101
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Salem V, Bloom SR. Approaches to the pharmacological treatment of obesity. Expert Rev Clin Pharmacol 2014; 3:73-88. [DOI: 10.1586/ecp.09.54] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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102
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Abstract
The ubiquitous gaseous signaling molecule nitric oxide participates in the regulation of a variety of physiological and pathological processes, including adult neurogenesis. Adult neurogenesis, or the generation of new neurons in the adult brain, is a restricted event confined to areas with neurogenic capability. Although nitric oxide has been shown to mediate conflicting effects on adult neurogenesis, which may be partly explained by its unique characteristics, more studies are required in order to fully comprehend and appreciate the mechanisms involved. Neuropeptide Y, a neurotransmitter shown to be an important regulator of adult hippocampal neurogenesis, acts through intracellular nitric oxide to induce an increase in neural progenitor cell proliferation.
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103
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Plescia F, Brancato A, Marino RAM, Vita C, Navarra M, Cannizzaro C. Effect of Acetaldehyde Intoxication and Withdrawal on NPY Expression: Focus on Endocannabinoidergic System Involvement. Front Psychiatry 2014; 5:138. [PMID: 25324788 PMCID: PMC4181239 DOI: 10.3389/fpsyt.2014.00138] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 09/18/2014] [Indexed: 01/17/2023] Open
Abstract
Acetaldehyde (ACD), the first alcohol metabolite, plays a pivotal role in the rewarding, motivational, and addictive properties of the parental compound. Many studies have investigated the role of ACD in mediating neurochemical and behavioral effects induced by alcohol administration, but very little is known about the modulation of neuropeptide systems following ACD intoxication and withdrawal. Indeed, the neuropeptide Y (NPY) system is altered during alcohol withdrawal in key regions for cerebrocortical excitability and neuroplasticity. The primary goal of this research was to investigate the effects of ACD intoxication and withdrawal by recording rat behavior and by measuring NPY immunoreactivity in hippocampus and NAcc, two brain regions mainly involved in processes which encompass neuroplasticity in alcohol dependence. Furthermore, on the basis of the involvement of endocannabinoidergic system in alcohol and ACD reinforcing effects, the role of the selective CB1 receptor antagonist AM281 in modulating NPY expression during withdrawal was assessed. Our results indicate that (i) ACD intoxication induced a reduction in NPY expression in hippocampus and NAcc; (ii) symptoms of physical dependence, similar to alcohol's, were scored at 12 h from the last administration of ACD; and (iii) NPY levels increased in early and prolonged acute withdrawal in both brain regions examined. The administration of AM281 was able to blunt signs of ACD-induced physical dependence, to modulate NPY levels, and to further increase NPY expression during ACD withdrawal both in hippocampus and NAcc. In conclusion, the present study shows that complex plastic changes take place in NPY system during ACD intoxication and subsequent withdrawal in rat hippocampal formation and NAcc. The pharmacological inhibition of CB1 signaling could counteract the neurochemical imbalance associated with ACD, and alcohol withdrawal, likely boosting the setting up of homeostatic functional recovery.
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Affiliation(s)
- Fulvio Plescia
- Department of Sciences for Health Promotion and Mother and Child Care "Giuseppe D'Alessandro", University of Palermo , Palermo , Italy
| | - Anna Brancato
- Department of Sciences for Health Promotion and Mother and Child Care "Giuseppe D'Alessandro", University of Palermo , Palermo , Italy
| | - Rosa Anna Maria Marino
- Department of Sciences for Health Promotion and Mother and Child Care "Giuseppe D'Alessandro", University of Palermo , Palermo , Italy
| | - Carlotta Vita
- Department of Sciences for Health Promotion and Mother and Child Care "Giuseppe D'Alessandro", University of Palermo , Palermo , Italy
| | - Michele Navarra
- Department of Drug Sciences and Products for Health, University of Messina , Messina , Italy
| | - Carla Cannizzaro
- Department of Sciences for Health Promotion and Mother and Child Care "Giuseppe D'Alessandro", University of Palermo , Palermo , Italy
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104
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Abstract
Body weight is determined by a balance between food intake and energy expenditure. Multiple neural circuits in the brain have evolved to process information about food, food-related cues and food consumption to control feeding behavior. Numerous gastrointestinal endocrine cells produce and secrete satiety hormones in response to food consumption and digestion. These hormones suppress hunger and promote satiation and satiety mainly through hindbrain circuits, thus governing meal-by-meal eating behavior. In contrast, the hypothalamus integrates adiposity signals to regulate long-term energy balance and body weight. Distinct hypothalamic areas and various orexigenic and anorexigenic neurons have been identified to homeostatically regulate food intake. The hypothalamic circuits regulate food intake in part by modulating the sensitivity of the hindbrain to short-term satiety hormones. The hedonic and incentive properties of foods and food-related cues are processed by the corticolimbic reward circuits. The mesolimbic dopamine system encodes subjective "liking" and "wanting" of palatable foods, which is subjected to modulation by the hindbrain and the hypothalamic homeostatic circuits and by satiety and adiposity hormones. Satiety and adiposity hormones also promote energy expenditure by stimulating brown adipose tissue (BAT) activity. They stimulate BAT thermogenesis mainly by increasing the sympathetic outflow to BAT. Many defects in satiety and/or adiposity hormone signaling and in the hindbrain and the hypothalamic circuits have been described and are believed to contribute to the pathogenesis of energy imbalance and obesity.
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Affiliation(s)
- Liangyou Rui
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48109-0622, USA,
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105
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Neuropeptide y gates a stress-induced, long-lasting plasticity in the sympathetic nervous system. J Neurosci 2013; 33:12705-17. [PMID: 23904607 DOI: 10.1523/jneurosci.3132-12.2013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Acute stress evokes the fight-or-flight reflex, which via release of the catecholamine hormones affects the function of every major organ. Although the reflex is transient, it has lasting consequences that produce an exaggerated response when stress is reexperienced. How this change is encoded is not known. We investigated whether the reflex affects the adrenal component of the sympathetic nervous system, a major branch of the stress response. Mice were briefly exposed to the cold-water forced swim test (FST) which evoked an increase in circulating catecholamines. Although this hormonal response was transient, the FST led to a long-lasting increase in the catecholamine secretory capacity measured amperometrically from chromaffin cells and in the expression of tyrosine hydroxylase. A variety of approaches indicate that these changes are regulated postsynaptically by neuropeptide Y (NPY), an adrenal cotransmitter. Using immunohistochemistry, RT-PCR, and NPY(GFP) BAC mice, we find that NPY is synthesized by all chromaffin cells. Stress failed to increase secretory capacity in NPY knock-out mice. Genetic or pharmacological interference with NPY and Y1 (but not Y2 or Y5) receptor signaling attenuated the stress-induced change in tyrosine hydroxylase expression. These results indicate that, under basal conditions, adrenal signaling is tonically inhibited by NPY, but stress overrides this autocrine negative feedback loop. Because acute stress leads to a lasting increase in secretory capacity in vivo but does not alter sympathetic tone, these postsynaptic changes appear to be an adaptive response. We conclude that the sympathetic limb of the stress response exhibits an activity-dependent form of long-lasting plasticity.
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106
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Krashes MJ, Shah BP, Koda S, Lowell BB. Rapid versus delayed stimulation of feeding by the endogenously released AgRP neuron mediators GABA, NPY, and AgRP. Cell Metab 2013; 18:588-95. [PMID: 24093681 PMCID: PMC3822903 DOI: 10.1016/j.cmet.2013.09.009] [Citation(s) in RCA: 263] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 07/30/2013] [Accepted: 09/06/2013] [Indexed: 01/12/2023]
Abstract
Agouti-related peptide (AgRP) neurons of the hypothalamus release a fast transmitter (GABA) in addition to neuropeptides (neuropeptide Y [NPY] and Agouti-related peptide [AgRP]). This raises questions as to their respective functions. The acute activation of AgRP neurons robustly promotes food intake, while central injections of AgRP, NPY, or GABA agonist results in the marked escalation of food consumption with temporal variance. Given the orexigenic capability of all three of these neuroactive substances in conjunction with their coexpression in AgRP neurons, we looked to unravel their relative temporal role in driving food intake. After the acute stimulation of AgRP neurons with DREADD technology, we found that either GABA or NPY is required for the rapid stimulation of feeding, and the neuropeptide AgRP, through action on MC4 receptors, is sufficient to induce feeding over a delayed yet prolonged period. These studies help to elucidate the neurochemical mechanisms of AgRP neurons in controlling temporally distinct phases of eating.
