1
|
Rahmouni K. Neural Circuits Underlying Reciprocal Cardiometabolic Crosstalk: 2023 Arthur C. Corcoran Memorial Lecture. Hypertension 2024; 81:1233-1243. [PMID: 38533662 PMCID: PMC11096079 DOI: 10.1161/hypertensionaha.124.22066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
The interplay of various body systems, encompassing those that govern cardiovascular and metabolic functions, has evolved alongside the development of multicellular organisms. This evolutionary process is essential for the coordination and maintenance of homeostasis and overall health by facilitating the adaptation of the organism to internal and external cues. Disruption of these complex interactions contributes to the development and progression of pathologies that involve multiple organs. Obesity-associated cardiovascular risks, such as hypertension, highlight the significant influence that metabolic processes exert on the cardiovascular system. This cardiometabolic communication is reciprocal, as indicated by substantial evidence pointing to the ability of the cardiovascular system to affect metabolic processes, with pathophysiological implications in disease conditions. In this review, I outline the bidirectional nature of the cardiometabolic interaction, with special emphasis on the impact that metabolic organs have on the cardiovascular system. I also discuss the contribution of the neural circuits and autonomic nervous system in mediating the crosstalk between cardiovascular and metabolic functions in health and disease, along with the molecular mechanisms involved.
Collapse
Affiliation(s)
- Kamal Rahmouni
- Department of Neuroscience and Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa
- Veterans Affairs Health Care System, Iowa City, Iowa
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa
- Obesity Research and Education Initiative, University of Iowa Carver College of Medicine, Iowa City, Iowa
- Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, Iowa City, Iowa
| |
Collapse
|
2
|
Roujeau C, Jockers R, Dam J. Endospanin 1 Determines the Balance of Leptin-Regulated Hypothalamic Functions. Neuroendocrinology 2019; 108:132-141. [PMID: 30326479 DOI: 10.1159/000494557] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Accepted: 10/16/2018] [Indexed: 11/19/2022]
Abstract
Endospanin 1 (Endo1), a protein encoded in humans by the same gene than the leptin receptor (ObR), and increased by diet-induced obesity, is an important regulator of ObR trafficking and cell surface exposure, determining leptin signaling strength. Defective intracellular trafficking of the leptin receptor to the neuronal plasma membrane has been proposed as a mechanism underlying the development of leptin resistance observed in human obesity. More recently, Endo1 has emerged as a mediator of "selective leptin resistance." The underlying mechanisms of the latter are not completely understood, but the possibility of differential activation of leptin signaling pathways was suggested among others. In this respect, the expression level of Endo1 is crucial for the appropriate balance between different leptin signaling pathways and leptin functions in the hypothalamus and is likely participating in selective leptin resistance for the control of energy and glucose homeostasis.
Collapse
Affiliation(s)
- Clara Roujeau
- Inserm U1016, CNRS UMR 8104, Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Ralf Jockers
- Inserm U1016, CNRS UMR 8104, Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Julie Dam
- Inserm U1016, CNRS UMR 8104, Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, Paris,
| |
Collapse
|
3
|
Zhang L, Qin Y, Liang D, Li L, Liang Y, Chen L, Tong L, Zhou J, Li H, Zhang H. Association of polymorphisms in LEPR with type 2 diabetes and related metabolic traits in a Chinese population. Lipids Health Dis 2018; 17:2. [PMID: 29301582 PMCID: PMC5753482 DOI: 10.1186/s12944-017-0644-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 12/13/2017] [Indexed: 12/21/2022] Open
Abstract
Background Leptin acts as a mediator of inflammation and energy homeostasis by activating leptin receptor (LEPR). We conducted this study to explore the association of polymorphisms in LEPR with type 2 diabetes mellitus (T2DM) and its related metabolic traits. Methods We performed a case–control study to investigate the association of polymorphisms in LEPR with T2DM and related metabolic traits in a Chinese population, with a total of 922 T2DM patients and 1031 nondiabetic subjects. Polymorphisms were genotyped using MassARRAY assay. Results The G allele of rs1327118 was associated with a decreased risk of T2DM in men (P = 0.044, odds ratio = 0.707, 95% confidence interval = 0.504–0.991) and the G allele of rs3806318 was associated with increased systolic blood pressure (SBP) in men with T2DM. Besides, the women patients carrying the G allele of rs1327118 showed increased SBP and diastolic blood pressure (DBP) levels, but decreased high density lipoprotein cholesterol (HDL-C) level. Conclusion Our results suggest that rs1327118 may be associated with SBP, DBP and HDL-C levels in women with T2DM, and rs3806318 may be associated with T2DM and SBP level in men with T2DM. Further studies with larger sample size or functional experiments focused on exact mechanism are required to verify our observations.
