of Wollongong, NSW 2522, Australia; Schizophrenia Research Institute (SRI), 405 Liverpool St, Sydney, NSW 2010, Australia
| | - Alexander Szabo
- School of Medicine, Illawarra Health and Medical Research Institute, University of Wollongong, NSW 2522, Australia; ANSTO Life Sciences, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
| | - Hongqin Wang
- School of Medicine, Illawarra Health and Medical Research Institute, University of Wollongong, NSW 2522, Australia
| | - Xu-Feng Huang
- School of Medicine, Illawarra Health and Medical Research Institute, University of Wollongong, NSW 2522, Australia; Schizophrenia Research Institute (SRI), 405 Liverpool St, Sydney, NSW 2010, Australia.
| |
Collapse
|
11
|
Head GA, Lim K, Barzel B, Burke SL, Davern PJ. Central nervous system dysfunction in obesity-induced hypertension. Curr Hypertens Rep 2015; 16:466. [PMID: 25090962 DOI: 10.1007/s11906-014-0466-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The activation of the sympathetic nervous system is a major mechanism underlying both human and experimental models of obesity-related hypertension. While insulin and the adipokine leptin have long been thought to contribute to obesity-related neurogenic mechanisms, the evidence is now very strong that they play a major role, shown particularly in animal studies using selective receptor antagonists. There is not just maintenance of leptin's sympatho-excitatory actions as previously suggested but considerable amplification particularly in renal sympathetic nervous activity. Importantly, these changes are not dependent on short-term elevation or reduction in plasma leptin or insulin, but require some weeks to develop indicating a slow "neural adaptivity" within hypothalamic signalling. These effects can be carried across generations even when offspring are raised on a normal diet. A better understanding of the underlying mechanism should be a high research priority given the prevalence of obesity not just in the current population but also for future generations.
Collapse
Affiliation(s)
- Geoffrey A Head
- Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Institute, P.O. Box 6492, Melbourne, Victoria, 3004, Australia,
| | | | | | | | | |
Collapse
|
12
|
Kandilis AN, Papadopoulou IP, Koskinas J, Sotiropoulos G, Tiniakos DG. Liver innervation and hepatic function: new insights. J Surg Res 2015; 194:511-519. [DOI: 10.1016/j.jss.2014.12.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 11/04/2014] [Accepted: 12/03/2014] [Indexed: 12/14/2022]
|
13
|
Cheng L, Yu Y, Szabo A, Wu Y, Wang H, Camer D, Huang XF. Palmitic acid induces central leptin resistance and impairs hepatic glucose and lipid metabolism in male mice. J Nutr Biochem 2015; 26:541-8. [PMID: 25724108 DOI: 10.1016/j.jnutbio.2014.12.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 11/19/2014] [Accepted: 12/08/2014] [Indexed: 12/12/2022]
Abstract
The consumption of diets rich in saturated fat largely contributes to the development of obesity in modern societies. A diet high in saturated fats can induce inflammation and impair leptin signaling in the hypothalamus. However, the role of saturated fatty acids on hypothalamic leptin signaling, and hepatic glucose and lipid metabolism remains largely undiscovered. In this study, we investigated the effects of intracerebroventricular (icv) administration of a saturated fatty acid, palmitic acid (PA, C16:0), on central leptin sensitivity, hypothalamic leptin signaling, inflammatory molecules and hepatic energy metabolism in C57BL/6J male mice. We found that the icv administration of PA led to central leptin resistance, evidenced by the inhibition of central leptin's suppression of food intake. Central leptin resistance was concomitant with impaired hypothalamic leptin signaling (JAK2-STAT3, PKB/Akt-FOXO1) and a pro-inflammatory response (TNF-α, IL1-β, IL-6 and pIκBa) in the mediobasal hypothalamus and paraventricular hypothalamic nuclei. Furthermore, the pre-administration of icv PA blunted the effect of leptin-induced decreases in mRNA expression related to gluconeogenesis (G6Pase and PEPCK), glucose transportation (GLUT2) and lipogenesis (FAS and SCD1) in the liver of mice. Therefore, elevated central PA concentrations can induce pro-inflammatory responses and leptin resistance, which are associated with disorders of energy homeostasis in the liver as a result of diet-induced obesity.
Collapse
Affiliation(s)
- Licai Cheng
- School of Medicine, University of Wollongong and Illawarra Health and Medical Research Institute, NSW 2522, Australia
| | - Yinghua Yu
- School of Medicine, University of Wollongong and Illawarra Health and Medical Research Institute, NSW 2522, Australia; Schizophrenia Research Institute (SRI), 405 Liverpool St, Sydney, NSW 2010, Australia
| | - Alexander Szabo
- School of Medicine, University of Wollongong and Illawarra Health and Medical Research Institute, NSW 2522, Australia; ANSTO Life Sciences, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
| | - Yizhen Wu
- School of Medicine, University of Wollongong and Illawarra Health and Medical Research Institute, NSW 2522, Australia
| | - Hongqin Wang
- School of Medicine, University of Wollongong and Illawarra Health and Medical Research Institute, NSW 2522, Australia
| | - Danielle Camer
- School of Medicine, University of Wollongong and Illawarra Health and Medical Research Institute, NSW 2522, Australia
| | - Xu-Feng Huang
- School of Medicine, University of Wollongong and Illawarra Health and Medical Research Institute, NSW 2522, Australia; Schizophrenia Research Institute (SRI), 405 Liverpool St, Sydney, NSW 2010, Australia.