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Affiliation(s)
- Michael J. Krashes
- Division of Endocrinology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Bhavik P. Shah
- Division of Endocrinology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Shuichi Koda
- Division of Endocrinology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
- Asubio Pharma Co., Ltd., Kobe 650-0047, Japan
| | - Bradford B. Lowell
- Division of Endocrinology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
- Correspondence: (B.B.L)
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107
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Elms J, Powell KL, van Raay L, Dedeurwaerdere S, O’Brien TJ, Morris MJ. Long-term valproate treatment increases brain neuropeptide Y expression and decreases seizure expression in a genetic rat model of absence epilepsy. PLoS One 2013; 8:e73505. [PMID: 24039965 PMCID: PMC3767750 DOI: 10.1371/journal.pone.0073505] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 07/23/2013] [Indexed: 11/19/2022] Open
Abstract
The mechanisms by which valproate, one of the most widely prescribed anti-epileptic drugs, suppresses seizures have not been fully elucidated but may involve up-regulation of neuropeptide Y (NPY). We investigated the effects of valproate treatment in Genetic Absence Epilepsy Rats from Strasbourg (GAERS) on brain NPY mRNA expression and seizure control. GAERS were administered either valproate (42 mg.kg−1 hr−1) or saline continuously for 5 days. Electroencephalograms were recorded for 24 hrs on treatment days 1, 3 and 5 and the percentage of time spent in seizure activity was analysed. NPY mRNA expression was measured in different brain regions using qPCR. Valproate treatment suppressed seizures by 80% in GAERS (p<0.05) and increased NPY mRNA expression in the thalamus (p<0.05) compared to saline treatment. These results demonstrate that long-term valproate treatment results in an upregulation of thalamic expression of NPY implicating this as a potential contributor to the mechanism by which valproate suppresses absence seizures.
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Affiliation(s)
- Johanna Elms
- Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
- The Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Melbourne, Australia
| | - Kim L. Powell
- The Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Melbourne, Australia
| | - Leena van Raay
- The Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Melbourne, Australia
| | | | - Terence J. O’Brien
- The Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Melbourne, Australia
| | - Margaret J. Morris
- Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
- * E-mail:
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108
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Interneuron development and epilepsy: early genetic defects cause long-term consequences in seizures and susceptibility. Epilepsy Curr 2013; 13:172-6. [PMID: 24009481 DOI: 10.5698/1535-7597-13.4.172] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Errors in the generation of the inhibitory GABAergic interneurons of the cerebral cortex and hippocampus have variable consequences. Studies of the molecular pathways of interneuron development reveal genes that are associated with human epilepsies. Animal models of gene variants exhibit seizures and abnormal electroencephalographic activity, providing unique models for discovering better treatments for individual forms of epilepsy.
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109
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Misra M. Obesity pharmacotherapy: current perspectives and future directions. Curr Cardiol Rev 2013; 9:33-54. [PMID: 23092275 PMCID: PMC3584306 DOI: 10.2174/157340313805076322] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 07/31/2012] [Accepted: 08/27/2012] [Indexed: 02/06/2023] Open
Abstract
The rising tide of obesity and its related disorders is one of the most pressing health concerns worldwide, yet existing medicines to combat the problem are disappointingly limited in number and effectiveness. Recent advances in mechanistic insights into the neuroendocrine regulation of body weight have revealed an expanding list of molecular targets for novel, rationally designed antiobesity pharmaceutical agents. Antiobesity drugs act via any of four mechanisms: 1) decreasing energy intake, 2) increasing energy expenditure or modulating lipid metabolism, 3) modulating fat stores or adipocyte differentiation, and 4) mimicking caloric restriction. Various novel drug candidates and targets directed against obesity are currently being explored. A few of them are also in the later phases of clinical trials. This review discusses the development of novel antiobesity drugs based on current understanding of energy homeostasis
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Affiliation(s)
- Monika Misra
- Department of Pharmacology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, 202002, India.
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110
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Stricker-Krongrad A, Beck B. Up-regulation of Neuropeptide Y Receptors in the Hypothalamus of Monosodium Glutamate-lesioned Sprague-Dawley Rats. Nutr Neurosci 2013; 7:241-5. [PMID: 15682651 DOI: 10.1080/10284150412331281040] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Monosodium-glutamate (MSG) is neurotoxic for brain regions devoid of blood-brain barrier when it is injected at high doses during the neonatal period. Neuropeptide Y (NPY) neurons in the arcuate nucleus are particularly sensitive to MSG treatment. But, despite of the large decrease of this potent orexigenic peptide, feeding behavior is only slightly affected. We hypothesized that the hypothalamic NPY receptor system might be modified in these rats. The present study characterizes hypothalamic NPY and NPY receptors in normal and MSG-treated rats. MSG-treated rats were lighter (p < 0.01) and ate 17% less than the control rats (p < 0.01). NPY levels in the mediobasal and mediodorsal hypothalamus were reduced in MSG-treated rats compared to normal rats (-26% and -43%, p < 0.05 and p < 0.01, respectively). Combined hypothalamic Y1 and Y5 NPY receptor density was increased in MSG-treated rats compared to normal rats (+25%, p < 0.04), but affinity remained unaltered. Blockade with a selective Y1 antagonist showed that the Y1 receptor subtype represented more than 90% of the combined Y1 and Y5 receptor populations. The up-regulation of the NPY receptors is an element necessary to maintain food intake at a sufficient level to allow survival and growth of the lesioned rats.
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Affiliation(s)
- A Stricker-Krongrad
- UHP/EA 3453, Systèmes Neuromodulateurs des Comportements Ingestifs, NANCY, France
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111
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Sohn JW, Elmquist JK, Williams KW. Neuronal circuits that regulate feeding behavior and metabolism. Trends Neurosci 2013; 36:504-12. [PMID: 23790727 DOI: 10.1016/j.tins.2013.05.003] [Citation(s) in RCA: 187] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 05/06/2013] [Accepted: 05/20/2013] [Indexed: 12/24/2022]
Abstract
Neurons within the central nervous system receive humoral and central (neurotransmitter or neuropeptide) signals that ultimately regulate ingestive behavior and metabolism. Recent advances in mouse genetics combined with neuroanatomical and electrophysiological techniques have contributed to a better understanding of these central mechanisms. This review integrates recently defined cellular mechanisms and neural circuits relevant to the regulation of feeding behavior, energy expenditure, and glucose homeostasis by metabolic signals.
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Affiliation(s)
- Jong-Woo Sohn
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
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112
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Adiponectin regulates bone mass via opposite central and peripheral mechanisms through FoxO1. Cell Metab 2013; 17:901-915. [PMID: 23684624 PMCID: PMC3679303 DOI: 10.1016/j.cmet.2013.04.009] [Citation(s) in RCA: 162] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 03/16/2013] [Accepted: 04/10/2013] [Indexed: 11/24/2022]
Abstract
The synthesis of adiponectin, an adipokine with ill-defined functions in animals fed a normal diet, is enhanced by the osteoblast-derived hormone osteocalcin. Here we show that adiponectin signals back in osteoblasts to hamper their proliferation and favor their apoptosis, altogether decreasing bone mass and circulating osteocalcin levels. Adiponectin fulfills these functions, independently of its known receptors and signaling pathways, by decreasing FoxO1 activity in a PI3-kinase-dependent manner. Over time, however, these local effects are masked because adiponectin signals in neurons of the locus coeruleus, also through FoxO1, to decrease the sympathetic tone, thereby increasing bone mass and decreasing energy expenditure. This study reveals that adiponectin has the unusual ability to regulate the same function in two opposite manners depending on where it acts and that it opposes, partially, leptin's influence on the sympathetic nervous system. It also proposes that adiponectin regulation of bone mass occurs through a PI3-kinase-FoxO1 pathway.
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113
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Chandrasekharan B, Nezami BG, Srinivasan S. Emerging neuropeptide targets in inflammation: NPY and VIP. Am J Physiol Gastrointest Liver Physiol 2013; 304:G949-57. [PMID: 23538492 PMCID: PMC3680683 DOI: 10.1152/ajpgi.00493.2012] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The enteric nervous system (ENS), referred to as the "second brain," comprises a vast number of neurons that form an elegant network throughout the gastrointestinal tract. Neuropeptides produced by the ENS play a crucial role in the regulation of inflammatory processes via cross talk with the enteric immune system. In addition, neuropeptides have paracrine effects on epithelial secretion, thus regulating epithelial barrier functions and thereby susceptibility to inflammation. Ultimately the inflammatory response damages the enteric neurons themselves, resulting in deregulations in circuitry and gut motility. In this review, we have emphasized the concept of neurogenic inflammation and the interaction between the enteric immune system and enteric nervous system, focusing on neuropeptide Y (NPY) and vasoactive intestinal peptide (VIP). The alterations in the expression of NPY and VIP in inflammation and their significant roles in immunomodulation are discussed. We highlight the mechanism of action of these neuropeptides on immune cells, focusing on the key receptors as well as the intracellular signaling pathways that are activated to regulate the release of cytokines. In addition, we also examine the direct and indirect mechanisms of neuropeptide regulation of epithelial tight junctions and permeability, which are a crucial determinant of susceptibility to inflammation. Finally, we also discuss the potential of emerging neuropeptide-based therapies that utilize peptide agonists, antagonists, siRNA, oligonucleotides, and lentiviral vectors.
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Affiliation(s)
- Bindu Chandrasekharan
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, GA 30322, USA.
