1
|
Bach P, Koopmann A, Kiefer F. The Impact of Appetite-Regulating Neuropeptide Leptin on Alcohol Use, Alcohol Craving and Addictive Behavior: A Systematic Review of Preclinical and Clinical Data. Alcohol Alcohol 2020; 56:149-165. [PMID: 32490525 DOI: 10.1093/alcalc/agaa044] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 04/27/2020] [Accepted: 04/28/2020] [Indexed: 12/18/2022] Open
Abstract
AIMS The appetite regulating hormone leptin, which is mainly secreted from adipose tissue, is an important regulator of food intake and modulator of reward-driven behavior. Leptin exerts its biological actions via binding to the leptin receptor, which is expressed in the hypothalamus, but also in the hippocampus, the amygdala and the substantia nigra. In the ventral tegmental area (VTA), leptin attenuates the firing rate of dopaminergic neurons that project to the Nucleus accumbens (NAc), which serves as relay to other brain areas of the "addiction network", such as the prefrontal cortex. This suggests that leptin plays a role in the processing of rewards in the context of substance use disorders such as alcohol use disorder, especially through attenuation of dopaminergic activity in the mesolimbic reward system. This supports the plausibility of leptin's potential effects in alcohol use disorder. METHODS We searched MEDLINE from 1990 to February 2020. All abstracts were screened for relevance and we only included publications reporting original data with a full text available in English language. Studies that did not report leptin-data, reviews or case reports/series were not included. RESULTS We identified a total of N=293 studies of whom a total of N=55 preclinical and clinical studies met the specified criteria. N=40 studies investigated the effects of alcohol on leptin plasma levels, N=9 studies investigated the effects of leptin on alcohol craving and N=6 studies investigated the effects of leptin on relapse and alcohol consumption. CONCLUSIONS In this review of preclinical and clinical data, we assess the role of leptin in alcohol use and the development and maintenance of an alcohol use disorder, alcohol craving and relapse. Integrating the existing preclinical and clinical data on leptin may reveal new and innovative targets for the treatment of substance use disorders in the future.
Collapse
Affiliation(s)
- Patrick Bach
- Department of Addictive Behavior and Addiction Medicine, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, J5/68159 Mannheim, Germany.,Feuerlein Center on Translational Addiction Medicine (FCTS), University of Heidelberg, J5/68159 Mannheim, Germany
| | - Anne Koopmann
- Department of Addictive Behavior and Addiction Medicine, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, J5/68159 Mannheim, Germany.,Feuerlein Center on Translational Addiction Medicine (FCTS), University of Heidelberg, J5/68159 Mannheim, Germany
| | - Falk Kiefer
- Department of Addictive Behavior and Addiction Medicine, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, J5/68159 Mannheim, Germany.,Feuerlein Center on Translational Addiction Medicine (FCTS), University of Heidelberg, J5/68159 Mannheim, Germany
| |
Collapse
|
2
|
Giménez-Gómez P, Pérez-Hernández M, Gutiérrez-López MD, Vidal R, Abuin-Martínez C, O'Shea E, Colado MI. Increasing kynurenine brain levels reduces ethanol consumption in mice by inhibiting dopamine release in nucleus accumbens. Neuropharmacology 2018; 135:581-591. [PMID: 29705534 DOI: 10.1016/j.neuropharm.2018.04.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 03/22/2018] [Accepted: 04/17/2018] [Indexed: 12/11/2022]
Abstract
Recent research suggests that ethanol (EtOH) consumption behaviour can be regulated by modifying the kynurenine (KYN) pathway, although the mechanisms involved have not yet been well elucidated. To further explore the implication of the kynurenine pathway in EtOH consumption we inhibited kynurenine 3-monooxygenase (KMO) activity with Ro 61-8048 (100 mg/kg, i.p.), which shifts the KYN metabolic pathway towards kynurenic acid (KYNA) production. KMO inhibition decreases voluntary binge EtOH consumption and EtOH preference in mice subjected to "drinking in the dark" (DID) and "two-bottle choice" paradigms, respectively. This effect seems to be a consequence of increased KYN concentration, since systemic KYN administration (100 mg/kg, i.p.) similarly deters binge EtOH consumption in the DID model. Despite KYN and KYNA being well-established ligands of the aryl hydrocarbon receptor (AhR), administration of AhR antagonists (TMF 5 mg/kg and CH-223191 20 mg/kg, i.p.) and of an agonist (TCDD 50 μg/kg, intragastric) demonstrates that signalling through this receptor is not involved in EtOH consumption behaviour. Ro 61-8048 did not alter plasma acetaldehyde concentration, but prevented EtOH-induced dopamine release in the nucleus accumbens shell. These results point to a critical involvement of the reward circuitry in the reduction of EtOH consumption induced by KYN and KYNA increments. PNU-120596 (3 mg/kg, i.p.), a positive allosteric modulator of α7-nicotinic acetylcholine receptors, partially prevented the Ro 61-8048-induced decrease in EtOH consumption. Overall, our results highlight the usefulness of manipulating the KYN pathway as a pharmacological tool for modifying EtOH consumption and point to a possible modulator of alcohol drinking behaviour.
Collapse
Affiliation(s)
- Pablo Giménez-Gómez
- Departamento de Farmacología y Toxicología, Facultad de Medicina, Universidad Complutense, Pza. Ramón y Cajal s/n, 28040, Madrid, Spain; Instituto de Investigación Sanitaria Hospital 12 de Octubre, 28041, Madrid, Spain; Red de Trastornos Adictivos del Instituto de Salud Carlos III, 28029, Madrid, Spain
| | - Mercedes Pérez-Hernández
- Departamento de Farmacología y Toxicología, Facultad de Medicina, Universidad Complutense, Pza. Ramón y Cajal s/n, 28040, Madrid, Spain; Instituto de Investigación Sanitaria Hospital 12 de Octubre, 28041, Madrid, Spain; Red de Trastornos Adictivos del Instituto de Salud Carlos III, 28029, Madrid, Spain
| | - María Dolores Gutiérrez-López
- Departamento de Farmacología y Toxicología, Facultad de Medicina, Universidad Complutense, Pza. Ramón y Cajal s/n, 28040, Madrid, Spain; Instituto de Investigación Sanitaria Hospital 12 de Octubre, 28041, Madrid, Spain; Red de Trastornos Adictivos del Instituto de Salud Carlos III, 28029, Madrid, Spain
| | - Rebeca Vidal
- Departamento de Farmacología y Toxicología, Facultad de Medicina, Universidad Complutense, Pza. Ramón y Cajal s/n, 28040, Madrid, Spain; Instituto de Investigación Sanitaria Hospital 12 de Octubre, 28041, Madrid, Spain; Red de Trastornos Adictivos del Instituto de Salud Carlos III, 28029, Madrid, Spain
| | - Cristina Abuin-Martínez
- Departamento de Farmacología y Toxicología, Facultad de Medicina, Universidad Complutense, Pza. Ramón y Cajal s/n, 28040, Madrid, Spain; Instituto de Investigación Sanitaria Hospital 12 de Octubre, 28041, Madrid, Spain; Red de Trastornos Adictivos del Instituto de Salud Carlos III, 28029, Madrid, Spain
| | - Esther O'Shea
- Departamento de Farmacología y Toxicología, Facultad de Medicina, Universidad Complutense, Pza. Ramón y Cajal s/n, 28040, Madrid, Spain; Instituto de Investigación Sanitaria Hospital 12 de Octubre, 28041, Madrid, Spain; Red de Trastornos Adictivos del Instituto de Salud Carlos III, 28029, Madrid, Spain.