| |
Collapse
|
14
|
Suzuki T, Muramatsu T, Morioka K, Goda T, Mochizuki K. ChREBP binding and histone modifications modulate hepatic expression of the Fasn gene in a metabolic syndrome rat model. Nutrition 2015; 31:877-83. [PMID: 25933497 DOI: 10.1016/j.nut.2015.01.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 12/25/2014] [Accepted: 01/14/2015] [Indexed: 11/17/2022]
Abstract
OBJECTIVE Although the expression of hepatic lipogenic genes is enhanced in insulin resistance, the underlying mechanism is unclear. To reveal the details, the aim of this study was to investigate whether the expression of hepatic lipogenic genes are mediated by epigenetic regulation and specific transcription factors in an insulin resistance model of rats. METHODS Using a rat model of insulin resistance (SHR/NDmc-cp), we investigated the relationship between hepatic expression of the lipogenic gene fatty-acid synthase (Fasn), binding of the transcription factor carbohydrate-responsive element-binding protein (ChREBP) to the Fasn gene, and histone modifications in the region of the Fasn gene by real-time reverse transcriptase polymerase chain reaction, immunoblotting, and chromatin immunoprecipitation assay. RESULTS Compared with control rats, Fasn mRNA expression and protein levels were higher in the livers of SHR/NDmc-cp rats, as were protein expression levels and Fasn binding of ChREBP and RNA polymerase II. Moreover, compared with the livers of control rats, levels of mono-methylated histone H3 lysine (K) 4 and acetylated histone H4 were higher in the promoter/enhancer region of the Fasn gene in the livers of SHR/NDmc-cp rats. Levels of trimethylated histone H3K4 and acetylated histone H3 were higher in the transcribed region. CONCLUSION The results of this study indicate that expression of the Fasn gene in the livers of insulin-resistant rats is associated with increased H3K4 methylation, increased histone H3 acetylation, and increased H4 acetylation, and also, binding levels of ChREBP to promoter/enhancer region of Fasn gene is involved in the Fasn gene expression caused by hyperglycemia.
Collapse
Affiliation(s)
- Takuji Suzuki
- Laboratory of Nutritional Physiology, Graduate School of Nutritional and Environmental Sciences, Global COE Program, University of Shizuoka, Shizuoka, Japan; Food Environmental Design Course, Faculty of Education, Art and Science, Yamagata University, Yamagata, Japan
| | - Takeshi Muramatsu
- Laboratory of Nutritional Physiology, Graduate School of Nutritional and Environmental Sciences, Global COE Program, University of Shizuoka, Shizuoka, Japan
| | - Kousuke Morioka
- Laboratory of Nutritional Physiology, Graduate School of Nutritional and Environmental Sciences, Global COE Program, University of Shizuoka, Shizuoka, Japan
| | - Toshinao Goda
- Laboratory of Nutritional Physiology, Graduate School of Nutritional and Environmental Sciences, Global COE Program, University of Shizuoka, Shizuoka, Japan
| | - Kazuki Mochizuki
- Laboratory of Nutritional Physiology, Graduate School of Nutritional and Environmental Sciences, Global COE Program, University of Shizuoka, Shizuoka, Japan; Laboratory of Food and Nutritional Sciences, Faculty of Life and Environmental Sciences, University of Yamanashi, Yamanashi, Japan.
| |
Collapse
|
15
|
Tanida M, Yamamoto N, Morgan DA, Kurata Y, Shibamoto T, Rahmouni K. Leptin receptor signaling in the hypothalamus regulates hepatic autonomic nerve activity via phosphatidylinositol 3-kinase and AMP-activated protein kinase. J Neurosci 2015; 35:474-84. [PMID: 25589743 PMCID: PMC4293404 DOI: 10.1523/jneurosci.1828-14.2015] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 10/31/2014] [Accepted: 11/03/2014] [Indexed: 12/12/2022] Open
Abstract
Leptin action in the brain has emerged as an important regulator of liver function independently from its effects on food intake and body weight. The autonomic nervous system plays a key role in the regulation of physiological processes by leptin. Here, we used direct recording of nerve activity from sympathetic or vagal nerves subserving the liver to investigate how brain action of leptin controls hepatic autonomic nerve activity. Intracerebroventricular (ICV) administration of leptin activated hepatic sympathetic traffic in rats and mice in dose- and receptor-dependent manners. The hepatic sympatho-excitatory effects of leptin were also observed when leptin was microinjected directly into the arcuate nucleus (ARC), but not into the ventromedial hypothalamus (VMH). Moreover, using pharmacological and genetic approaches, we show that leptin-induced increase in hepatic sympathetic outflow depends on PI3K but not AMP-activated protein kinase (AMPK), STAT3, or ERK1/2. Interestingly, ICV leptin also increased hepatic vagal nerve activity in rats. We show that this response is reproduced by intra-ARC, but not intra-VMH, leptin administration and requires PI3K and AMPK. We conclude that central leptin signaling conveys the information to the liver through the sympathetic and parasympathetic branches of the autonomic nervous system. Our data also provide important insight into the molecular events underlying leptin's control of hepatic autonomic nerve activity by implicating PI3K and AMPK pathways.