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114
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Compensatory actions of orexinergic neurons in the lateral hypothalamus during metabolic or cortical challenges may enable the coupling of metabolic dysfunction and cortical dysfunction. Med Hypotheses 2013; 80:520-6. [DOI: 10.1016/j.mehy.2013.02.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 01/03/2013] [Accepted: 02/07/2013] [Indexed: 11/20/2022]
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115
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Abstract
Neural processes that direct an animal's actions toward environmental goals are critical elements for understanding behavior. The hypothalamus is closely associated with motivated behaviors required for survival and reproduction. Intense feeding, drinking, aggressive, and sexual behaviors can be produced by a simple neuronal stimulus applied to discrete hypothalamic regions. What can these "evoked behaviors" teach us about the neural processes that determine behavioral intent and intensity? Small populations of neurons sufficient to evoke a complex motivated behavior may be used as entry points to identify circuits that energize and direct behavior to specific goals. Here, I review recent applications of molecular genetic, optogenetic, and pharmacogenetic approaches that overcome previous limitations for analyzing anatomically complex hypothalamic circuits and their interactions with the rest of the brain. These new tools have the potential to bridge the gaps between neurobiological and psychological thinking about the mechanisms of complex motivated behavior.
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Affiliation(s)
- Scott M Sternson
- Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA.
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116
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Dorsomedial hypothalamic NPY modulation of adiposity and thermogenesis. Physiol Behav 2013; 121:56-60. [PMID: 23562863 DOI: 10.1016/j.physbeh.2013.03.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Revised: 03/08/2013] [Accepted: 03/19/2013] [Indexed: 12/23/2022]
Abstract
In addition to controlling food intake, the dorsomedial hypothalamus (DMH) plays an important role in thermoregulation. Within the DMH, a number of neuropeptides and receptors have been found and their roles in controlling energy balance are being investigated. We recently found that the orexigenic neuropeptide Y (NPY) in the DMH has specific actions on body adiposity and thermogenesis using a viral-mediated manipulation of NPY in the DMH. Knockdown of NPY in the DMH promotes the development of brown adipocytes in white adipose tissue and increases brown adipocyte activity. DMH NPY knockdown also causes increased thermogenesis and energy expenditure. Finally, DMH NPY knockdown prevents high-fat diet-induced obesity and improves glucose homeostasis. This review focuses on the role of DMH NPY in modulating body adiposity and thermogenesis.
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117
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Donovan MH, Tecott LH. Serotonin and the regulation of mammalian energy balance. Front Neurosci 2013; 7:36. [PMID: 23543912 PMCID: PMC3608917 DOI: 10.3389/fnins.2013.00036] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 03/03/2013] [Indexed: 01/17/2023] Open
Abstract
Maintenance of energy balance requires regulation of the amount and timing of food intake. Decades of experiments utilizing pharmacological and later genetic manipulations have demonstrated the importance of serotonin signaling in this regulation. Much progress has been made in recent years in understanding how central nervous system (CNS) serotonin systems acting through a diverse array of serotonin receptors impact feeding behavior and metabolism. Particular attention has been paid to mechanisms through which serotonin impacts energy balance pathways within the hypothalamus. How upstream factors relevant to energy balance regulate the release of hypothalamic serotonin is less clear, but work addressing this issue is underway. Generally, investigation into the central serotonergic regulation of energy balance has had a predominantly “hypothalamocentric” focus, yet non-hypothalamic structures that have been implicated in energy balance regulation also receive serotonergic innervation and express multiple subtypes of serotonin receptors. Moreover, there is a growing appreciation of the diverse mechanisms through which peripheral serotonin impacts energy balance regulation. Clearly, the serotonergic regulation of energy balance is a field characterized by both rapid advances and by an extensive and diverse set of central and peripheral mechanisms yet to be delineated.
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Affiliation(s)
- Michael H Donovan
- Department of Psychiatry, University of California San Francisco CA, USA
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118
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Neuropeptide Y is produced by adipose tissue macrophages and regulates obesity-induced inflammation. PLoS One 2013; 8:e57929. [PMID: 23472120 PMCID: PMC3589443 DOI: 10.1371/journal.pone.0057929] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 01/28/2013] [Indexed: 12/18/2022] Open
Abstract
Neuropeptide Y (NPY) is induced in peripheral tissues such as adipose tissue with obesity. The mechanism and function of NPY induction in fat are unclear. Given the evidence that NPY can modulate inflammation, we examined the hypothesis that NPY regulates the function of adipose tissue macrophages (ATMs) in response to dietary obesity in mice. NPY was induced by dietary obesity in the stromal vascular cells of visceral fat depots from mice. Surprisingly, the induction of Npy was limited to purified ATMs from obese mice. Significant basal production of NPY was observed in cultured bone marrow derived macrophage and dendritic cells (DCs) and was increased with LPS stimulation. In vitro, addition of NPY to myeloid cells had minimal effects on their activation profiles. NPY receptor inhibition promoted DC maturation and the production of IL-6 and TNFα suggesting an anti-inflammatory function for NPY signaling in DCs. Consistent with this, NPY injection into lean mice decreased the quantity of M1-like CD11c+ ATMs and suppressed Ly6chi monocytes. BM chimeras generated from Npy−/− donors demonstrated that hematopoietic NPY contributes to the obesity-induced induction of Npy in fat. In addition, loss of Npy expression from hematopoietic cells led to an increase in CD11c+ ATMs in visceral fat with high fat diet feeding. Overall, our studies suggest that NPY is produced by a range of myeloid cells and that obesity activates the production of NPY in adipose tissue macrophages with autocrine and paracrine effects.
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119
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Komarnytsky S, Esposito D, Rathinasabapathy T, Poulev A, Raskin I. Effects of pregnane glycosides on food intake depend on stimulation of the melanocortin pathway and BDNF in an animal model. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:1841-9. [PMID: 23308358 PMCID: PMC3805381 DOI: 10.1021/jf3033649] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Pregnane glycosides appear to modulate food intake by possibly affecting the hypothalamic feeding circuits; however, the mechanisms of the appetite-regulating effect of pregnane glycosides remain obscure. Here, we show that pregnane glycoside-enriched extracts from swamp milkweed Asclepias incarnata at 25-100 mg/kg daily attenuated food intake (up to 47.1 ± 8.5% less than controls) and body weight gain in rats (10% for males and 9% for females, respectively) by activating melanocortin signaling and inhibiting gastric emptying. The major milkweed pregnane glycoside, ikemagenin, exerted its appetite-regulating effect by decreasing levels of agouti-related protein (0.6-fold) but not NPY satiety peptides. Ikemagenin treatment also increased secretion of brain-derived neurotropic factor (BDNF) downstream of melanocortin receptors in the hypothalamus (1.4-fold) and in the C6 rat glioma cell culture in vitro (up to 6-fold). These results support the multimodal effects of pregnane glycosides on feeding regulation, which depends on the activity of the melanocortin signaling pathway and BDNF.
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Affiliation(s)
- Slavko Komarnytsky
- Plants for Human Health Institute, North Carolina State University, Kannapolis, North Carolina 28081, United States.
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120
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Casillas-Espinosa PM, Powell KL, O'Brien TJ. Regulators of synaptic transmission: roles in the pathogenesis and treatment of epilepsy. Epilepsia 2013; 53 Suppl 9:41-58. [PMID: 23216578 DOI: 10.1111/epi.12034] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Synaptic transmission is the communication between a presynaptic and a postsynaptic neuron, and the subsequent processing of the signal. These processes are complex and highly regulated, reflecting their importance in normal brain functioning and homeostasis. Sustaining synaptic transmission depends on the continuing cycle of synaptic vesicle formation, release, and endocytosis, which requires proteins such as dynamin, syndapin, synapsin, and synaptic vesicle protein 2A. Synaptic transmission is regulated by diverse mechanisms, including presynaptic modulators of synaptic vesicle formation and release, postsynaptic receptors and signaling, and modulators of neurotransmission. Neurotransmitters released presynaptically can bind to their postsynaptic receptors, the inhibitory γ-aminobutyric acid (GABA)ergic receptors or the excitatory glutamate receptors. Once released, glutamate activates a variety of postsynaptic receptors including α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-D-aspartate (NMDA), kainate, and metabotropic receptors. The activation of the receptors triggers downstream signaling cascades generating a vast array of effects, which can be modulated by a numerous auxiliary regulatory subunits. Moreover, different neuropeptides such as neuropeptide Y, brain-derived neurotrophic factor (BDNF), somatostatin, ghrelin, and galanin, act as regulators of diverse synaptic functions and along with the classic neurotransmitters. Abnormalities in the regulation of synaptic transmission play a critical role in the pathogenesis of numerous brain diseases, including epilepsy. This review focuses on the different mechanisms involved in the regulation of synaptic transmission, which may play a role in the pathogenesis of epilepsy: the presynaptic modulators of synaptic vesicle formation and release, postsynaptic receptors, and modulators of neurotransmission, including the mechanism by which drugs can modulate the frequency and severity of epileptic seizures.