| | - María Isabel Colado
- Departamento de Farmacología y Toxicología, Facultad de Medicina, Universidad Complutense, Pza. Ramón y Cajal s/n, 28040, Madrid, Spain; Instituto de Investigación Sanitaria Hospital 12 de Octubre, 28041, Madrid, Spain; Red de Trastornos Adictivos del Instituto de Salud Carlos III, 28029, Madrid, Spain.
| |
Collapse
|
3
|
Gelineau RR, Arruda NL, Hicks JA, Monteiro De Pina I, Hatzidis A, Seggio JA. The behavioral and physiological effects of high-fat diet and alcohol consumption: Sex differences in C57BL6/J mice. Brain Behav 2017; 7:e00708. [PMID: 28638713 PMCID: PMC5474711 DOI: 10.1002/brb3.708] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND AND OBJECTIVE Animal studies can be a great tool to investigate sex differences in a variety of different ways, including behavioral and physiological responses to drug treatments and different "lifestyle variables" such as diets. Consumption of both high-fat diets and alcohol is known to affect anxiety behaviors and overall health. This project investigated how high-fat diet and alcohol access and its combination affected the behavior and physiology of male and female C57BL/6J mice. METHOD Mice were separated into three food groups: high-fat diet, 10% fat diet, and regular chow, and each group was paired with either water or 10% alcohol. Behavioral assays included diet and alcohol preference, light-dark box, open field, and feeding and drinking measurements. Physiological measures included glucose tolerance tests and measurement of brain-derived neurotrophic factor, insulin, and leptin levels. RESULTS Females and males differed in the open field, as male mice decreased activity, while females increased activity when consuming high-fat diet. While females consumed more ethanol than males, alcohol consumption was able to improve glucose tolerance and increase anxiety in both sexes. Lastly, females were more resistant to the physiological changes caused by high-fat diet than males, as females consuming high-fat diet exhibited decreased insulin secretion, less change to brain-derived neurotrophic factor levels, and better glucose tolerance than males consuming high-fat diet. CONCLUSION These results suggest that the response to high-fat diet and alcohol consumption is sex dependent and that males are more affected both behaviorally and physiologically by high-fat diet compared to females.
Collapse
Affiliation(s)
- Rachel R Gelineau
- Department of Biological Sciences Bridgewater State University Bridgewater MA USA
| | - Nicole L Arruda
- Department of Biological Sciences Bridgewater State University Bridgewater MA USA
| | - Jasmin A Hicks
- Department of Biological Sciences Bridgewater State University Bridgewater MA USA
| | | | - Aikaterini Hatzidis
- Department of Biological Sciences Bridgewater State University Bridgewater MA USA
| | - Joseph A Seggio
- Department of Biological Sciences Bridgewater State University Bridgewater MA USA
| |
Collapse
|
4
|
Vallöf D, Ulenius L, Egecioglu E, Engel JA, Jerlhag E. Central administration of the anorexigenic peptide neuromedin U decreases alcohol intake and attenuates alcohol-induced reward in rodents. Addict Biol 2017; 22:640-651. [PMID: 26769653 PMCID: PMC6680249 DOI: 10.1111/adb.12355] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 10/26/2015] [Accepted: 12/01/2015] [Indexed: 01/24/2023]
Abstract
By investigating the neurochemical mechanisms through which alcohol activates the brain reward systems, novel treatment strategies for alcohol use disorder (AUD), a chronic relapsing disease, can be developed. In contrast to the common view of the function of gut-brain peptides, such as neuromedin U (NMU), to regulate food intake and appetite, a novel role in reinforcement mediation has been implied. The anorexigenic effects of NMU are mediated via NMU2 receptors, preferably in the arcuate nucleus and paraventricular nucleus. The expression of NMU2 receptors is also expressed in several reward-related areas in the brain, suggesting a role in reward regulation. The present experiments were therefore set up to investigate the effect of intracerebroventricular administration of NMU on alcohol-mediated behaviors in rodents. We found that central administration of NMU attenuated alcohol-induced locomotor stimulation, accumbal dopamine release and the expression of conditioned place preference in mice. In addition, NMU dose dependently decreased alcohol intake in high, but not in low, alcohol-consuming rats. Central NMU administration did not alter the blood alcohol concentrations nor change the corticosterone levels in rodents. Given that AUD is a major health-care challenge causing an enormous cost to society and novel treatment strategies are warranted, our data suggest that NMU analogues deserve to be evaluated as novel treatment of AUD in humans.