Collapse
Affiliation(s)
- Mamoru Tanida
- Department of Physiology II, Kanazawa Medical University, Uchinada, Ishikawa 920-0293, Japan, Department of Internal Medicine, and
| | - Naoki Yamamoto
- College of Pharmacology, Hokuriku University, Kanazawa, Ishikawa 920-1180, Japan, and
| | | | - Yasutaka Kurata
- Department of Physiology II, Kanazawa Medical University, Uchinada, Ishikawa 920-0293, Japan
| | - Toshishige Shibamoto
- Department of Physiology II, Kanazawa Medical University, Uchinada, Ishikawa 920-0293, Japan
| | - Kamal Rahmouni
- Department of Pharmacology, Department of Internal Medicine, and Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242
| |
Collapse
|
16
|
Yue JTY, Abraham MA, LaPierre MP, Mighiu PI, Light PE, Filippi BM, Lam TKT. A fatty acid-dependent hypothalamic–DVC neurocircuitry that regulates hepatic secretion of triglyceride-rich lipoproteins. Nat Commun 2015; 6:5970. [DOI: 10.1038/ncomms6970] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 11/26/2014] [Indexed: 12/31/2022] Open
|
17
|
Abstract
The liver is an essential metabolic organ, and its metabolic function is controlled by insulin and other metabolic hormones. Glucose is converted into pyruvate through glycolysis in the cytoplasm, and pyruvate is subsequently oxidized in the mitochondria to generate ATP through the TCA cycle and oxidative phosphorylation. In the fed state, glycolytic products are used to synthesize fatty acids through de novo lipogenesis. Long-chain fatty acids are incorporated into triacylglycerol, phospholipids, and/or cholesterol esters in hepatocytes. These complex lipids are stored in lipid droplets and membrane structures, or secreted into the circulation as very low-density lipoprotein particles. In the fasted state, the liver secretes glucose through both glycogenolysis and gluconeogenesis. During pronged fasting, hepatic gluconeogenesis is the primary source for endogenous glucose production. Fasting also promotes lipolysis in adipose tissue, resulting in release of nonesterified fatty acids which are converted into ketone bodies in hepatic mitochondria though β-oxidation and ketogenesis. Ketone bodies provide a metabolic fuel for extrahepatic tissues. Liver energy metabolism is tightly regulated by neuronal and hormonal signals. The sympathetic system stimulates, whereas the parasympathetic system suppresses, hepatic gluconeogenesis. Insulin stimulates glycolysis and lipogenesis but suppresses gluconeogenesis, and glucagon counteracts insulin action. Numerous transcription factors and coactivators, including CREB, FOXO1, ChREBP, SREBP, PGC-1α, and CRTC2, control the expression of the enzymes which catalyze key steps of metabolic pathways, thus controlling liver energy metabolism. Aberrant energy metabolism in the liver promotes insulin resistance, diabetes, and nonalcoholic fatty liver diseases.
Collapse
Affiliation(s)
- Liangyou Rui
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan
| |
Collapse
|
18
|
Sumita T, Ono H, Suzuki T, Sakai G, Inukai K, Katagiri H, Asano T, Katayama S, Awata T. Mediobasal hypothalamic PTEN modulates hepatic insulin resistance independently of food intake in rats. Am J Physiol Endocrinol Metab 2014; 307:E47-60. [PMID: 24824654 DOI: 10.1152/ajpendo.00361.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Phosphatase and tensin homolog (PTEN) dephosphorylates phosphatidylinositol (PI) 3,4,5-triphosphate and antagonizes PI 3-kinase. Insulin acts in the mediobasal hypothalamus (MBH) to not only suppress food intake and weight gain but also improve glucose metabolism via PI 3-kinase activation. Thus, the blocking of hypothalamic PTEN is a potential target for treating obesity as well as diabetes. However, genetic modification of PTEN in specific neuronal populations in the MBH yielded complex results, and no postnatal intervention for hypothalamic PTEN has been reported yet. To elucidate how postnatal modification of hypothalamic PTEN influences food intake as well as glucose metabolism, we bidirectionally altered PTEN activity in the MBH of rats by adenoviral gene delivery. Inhibition of MBH PTEN activity reduced food intake and weight gain, whereas constitutive activation of PTEN tended to induce the opposite effects. Interestingly, the effects of MBH PTEN intervention on food intake and body weight were blunted by high-fat feeding. However, MBH PTEN blockade improved hepatic insulin sensitivity even under high-fat-fed conditions. On the other hand, constitutive activation of MBH PTEN induced hepatic insulin resistance. Hepatic Akt phosphorylation and the G6Pase expression level were modulated bidirectionally by MBH PTEN intervention. These results demonstrate that PTEN in the MBH regulates hepatic insulin sensitivity independently of the effects on food intake and weight gain. Therefore, hypothalamic PTEN is a promising target for treating insulin resistance even in states of overnutrition.