Collapse
Affiliation(s)
- Lulu Zhang
- School of Public Health, Guangxi Medical University, Nanning, 530021, People's Republic of China.,Guangxi Colleges and Universities Key Laboratory of Prevention and Control of Highly Prevalent Diseases, Guangxi Medical University, Nanning, 530021, People's Republic of China
| | - Yingfen Qin
- Department of Endocrine, First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, People's Republic of China
| | - Danyan Liang
- Third Affiliated Hospital of Guangxi Medical University, Nanning, 530021, People's Republic of China
| | - Li Li
- Department of Endocrine, First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, People's Republic of China
| | - Yaojie Liang
- Beihai Center for Disease Prevention and Control, Beihai, 536000, People's Republic of China
| | - Lulin Chen
- School of Public Health, Guangxi Medical University, Nanning, 530021, People's Republic of China.,Guangxi Colleges and Universities Key Laboratory of Prevention and Control of Highly Prevalent Diseases, Guangxi Medical University, Nanning, 530021, People's Republic of China
| | - Lei Tong
- School of Public Health, Guangxi Medical University, Nanning, 530021, People's Republic of China.,Guangxi Colleges and Universities Key Laboratory of Prevention and Control of Highly Prevalent Diseases, Guangxi Medical University, Nanning, 530021, People's Republic of China
| | - Jia Zhou
- Department of Endocrine, First Affiliated Hospital of Guangxi Medical University, Nanning, 530021, People's Republic of China
| | - Hong Li
- School of General Medicine, Guangxi Medical University, Nanning, 530021, People's Republic of China.
| | - Haiying Zhang
- School of Public Health, Guangxi Medical University, Nanning, 530021, People's Republic of China. .,Guangxi Colleges and Universities Key Laboratory of Prevention and Control of Highly Prevalent Diseases, Guangxi Medical University, Nanning, 530021, People's Republic of China. .,Guangxi key laboratory for genomic and personalized medicine, Guangxi collaborative innovation center for genomic and personalized medicine, Guangxi Medical University, Nanning, 530021, People's Republic of China.
| |
Collapse
|
4
|
|
5
|
Shi Z, Madden CJ, Brooks VL. Arcuate neuropeptide Y inhibits sympathetic nerve activity via multiple neuropathways. J Clin Invest 2017. [PMID: 28628036 PMCID: PMC5490747 DOI: 10.1172/jci92008] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Obesity increases sympathetic nerve activity (SNA) via activation of proopiomelanocortin neurons in the arcuate nucleus (ArcN), and this action requires simultaneous withdrawal of tonic neuropeptide Y (NPY) sympathoinhibition. However, the sites and neurocircuitry by which NPY decreases SNA are unclear. Here, using designer receptors exclusively activated by designer drugs (DREADDs) to selectively activate or inhibit ArcN NPY neurons expressing agouti-related peptide (AgRP) in mice, we have demonstrated that this neuronal population tonically suppresses splanchnic SNA (SSNA), arterial pressure, and heart rate via projections to the paraventricular nucleus (PVN) and dorsomedial hypothalamus (DMH). First, we found that ArcN NPY/AgRP fibers closely appose PVN and DMH presympathetic neurons. Second, nanoinjections of NPY or an NPY receptor Y1 (NPY1R) antagonist into PVN or DMH decreased or increased SSNA, respectively. Third, blockade of DMH NPY1R reversed the sympathoinhibition elicited by selective, DREADD-mediated activation of ArcN NPY/AgRP neurons. Finally, stimulation of ArcN NPY/AgRP terminal fields in the PVN and DMH decreased SSNA. Considering that chronic obesity decreases ArcN NPY content, we propose that the ArcN NPY neuropathway to the PVN and DMH is pivotal in obesity-induced elevations in SNA.