Collapse
Affiliation(s)
- Daniel Vallöf
- Department of Pharmacology, Institute of Neuroscience and PhysiologyThe Sahlgrenska Academy at the University of GothenburgGothenburgSweden
| | - Lisa Ulenius
- Department of Pharmacology, Institute of Neuroscience and PhysiologyThe Sahlgrenska Academy at the University of GothenburgGothenburgSweden
| | - Emil Egecioglu
- Department of Pharmacology, Institute of Neuroscience and PhysiologyThe Sahlgrenska Academy at the University of GothenburgGothenburgSweden
| | - Jörgen A. Engel
- Department of Pharmacology, Institute of Neuroscience and PhysiologyThe Sahlgrenska Academy at the University of GothenburgGothenburgSweden
| | - Elisabet Jerlhag
- Department of Pharmacology, Institute of Neuroscience and PhysiologyThe Sahlgrenska Academy at the University of GothenburgGothenburgSweden
| |
Collapse
|
5
|
Muelbl MJ, Nawarawong NN, Clancy PT, Nettesheim CE, Lim YW, Olsen CM. Responses to drugs of abuse and non-drug rewards in leptin deficient ob/ob mice. Psychopharmacology (Berl) 2016; 233:2799-811. [PMID: 27256358 PMCID: PMC5095929 DOI: 10.1007/s00213-016-4323-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 05/09/2016] [Indexed: 12/28/2022]
Abstract
RATIONALE Although leptin receptors are found in hypothalamic nuclei classically associated with homeostatic feeding mechanisms, they are also present in brain regions known to regulate hedonic-based feeding, natural reward processing, and responses to drugs of abuse. The ob/ob mouse is deficient in leptin signaling, and previous work has found altered mesolimbic dopamine signaling and sensitivity to the locomotor activating effects of amphetamine in these mice. OBJECTIVES We directly assessed responses to three drugs of abuse and non-drug rewards in the leptin-deficient ob/ob mouse. METHODS Ob/ob mice were tested in assays of sweet preference, novelty seeking, and drug reward/reinforcement. RESULTS In assays of novelty seeking, novel open field activity and operant sensation seeking were reduced in ob/ob mice, although novel object interaction and novel environment preference were comparable to wild types. We also found that ob/ob mice had specific phenotypes in regard to cocaine: conditioned place preference for 2.5 mg/kg was increased, while the locomotor response to 10 mg/kg was reduced, and cocaine self-administration was the same as wild types. Ob/ob mice also acquired self-administration of the potent opioid remifentanil, but breakpoints for the drug were significantly reduced. Finally, we found significant differences in ethanol drinking in ob/ob mice that correlated negatively with body weight and positively with operant sensation seeking. CONCLUSIONS In conclusion, ob/ob mice displayed task-specific deficits in novelty seeking and dissociable differences in reward/reinforcement associated with cocaine, remifentanil, and ethanol.
Collapse
Affiliation(s)
- Matthew J. Muelbl
- Neuroscience Research Center and Department of Pharmacology & Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Natalie N. Nawarawong
- Neuroscience Research Center and Department of Pharmacology & Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Patrick T. Clancy
- Neuroscience Research Center and Department of Pharmacology & Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Catherine E. Nettesheim
- Neuroscience Research Center and Department of Pharmacology & Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Yi Wei Lim
- Neuroscience Research Center and Department of Pharmacology & Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Christopher M. Olsen
- Neuroscience Research Center and Department of Pharmacology & Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| |
Collapse
|
6
|
Vallöf D, Vestlund J, Engel JA, Jerlhag E. The Anorexigenic Peptide Neuromedin U (NMU) Attenuates Amphetamine-Induced Locomotor Stimulation, Accumbal Dopamine Release and Expression of Conditioned Place Preference in Mice. PLoS One 2016; 11:e0154477. [PMID: 27139195 PMCID: PMC4854378 DOI: 10.1371/journal.pone.0154477] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 04/14/2016] [Indexed: 12/28/2022] Open
Abstract
Amphetamine dependence, besides its substantial economical consequence, is a serious cause of mortality and morbidity. By investigations of the neurochemical correlates through which addictive drugs, such as amphetamine, activate the mesoaccumbal dopamine system unique targets for treatment of drug addiction can be identified. This reward link consists of a dopamine projection from the ventral tegmental area to the nucleus accumbens (NAc) suggesting that these brain areas are important for reward. The physiological function of gut-brain peptides has expanded beyond food intake modulation and involves regulation of drug reinforcement. A novel candidate for reward regulation is the anorexigenic peptide neuromedin U (NMU). We therefore investigated the effects of intracerebroventricular (icv) administration of NMU on amphetamine’s well-documented effects on the mesoaccumbal dopamine system, i.e. locomotor stimulation and accumbal dopamine release in mice. In addition, the effect of accumbal NMU administration on locomotor activity was examined. The effect of NMU, icv or intra-NAc, on the expression of conditioned place preference (CPP) was elucidated. Firstly, we showed that icv administration of NMU attenuate the amphetamine-induced locomotor stimulation, accumbal dopamine release and expression of CPP in mice. Secondly, we found that a lower dose of NMU (icv) reduce the amphetamine-induced locomotor stimulation in mice. Thirdly, we demonstrated that NMU administration into the NAc block the ability of amphetamine to cause a locomotor stimulation in mice. However, accumbal NMU administration did not attenuate the amphetamine-induced expression of CPP in mice. Our novel data suggest that central NMU signalling is involved in development of amphetamine dependence.
Collapse
Affiliation(s)
- Daniel Vallöf
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Jesper Vestlund
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Jörgen A Engel
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Elisabet Jerlhag
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| |
Collapse
|
7
|
Mayfield J, Arends MA, Harris RA, Blednov YA. Genes and Alcohol Consumption: Studies with Mutant Mice. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 126:293-355. [PMID: 27055617 PMCID: PMC5302130 DOI: 10.1016/bs.irn.2016.02.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In this chapter, we review the effects of global null mutant and overexpressing transgenic mouse lines on voluntary self-administration of alcohol. We examine approximately 200 publications pertaining to the effects of 155 mouse genes on alcohol consumption in different drinking models. The targeted genes vary in function and include neurotransmitter, ion channel, neuroimmune, and neuropeptide signaling systems. The alcohol self-administration models include operant conditioning, two- and four-bottle choice continuous and intermittent access, drinking in the dark limited access, chronic intermittent ethanol, and scheduled high alcohol consumption tests. Comparisons of different drinking models using the same mutant mice are potentially the most informative, and we will highlight those examples. More mutants have been tested for continuous two-bottle choice consumption than any other test; of the 137 mouse genes examined using this model, 97 (72%) altered drinking in at least one sex. Overall, the effects of genetic manipulations on alcohol drinking often depend on the sex of the mice, alcohol concentration and time of access, genetic background, as well as the drinking test.