Collapse
Affiliation(s)
- Takashi Sumita
- Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan
| | - Hiraku Ono
- Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan;
| | - Tokuko Suzuki
- Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan
| | - Gota Sakai
- Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan
| | - Kouichi Inukai
- Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan
| | - Hideki Katagiri
- Department of Metabolic Diseases, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan; and
| | - Tomoichiro Asano
- Department of Medical Science, Graduate School of Medicine, University of Hiroshima, Hiroshima, Japan
| | - Shigehiro Katayama
- Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan
| | - Takuya Awata
- Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama, Japan
| |
Collapse
|
19
|
Knobler H, Elson A. Metabolic regulation by protein tyrosine phosphatases. J Biomed Res 2014; 28:157-68. [PMID: 25013399 PMCID: PMC4085553 DOI: 10.7555/jbr.28.20140012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 01/28/2014] [Indexed: 01/14/2023] Open
Abstract
Obesity and the metabolic syndrome and their associated morbidities are major public health issues, whose prevalence will continue to increase in the foreseeable future. Aberrant signaling by the receptors for leptin and insulin plays a pivotal role in development of the metabolic syndrome. More complete molecular-level understanding of how both of these key signaling pathways are regulated is essential for full characterization of obesity, the metabolic syndrome, and type II diabetes, and for developing novel treatments for these diseases. Phosphorylation of proteins on tyrosine residues plays a key role in mediating the effects of leptin and insulin on their target cells. Here, we discuss the molecular methods by which protein tyrosine phosphatases, which are key physiological regulators of protein phosphorylation in vivo, affect signaling by the leptin and insulin receptors in their major target tissues.
Collapse
Affiliation(s)
- Hilla Knobler
- Diabetes and Metabolic Disease Unit, Kaplan Medical Center, Rehovot 76100, Israel
| | - Ari Elson
- Department of Molecular Genetics, the Weizmann Institute of Science, Rehovot 76100, Israel
| |
Collapse
|
20
|
Geerling JJ, Boon MR, Kooijman S, Parlevliet ET, Havekes LM, Romijn JA, Meurs IM, Rensen PCN. Sympathetic nervous system control of triglyceride metabolism: novel concepts derived from recent studies. J Lipid Res 2014; 55:180-9. [PMID: 24285857 PMCID: PMC3886657 DOI: 10.1194/jlr.r045013] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 11/27/2013] [Indexed: 12/16/2022] Open
Abstract
Important players in triglyceride (TG) metabolism include the liver (production), white adipose tissue (WAT) (storage), heart and skeletal muscle (combustion to generate ATP), and brown adipose tissue (BAT) (combustion toward heat), the collective action of which determine plasma TG levels. Interestingly, recent evidence points to a prominent role of the hypothalamus in TG metabolism through innervating the liver, WAT, and BAT mainly via sympathetic branches of the autonomic nervous system. Here, we review the recent findings in the area of sympathetic control of TG metabolism. Various neuronal populations, such as neuropeptide Y (NPY)-expressing neurons and melanocortin-expressing neurons, as well as peripherally produced hormones (i.e., GLP-1, leptin, and insulin), modulate sympathetic outflow from the hypothalamus toward target organs and thereby influence peripheral TG metabolism. We conclude that sympathetic stimulation in general increases lipolysis in WAT, enhances VLDL-TG production by the liver, and increases the activity of BAT with respect to lipolysis of TG, followed by combustion of fatty acids toward heat. Moreover, the increased knowledge about the involvement of the neuroendocrine system in TG metabolism presented in this review offers new therapeutic options to fight hypertriglyceridemia by specifically modulating sympathetic nervous system outflow toward liver, BAT, or WAT.