Collapse
Affiliation(s)
- Zhigang Shi
- Department of Physiology and Pharmacology and
| | - Christopher J Madden
- Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon, USA
| | | |
Collapse
|
6
|
Belin de Chantemèle EJ. Sex Differences in Leptin Control of Cardiovascular Function in Health and Metabolic Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1043:87-111. [DOI: 10.1007/978-3-319-70178-3_6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
7
|
Abstract
Hypertension and associated cardiovascular diseases represent the most common health complication of obesity and the leading cause of morbidity and mortality in overweight and obese patients. Emerging evidence suggests a critical role for the central nervous system particularly the brain action of the adipocyte-derived hormone leptin in linking obesity and hypertension. The preserved ability of leptin to cause cardiovascular sympathetic nerve activation despite the resistance to the metabolic actions of the hormone appears essential in this pathological process. This review describes the evidence supporting the neurogenic bases for obesity-associated hypertension with a particular focus on the neuronal and molecular signaling pathways underlying leptin's effects on sympathetic nerve activity and blood pressure.
Collapse
Affiliation(s)
- Balyssa B Bell
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Kamal Rahmouni
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA.
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA, USA.
| |
Collapse
|
8
|
Abstract
Hypertension affects over 25 % of the population with the incidence continuing to rise, due in part to the growing obesity epidemic. Chronic elevations in sympathetic nerve activity (SNA) are a hallmark of the disease and contribute to elevations in blood pressure through influences on the vasculature, kidney, and heart (i.e., neurogenic hypertension). In this regard, a number of central nervous system mechanisms and neural pathways have emerged as crucial in chronically elevating SNA. However, it is important to consider that "sympathetic signatures" are present, with differential increases in SNA to regional organs that are dependent upon the disease progression. Here, we discuss recent findings on the central nervous system mechanisms and autonomic regulatory networks involved in neurogenic hypertension, in both non-obesity- and obesity-associated hypertension, with an emphasis on angiotensin-II, salt, oxidative and endoplasmic reticulum stress, inflammation, and the adipokine leptin.
Collapse
|
9
|
Chen W, Leo S, Weng C, Yang X, Wu Y, Tang X. Mechanisms mediating renal sympathetic nerve activation in obesity-related hypertension. Herz 2015; 40 Suppl 2:190-6. [PMID: 24609799 DOI: 10.1007/s00059-014-4072-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Excessive renal sympathetic nerve activation may be one of the mechanisms underlying obesity-related hypertension. Impaired baroreflex sensitivity, adipokine disorders-such as leptin, adiponectin, and resistin-activation of the renin-angiotensin system, hyperinsulinemia, insulin resistance, and renal sodium retention present in obesity increase renal sympathetic nerve activity, thus contributing to the development of hypertension. Renal sympathetic denervation reduces both renal sympathetic activity and blood pressure in patients with obesity-related hypertension.
Collapse
Affiliation(s)
- W Chen
- Department of Cardiology, The Third Xiangya Hospital, Central South University, 410013, Changsha, China
| | | | | | | | | | | |
Collapse
|
10
|
Morgan DA, Despas F, Rahmouni K. Effects of leptin on sympathetic nerve activity in conscious mice. Physiol Rep 2015; 3:3/9/e12554. [PMID: 26381017 PMCID: PMC4600394 DOI: 10.14814/phy2.12554] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The adipocyte-derived hormone, leptin, has emerged as an important regulator of regional sympathetic nerve activity (SNA) with pathophysiological implications in obesity. Genetically engineered mice are useful to understand the molecular pathways underlying the SNA responses evoked by leptin. However, so far the effect of leptin on direct SNA in mice has been studied under general anesthesia. Here, we examined the sympathetic responses evoked by leptin in conscious mice. Mice were instrumented, under ketamine/xylazine anesthesia, with renal or lumbar SNA recordings using a thin (40 gauge) bipolar platinum-iridium wire. The electrodes were exteriorized at the nape of the neck and mice were allowed (5 h) to recover from anesthesia. Interestingly, the reflex increases in renal and lumbar SNA caused by sodium nitroprusside (SNP)-induced hypotension was higher in the conscious phase versus the anesthetized state, whereas the increase in both renal and lumbar SNA evoked by leptin did not differ between anesthetized or conscious mice. Next, we assessed whether isoflurane anesthesia would yield a better outcome. Again, the SNP-induced increase in renal SNA and baroreceptor-renal SNA reflex were significantly elevated in the conscious states relative to isoflurane-anesthetized phase, but the renal SNA response induced by leptin in the conscious states were qualitatively comparable to those evoked above. Thus, despite improvement in sympathetic reflexes in conscious mice the sympathetic responses evoked by leptin mimic those induced during anesthesia.