Collapse
Affiliation(s)
- J Mayfield
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, United States
| | - M A Arends
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, United States
| | - R A Harris
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, United States.
| | - Y A Blednov
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX, United States
| |
Collapse
|
8
|
Korpi ER, den Hollander B, Farooq U, Vashchinkina E, Rajkumar R, Nutt DJ, Hyytiä P, Dawe GS. Mechanisms of Action and Persistent Neuroplasticity by Drugs of Abuse. Pharmacol Rev 2015; 67:872-1004. [DOI: 10.1124/pr.115.010967] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
|
9
|
Beckett EL, Martin C, Yates Z, Veysey M, Duesing K, Lucock M. Bitter taste genetics--the relationship to tasting, liking, consumption and health. Food Funct 2015; 5:3040-54. [PMID: 25286017 DOI: 10.1039/c4fo00539b] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Bitter is the most complex of human tastes, and is arguably the most important. Aversion to bitter taste is important for detecting toxic compounds in food; however, many beneficial nutrients also taste bitter and these may therefore also be avoided as a consequence of bitter taste. While many polymorphisms in TAS2R genes may result in phenotypic differences that influence the range and sensitivity of bitter compounds detected, the full extent to which individuals differ in their abilities to detect bitter compounds remains unknown. Simple logic suggests that taste phenotypes influence food preferences, intake and consequently health status. However, it is becoming clear that genetics only plays a partial role in predicting preference, intake and health outcomes, and the complex, pleiotropic relationships involved are yet to be fully elucidated.
Collapse
Affiliation(s)
- Emma L Beckett
- School of Environmental and Life Sciences, University of Newcastle, Brush Rd, Ourimbah, NSW 2258, Australia.
| | | | | | | | | | | |
Collapse
|
10
|
Xu L. Leptin action in the midbrain: From reward to stress. J Chem Neuroanat 2014; 61-62:256-65. [DOI: 10.1016/j.jchemneu.2014.06.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 06/13/2014] [Accepted: 06/25/2014] [Indexed: 12/11/2022]
|
11
|
Modeling combined schizophrenia-related behavioral and metabolic phenotypes in rodents. Behav Brain Res 2014; 276:130-42. [PMID: 24747658 DOI: 10.1016/j.bbr.2014.04.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/08/2014] [Accepted: 04/09/2014] [Indexed: 12/11/2022]
Abstract
Schizophrenia is a chronic, debilitating disorder with a complex behavioral and cognitive phenotype underlined by a similarly complex etiology involving an interaction between susceptibility genes and environmental factors during early development. Limited progress has been made in developing novel pharmacotherapy, partly due to a lack of valid animal models. The recent recognition of the potentially causal role of central and peripheral energy metabolism in the pathophysiology of schizophrenia raises the need of research on animal models that combine both behavioral and metabolic phenotypic domains, similar to what have been identified in humans. In this review we focus on selected genetic (DBA/2J mice, leptin receptor mutants, and PSD-93 knockout mice), early neurodevelopmental (maternal protein deprivation) and pharmacological (acute phencyclidine) animal models that capture the combined behavioral and metabolic abnormalities shown by schizophrenic patients. In reviewing behavioral phenotypes relevant to schizophrenia we apply the principles established by the Research Domain Criteria (RDoC) for better translation. We demonstrate that etiologically diverse manipulations such as specific breeding, deletion of genes that are primarily involved in metabolic regulation and in synaptic plasticity, as well as early metabolic deprivation and adult pharmacological challenge of the glutamate system can lead to schizophrenia-related behavioral and metabolic phenotypes, which suggest that these pathways might be interlinked. We propose that using animal models that combine different domains of schizophrenia can be used as a translationally valid approach to capture the system-level complex interplay between peripheral and central processes in the development of psychopathology.
Collapse
|
12
|
Engel JA, Jerlhag E. Role of appetite-regulating peptides in the pathophysiology of addiction: implications for pharmacotherapy. CNS Drugs 2014; 28:875-86. [PMID: 24958205 PMCID: PMC4181507 DOI: 10.1007/s40263-014-0178-y] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Food intake and appetite are regulated by various circulating hormones including ghrelin and glucagon-like-peptide 1 (GLP-1). Ghrelin, mainly released from the stomach, increases food intake, induces appetite, enhances adiposity as well as releases growth hormone. Hypothalamic "ghrelin receptors" (GHS-R1A) have a critical role in food intake regulation, but GHS-R1A are also expressed in reward related areas. GLP-1 is produced in the intestinal mucosa as well as in the hindbrain in response to nutrient ingestion. This gut-brain hormone reduces food intake as well as regulates glucose homeostasis, foremost via GLP-1 receptors in hypothalamus and brain stem. However, GLP-1 receptors are expressed in areas intimately associated with reward regulation. Given that regulation of food and drug intake share common neurobiological substrates, the possibility that ghrelin and GLP-1 play an important role in reward regulation should be considered. Indeed, this leading article describes that the orexigenic peptide ghrelin activates the cholinergic-dopaminergic reward link, an important part of the reward systems in the brain associated with reinforcement and thereby increases the incentive salience for motivated behaviors via this system. We also review the role of ghrelin signaling for reward induced by alcohol and addictive drugs from a preclinical, clinical and human genetic perspective. In addition, the recent findings showing that GLP-1 controls reward induced by alcohol, amphetamine, cocaine and nicotine in rodents are overviewed herein. Finally, the role of several other appetite regulatory hormones for reward and addiction is briefly discussed. Collectively, these data suggest that ghrelin and GLP-1 receptors may be novel targets for development of pharmacological treatments of alcohol and drug dependence.
Collapse
Affiliation(s)
- Jörgen A. Engel
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, POB 431, 405 30 Gothenburg, Sweden
| | - Elisabet Jerlhag
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, POB 431, 405 30 Gothenburg, Sweden
| |
Collapse
|
13
|
Suchankova P, Steensland P, Fredriksson I, Engel JA, Jerlhag E. Ghrelin receptor (GHS-R1A) antagonism suppresses both alcohol consumption and the alcohol deprivation effect in rats following long-term voluntary alcohol consumption. PLoS One 2013; 8:e71284. [PMID: 23977009 PMCID: PMC3748070 DOI: 10.1371/journal.pone.0071284] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 07/04/2013] [Indexed: 11/19/2022] Open
Abstract
Alcohol dependence is a heterogeneous disorder where several signalling systems play important roles. Recent studies implicate that the gut-brain hormone ghrelin, an orexigenic peptide, is a potential mediator of alcohol related behaviours. Ghrelin increases whereas a ghrelin receptor (GHS-R1A) antagonist decreases alcohol consumption as well as operant self-administration of alcohol in rodents that have consumed alcohol for twelve weeks. In the present study we aimed at investigating the effect of acute and repeated treatment with the GHS-R1A antagonist JMV2959 on alcohol intake in a group of rats following voluntarily alcohol consumption for two, five and eight months. After approximately ten months of voluntary alcohol consumption the expression of the GHS-R1A gene (Ghsr) as well as the degree of methylation of a CpG island found in Ghsr was examined in reward related brain areas. In a separate group of rats, we examined the effect of the JMV2959 on alcohol relapse using the alcohol deprivation paradigm. Acute JMV2959 treatment was found to decrease alcohol intake and the effect was more pronounced after five, compared to two months of alcohol exposure. In addition, repeated JMV2959 treatment decreased alcohol intake without inducing tolerance or rebound increase in alcohol intake after the treatment. The GHS-R1A antagonist prevented the alcohol deprivation effect in rats. There was a significant down-regulation of the Ghsr expression in the ventral tegmental area (VTA) in high- compared to low-alcohol consuming rats after approximately ten months of voluntary alcohol consumption. Further analysis revealed a negative correlation between Ghsr expression in the VTA and alcohol intake. No differences in methylation degree were found between high- compared to low-alcohol consuming rats. These findings support previous studies showing that the ghrelin signalling system may constitute a potential target for development of novel treatment strategies for alcohol dependence.