Collapse
Affiliation(s)
- Janine J. Geerling
- Departments of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Mariëtte R. Boon
- Departments of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - Sander Kooijman
- Departments of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Edwin T. Parlevliet
- Departments of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
- Department of Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Louis M. Havekes
- Departments of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
- Gaubius Laboratory, Netherlands Organization for Applied Scientific Research - Metabolic Health Research, Leiden, The Netherlands
| | - Johannes A. Romijn
- Department of Medicine, Academic Medical Center, University of Amsterdam, The Netherlands
| | - Illiana M. Meurs
- Departments of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Patrick C. N. Rensen
- Departments of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
- Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| |
Collapse
|
21
|
Guo S. Insulin signaling, resistance, and the metabolic syndrome: insights from mouse models into disease mechanisms. J Endocrinol 2014; 220:T1-T23. [PMID: 24281010 PMCID: PMC4087161 DOI: 10.1530/joe-13-0327] [Citation(s) in RCA: 326] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Insulin resistance is a major underlying mechanism responsible for the 'metabolic syndrome', which is also known as insulin resistance syndrome. The incidence of the metabolic syndrome is increasing at an alarming rate, becoming a major public and clinical problem worldwide. The metabolic syndrome is represented by a group of interrelated disorders, including obesity, hyperglycemia, hyperlipidemia, and hypertension. It is also a significant risk factor for cardiovascular disease and increased morbidity and mortality. Animal studies have demonstrated that insulin and its signaling cascade normally control cell growth, metabolism, and survival through the activation of MAPKs and activation of phosphatidylinositide-3-kinase (PI3K), in which the activation of PI3K associated with insulin receptor substrate 1 (IRS1) and IRS2 and subsequent Akt→Foxo1 phosphorylation cascade has a central role in the control of nutrient homeostasis and organ survival. The inactivation of Akt and activation of Foxo1, through the suppression IRS1 and IRS2 in different organs following hyperinsulinemia, metabolic inflammation, and overnutrition, may act as the underlying mechanisms for the metabolic syndrome in humans. Targeting the IRS→Akt→Foxo1 signaling cascade will probably provide a strategy for therapeutic intervention in the treatment of type 2 diabetes and its complications. This review discusses the basis of insulin signaling, insulin resistance in different mouse models, and how a deficiency of insulin signaling components in different organs contributes to the features of the metabolic syndrome. Emphasis is placed on the role of IRS1, IRS2, and associated signaling pathways that are coupled to Akt and the forkhead/winged helix transcription factor Foxo1.
Collapse
Affiliation(s)
- Shaodong Guo
- Division of Molecular Cardiology, Department of Medicine, College of Medicine, Texas A&M University Health Science Center, Scott & White, Central Texas Veterans Health Care System, 1901 South 1st Street, Bldg. 205, Temple, Texas 76504, USA
| |
Collapse
|
22
|
Carey M, Kehlenbrink S, Hawkins M. Evidence for central regulation of glucose metabolism. J Biol Chem 2013; 288:34981-8. [PMID: 24142701 DOI: 10.1074/jbc.r113.506782] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Evidence for central regulation of glucose homeostasis is accumulating from both animal and human studies. Central nutrient and hormone sensing in the hypothalamus appears to coordinate regulation of whole body metabolism. Central signals activate ATP-sensitive potassium (KATP) channels, thereby down-regulating glucose production, likely through vagal efferent signals. Recent human studies are consistent with this hypothesis. The contributions of direct and central inputs to metabolic regulation are likely of comparable magnitude, with somewhat delayed central effects and more rapid peripheral effects. Understanding central regulation of glucose metabolism could promote the development of novel therapeutic approaches for such metabolic conditions as diabetes mellitus.
Collapse
Affiliation(s)
- Michelle Carey
- From the Department of Medicine and Diabetes Research Center, Albert Einstein College of Medicine, Bronx, New York 10461
| | | | | |
Collapse
|
23
|
Coordinated regulation of hepatic energy stores by leptin and hypothalamic agouti-related protein. J Neurosci 2013; 33:11972-85. [PMID: 23864684 DOI: 10.1523/jneurosci.0830-13.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Like obesity, prolonged food deprivation induces severe hepatic steatosis; however, the functional significance of this phenomenon is not well understood. In this study, we show that the fall in plasma leptin concentration during fasting is required for the development of hepatic steatosis in mice. Removal of leptin receptors from AGRP neurons diminishes fasting-induced hepatic steatosis. Furthermore, the suppressive effects of leptin on fasting-induced hepatic steatosis are absent in mice lacking the gene encoding agouti-related protein (Agrp), suggesting that this function of leptin is mediated by AGRP. Prolonged fasting leads to suppression of hepatic sympathetic activity, increased expression of acyl CoA:diacylglycerol acyltransferase-2 in the liver, and elevation of hepatic triglyceride content and all of these effects are blunted in the absence of AGRP. AGRP deficiency, despite having no effects on feeding or body adiposity in the free-fed state, impairs triglyceride and ketone body release from the liver during prolonged fasting. Furthermore, reducing CNS Agrp expression in wild-type mice by RNAi protected against the development of hepatic steatosis not only during starvation, but also in response to consumption of a high-fat diet. These findings identify the leptin-AGRP circuit as a critical modulator of hepatic triglyceride stores in starvation and suggest a vital role for this circuit in sustaining the supply of energy from the liver to extrahepatic tissues during periods of prolonged food deprivation.
Collapse
|
24
|
Abstract
In addition to effects on appetite and metabolism, leptin influences many neuroendocrine and physiological systems, including the sympathetic nervous system. Building on my Carl Ludwig Lecture of the American Physiological Society, I review the sympathetic and cardiovascular actions of leptin. The review focuses on a critical analysis of the concept of selective leptin resistance (SLR) and the role of leptin in the pathogenesis of obesity-induced hypertension in both experimental animals and humans. We introduced the concept of SLR in 2002 to explain how leptin might increase blood pressure (BP) in obese states, such as diet-induced obesity (DIO), that are accompanied by partial leptin resistance. This concept, analogous to selective insulin resistance in the metabolic syndrome, holds that in several genetic and acquired models of obesity, there is preservation of the renal sympathetic and pressor actions of leptin despite attenuation of the appetite and weight-reducing actions. Two potential overlapping mechanisms of SLR are reviewed: 1) differential leptin molecular signaling pathways that mediate selective as opposed to universal leptin action and 2) brain site-specific leptin action and resistance. Although the phenomenon of SLR in DIO has so far focused on preservation of sympathetic and BP actions of leptin, consideration should be given to the possibility that this concept may extend to preservation of other actions of leptin. Finally, I review perplexing data on the effects of leptin on sympathetic activity and BP in humans and its role in human obesity-induced hypertension.