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Affiliation(s)
- Pablo M Casillas-Espinosa
- The Departments of Medicine and Neurology, The Royal Melbourne Hospital, The Melbourne Brain Centre, The University of Melbourne, Parkville, Victoria, Australia
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Liu T, Wang Q, Berglund ED, Tong Q. Action of Neurotransmitter: A Key to Unlock the AgRP Neuron Feeding Circuit. Front Neurosci 2013; 6:200. [PMID: 23346045 PMCID: PMC3549528 DOI: 10.3389/fnins.2012.00200] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 12/31/2012] [Indexed: 01/08/2023] Open
Abstract
The current obesity epidemic and lack of efficient therapeutics demand a clear understanding of the mechanism underlying body weight regulation. Despite intensive research focus on obesity pathogenesis, an effective therapeutic strategy to treat and cure obesity is still lacking. Exciting studies in last decades have established the importance of hypothalamic agouti-related protein-expressing neurons (AgRP neurons) in the regulation of body weight homeostasis. AgRP neurons are both required and sufficient for feeding regulation. The activity of AgRP neurons is intricately regulated by nutritional hormones as well as synaptic inputs from upstream neurons. Changes in AgRP neuron activity lead to alterations in the release of mediators, including neuropeptides Neuropeptide Y (NPY) and AgRP, and fast-acting neurotransmitter GABA. Recent studies based on mouse genetics, novel optogenetics, and designer receptor exclusively activated by designer drugs have identified a critical role for GABA release from AgRP neurons in the parabrachial nucleus and paraventricular hypothalamus in feeding control. This review will summarize recent findings about AgRP neuron-mediated control of feeding circuits with a focus on the role of neurotransmitters. Given the limited knowledge on feeding regulation, understanding the action of neurotransmitters may be a key to unlock neurocircuitry that governs feeding.
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Affiliation(s)
- Tiemin Liu
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center at Dallas Dallas, TX, USA
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122
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Abstract
Neuropeptides are found in many mammalian CNS neurons where they play key roles in modulating neuronal activity. In contrast to amino acid transmitter release at the synapse, neuropeptide release is not restricted to the synaptic specialization, and after release, a neuropeptide may diffuse some distance to exert its action through a G protein-coupled receptor. Some neuropeptides such as hypocretin/orexin are synthesized only in single regions of the brain, and the neurons releasing these peptides probably have similar functional roles. Other peptides such as neuropeptide Y (NPY) are synthesized throughout the brain, and neurons that synthesize the peptide in one region have no anatomical or functional connection with NPY neurons in other brain regions. Here, I review converging data revealing a complex interaction between slow-acting neuromodulator peptides and fast-acting amino acid transmitters in the control of energy homeostasis, drug addiction, mood and motivation, sleep-wake states, and neuroendocrine regulation.
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Bi S, Kim YJ, Zheng F. Dorsomedial hypothalamic NPY and energy balance control. Neuropeptides 2012; 46:309-14. [PMID: 23083763 PMCID: PMC3508095 DOI: 10.1016/j.npep.2012.09.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 09/04/2012] [Accepted: 09/11/2012] [Indexed: 12/15/2022]
Abstract
Neuropeptide Y (NPY) is a potent hypothalamic orexigenic peptide. Within the hypothalamus, Npy is primarily expressed in the arcuate nucleus (ARC) and the dorsomedial hypothalamus (DMH). While the actions of ARC NPY in energy balance control have been well studied, a role for DMH NPY is still being unraveled. In contrast to ARC NPY that serves as one of downstream mediators of actions of leptin in maintaining energy homeostasis, DMH NPY is not under the control of leptin. Npy gene expression in the DMH is regulated by brain cholecystokinin (CCK) and other yet to be identified molecules. The findings of DMH NPY overexpression or induction in animals with increased energy demands and in certain rodent models of obesity implicate a role for DMH NPY in maintaining energy homeostasis. In support of this view, adeno-associated virus (AAV)-mediated overexpression of NPY in the DMH causes increases in food intake and body weight and exacerbates high-fat diet-induced hyperphagia and obesity. Knockdown of NPY in the DMH via AAV-mediated RNAi ameliorates hyperphagia, obesity and glucose intolerance of Otsuka Long-Evans Tokushima Fatty rats in which DMH NPY overexpression has been proposed to play a causal role. NPY knockdown in the DMH also prevents high-fat diet-induced hyperphagia, obesity and impaired glucose homeostasis. A detailed examination of actions of DMH NPY reveals that DMH NPY specifically affects nocturnal meal size and produces an inhibitory action on within meal satiety signals. In addition, DMH NPY modulates energy expenditure likely through affecting brown adipocyte formation and thermogenic activity. Overall, the recent findings provide clear evidence demonstrating critical roles for DMH NPY in energy balance control, and also imply a potential role for DMH NPY in maintaining glucose homeostasis.
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Affiliation(s)
- Sheng Bi
- Department of Psychiatry and Behavioral Science, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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125
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Decressac M, Barker RA. Neuropeptide Y and its role in CNS disease and repair. Exp Neurol 2012; 238:265-72. [PMID: 23022456 DOI: 10.1016/j.expneurol.2012.09.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 09/09/2012] [Accepted: 09/20/2012] [Indexed: 01/04/2023]
Abstract
Neuropeptide Y (NPY) is widely expressed throughout the CNS and exerts a number of important physiological functions as well as playing a role in pathological conditions such as obesity, anxiety, epilepsy, chronic pain and neurodegenerative disorders. In this review, we highlight some of the recent advances in our understanding of NPY biology and how this may help explain not only its role in health and disease, but also its possible use therapeutically.
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Affiliation(s)
- M Decressac
- Wallenberg Neuroscience Center, Department of Experimental Medical Sciences, Lund University, Lund, Sweden.
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126
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Abstract
Over the past 20 years, genetic studies have illuminated critical pathways in the hypothalamus and brainstem mediating energy homeostasis, such as the melanocortin, leptin, 5-hydroxytryptamine and brain-derived neurotrophic factor signaling axes. The identification of these pathways necessary for appropriate appetitive responses to energy state has yielded insight into normal homeostatic processes. Although monogenic alterations in each of these axes result in severe obesity, such cases remain rare. The major burden of disease is carried by those with common obesity, which has so far resisted yielding meaningful biological insights. Recent progress into the etiology of common obesity has been made with genome-wide association studies. Such studies now reveal more than 32 different candidate obesity genes, most of which are highly expressed or known to act in the CNS, emphasizing, as in rare monogenic forms of obesity, the role of the brain in predisposition to obesity.
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127
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Abstract
Hunger is a complex behavioural state that elicits intense food seeking and consumption. These behaviours are rapidly recapitulated by activation of starvation-sensitive AGRP neurons, which present an entry point for reverse-engineering neural circuits for hunger. We mapped synaptic interactions of AGRP neurons with multiple cell populations and probed the contribution of these distinct circuits to feeding behaviour using optogenetic and pharmacogenetic techniques. An inhibitory circuit with paraventricular hypothalamus (PVH) neurons substantially accounted for acute AGRP neuron-evoked eating, whereas two other prominent circuits were insufficient. Within the PVH, we found that AGRP neurons target and inhibit oxytocin neurons, a small population that is selectively lost in Prader-Willi syndrome, a condition involving insatiable hunger. By developing strategies for evaluating molecularly-defined circuits, we show that AGRP neuron suppression of oxytocin neurons is critical for evoked feeding. These experiments reveal a new neural circuit that regulates hunger state and pathways associated with overeating disorders.
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128
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Gelegen C, Chandarana K, Choudhury AI, Al-Qassab H, Evans IM, Irvine EE, Hyde CB, Claret M, Andreelli F, Sloan SE, Leiter AB, Withers DJ, Batterham RL. Regulation of hindbrain Pyy expression by acute food deprivation, prolonged caloric restriction, and weight loss surgery in mice. Am J Physiol Endocrinol Metab 2012; 303:E659-68. [PMID: 22761162 PMCID: PMC3468511 DOI: 10.1152/ajpendo.00033.2012] [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: 01/01/2023]
Abstract
PYY is a gut-derived putative satiety signal released in response to nutrient ingestion and is implicated in the regulation of energy homeostasis. Pyy-expressing neurons have been identified in the hindbrain of river lamprey, rodents, and primates. Despite this high evolutionary conservation, little is known about central PYY neurons. Using in situ hybridization, PYY-Cre;ROSA-EYFP mice, and immunohistochemistry, we identified PYY cell bodies in the gigantocellular reticular nucleus region of the hindbrain. PYY projections were present in the dorsal vagal complex and hypoglossal nucleus. In the hindbrain, Pyy mRNA was present at E9.5, and expression peaked at P2 and then decreased significantly by 70% at adulthood. We found that, in contrast to the circulation, PYY-(1-36) is the predominant isoform in mouse brainstem extracts in the ad libitum-fed state. However, following a 24-h fast, the relative amounts of PYY-(1-36) and PYY-(3-36) isoforms were similar. Interestingly, central Pyy expression showed nutritional regulation and decreased significantly by acute starvation, prolonged caloric restriction, and bariatric surgery (enterogastroanastomosis). Central Pyy expression correlated with body weight loss and circulating leptin and PYY concentrations. Central regulation of energy metabolism is not limited to the hypothalamus but also includes the midbrain and the brainstem. Our findings suggest a role for hindbrain PYY in the regulation of energy homeostasis and provide a starting point for further research on gigantocellular reticular nucleus PYY neurons, which will increase our understanding of the brain stem pathways in the integrated control of appetite and energy metabolism.