Collapse
Affiliation(s)
- Petra Suchankova
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Pia Steensland
- Department of Clinical Neuroscience, Division of Psychiatry, Karolinska Institutet, Stockholm, Sweden
| | - Ida Fredriksson
- Department of Clinical Neuroscience, Division of Psychiatry, Karolinska Institutet, Stockholm, Sweden
| | - Jörgen A. Engel
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Elisabet Jerlhag
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| |
Collapse
|
14
|
Egecioglu E, Steensland P, Fredriksson I, Feltmann K, Engel JA, Jerlhag E. The glucagon-like peptide 1 analogue Exendin-4 attenuates alcohol mediated behaviors in rodents. Psychoneuroendocrinology 2013; 38:1259-70. [PMID: 23219472 DOI: 10.1016/j.psyneuen.2012.11.009] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 11/06/2012] [Accepted: 11/07/2012] [Indexed: 12/25/2022]
Abstract
Development of alcohol use disorders largely depends on the effects of alcohol on the brain reward systems. Emerging evidence indicate that common mechanisms regulate food and alcohol intake and raise the possibility that endocrine signals from the gut may play an important role for alcohol consumption, alcohol-induced reward and the motivation to consume alcohol. Glucagon-like peptide 1 (GLP-1), a gastrointestinal peptide regulating food intake and glucose homeostasis, has recently been shown to target central brain areas involved in reward and motivation, including the ventral tegmental area and nucleus accumbens. Herein we investigated the effects of the GLP-1 receptor agonist, Exendin-4 (Ex4), on various measures of alcohol-induced reward as well as on alcohol intake and alcohol seeking behavior in rodents. Treatment with Ex4, at a dose with no effect per se, attenuated alcohol-induced locomotor stimulation and accumbal dopamine release in mice. Furthermore, conditioned place preference for alcohol was abolished by both acute and chronic treatment with Ex4 in mice. Finally we found that Ex4 treatment decreased alcohol intake, using the intermittent access 20% alcohol two-bottle-choice model, as well as alcohol seeking behavior, using the progressive ratio test in the operant self-administration model, in rats. These novel findings indicate that GLP-1 signaling attenuates the reinforcing properties of alcohol implying that the physiological role of GLP-1 extends beyond glucose homeostasis and food intake regulation. Collectively these findings implicate that the GLP-1 receptor may be a potential target for the development of novel treatment strategies for alcohol use disorders.
Collapse
Affiliation(s)
- Emil Egecioglu
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | | | | | | | | | | |
Collapse
|
15
|
Pohl JB, Baldwin BA, Dinh BL, Rahman P, Smerek D, Prado FJ, Sherazee N, Atkinson NS. Ethanol preference in Drosophila melanogaster is driven by its caloric value. Alcohol Clin Exp Res 2012; 36:1903-12. [PMID: 22551215 DOI: 10.1111/j.1530-0277.2012.01817.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 02/15/2012] [Indexed: 12/01/2022]
Abstract
BACKGROUND Perhaps the most difficult thing to ascertain concerning the behavior of another animal is its motivation. The motivation underlying the preference of Drosophila melanogaster for ethanol (EtOH)-rich food has long been ascribed to its value as a food. A recently introduced idea is that, as in humans, the pharmacological effects of EtOH also motivate the fly to choose EtOH-rich food over nonalcoholic food. METHODS Flies are given a choice between pipets that contain liquid food and liquid food supplemented with EtOH. In some experiments, carbohydrates are added to the non-EtOH-containing food to balance the calories for EtOH. RESULTS We confirm that D. melanogaster indeed prefer food that is supplemented with EtOH. However, if the alternative food choice is isocaloric, D. melanogaster usually do not show any preference for a 10% EtOH solution. Even after EtOH preference has been established, it can be completely reversed if the alternative food is calorically supplemented. This occurs even when the carbohydrate solution used to balance calories is not gustatorily attractive. Furthermore, if the alternative food contains more calories than the EtOH food, the flies will prefer the non-EtOH food. We go on to show that during the preference assay that EtOH in the fly does not exceed 4 mM, which in mammals is a nonintoxicating dose. CONCLUSIONS We conclude that preference for EtOH in this assay arises not from the pharmacological effects of EtOH but rather because of its nutritive value.
Collapse
Affiliation(s)
- Jascha B Pohl
- Waggoner Center for Alcohol and Addiction Research , Section of Neurobiology, The University of Texas at Austin, TX 78712, USA
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Giardino WJ, Cocking DL, Kaur S, Cunningham CL, Ryabinin AE. Urocortin-1 within the centrally-projecting Edinger-Westphal nucleus is critical for ethanol preference. PLoS One 2011; 6:e26997. [PMID: 22046429 PMCID: PMC3203949 DOI: 10.1371/journal.pone.0026997] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 10/07/2011] [Indexed: 12/03/2022] Open
Abstract
Converging lines of evidence point to the involvement of neurons of the centrally projecting Edinger-Westphal nucleus (EWcp) containing the neuropeptide Urocortin-1 (Ucn1) in excessive ethanol (EtOH) intake and EtOH sensitivity. Here, we expanded these previous findings by using a continuous-access, two-bottle choice drinking paradigm (3%, 6%, and 10% EtOH vs. tap water) to compare EtOH intake and EtOH preference in Ucn1 genetic knockout (KO) and wild-type (WT) mice. Based on previous studies demonstrating that electrolytic lesion of the EWcp attenuated EtOH intake and preference in high-drinking C57BL/6J mice, we also set out to determine whether EWcp lesion would differentially alter EtOH consumption in Ucn1 KO and WT mice. Finally, we implemented well-established place conditioning procedures in KO and WT mice to determine whether Ucn1 and the corticotropin-releasing factor type-2 receptor (CRF-R2) were involved in the rewarding and aversive effects of EtOH (2 g/kg, i.p.). Results from these studies revealed that (1) genetic deletion of Ucn1 dampened EtOH preference only in mice with an intact EWcp, but not in mice that received lesion of the EWcp, (2) lesion of the EWcp dampened EtOH intake in Ucn1 KO and WT mice, but dampened EtOH preference only in WT mice expressing Ucn1, and (3) genetic deletion of Ucn1 or CRF-R2 abolished the conditioned rewarding effects of EtOH, but deletion of Ucn1 had no effect on the conditioned aversive effects of EtOH. The current findings provide strong support for the hypothesis that EWcp-Ucn1 neurons play an important role in EtOH intake, preference, and reward.