Collapse
Affiliation(s)
- Allyn L Mark
- Department of Internal Medicine and the Obesity Research and Education Initiative, University of Iowa Carver College of Medicine, Iowa City, Iowa
| |
Collapse
|
25
|
Toda C, Shiuchi T, Kageyama H, Okamoto S, Coutinho EA, Sato T, Okamatsu-Ogura Y, Yokota S, Takagi K, Tang L, Saito K, Shioda S, Minokoshi Y. Extracellular signal-regulated kinase in the ventromedial hypothalamus mediates leptin-induced glucose uptake in red-type skeletal muscle. Diabetes 2013; 62:2295-307. [PMID: 23530005 PMCID: PMC3712028 DOI: 10.2337/db12-1629] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Leptin is a key regulator of glucose metabolism in mammals, but the mechanisms of its action have remained elusive. We now show that signaling by extracellular signal-regulated kinase (ERK) and its upstream kinase MEK in the ventromedial hypothalamus (VMH) mediates the leptin-induced increase in glucose utilization as well as its insulin sensitivity in the whole body and in red-type skeletal muscle of mice through activation of the melanocortin receptor (MCR) in the VMH. In contrast, activation of signal transducer and activator of transcription 3 (STAT3), but not the MEK-ERK pathway, in the VMH by leptin enhances the insulin-induced suppression of endogenous glucose production in an MCR-independent manner, with this effect of leptin occurring only in the presence of an increased plasma concentration of insulin. Given that leptin requires 6 h to increase muscle glucose uptake, the transient activation of the MEK-ERK pathway in the VMH by leptin may play a role in the induction of synaptic plasticity in the VMH, resulting in the enhancement of MCR signaling in the nucleus and leading to an increase in insulin sensitivity in red-type muscle.
Collapse
Affiliation(s)
- Chitoku Toda
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
| | - Tetsuya Shiuchi
- Department of Integrative Physiology, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Haruaki Kageyama
- Department of Anatomy, Showa University School of Medicine, Shinagawa-ku, Tokyo, Japan
- Faculty of Health Care, Kiryu University, Midori, Gunma, Japan
| | - Shiki Okamoto
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
- Department of Physiological Sciences, Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa, Japan
| | - Eulalia A. Coutinho
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
- Department of Physiological Sciences, Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa, Japan
| | - Tatsuya Sato
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
- Department of Physiological Sciences, Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa, Japan
| | - Yuko Okamatsu-Ogura
- Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Shigefumi Yokota
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
- Department of Physiological Sciences, Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa, Japan
| | - Kazuyo Takagi
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
- Department of Physiological Sciences, Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa, Japan
| | - Lijun Tang
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
- Department of Physiological Sciences, Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa, Japan
| | - Kumiko Saito
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
| | - Seiji Shioda
- Department of Anatomy, Showa University School of Medicine, Shinagawa-ku, Tokyo, Japan
| | - Yasuhiko Minokoshi
- Division of Endocrinology and Metabolism, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
- Department of Physiological Sciences, Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa, Japan
- Corresponding author: Yasuhiko Minokoshi,
| |
Collapse
|
26
|
Guo S. Molecular Basis of Insulin Resistance: The Role of IRS and Foxo1 in the Control of Diabetes Mellitus and Its Complications. ACTA ACUST UNITED AC 2013; 10:e27-e33. [PMID: 24015152 DOI: 10.1016/j.ddmec.2013.06.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Insulin/IGF-1 signaling plays a central role in control of cellular metabolism and survival, while insulin receptor substrate (IRS) protein -1 and -2 and downstream PI-3 kinase→Akt→Foxo1 signaling cascade play key roles in many functions of insulin/IGF-1. Dysregulation of this branch of signaling cascades may provide a mechanism for insulin resistance as we observed in cells, animals, and even humans. Targeting this branch of IRS→Foxo1 signaling may provide us with fundamental strategies for drug development in the future.
Collapse
Affiliation(s)
- Shaodong Guo
- Division of Molecular Cardiology, Cardiovascular Research Institute, College of Medicine, Texas A&M University Health Science Center, Scott & White; Central Texas Veterans Health Care System, Temple, TX 76504, USA
| |
Collapse
|
27
|
Scherer T, Lehnert H, Hallschmid M. Brain insulin and leptin signaling in metabolic control: from animal research to clinical application. Endocrinol Metab Clin North Am 2013; 42:109-25. [PMID: 23391243 DOI: 10.1016/j.ecl.2012.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Besides the well-characterized effects of brain insulin and leptin in regulating food intake, insulin and leptin signaling to the central nervous system modulates a variety of metabolic processes, such as glucose and lipid homeostasis, as well as energy expenditure. This review summarizes the current literature on the contribution of central nervous insulin and leptin action to metabolic control in animals and humans. Potential therapeutic options based on the direct delivery of these peptides to the brain by, for example, intranasal administration, are discussed.