Collapse
Affiliation(s)
- Donald A Morgan
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Fabien Despas
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Kamal Rahmouni
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
| |
Collapse
|
11
|
Harlan SM, Ostroski RA, Coskun T, Yantis LD, Breyer MD, Heuer JG. Viral transduction of renin rapidly establishes persistent hypertension in diverse murine strains. Am J Physiol Regul Integr Comp Physiol 2015; 309:R467-74. [DOI: 10.1152/ajpregu.00106.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 06/17/2015] [Indexed: 01/13/2023]
Abstract
Mice provide a unique platform to dissect disease pathogenesis, with the availability of recombinant inbred strains and diverse genetically modified strains. Leveraging these reagents to elucidate the mechanisms of hypertensive tissue injury has been hindered by difficulty establishing persistent hypertension in these inbred lines. ANG II infusion provides relatively short-term activation of the renin-angiotensinogen system (RAS) with concomitant elevated arterial pressure. Longer-duration studies using renin transgenic mice are powerful models of chronic hypertension, yet are limited by the genetic background on which the transgene exists and the exposure throughout development. The present studies characterized hypertension produced by transduction with a renin-coding adeno-associated virus (ReninAAV). ReninAAV mice experienced elevated circulating renin with concurrent elevations in arterial pressure. Following a single injection of ReninAAV, arterial pressure increased on average +56 mmHg, an increase that persisted for at least 12 wk in three distinct and widely used strains of adult mice: 129/S6, C56BL/6, and DBA/2J. This was accomplished without surgical implantation of pumps or complex breeding and backcrossing. In addition, ReninAAV mice developed pathophysiological changes associated with chronic hypertension, including increased heart weight and albuminuria. Thus ReninAAV provides a unique tool to study the onset of and effects of persistent hypertension in diverse murine models. This model should facilitate our understanding of the pathogenesis of hypertensive injury.
Collapse
Affiliation(s)
- Shannon M. Harlan
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Robert A. Ostroski
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Tamer Coskun
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Loudon D. Yantis
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Matthew D. Breyer
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| | - Josef G. Heuer
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana
| |
Collapse
|
12
|
Lambert EA, Straznicky NE, Dixon JB, Lambert GW. Should the sympathetic nervous system be a target to improve cardiometabolic risk in obesity? Am J Physiol Heart Circ Physiol 2015; 309:H244-58. [DOI: 10.1152/ajpheart.00096.2015] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 05/11/2015] [Indexed: 02/03/2023]
Abstract
The sympathetic nervous system (SNS) plays a key role in both cardiovascular and metabolic regulation; hence, disturbances in SNS regulation are likely to impact on both cardiovascular and metabolic health. With excess adiposity, in particular when visceral fat accumulation is present, sympathetic activation commonly occurs. Experimental investigations have shown that adipose tissue releases a large number of adipokines, cytokines, and bioactive mediators capable of stimulating the SNS. Activation of the SNS and its interaction with adipose tissue may lead to the development of hypertension and end-organ damage including vascular, cardiac, and renal impairment and in addition lead to metabolic abnormalities, especially insulin resistance. Lifestyle changes such as weight loss and exercise programs considerably improve the cardiovascular and metabolic profile of subjects with obesity and decrease their cardiovascular risk, but unfortunately weight loss is often difficult to achieve and sustain. Pharmacological and device-based approaches to directly or indirectly target the activation of the SNS may offer some benefit in reducing the cardiometabolic consequences of obesity. Preliminary evidence is encouraging, but more trials are needed to investigate whether sympathetic inhibition could be used in obesity to reverse or prevent cardiometabolic disease development. The purpose of this review article is to highlight the current knowledge of the role that SNS plays in obesity and its associated metabolic disorders and to review the potential benefits of sympathoinhibition on metabolic and cardiovascular functions.