Collapse
Affiliation(s)
- William J. Giardino
- Department of Behavioral Neuroscience and Portland Alcohol Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Davelle L. Cocking
- Department of Behavioral Neuroscience and Portland Alcohol Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Simranjit Kaur
- Department of Behavioral Neuroscience and Portland Alcohol Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Christopher L. Cunningham
- Department of Behavioral Neuroscience and Portland Alcohol Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Andrey E. Ryabinin
- Department of Behavioral Neuroscience and Portland Alcohol Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
- * E-mail:
| |
Collapse
|
17
|
Lyons AM, Lowery EG, Sparta DR, Thiele TE. Effects of food availability and administration of orexigenic and anorectic agents on elevated ethanol drinking associated with drinking in the dark procedures. Alcohol Clin Exp Res 2009; 32:1962-8. [PMID: 18782340 DOI: 10.1111/j.1530-0277.2008.00784.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
BACKGROUND Drinking in the dark (DID) procedures have recently been developed to induce high levels of ethanol drinking in C57BL/6J mice, which result in blood ethanol concentrations reaching levels that have measurable affects on physiology and/or behavior. The present study determined if increased ethanol drinking associated with DID procedures may be motivated by caloric need rather than by the postingestive pharmacological effects of ethanol. To this end, food availability was manipulated or mice were given peripheral administration of orexigenic or anorectic agents during DID procedures. METHODS C57BL/6J had 2-hours of access to the 20% (v/v) ethanol solution beginning 3-hours into the dark cycle on days 1 to 3, and 4-hours of access to the ethanol bottle on day 4 of DID procedures. In Experiment 1, the effects of food deprivation on ethanol consumption during DID procedures was assessed. In Experiments 2 and 3, mice were given intraperitoneal (i.p.) injection of the orexigenic peptide ghrelin (0, 10 or 30 mg/kg) or the anorectic protein leptin (0 or 20 microg/g), respectively, before access to ethanol on day 4 of DID procedures. In Experiment 4, hourly consumption of food and a 0.05% saccharin solution were assessed over a period of hours that included those used with DID procedures. RESULTS Consistent with previous research, mice achieved blood ethanol concentrations (BECs) that ranged between 100 and 150 mg% on day 4 of DID experiments. Neither food deprivation nor administration of orexigenic or anorectic compounds significantly altered ethanol drinking with DID procedures. Interestingly, mice exhibited their highest level of food and saccharin solution consumption during hours that overlapped with DID procedures. CONCLUSIONS The present observations are inconsistent with the hypothesis that C57BL/6J mice consume large amounts of ethanol during DID procedures in order to satisfy a caloric need.
Collapse
Affiliation(s)
- Angela M Lyons
- Department of Psychology, Bowles Center for Alcohol Studies, University of North Carolina, Chapel Hill, North Carolina 27599-3270, USA
| | | | | | | |
Collapse
|
18
|
Pan W, Barron M, Hsuchou H, Tu H, Kastin AJ. Increased leptin permeation across the blood-brain barrier after chronic alcohol ingestion. Neuropsychopharmacology 2008; 33:859-66. [PMID: 17487223 PMCID: PMC3939624 DOI: 10.1038/sj.npp.1301452] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Leptin, a polypeptide mainly produced in the periphery, crosses the blood-brain barrier (BBB) by receptor-mediated transport to exert multiple central nervous system actions including decreased food intake. The reciprocal interactions between leptin transport and alcohol drinking are not clear. In this study, we tested whether alcohol increases leptin entry into brain and, if this occurs, whether it is a consequence of a generalized increase in the permeability of the BBB. BBB permeability to albumin, the increased permeation of which indicates BBB disruption, as well as to leptin was measured after alcohol ingestion. CD1 and B6 mice ingested a 5% liquid alcohol diet or its isocaloric control for 2 weeks. Alcohol ingestion resulted in increased blood-alcohol levels, decreased blood-leptin concentrations, and increased permeation of radioactively labeled leptin across the BBB as shown by in situ perfusion. Although the increased influx of the vascular marker albumin into brain showed partial disruption of the BBB, the influx of (125)I-leptin still could be suppressed by excess unlabeled leptin, indicating persistence of its saturable transport system. When given a choice of either alcohol or control diet, even the alcohol-preferring B6 mice showed a significantly greater preference for the control liquid diet, and there was no evidence of BBB disruption or alterated leptin transport. Furthermore, acute alcohol intoxication induced by intraperitoneal injection of 20% alcohol did not result in BBB disruption or increased leptin permeation 4 h later. Thus, partial disruption of the BBB and increased permeation of leptin in both CD1 and B6 mice were only induced by chronic alcohol ingestion. The results showing increased leptin permeation across the BBB lead to the speculation that leptin may serve as a homeostatic feeding signal in these mice.