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Affiliation(s)
- C. Gelegen
- 1Centre for Obesity Research, Department of Medicine, University College London, Rayne Institute, London, United Kingdom;
| | - K. Chandarana
- 1Centre for Obesity Research, Department of Medicine, University College London, Rayne Institute, London, United Kingdom;
| | - A. I. Choudhury
- 2Metabolic Signalling Group, Medical Research Council Clinical Sciences Centre, Imperial College, London, United Kingdom;
| | - H. Al-Qassab
- 1Centre for Obesity Research, Department of Medicine, University College London, Rayne Institute, London, United Kingdom;
| | - I. M. Evans
- 3Centre for Cardiovascular Biology and Medicine, Department of Medicine, Rayne Institute, London, United Kingdom;
| | - E. E. Irvine
- 1Centre for Obesity Research, Department of Medicine, University College London, Rayne Institute, London, United Kingdom;
| | - C. B. Hyde
- 4Scientific Support Services, Wolfson Institute for Biomedical Research and the University College London Cancer Institute, London, United Kingdom;
| | - M. Claret
- 5Diabetes and Obesity Laboratory, Institut d′Investigacions Biomèdiques August Pi i Sunyer, Centre Esther Koplowitz, Barcelona, Spain;
| | - F. Andreelli
- 6Institut Cochin, Université Paris Descartes, Paris, France;
- 7Department of Diabetology, Pitié-Salpêtrière Hospital, University Pierre et Marie Curie-Paris 6, Paris, France;
| | - S. E. Sloan
- 8University of Massachusetts Medical School, Department of Medicine, Worcester, Massachusetts
| | - A. B. Leiter
- 8University of Massachusetts Medical School, Department of Medicine, Worcester, Massachusetts
| | - D. J. Withers
- 2Metabolic Signalling Group, Medical Research Council Clinical Sciences Centre, Imperial College, London, United Kingdom;
| | - R. L. Batterham
- 1Centre for Obesity Research, Department of Medicine, University College London, Rayne Institute, London, United Kingdom;
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Leitermann RJ, Sajdyk TJ, Urban JH. Cell-specific expression of calcineurin immunoreactivity within the rat basolateral amygdala complex and colocalization with the neuropeptide Y Y1 receptor. J Chem Neuroanat 2012; 45:50-6. [PMID: 22884996 DOI: 10.1016/j.jchemneu.2012.07.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 07/27/2012] [Accepted: 07/28/2012] [Indexed: 11/17/2022]
Abstract
Neuropeptide Y (NPY) produces potent anxiolytic effects via activation of NPY Y1 receptors (Y1r) within the basolateral amygdaloid complex (BLA). The role of NPY in the BLA was recently expanded to include the ability to produce stress resilience and long-lasting reductions in anxiety-like behavior. These persistent behavioral effects are dependent upon activity of the protein phosphatase, calcineurin (CaN), which has long been associated with shaping long-term synaptic signaling. Furthermore, NPY-induced reductions in anxiety-like behavior persist months after intra-BLA delivery, which together indicate a form of neuronal plasticity had likely occurred. To define a site of action for NPY-induced CaN signaling within the BLA, we employed multi-label immunohistochemistry to determine which cell types express CaN and if CaN colocalizes with the Y1r. We have previously reported that both major neuronal cell populations in the BLA, pyramidal projection neurons and GABAergic interneurons, express the Y1r. Therefore, this current study evaluated CaN immunoreactivity in these cell types, along with Y1r immunoreactivity. Antibodies against calcium-calmodulin kinase II (CaMKII) and GABA were used to identify pyramidal neurons and GABAergic interneurons, respectively. A large population of CaN immunoreactive cells displayed Y1r immunoreactivity (90%). Nearly all (98%) pyramidal neurons displayed CaN immunoreactivity, while only a small percentage of interneurons (10%) contained CaN immunoreactivity. Overall, these anatomical findings provide a model whereby NPY could directly regulate CaN activity in the BLA via activation of the Y1r on CaN-expressing, pyramidal neurons. Importantly, they support BLA pyramidal neurons as prime targets for neuronal plasticity associated with the long-term reductions in anxiety-like behavior produced by NPY injections into the BLA.
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Affiliation(s)
- Randy J Leitermann
- Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA.
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130
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Zhang L, Nguyen AD, Lee ICJ, Yulyaningsih E, Riepler SJ, Stehrer B, Enriquez RF, Lin S, Shi YC, Baldock PA, Sainsbury A, Herzog H. NPY modulates PYY function in the regulation of energy balance and glucose homeostasis. Diabetes Obes Metab 2012; 14:727-36. [PMID: 22369253 DOI: 10.1111/j.1463-1326.2012.01592.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
AIMS Both the neuronal-derived neuropeptide Y (NPY) and the gut hormone peptide YY (PYY) have been implicated in the regulation of energy balance and glucose homeostasis. However, despite similar affinities for the same Y receptors, the co-ordinated actions of these two peptides in energy and glucose homeostasis remain largely unknown. METHODS To investigate the mechanisms and possible interactions between PYY with NPY in the regulation of these processes, we utilized NPY/PYY single and double mutant mouse models and examined parameters of energy balance and glucose homeostasis. RESULTS PYY(-/-) mice exhibited increased fasting-induced food intake, enhanced fasting and oral glucose-induced serum insulin levels, and an impaired insulin tolerance, - changes not observed in NPY(-/-) mice. Interestingly, whereas PYY deficiency-induced impairment in insulin tolerance remained in NPY(-/-) PYY(-/-) mice, effects of PYY deficiency on fasting-induced food intake and serum insulin concentrations at baseline and after the oral glucose bolus were absent in NPY(-/-) PYY(-/-) mice, suggesting that NPY signalling may be required for PYY's action on insulin secretion and fasting-induced hyperphagia. Moreover, NPY(-/-) PYY(-/-) , but not NPY(-/-) or PYY(-/-) mice had significantly decreased daily food intake, indicating interactive control by NPY and PYY on spontaneous food intake. Furthermore, both NPY(-/-) and PYY(-/-) mice showed significantly reduced respiratory exchange ratio during the light phase, with no additive effects observed in NPY(-/-) PYY(-/-) mice, indicating that NPY and PYY may regulate oxidative fuel selection via partly shared mechanisms. Overall, physical activity and energy expenditure, however, are not significantly altered by NPY and PYY single or double deficiencies. CONCLUSIONS These findings show significant and diverse interactions between NPY and PYY signalling in the regulation of different aspects of energy balance and glucose homeostasis.
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Affiliation(s)
- L Zhang
- Neuroscience Research Program, Garvan Institute of Medical Research, St Vincent's Hospital, Darlinghurst, Sydney, New South Wales, Australia
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Cheung A, Newland PL, Zaben M, Attard GS, Gray WP. Intracellular nitric oxide mediates neuroproliferative effect of neuropeptide y on postnatal hippocampal precursor cells. J Biol Chem 2012; 287:20187-96. [PMID: 22474320 PMCID: PMC3370201 DOI: 10.1074/jbc.m112.346783] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Revised: 03/23/2012] [Indexed: 01/25/2023] Open
Abstract
Neuropeptide Y (NPY) is widely expressed in the central and peripheral nervous systems and is proliferative for a range of cells types in vitro. NPY plays a key role in regulating adult hippocampal neurogenesis in vivo under both basal and pathological conditions, although the underlying mechanisms are largely unknown. We have investigated the role of nitric oxide (NO) on the neurogenic effects of NPY. Using postnatal rat hippocampal cultures, we show that the proliferative effect of NPY on nestin(+) precursor cells is NO-dependent. As well as the involvement of neuronal nitric-oxide synthase, the proliferative effect is mediated via an NO/cyclic guanosine monophosphate (cGMP)/cGMP-dependent protein kinase (PKG) and extracellular signal-regulated kinase (ERK) 1/2 signaling pathway. We show that NPY-mediated intracellular NO signaling results in an increase in neuroproliferation. By contrast, extracellular NO had an opposite, inhibitory effect on proliferation. The importance of the NO-cGMP-PKG signaling pathway in ERK1/2 activation was confirmed using Western blotting. This work unites two significant modulators of hippocampal neurogenesis within a common signaling framework and provides a mechanism for the independent extra- and intracellular regulation of postnatal neural precursors by NO.
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Affiliation(s)
- Angela Cheung
- From the Division of Clinical Neurosciences
- Centre for Biological Sciences, and
| | | | | | - George S. Attard
- School of Chemistry, University of Southampton, Southampton SO17 1BJ and
| | - William P. Gray
- From the Division of Clinical Neurosciences
- the Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF14 4XN, Wales, United Kingdom
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132
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Sørensen G, Woldbye DPD. Mice lacking neuropeptide Y show increased sensitivity to cocaine. Synapse 2012; 66:840-3. [PMID: 22544368 DOI: 10.1002/syn.21568] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 04/24/2012] [Indexed: 11/08/2022]
Abstract
There is increasing data implicating neuropeptide Y (NPY) in the neurobiology of addiction. This study explored the possible role of NPY in cocaine-induced behavior using NPY knockout mice. The transgenic mice showed a hypersensitive response to cocaine in three animal models of cocaine addiction. Whether this is due to an observed compensatory increase in striatal dopamine transporter binding or an anxiogenic phenotype of the transgenic mice remains to be determined.