Collapse
Affiliation(s)
- Elisabeth A. Lambert
- Human Neurotransmitters Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Australia
- Department of Physiology, Monash University, Clayton, Australia
| | - Nora E. Straznicky
- Human Neurotransmitters Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Australia
| | - John B. Dixon
- Clinical Obesity Research Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Australia; and
| | - Gavin W. Lambert
- Human Neurotransmitters Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Australia
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Australia
| |
Collapse
|
13
|
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
|
14
|
Affiliation(s)
- Kamal Rahmouni
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| |
Collapse
|
15
|
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
|
16
|
Harlan SM, Guo DF, Morgan DA, Fernandes-Santos C, Rahmouni K. Hypothalamic mTORC1 signaling controls sympathetic nerve activity and arterial pressure and mediates leptin effects. Cell Metab 2013; 17:599-606. [PMID: 23541372 PMCID: PMC3657313 DOI: 10.1016/j.cmet.2013.02.017] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 01/15/2013] [Accepted: 02/25/2013] [Indexed: 02/06/2023]
Abstract
The fundamental importance of the hypothalamus in the regulation of autonomic and cardiovascular functions is well established. However, the molecular processes involved are not well understood. Here, we show that the mammalian (or mechanistic) target of rapamycin (mTOR) signaling in the hypothalamus is tied to the activity of the sympathetic nervous system and to cardiovascular function. Modulation of mTOR complex 1 (mTORC1) signaling caused dramatic changes in sympathetic traffic, blood flow, and arterial pressure. Our data also demonstrate the importance of hypothalamic mTORC1 signaling in transducing the sympathetic and cardiovascular actions of leptin. Moreover, we show that the PI3K pathway links the leptin receptor to mTORC1 signaling and that changes in its activity impact sympathetic traffic and arterial pressure. These findings establish mTORC1 activity in the hypothalamus as a key determinant of sympathetic and cardiovascular regulation and suggest that dysregulated hypothalamic mTORC1 activity may influence the development of cardiovascular diseases.
Collapse
Affiliation(s)
- Shannon M. Harlan
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Deng-Fu Guo
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Donald A. Morgan
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | | | - Kamal Rahmouni
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
| |
Collapse
|
17
|
Harlan SM, Rahmouni K. PI3K signaling: A key pathway in the control of sympathetic traffic and arterial pressure by leptin. Mol Metab 2013; 2:69-73. [PMID: 24199153 DOI: 10.1016/j.molmet.2013.03.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 03/14/2013] [Accepted: 03/15/2013] [Indexed: 02/07/2023] Open
Abstract
The adipocyte-derived hormone, leptin, is a master regulator of energy homeostasis. Leptin action in the central nervous system also contributes to arterial pressure regulation through its capacity to increase renal sympathetic outflow. The accumulating evidence pointing to a key role for leptin in the adverse sympathetic and cardiovascular consequences of excessive adiposity highlight the importance of understanding the mechanisms underlying the sympathetic and cardiovascular effects of leptin. The ability of the leptin receptor to stimulate various intracellular pathways allows leptin to regulate physiological processes in a specific manner. In this review, we examine the role of the PI3K pathway emanating from the leptin receptor in mediating the sympathetic and arterial pressure effects of leptin. We also discuss the relevance of PI3K signaling for obesity-induced hypertension through its role in mediating selective leptin resistance.