Collapse
Affiliation(s)
- Weihong Pan
- Blood-Brain Barrier Lab, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA.
| | | | | | | | | |
Collapse
|
19
|
Jerlhag E, Egecioglu E, Dickson SL, Douhan A, Svensson L, Engel JA. Ghrelin administration into tegmental areas stimulates locomotor activity and increases extracellular concentration of dopamine in the nucleus accumbens. Addict Biol 2007; 12:6-16. [PMID: 17407492 DOI: 10.1111/j.1369-1600.2006.00041.x] [Citation(s) in RCA: 320] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Ghrelin stimulates appetite, increases food intake and causes adiposity by mechanisms that include direct actions on the brain. Previously, we showed that intracerebroventricular administration of ghrelin has stimulatory and dopamine-enhancing properties. These effects of ghrelin are mediated via central nicotine receptors, suggesting that ghrelin can activate the acetylcholine-dopamine reward link. This reward link consists of cholinergic input from the laterodorsal tegmental area (LDTg) to the mesolimbic dopamine system that originates in the ventral tegmental area (VTA) and projects to the nucleus accumbens. Given that growth hormone secretagogue receptors (GHSR-1A) are expressed in the VTA and LDTg, brain areas involved in reward, the present series of experiments were undertaken to examine the hypothesis that these regions may mediate the stimulatory and dopamine-enhancing effects of ghrelin, by means of locomotor activity and in vivo microdialysis in freely moving mice. We found that local administration of ghrelin into the VTA (1 microg in 1 microl) induced an increase in locomotor activity and in the extracellular concentration of accumbal dopamine. In addition, local administration of ghrelin into the LDTg (1 microg in 1 microl) caused a locomotor stimulation and an increase in the extracellular levels of accumbal dopamine. Taken together, this indicates that ghrelin might, via activation of GHSR-1A in the VTA and LDTg, stimulate the acetylcholine-dopamine reward link, implicating that ghrelin is a part of the neurochemical overlap between the reward systems and those that regulate energy balance.
Collapse
Affiliation(s)
- Elisabet Jerlhag
- Institute of Neuroscience and Physiology, Department of Pharmacology, Göteborg University, Göteborg, Sweden
| | | | | | | | | | | |
Collapse
|
20
|
Erhardt E, Zibetti LCE, Godinho JM, Bacchieri B, Barros HMT. Behavioral changes induced by cocaine in mice are modified by a hyperlipidic diet or recombinant leptin. Braz J Med Biol Res 2006; 39:1625-35. [PMID: 17160272 DOI: 10.1590/s0100-879x2006001200014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2005] [Accepted: 08/21/2006] [Indexed: 11/22/2022] Open
Abstract
The objective of the present study was to determine if the acute behavioral effects of cocaine acutely administered intraperitoneally (ip) at doses of 5, 10 and 20 mg/kg on white male CF1 mice, 90 days of age, would be influenced by leptin acutely administered ip (at doses of 5, 10 and 20 microg/kg) or by endogenous leptin production enhanced by a high-fat diet. The acute behavioral effects of cocaine were evaluated in open-field, elevated plus-maze and forced swimming tests. Results were compared between a group of 80 mice consuming a balanced diet and a high-fat diet, and a group of 80 mice fed a commercially available rodent chow formula (Ralston Purina) but receiving recombinant leptin (rLeptin) or saline ip. Both the high-fat-fed and rLeptin-treated mice showed decreased locomotion in the open-field test, spent more time in the open arms of the elevated plus-maze and showed less immobility time in the forced swimming test (F(1,68) = 7.834, P = 0.007). There was an interaction between diets and cocaine/saline treatments in locomotion (F(3,34) = 3.751, P = 0.020) and exploration (F(3,34) = 3.581, P = 0.024). These results suggest that anxiolytic effects and increased general activity were induced by leptin in cocaine-treated mice and that low leptin levels are associated with behavioral depression. Chronic changes in diet composition producing high leptin levels or rLeptin treatment may result in an altered response to cocaine in ethologic tests that measure degrees of anxiety and depression, which could be attributed to an antagonistic effect of leptin.
Collapse
Affiliation(s)
- E Erhardt
- Departamento de Farmacologia, Faculdade Federal de Ciencias Medicas de Porto Alegre, Av. Neuza G. Brizola 495, 90460-230 Porto Alegre, RS, Brazil.
| | | | | | | | | |
Collapse
|
21
|
Crabbe JC, Phillips TJ, Harris RA, Arends MA, Koob GF. Alcohol-related genes: contributions from studies with genetically engineered mice. Addict Biol 2006; 11:195-269. [PMID: 16961758 DOI: 10.1111/j.1369-1600.2006.00038.x] [Citation(s) in RCA: 195] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Since 1996, nearly 100 genes have been studied for their effects related to ethanol in mice using genetic modifications including gene deletion, gene overexpression, gene knock-in, and occasionally by studying existing mutants. Nearly all such studies have concentrated on genes expressed in brain, and the targeted genes range widely in their function, including most of the principal neurotransmitter systems, several neurohormones, and a number of signaling molecules. We review 141 published reports of effects (or lack thereof) of 93 genes on responses to ethanol. While most studies have focused on ethanol self-administration and reward, and/or sedative effects, other responses studied include locomotor stimulation, anxiolytic effects, and neuroadaptation (tolerance, sensitization, withdrawal). About 1/4 of the engineered mutations increase self-administration, 1/3 decrease it, and about 40% have no significant effect. In many cases, the effects on self-administration are rather modest and/or depend on the specific experimental procedures. In some cases, genes in the background strains on which the mutant is placed are important for results. Not surprisingly, review of the systems affected further supports roles for serotonin, gamma-aminobutyric acid, opioids and dopamine, all of which have long been foci of alcohol research. Novel modulatory effects of protein kinase C and G protein-activated inwardly rectifying K+ (GIRK) channels are also suggested. Some newer research with cannabinoid systems is promising, and has led to ongoing clinical trials.
Collapse
Affiliation(s)
- John C Crabbe
- Portland Alcohol Research Center, Department of Behavioral Neuroscience, Oregon Health & Science University, and Department of Veterans Affairs Medical Center, USA
| | | | | | | | | |
Collapse
|
22
|
Ealey KN, Fonseca D, Archer MC, Ward WE. Bone abnormalities in adolescent leptin-deficient mice. ACTA ACUST UNITED AC 2006; 136:9-13. [PMID: 16764953 DOI: 10.1016/j.regpep.2006.04.013] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2005] [Revised: 03/24/2006] [Accepted: 04/28/2006] [Indexed: 11/30/2022]
Abstract
Ob/ob and db/db mice have different aberrations in leptin signaling that both lead to abnormalities in bone mineral density (BMD), and bone histological and histomorphometric outcomes. A few studies have directly compared bone metabolism in ob/ob and db/db mice, and biomechanical strength properties that are surrogate measures of fracture risk, have not been extensively studied. This study compared bone mineral content (BMC), BMD and biomechanical strength properties of femurs and lumbar vertebrae among 10 week old male ob/ob, db/db and C57Bl/6 wildtype (WT) mice. Femurs and lumbar vertebrae were specifically studied to determine if trabecular and cortical bone are regulated by leptin in a similar manner in ob/ob and db/db mice. Femurs of ob/ob and db/db mice had lower BMC, BMD and biomechanical strength properties, including peak load, compared to WT mice. In contrast, lumbar vertebrae BMC and BMD did not differ among genotypes, nor did the peak load from compression testing of an individual lumbar vertebra differ among groups. These findings suggest that leptin deficiency in adolescent male mice first results in changes in femurs, a representative long bone, and alterations in lumbar vertebrae may occur later in life.