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Affiliation(s)
- Gunnar Sørensen
- Laboratory of Neuropsychiatry, Department of Neuroscience and Pharmacology, Psychiatric Center Copenhagen, University of Copenhagen, Copenhagen, Denmark
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133
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Weston-Green K, Huang XF, Deng C. Alterations to melanocortinergic, GABAergic and cannabinoid neurotransmission associated with olanzapine-induced weight gain. PLoS One 2012; 7:e33548. [PMID: 22438946 PMCID: PMC3306411 DOI: 10.1371/journal.pone.0033548] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 02/11/2012] [Indexed: 12/30/2022] Open
Abstract
Background/Aim Second generation antipsychotics (SGAs) are used to treat schizophrenia but can cause serious metabolic side-effects, such as obesity and diabetes. This study examined the effects of low to high doses of olanzapine on appetite/metabolic regulatory signals in the hypothalamus and brainstem to elucidate the mechanisms underlying olanzapine-induced obesity. Methodology/Results Levels of pro-opiomelanocortin (POMC), neuropeptide Y (NPY) and glutamic acid decarboxylase (GAD65, enzyme for GABA synthesis) mRNA expression, and cannabinoid CB1 receptor (CB1R) binding density (using [3H]SR-141716A) were examined in the arcuate nucleus (Arc) and dorsal vagal complex (DVC) of female Sprague Dawley rats following 0.25, 0.5, 1.0 or 2.0 mg/kg olanzapine or vehicle (3×/day, 14-days). Consistent with its weight gain liability, olanzapine significantly decreased anorexigenic POMC and increased orexigenic NPY mRNA expression in a dose-sensitive manner in the Arc. GAD65 mRNA expression increased and CB1R binding density decreased in the Arc and DVC. Alterations to neurotransmission signals in the brain significantly correlated with body weight and adiposity. The minimum dosage threshold required to induce weight gain in the rat was 0.5 mg/kg olanzapine. Conclusions Olanzapine-induced weight gain is associated with reduced appetite-inhibiting POMC and increased NPY. This study also supports a role for the CB1R and GABA in the mechanisms underlying weight gain side-effects, possibly by altering POMC transmission. Metabolic dysfunction can be modelled in the female rat using low, clinically-comparable olanzapine doses when administered in-line with the half-life of the drug.
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Affiliation(s)
- Katrina Weston-Green
- Centre for Translational Neuroscience, School of Health Sciences, University of Wollongong, Wollongong, Australia
- Schizophrenia Research Institute, Darlinghurst, Australia
| | - Xu-Feng Huang
- Centre for Translational Neuroscience, School of Health Sciences, University of Wollongong, Wollongong, Australia
- Schizophrenia Research Institute, Darlinghurst, Australia
| | - Chao Deng
- Centre for Translational Neuroscience, School of Health Sciences, University of Wollongong, Wollongong, Australia
- Schizophrenia Research Institute, Darlinghurst, Australia
- * E-mail:
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134
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Higuchi H. Molecular analysis of central feeding regulation by neuropeptide Y (NPY) neurons with NPY receptor small interfering RNAs (siRNAs). Neurochem Int 2012; 61:936-41. [PMID: 22414532 DOI: 10.1016/j.neuint.2012.02.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 02/22/2012] [Accepted: 02/25/2012] [Indexed: 01/17/2023]
Abstract
Hypothalamic neuropeptides play important roles in central feeding behavior. Among them, neuropeptide Y (NPY) has the strongest orexigenic action. It is synthesized in NPY-expressing neurons in the arcuate nucleus (ARC), which projects to other nuclei, mainly to the paraventricular nucleus (PVN). PVN, which possesses NPY-Y1, -Y2 and -Y4, -Y5 receptors, is considered as feeding center for central feeding behavior. Herein I review recent results on feeding behavior obtained by gene knockdown technologies. The small interfering RNA (siRNA) plasmid-based vectors, which drive transcription of siRNA by U6 RNA polymerase III promoter to produce knockdown of the NPY and its receptor (Y1, Y2, Y4 and Y5) genes, were stereotaxically injected into mouse ARC and PVN. Feeding behaviors were measured for 6days after siRNA vector injection. NPY and its receptor mRNA levels were decreased, which were measured by RT-PCR and in situ hybridization, and simultaneous decrease in their proteins was also detected in separate nuclei by immunohistochemistry. In the NPY system, decrease in NPY, Y1 and Y5 expressions in specialized nuclei diminished central feeding behavior, whereas decrease in Y2 or Y4 expression in both ARC or PVN did not affect feeding behavior. Thus, specialized change in expressions of NPY and its receptors (especially Y1 and Y5) are important for regulation of endogenous feeding behavior in central regulation. Further analysis of NPY receptors may provide better understanding of feeding behavior and of potential therapeutic targets.
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Affiliation(s)
- Hiroshi Higuchi
- Department of Pharmacology, Molecular and Cellular Medicine, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata 951-8510, Japan.
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135
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Affiliation(s)
- Christopher D Morrison
- Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USA.
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136
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Hayes DM, Fee JR, McCown TJ, Knapp DJ, Breese GR, Cubero I, Carvajal F, Lerma-Cabrera JM, Navarro M, Thiele TE. Neuropeptide Y signaling modulates the expression of ethanol-induced behavioral sensitization in mice. Addict Biol 2012; 17:338-50. [PMID: 21762289 DOI: 10.1111/j.1369-1600.2011.00336.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Neuropeptide Y (NPY) and protein kinase A (PKA) have been implicated in neurobiological responses to ethanol. We have previously reported that mutant mice lacking normal production of the RIIβ subunit of PKA (RIIβ-/- mice) show enhanced sensitivity to the locomotor stimulant effects of ethanol and increased behavioral sensitization relative to littermate wild-type RIIβ+/+ mice. We now report that RIIβ-/- mice also show increased NPY immunoreactivity in the nucleus accumbens (NAc) core and the ventral striatum relative to RIIβ+/+ mice. These observations suggest that elevated NPY signaling in the NAc and/or striatum may contribute to the increased sensitivity to ethanol-induced behavioral sensitization that is a characteristic of RIIβ-/- mice. Consistently, NPY-/- mice failed to display ethanol-induced behavioral sensitization that was evident in littermate NPY+/+ mice. To examine more directly the role of NPY in the locomotor stimulant effects of ethanol, we infused a recombinant adeno-associated virus (rAAV) into the region of the NAc core of DBA/2J mice. The rAAV-fibronectin (FIB)-NPY(13-36) vector expresses and constitutively secretes the NPY fragment NPY(13-36) (a selective Y(2) receptor agonist) from infected cells in vivo. Mice treated with the rAAV-FIB-NPY(13-36) vector exhibited reduced expression of ethanol-induced behavioral sensitization compared with mice treated with a control vector. Taken together, the current data provide the first evidence that NPY signaling in the NAc core and the Y(2) receptor modulate ethanol-induced behavioral sensitization.
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Affiliation(s)
- Dayna M Hayes
- Department of Psychology, Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, NC, USA
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Doyle KL, Hort YJ, Herzog H, Shine J. Neuropeptide Y and peptide YY have distinct roles in adult mouse olfactory neurogenesis. J Neurosci Res 2012; 90:1126-35. [PMID: 22354615 DOI: 10.1002/jnr.23008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2011] [Revised: 11/22/2011] [Accepted: 11/23/2011] [Indexed: 01/19/2023]
Abstract
Neuropeptide Y (NPY) and peptide YY (PYY) are differentially expressed throughout the olfactory neuroepithelium (ON), with NPY expression present in sustentacular cells, olfactory ensheathing cells, and olfactory receptor neurons and PYY expressed only in sustentacular cells. Examination of the anatomical morphology of the ON in NPY knockout (NPY⁻/⁻) and PYY knockout (PYY⁻/⁻) mice shows that there are significantly more neurons in PYY⁻/⁻ mice and significantly fewer neurons in NPY⁻/⁻ mice. Interestingly, the mature neurons of NPY⁻/⁻ mice were undergoing apoptosis. The transcription factor Mash1, which is critical in the production of olfactory precursors, is also differentially expressed in NPY⁻/⁻ and PYY⁻/⁻ ON. It is upregulated in the neurons of NPY⁻/⁻ mice and unchanged in PYY⁻/⁻ mice. Furthermore, significantly fewer olfactory neurospheres are present in cultures prepared from PYY⁻/⁻ mice in the first 2 weeks compared with NPY⁻/⁻ and wild-type mice. Together these results suggest that, during olfactory neurogenesis, NPY acts as a trophic factor for the maturation and survival of olfactory receptor neurons, whereas PYY has an important role in the regulation of olfactory neuron differentiation.
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Affiliation(s)
- Kharen L Doyle
- Neuroscience Research Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia; University of New South Wales, New South Wales, Australia.