Collapse
Affiliation(s)
- Shannon M Harlan
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | | |
Collapse
|
18
|
Tanida M, Yamamoto N, Shibamoto T, Rahmouni K. Involvement of hypothalamic AMP-activated protein kinase in leptin-induced sympathetic nerve activation. PLoS One 2013; 8:e56660. [PMID: 23418591 PMCID: PMC3572050 DOI: 10.1371/journal.pone.0056660] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 01/13/2013] [Indexed: 11/19/2022] Open
Abstract
In mammals, leptin released from the white adipose tissue acts on the central nervous system to control feeding behavior, cardiovascular function, and energy metabolism. Central leptin activates sympathetic nerves that innervate the kidney, adipose tissue, and some abdominal organs in rats. AMP-activated protein kinase (AMPK) is essential in the intracellular signaling pathway involving the activation of leptin receptors (ObRb). We investigated the potential of AMPKα2 in the sympathetic effects of leptin using in vivo siRNA injection to knockdown AMPKα2 in rats, to produce reduced hypothalamic AMPKα2 expression. Leptin effects on body weight, food intake, and blood FFA levels were eliminated in AMPKα2 siRNA-treated rats. Leptin-evoked enhancements of the sympathetic nerve outflows to the kidney, brown and white adipose tissues were attenuated in AMPKα2 siRNA-treated rats. To check whether AMPKα2 was specific to sympathetic changes induced by leptin, we examined the effects of injecting MT-II, a melanocortin-3 and -4 receptor agonist, on the sympathetic nerve outflows to the kidney and adipose tissue. MT-II-induced sympatho-excitation in the kidney was unchanged in AMPKα2 siRNA-treated rats. However, responses of neural activities involving adipose tissue to MT-II were attenuated in AMPKα2 siRNA-treated rats. These results suggest that hypothalamic AMPKα2 is involved not only in appetite and body weight regulation but also in the regulation of sympathetic nerve discharges to the kidney and adipose tissue. Thus, AMPK might function not only as an energy sensor, but as a key molecule in the cardiovascular, thermogenic, and lipolytic effects of leptin through the sympathetic nervous system.
Collapse
Affiliation(s)
- Mamoru Tanida
- Department of Physiology II, Kanazawa Medical University, Uchinada, Ishikawa, Japan.
| | | | | | | |
Collapse
|
19
|
Moraes-Vieira PMM, Bassi EJ, Araujo RC, Câmara NOS. Leptin as a link between the immune system and kidney-related diseases: leading actor or just a coadjuvant? Obes Rev 2012; 13:733-43. [PMID: 22498577 DOI: 10.1111/j.1467-789x.2012.00997.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Food intake and nutritional status modify the physiological responses of the immune system to illness and infection and regulate the development of chronic inflammatory processes, such as kidney disease. Adipose tissue secretes immune-related proteins called adipokines that have pleiotropic effects on both the immune and neuroendocrine systems, linking metabolism and immune physiology. Leptin, an adipose tissue-derived adipokine, displays a variety of immune and physiological functions, and participates in several immune responses. Here, we review the current literature on the role of leptin in kidney diseases, linking adipose tissue and the immune system with kidney-related disorders. The modulation of this adipose hormone may have a major impact on the treatment of several immune- and metabolic-related kidney diseases.
Collapse
Affiliation(s)
- P M M Moraes-Vieira
- Immunology Department, Institute of Biomedical Science, University of São Paulo, SP, Brazil
| | | | | | | |
Collapse
|
20
|
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
|
21
|
Abel ED, Sweeney G. Modulation of the cardiovascular system by leptin. Biochimie 2012; 94:2097-103. [PMID: 22490727 DOI: 10.1016/j.biochi.2012.03.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 03/26/2012] [Indexed: 01/20/2023]
Abstract
It is well established that individuals with the metabolic syndrome have a significantly increased risk of cardiovascular disease and much effort has been expended to elicit the underlying mechanisms. Various studies have proposed that excessive or deficient physiological effects mediated by leptin make an important contribution, yet many paradoxical observations often preclude a clear definition of the role of leptin. This review article will briefly discuss principal and most recent evidence on direct and indirect regulation of the cardiovascular system by leptin, focusing on cardiac structural and functional as well as vascular effects.
Collapse
Affiliation(s)
- E Dale Abel
- Division of Endocrinology, Metabolism and Diabetes and Program in Molecular Medicine, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | | |
Collapse
|