Collapse
Affiliation(s)
- Kafi N Ealey
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, 150 College Street, Toronto, Ontario, Canada M5S 3E2
| | | | | | | |
Collapse
|
23
|
Jerlhag E, Egecioglu E, Dickson SL, Andersson M, Svensson L, Engel JA. Ghrelin stimulates locomotor activity and accumbal dopamine-overflow via central cholinergic systems in mice: implications for its involvement in brain reward. Addict Biol 2006; 11:45-54. [PMID: 16759336 DOI: 10.1111/j.1369-1600.2006.00002.x] [Citation(s) in RCA: 284] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
It is becoming increasingly apparent that there is a degree of neurochemical overlap between the reward systems and those regulating energy balance. We therefore investigated whether ghrelin, a stomach-derived and centrally derived orexigenic peptide, might act on the reward systems. Central ghrelin administration (1 microg/microL, to the third ventricle) induced an acute increase in locomotor activity as well as dopamine-overflow in the nucleus accumbens, suggesting that ghrelin can activate the mesoaccumbal dopamine system originating in the ventral tegmental area, a system associated with reward and motivated behaviour. The cholinergic afferents to the ventral tegmental area have been implicated in natural reward and in regulating mesoaccumbal dopamine neurons. The possibility that nicotinic receptors are involved in mediating the stimulatory and dopamine-enhancing effects of ghrelin is supported by the findings that peripheral injection of the unselective nicotinic antagonist mecamylamine (2.0 mg/kg) blocked these ghrelin-induced effects. Tentatively, ghrelin may, via activation of the acetylcholine-dopamine reward link, increase the incentive values of signals associated with motivated behaviours of importance for survival such as feeding behaviour. It will be important to discover whether this has therapeutic implications for compulsive addictive behaviours, such as eating behaviour disorders and drug dependence.
Collapse
Affiliation(s)
- Elisabet Jerlhag
- Institute of Pharmacology and Physiology, Department of Pharmacology, Göteborg University, Sweden
| | | | | | | | | | | |
Collapse
|
24
|
Duncan EA, Proulx K, Woods SC. Central administration of melanin-concentrating hormone increases alcohol and sucrose/quinine intake in rats. Alcohol Clin Exp Res 2005; 29:958-64. [PMID: 15976521 DOI: 10.1097/01.alc.0000167741.42353.10] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Alcohol is a caloric compound that can contribute to energy intake. Therefore, peptides that regulate energy balance likely modify the motivation to consume alcohol. Melanin-concentrating hormone (MCH) regulates energy homeostasis and has been implicated in other behaviors that impact alcohol consumption (i.e., anxiety, fluid balance, and reward). We tested the hypothesis that MCH would decrease the motivation to consume alcohol secondarily to reducing anxiety. METHODS Rats were trained to drink 10% ethanol or an isocaloric concentration of sucrose with use of a sucrose-fading technique. MCH (1, 5, or 10 microg) or its saline vehicle was administered into the third cerebral ventricle (i3vt), and intake of ethanol or sucrose and chow was assessed for 2 hr. Alcohol-naïve rats were evaluated in an elevated plus maze after i3vt MCH (10 microg), neuropeptide Y, or saline administration. RESULTS Contrary to the hypothesis, MCH dose-dependently increased alcohol intake: saline = 0.7 +/- 0.1 g/kg, 1 microg MCH = 1.0 +/- 0.1 g/kg, 5 microg MCH = 1.2 +/- 0.1 g/kg, and 10 microg MCH = 1.8 +/- 0.3 g/kg (p < 0.01), and this was true whether water was simultaneously available or not. MCH also significantly increased sucrose intake (saline = 1.0 +/- 0.3 g/kg, 10 mug MCH = 1.4 +/- 0.5 g/kg; p < 0.05). MCH had no effect on time spent in the open arms (54.3 +/- 11.5 sec) relative to saline (58.2 +/- 23.8 sec), whereas neuropeptide Y, a known anxiolytic, increased time spent on the open arms (119.2 +/- 22 sec, p < 0.05). CONCLUSIONS We conclude that MCH nonspecifically increases ingestive behavior. Furthermore, MCH had no apparent effect on anxiety. The ability of MCH to increase alcohol and/or sucrose intake may be explained by the effect of MCH on energy balance and/or reward processes.
Collapse
Affiliation(s)
- Elizabeth A Duncan
- Department of Psychiatry, University of Cincinnati, Cincinnati, Ohio 45237, USA.
| | | | | |
Collapse
|
25
|
Litten RZ, Fertig J, Mattson M, Egli M. Development of medications for alcohol use disorders: recent advances and ongoing challenges. Expert Opin Emerg Drugs 2005; 10:323-43. [PMID: 15934870 DOI: 10.1517/14728214.10.2.323] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
During the past decade, efforts to develop medications for alcoholism have burgeoned. Three agents, disulfiram, naltrexone and acamprosate, are now approved in a large number of countries. Although many patients have benefited from existing medications, their effects are moderate, and some alcoholics fail to respond to them. A host of new agents are currently under active investigation. Critical barriers must be overcome to ensure that future efforts in the development of medications for alcohol use disorders reach full fruition. These challenges include: establishing key targets for drug discovery; validating animal and human screening models; and developing biomarkers to help predict treatment success. In addition, it is important to formulate methodological and statistical strategies to efficiently conduct alcohol pharmacotherapy trials; to specify genetic and phenotypic patient characteristics associated with efficacy and safety for lead compounds; to forge productive alliances among governmental agencies, the pharmaceutical industry and academic researchers to further drug development; and, ultimately and perhaps most difficult, to engage the practitioner community to incorporate medications into the alcohol treatment process.
Collapse
Affiliation(s)
- Raye Z Litten
- Division of Treatment and Recovery Research, National Institute on Alcohol Abuse and Alcoholism, 5635 Fishers Lane, Room 2041, Bethesda, MD 20852-1705, USA.
| | | | | | | |
Collapse
|