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138
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Hypothalamic neuropeptides and the regulation of appetite. Neuropharmacology 2012; 63:18-30. [PMID: 22369786 DOI: 10.1016/j.neuropharm.2012.02.004] [Citation(s) in RCA: 163] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 12/23/2011] [Accepted: 02/07/2012] [Indexed: 12/24/2022]
Abstract
Neuropeptides released by hypothalamic neurons play a major role in the regulation of feeding, acting both within the hypothalamus, and at other appetite regulating centres throughout the brain. Where classical neurotransmitters signal only within synapses, neuropeptides diffuse over greater distances affecting both nearby and distant neurons expressing the relevant receptors, which are often extrasynaptic. As well as triggering a behavioural output, neuropeptides also act as neuromodulators: altering the response of neurons to both neurotransmitters and circulating signals of nutrient status. The mechanisms of action of hypothalamic neuropeptides with established roles in feeding, including melanin-concentrating hormone (MCH), the orexins, α-melanocyte stimulating hormone (α-MSH), agouti-gene related protein (AgRP), neuropeptide Y, and oxytocin, are reviewed in this article, with emphasis laid on both their effects on appetite regulating centres throughout the brain, and on examining the evidence for their physiological roles. In addition, evidence for the involvement of several putative appetite regulating hypothalamic neuropeptides is assessed including, ghrelin, cocaine and amphetamine-regulated transcript (CART), neuropeptide W and the galanin-like peptides. This article is part of a Special Issue entitled 'Central control of Food Intake'.
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139
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Wu G, Feder A, Wegener G, Bailey C, Saxena S, Charney D, Mathé AA. Central functions of neuropeptide Y in mood and anxiety disorders. Expert Opin Ther Targets 2012; 15:1317-31. [PMID: 21995655 DOI: 10.1517/14728222.2011.628314] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
INTRODUCTION Neuropeptide Y (NPY) is a highly conserved neuropeptide belonging to the pancreatic polypeptide family. Its potential role in the etiology and pathophysiology of mood and anxiety disorders has been extensively studied. NPY also has effects on feeding behavior, ethanol intake, sleep regulation, tissue growth and remodeling. Findings from animal studies have delineated the physiological and behavioral effects mediated by specific NPY receptor subtypes, of which Y1 and Y2 are the best understood. AREAS COVERED Physiological roles and alterations of the NPYergic system in anxiety disorders, depression, posttraumatic stress disorder (PTSD), alcohol dependence and epilepsy. For each disorder, studies in animal models and human investigations are outlined and discussed, focusing on behavior, neurophysiology, genetics and potential for novel treatment targets. EXPERT OPINION The wide implications of NPY in psychiatric disorders such as depression and PTSD make the NPYergic system a promising target for the development of novel therapeutic interventions. These include intranasal NPY administration, currently under study, and the development of agonists and antagonists targeting NPY receptors. Therefore, we are proposing that via this mode of administration, NPY might exert CNS therapeutic actions without untoward systemic effects. Future work will show if this is a feasible approach.
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Affiliation(s)
- Gang Wu
- Karolinska Institutet-Clinical Neuroscience, Stockholm, Sweden
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140
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Shi YC, Baldock PA. Central and peripheral mechanisms of the NPY system in the regulation of bone and adipose tissue. Bone 2012; 50:430-6. [PMID: 22008645 DOI: 10.1016/j.bone.2011.10.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 10/02/2011] [Accepted: 10/03/2011] [Indexed: 12/24/2022]
Abstract
Skeletal research is currently undergoing a period of marked expansion. The boundaries of "bone" research are being re-evaluated and with this, a growing recognition of a more complex and interconnected biology than previously considered. One aspect that has become the focus of particular attention is the relationship between bone and fat homeostasis. Evidence from a number of avenues indicates that bone and adipose regulation are both related and interdependent. This review examines the neuropeptide Y (NPY) system, known to exert powerful control over both bone and fat tissue. The actions of this system are characterized by signaling both within specific nuclei of the hypothalamus and also the target tissues, mediated predominantly through two G-protein coupled receptors (Y1 and Y2). In bone tissue, elevated NPY levels act consistently to repress osteoblast activity. Moreover, both central Y2 receptor and osteoblastic Y1 receptor signaling act similarly to repress bone formation. Conversely, loss of NPY expression or receptor signaling induces increased osteoblast activity and bone mass in both cortical and cancellous envelopes. In fat tissue, NPY action is more complex. Energy homeostasis is powerfully altered by elevations in hypothalamic NPY, resulting in increases in fat accretion and body-wide energy conservation, through the action of locally expressed Y1 receptors, while local Y2 receptors act to inhibit NPY-ergic tone. Loss of central NPY expression has a markedly reduced effect, consistent with a physiological drive to promote fat accretion. In fat tissue, NPY and Y1 receptors act to promote lipogenesis, consistent with their roles in the brain. Y2 receptors expressed in adipocytes also act in this manner, showing an opposing action to their role in the hypothalamus. While direct investigation of these processes has yet to be completed, these responses appear to be interrelated to some degree. The starvation-based signal of elevated central NPY inducing marked inhibition of osteoblast activity, whilst promoting fat accretion, indicating skeletal tissue is a component of the energy conservation system. Moreover, when NPY expression is reduced, consistent with high calorie intake and weight gain, bone formation is stimulated, strengthening the skeleton. In conclusion, NPY acts to regulate both bone and fat tissue in a coordinated manner, and remains a strong candidate for mediating interactions between these two tissues.
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Affiliation(s)
- Yan-Chuan Shi
- Neuroscience Research Program, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst NSW 2010, Australia
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141
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Patra SK, Arora S. Integrative role of neuropeptides and cytokines in cancer anorexia-cachexia syndrome. Clin Chim Acta 2012; 413:1025-34. [PMID: 22251421 DOI: 10.1016/j.cca.2011.12.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 12/02/2011] [Accepted: 12/08/2011] [Indexed: 12/31/2022]
Abstract
BACKGROUND The cachexia anorexia syndrome is a complex metabolic syndrome associated with cancer and some other palliative conditions characterized by involuntary weight loss involving fat and muscle, weight loss, anorexia, early satiety, fatigue, weakness due to shifts in metabolism caused by tumour by-products and cytokines. Various neuropeptides like Leptin, neuropeptide Y, melanocortin, agouti-related peptides have been known to regulate appetite and body weight. METHOD A comprehensive literature search was carried out on the websites of Pubmed Central (http://www.pubmedcentral.nih.gov/), National Library of Medicine (http://www.ncbl.nlm.nih.gov) and various other net resources. RESULT Data from observational studies shows that various cytokines (TNF-α, IL-6 and IL-1) are associated with metabolic changes resulting in cachexia in cancer patients. These cytokines may mimic the action of various neuropeptides resulting in anorexia, various metabolic effects resulting from enhanced catabolic state and weight loss. CONCLUSION There is a need to understand and explore the role of various neuropeptides and cytokines in the pathophysiology of cancer-anorexia syndrome so that therapeutic measures may be designed for effective palliative care.
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Affiliation(s)
- Surajeet K Patra
- Department of Biochemistry, Lady Hardinge Medical College, New Delhi-110001, India
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142
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van Raay L, Jovanovska V, Morris MJ, O'Brien TJ. Focal administration of neuropeptide Y into the S2 somatosensory cortex maximally suppresses absence seizures in a genetic rat model. Epilepsia 2012; 53:477-84. [PMID: 22220638 DOI: 10.1111/j.1528-1167.2011.03370.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
PURPOSE Neuropeptide Y (NPY) is an inhibitory neurotransmitter that suppresses focal and generalized seizures in animal models. In this study, we investigated the sites within the thalamocortical circuit that NPY acts to suppress seizures in genetic absence epilepsy rats from Strasbourg (GAERS). METHODS In conscious freely moving GAERS, NPY was administered via intracerebral microcannulae implanted bilaterally into one of the following regions: primary somatosensory cortex (S1), secondary somatosensory cortex (S2), the primary motor cortex (M1), caudal nucleus reticular thalamus (nRT), or ventrobasal thalamus (VB). Animals received vehicle and up to three doses of NPY, in a randomized order. Electroencephalography (EEG) recordings were carried out for 30 min prior to injection and 90 min after the injection of NPY or vehicle. KEY FINDINGS Focal microinjections of NPY into the S2 cortex suppressed seizures in a dose-dependent manner, with the response being significantly different at the highest dose (1.5 mm) compared to vehicle for total time in seizures postinjection (7.2 ± 3.0% of saline, p < 0.01) and average number of seizures (9.4 ± 4.9% of saline, p < 0.05). In contrast NPY microinjections into the VB resulted in an aggravation of seizures. SIGNIFICANCE NPY produces contrasting effects on absence-like seizures in GAERS depending on the site of injection within the thalamocortical circuit. The S2 is the site at which NPY most potently acts to suppress absence-like seizures in GAERS, whereas seizure-aggravating effects are seen in the VB. These results provide further evidence to support the proposition that these electroclinically "generalized" seizures are being driven by a topographically restricted region within the somatosensory cortex.