Collapse
Affiliation(s)
- Thomas Scherer
- Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna 1090, Austria.
| | | | | |
Collapse
|
28
|
Abstract
The central melanocortin system plays an essential role in the regulation of energy metabolism. Key to this regulation are the responses of neurons expressing proopiomelanocortin (POMC) and agouti-related protein (AgRP) to blood-borne metabolic signals. Recent evidence has demonstrated that POMC and AgRP neurons are not simply mirror opposites of each other in function and responsiveness to metabolic signals, nor are they exclusively first-order neurons. These neurons act as central transceivers, integrating both hormonal and neural signals, and then transmitting this information to peripheral tissues via the autonomic nervous system to coordinate whole-body energy metabolism. This review focuses on most recent developments obtained from rodent studies on the function, metabolic regulation, and circuitry of the central melanocortin system.
Collapse
Affiliation(s)
- James P. Warne
- Diabetes Center, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Allison W. Xu
- Diabetes Center, University of California, San Francisco, San Francisco, CA 94143, USA
| |
Collapse
|
29
|
Tsou RC, Bence KK. Central regulation of metabolism by protein tyrosine phosphatases. Front Neurosci 2013; 6:192. [PMID: 23308070 PMCID: PMC3538333 DOI: 10.3389/fnins.2012.00192] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 12/17/2012] [Indexed: 11/13/2022] Open
Abstract
Protein tyrosine phosphatases (PTPs) are important regulators of intracellular signaling pathways via the dephosphorylation of phosphotyrosyl residues on various receptor and non-receptor substrates. The phosphorylation state of central nervous system (CNS) signaling components underlies the molecular mechanisms of a variety of physiological functions including the control of energy balance and glucose homeostasis. In this review, we summarize the current evidence implicating PTPs as central regulators of metabolism, specifically highlighting their interactions with the neuronal leptin and insulin signaling pathways. We discuss the role of a number of PTPs (PTP1B, SHP2, TCPTP, RPTPe, and PTEN), reviewing the findings from genetic mouse models and in vitro studies which highlight these phosphatases as key central regulators of energy homeostasis.
Collapse
Affiliation(s)
- Ryan C Tsou
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania Philadelphia, PA, USA
| | | |
Collapse
|
30
|
Rojas JM, Stafford JM, Saadat S, Printz RL, Beck-Sickinger AG, Niswender KD. Central nervous system neuropeptide Y signaling via the Y1 receptor partially dissociates feeding behavior from lipoprotein metabolism in lean rats. Am J Physiol Endocrinol Metab 2012; 303:E1479-88. [PMID: 23074243 PMCID: PMC3532466 DOI: 10.1152/ajpendo.00351.2012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Elevated plasma triglyceride (TG) levels contribute to an atherogenic dyslipidemia that is associated with obesity, diabetes, and metabolic syndrome. Numerous models of obesity are characterized by increased central nervous system (CNS) neuropeptide Y (NPY) tone that contributes to excess food intake and obesity. Previously, we demonstrated that intracerebroventricular (icv) administration of NPY in lean fasted rats also elevates hepatic production of very low-density lipoprotein (VLDL)-TG. Thus, we hypothesize that elevated CNS NPY action contributes to not only the pathogenesis of obesity but also dyslipidemia. Here, we sought to determine whether the effects of NPY on feeding and/or obesity are dissociable from effects on hepatic VLDL-TG secretion. Pair-fed, icv NPY-treated, chow-fed Long-Evans rats develop hypertriglyceridemia in the absence of increased food intake and body fat accumulation compared with vehicle-treated controls. We then modulated CNS NPY signaling by icv injection of selective NPY receptor agonists and found that Y1, Y2, Y4, and Y5 receptor agonists all induced hyperphagia in lean, ad libitum chow-fed Long-Evans rats, with the Y2 receptor agonist having the most pronounced effect. Next, we found that at equipotent doses for food intake NPY Y1 receptor agonist had the most robust effect on VLDL-TG secretion, a Y2 receptor agonist had a modest effect, and no effect was observed for Y4 and Y5 receptor agonists. These findings, using selective agonists, suggest the possibility that the effect of CNS NPY signaling on hepatic VLDL-TG secretion may be relatively dissociable from effects on feeding behavior via the Y1 receptor.
Collapse
|
31
|
Marion V, Mockel A, De Melo C, Obringer C, Claussmann A, Simon A, Messaddeq N, Durand M, Dupuis L, Loeffler JP, King P, Mutter-Schmidt C, Petrovsky N, Stoetzel C, Dollfus H. BBS-induced ciliary defect enhances adipogenesis, causing paradoxical higher-insulin sensitivity, glucose usage, and decreased inflammatory response. Cell Metab 2012; 16:363-77. [PMID: 22958920 DOI: 10.1016/j.cmet.2012.08.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 06/13/2012] [Accepted: 08/16/2012] [Indexed: 01/11/2023]
Abstract
Studying ciliopathies, like the Bardet-Biedl syndrome (BBS), allow the identification of signaling pathways potentially involved in common diseases, sharing phenotypic features like obesity or type 2 diabetes. Given the close association between obesity and insulin resistance, obese BBS patients would be expected to be insulin resistant. Surprisingly, we found that a majority of obese BBS patients retained normal glucose tolerance and insulin sensitivity. Patient's adipose tissue biopsies revealed upregulation of adipogenic genes and decrease of inflammatory mediators. In vitro studies on human primary mesenchymal stem cells (MSCs) showed that BBS12 inactivation facilitated adipogenesis, increased insulin sensitivity, and glucose utilization. We generated a Bbs12(-/-) mouse model to assess the impact of Bbs12 inactivation on adipocyte biology. Despite increased obesity, glucose tolerance was increased with specific enhanced insulin sensitivity in the fat. This correlated with an active recruitment of MSCs resulting in adipose tissue hyperplasia and decreased in inflammation.
Collapse
Affiliation(s)
- Vincent Marion
- Laboratoire de Physiopathologie des Syndromes Rares Héréditaires, AVENIR-Inserm, EA3949, Université de Strasbourg, 11 rue Humann, 67085 Strasbourg, France.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Neuroanatomical determinants of the sympathetic nerve responses evoked by leptin. Clin Auton Res 2012; 23:1-7. [PMID: 22714900 DOI: 10.1007/s10286-012-0168-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 05/18/2012] [Indexed: 01/04/2023]
Abstract
Leptin is an adipocyte-derived hormone that relays a satiety signal to the brain. The effect of leptin on the sympathetic nervous system is an important aspect in the regulation of energy homeostasis as well as several other physiological functions. The arcuate nucleus of the hypothalamus is considered a major site for the regulation of physiological processes by leptin. However, there is growing recognition that other hypothalamic and extra-hypothalamic brain nuclei are important for leptin regulation of physiological processes including sympathetic nerve traffic. The current review discusses the various hypothalamic and extra-hypothalamic nuclei that have been implicated in leptin-induced increase in regional sympathetic nerve activity. The continuous rise in the prevalence of obesity underscores the importance of understanding the underlying neural mechanisms regulating sympathetic traffic to different tissues to design effective strategies to reverse obesity and associated diseases.
Collapse
|
33
|
Kim KW, Donato J, Berglund ED, Choi YH, Kohno D, Elias CF, Depinho RA, Elmquist JK. FOXO1 in the ventromedial hypothalamus regulates energy balance. J Clin Invest 2012; 122:2578-89. [PMID: 22653058 DOI: 10.1172/jci62848] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 04/18/2012] [Indexed: 12/15/2022] Open
Abstract
The transcription factor FOXO1 plays a central role in metabolic homeostasis by regulating leptin and insulin activity in many cell types, including neurons. However, the neurons mediating these effects and the identity of the molecular targets through which FOXO1 regulates metabolism remain to be defined. Here, we show that the ventral medial nucleus of the hypothalamus (VMH) is a key site of FOXO1 action. We found that mice lacking FOXO1 in steroidogenic factor 1 (SF-1) neurons of the VMH are lean due to increased energy expenditure. The mice also failed to appropriately suppress energy expenditure in response to fasting. Furthermore, these mice displayed improved glucose tolerance due to increased insulin sensitivity in skeletal muscle and heart. Gene expression profiling and sequence analysis revealed several pathways regulated by FOXO1. In addition, we identified the nuclear receptor SF-1 as a direct FOXO1 transcriptional target in the VMH. Collectively, our data suggest that the transcriptional networks modulated by FOXO1 in VMH neurons are key components in the regulation of energy balance and glucose homeostasis.
Collapse
Affiliation(s)
- Ki Woo Kim
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center(UT Southwestern), Dallas, TX, USA
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Ramnanan CJ, Edgerton DS, Cherrington AD. Evidence against a physiologic role for acute changes in CNS insulin action in the rapid regulation of hepatic glucose production. Cell Metab 2012; 15:656-64. [PMID: 22560218 PMCID: PMC3348512 DOI: 10.1016/j.cmet.2012.03.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This Perspective will discuss the physiologic relevance of data that suggest CNS insulin action is required for the rapid suppression of hepatic glucose production. It will also review data from experiments on the conscious dog, which show that although the canine brain can sense insulin and, thereby, regulate hepatic glucoregulatory enzyme expression, CNS insulin action is not essential for the rapid suppression of glucose production caused by the hormone. Insulin's direct hepatic effects are dominant, thus it appears that insulin's central effects are redundant in the acute regulation of hepatic glucose metabolism.
Collapse
Affiliation(s)
- Christopher J Ramnanan
- Vanderbilt University School of Medicine, Department of Molecular Physiology and Biophysics, Nashville, TN 37232, USA
| | | | | |
Collapse
|