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Affiliation(s)
- Leena van Raay
- The Departments of Medicine and Neurology, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia
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143
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Bolkvadze T, Pitkänen A. Development of post-traumatic epilepsy after controlled cortical impact and lateral fluid-percussion-induced brain injury in the mouse. J Neurotrauma 2012; 29:789-812. [PMID: 22023672 DOI: 10.1089/neu.2011.1954] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The present study investigated the development of hyperexcitability and epilepsy in mice with traumatic brain injury (TBI) induced by controlled cortical impact (CCI) or lateral fluid-percussion injury (FPI), which are the two most commonly used experimental models of human TBI in rodents. TBI was induced with CCI to 50 (14 controls) and with lateral FPI to 45 (15 controls) C57BL/6S adult male mice. The animals were followed-up for 9 months, including three 2-week periods of continuous video-electroencephalographic (EEG) monitoring, and a seizure susceptibility test with pentylenetetrazol (PTZ). In the end, the animals were perfusion-fixed for histology. The experiment included two independent cohorts of animals. Late post-traumatic spontaneous electrographic seizures were detected in 9% of mice after CCI and 3% after lateral FPI. Eighty-two percent of mice after CCI and 71% after lateral FPI had spontaneous epileptiform spiking on EEG. In addition, 58% of mice with lateral FPI showed spontaneous epileptiform discharges. A PTZ test demonstrated increased seizure susceptibility in the majority of mice in both models, compared to control mice. There was no further progression in the occurrence of epilepsy or epileptiform spiking when follow-up was extended from 6 to 9 months. The severity of cortical or hippocampal damage did not differentiate mice with or without epileptiform activity in either model. Finally, two independent series of experiments in both injury models provided comparable data demonstrating reproducibility of the modeling. These data show that different types of impact can trigger epileptogenesis in mice. Even though the frequency of spontaneous seizures in C57BL/6S mice is low, a large majority of animals develop hyperexcitability.
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Affiliation(s)
- Tamuna Bolkvadze
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
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144
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Abstract
When administered into the brain, NPY acts at Y1 and Y5 receptors to increase food intake. The response occurs with a short latency and is quite robust, such that exogenous NPY is generally considered to be the most potent of a growing list of orexigenic compounds that act in the brain. The role of endogenous NPY is not so straightforward, however. Evidence from diverse types of experiments suggests that rather than initiating behavioral eating per se, endogenous NPY elicits autonomic responses that prepare the individual to better cope with consuming a calorically large meal.
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Affiliation(s)
- Adam P Chambers
- Departments of Medicine, University of Cincinnati, OH 45237, USA
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145
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Menzies JRW, Skibicka KP, Dickson SL, Leng G. Neural substrates underlying interactions between appetite stress and reward. Obes Facts 2012; 5:208-20. [PMID: 22647303 DOI: 10.1159/000338237] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 06/16/2011] [Indexed: 12/21/2022] Open
Abstract
Neurobiological mechanisms that normally control food intake and energy expenditure can be overcome by environmental cues and by stress. Of particular importance is the influence of the mesolimbic reward pathway. In genetically susceptible individuals, problematic over-eating likely reflects a changing balance in the control exerted by homeostatic versus reward circuits that are strongly influenced by environmental factors such as stress. Both stress and activation of the reward pathway have been shown to increase food intake and promote a preference for palatable, high-energy foods. Recent research has focused on the important role of circulating and central neuropeptides that powerfully regulate the brain response to food cues. For example, ghrelin has a potent positive effect on the motivational aspects of food intake, and central oxytocin may be involved in satiety. Thus, the decision to eat, or indeed to over-eat, involves a complex integrated neurobiology that includes brain centres involved in energy balance, reward and stress and their regulation by metabolic and endocrine factors.
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Affiliation(s)
- John R W Menzies
- Centre for Integrative Physiology, School of Biomedical Sciences, University of Edinburgh, Edinburgh, UK
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146
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Niemann H, Kuhla B, Flachowsky G. Perspectives for feed-efficient animal production1. J Anim Sci 2011; 89:4344-63. [DOI: 10.2527/jas.2011-4235] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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147
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Stadler J, Le TP, Haas P, Nave H. Distinct effects of NPY13-36, a specific NPY Y2 agonist, in a model of rodent endotoxemia on leukocyte subsets and cytokine levels. Ann Anat 2011; 193:486-93. [PMID: 22074679 DOI: 10.1016/j.aanat.2011.10.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 10/09/2011] [Accepted: 10/10/2011] [Indexed: 11/30/2022]
Abstract
Even now, sepsis remains a major problem in modern clinical medicine, leading to systemic inflammatory response including altered leukocyte subset distribution and increased cytokine release. As immune cells are known to express NPY receptors, we investigated the effects of a specific NPY Y(2) receptor agonist (NPY(13-36)) and/or the corresponding Y(2) receptor antagonist BIIE0246 treatment on blood (by FACS analyses) and tissue (by immunohistochemistry) leukocyte subsets as well as on levels of IL-4, IL-6, IL-10, TNF-α, INF-γ (by Cytometric Bead Array) in healthy and acutely endotoxemic rats. Results show a significant decrease in blood monocytes after LPS challenge in endotoxemic control animals (by 93%), in endotoxemic NPY(13-36) treated animals (by 83%) and in endotoxemic BIIE0246 treated animals (by 88%) as compared to the corresponding healthy controls. Endotoxemic control animals showed a significant increase of TNF-α (by 98%) as compared to the healthy control group. A treatment with NPY(13-36) significantly stabilized TNF-α level in endotoxemic animals. This study indicates distinct subset- and cytokine-specific in vivo effects induced by an NPY Y(2) receptor specific treatment after a short-term LPS challenge.
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Affiliation(s)
- Jan Stadler
- Institute for Functional and Applied Anatomy, Hannover Medical School, Germany
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148
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Abstract
Peptide YY3-36 is a satiation hormone released postprandially into the bloodstream from L-endocrine cells in the gut epithelia. In the current report, we demonstrate PYY3-36 is also present in murine as well as in human saliva. In mice, salivary PYY3-36 derives from plasma and is also synthesized in the taste cells in taste buds of the tongue. Moreover, the cognate receptor Y2R is abundantly expressed in the basal layer of the progenitor cells of the tongue epithelia and von Ebner's gland. The acute augmentation of salivary PYY3-36 induced stronger satiation as demonstrated in feeding behavioral studies. The effect is mediated through the activation of the specific Y2 receptor expressed in the lingual epithelial cells. In a long-term study involving diet-induced obese (DIO) mice, a sustained increase in PYY3-36 was achieved using viral vector-mediated gene delivery targeting salivary glands. The chronic increase in salivary PYY3-36 resulted in a significant long-term reduction in food intake (FI) and body weight (BW). Thus this study provides evidence for new functions of the previously characterized gut peptide PYY3-36 suggesting a potential simple and efficient alternative therapeutic approach for the treatment of obesity.
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149
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Weinberg MS, McCown TJ. Current prospects and challenges for epilepsy gene therapy. Exp Neurol 2011; 244:27-35. [PMID: 22008258 DOI: 10.1016/j.expneurol.2011.10.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 09/16/2011] [Accepted: 10/03/2011] [Indexed: 12/25/2022]
Abstract
This review addresses the state of gene therapy research for the treatment of epilepsy. Preclinical studies have demonstrated the anti-seizure efficacy of viral vector-based gene transfer through the use of a variety of strategies - from modulating classic neurotransmitter systems to targeting or overexpressing of neuropeptide receptors in seizure-specific brain regions. While these studies provide substantive proof of principle for viral vector gene therapy, future studies must address the challenges of vector immunity, cellular specificity and effective global delivery. As these issues are resolved, viral vector gene therapy should significantly impact the treatment of intractable epilepsy.
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Affiliation(s)
- Marc S Weinberg
- University of North Carolina Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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150
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Mercer RE, Chee MJS, Colmers WF. The role of NPY in hypothalamic mediated food intake. Front Neuroendocrinol 2011; 32:398-415. [PMID: 21726573 DOI: 10.1016/j.yfrne.2011.06.001] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 05/17/2011] [Accepted: 06/13/2011] [Indexed: 12/29/2022]
Abstract
Neuropeptide Y (NPY) is a highly conserved neuropeptide with orexigenic actions in discrete hypothalamic nuclei that plays a role in regulating energy homeostasis. NPY signals via a family of high affinity receptors that mediate the widespread actions of NPY in all hypothalamic nuclei. These actions are also subject to tight, intricate regulation by numerous peripheral and central energy balance signals. The NPY system is embedded within a densely-redundant network designed to ensure stable energy homeostasis. This redundancy may underlie compensation for the loss of NPY or its receptors in germline knockouts, explaining why conventional knockouts of NPY or its receptors rarely yield a marked phenotypic change. We discuss insights into the hypothalamic role of NPY from studies of its physiological actions, responses to genetic manipulations and interactions with other energy balance signals. We conclude that numerous approaches must be employed to effectively study different aspects of NPY action.
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Affiliation(s)
- Rebecca E Mercer
- Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada T6G 2H7
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