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Caron A, Jane Michael N. New Horizons: Is Obesity a Disorder of Neurotransmission? J Clin Endocrinol Metab 2021; 106:e4872-e4886. [PMID: 34117881 DOI: 10.1210/clinem/dgab421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Indexed: 11/19/2022]
Abstract
Obesity is a disease of the nervous system. While some will view this statement as provocative, others will take it as obvious. Whatever our side is, the pharmacology tells us that targeting the nervous system works for promoting weight loss. It works, but at what cost? Is the nervous system a safe target for sustainable treatment of obesity? What have we learned-and unlearned-about the central control of energy balance in the last few years? Herein we provide a thought-provoking exploration of obesity as a disorder of neurotransmission. We discuss the state of knowledge on the brain pathways regulating energy homeostasis that are commonly targeted in anti-obesity therapy and explore how medications affecting neurotransmission such as atypical antipsychotics, antidepressants, and antihistamines relate to body weight. Our goal is to provide the endocrine community with a conceptual framework that will help expending our understanding of the pathophysiology of obesity, a disease of the nervous system.
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Affiliation(s)
- Alexandre Caron
- Faculty of Pharmacy, Université Laval, Quebec City, QC, Canada
- Quebec Heart and Lung Institute, Quebec City, QC, Canada
- Montreal Diabetes Research Center, Montreal, QC, Canada
| | - Natalie Jane Michael
- Faculty of Pharmacy, Université Laval, Quebec City, QC, Canada
- Quebec Heart and Lung Institute, Quebec City, QC, Canada
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Limón-Bernal E, Roa-Coria JE, Zúñiga-Romero Á, Huerta-Cruz JC, Ruíz-Velasco IRC, Flores-Murrieta FJ, Lara-Padilla E, Reyes-García JG, Rocha-González HI. Anorectic interaction and safety of 5-hydroxytryptophan/carbidopa plus phentermine or diethylpropion in rat. Behav Pharmacol 2021; 32:368-381. [PMID: 33660661 DOI: 10.1097/fbp.0000000000000625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Drug combinations are being studied as potential therapies to increase the efficacy or improve the safety profile of weight loss medications. This study was designed to determine the anorectic interaction and safety profile of 5-hydroxytryptophan (5-HTP)/carbidopa + diethylpropion and 5-HTP/carbidopa + phentermine combinations in rats. The anorectic effect of individual drugs or in combination was evaluated by the sweetened milk test. Isobologram and interaction index were employed to determine the anorectic interaction between 5-HTP/carbidopa and diethylpropion or phentermine. Plasma serotonin (5-HT) was measured by ELISA. Safety of repeated doses of both combinations in rats was evaluated using the tail sphygmomanometer, cardiac ultrasound, hematic biometry and blood chemistry. A single oral 5-HTP, diethylpropion or phentermine dose increased the anorectic effect, in a dose-dependent fashion, in 12 h-fasted rats. A dose of carbidopa at 30 mg/kg reduced the 5-HTP-induced plasmatic serotonin concentration and augmented the 5-HTP-induced anorectic effect. Isobologram and interaction index indicated a potentiation interaction between 5-HTP/30 mg/kg carbidopa + diethylpropion and 5-HTP/30 mg/kg carbidopa + phentermine. Chronic administration of experimental ED40 of 5-HTP/30 mg/kg carbidopa + phentermine, but not 5-HTP/30 mg/kg carbidopa + diethylpropion, increased the mitral valve leaflets area. Moreover, there were no other significant changes in cardiovascular, hematic or blood parameters. Both combinations induced around 20% body weight loss after 3 months of oral administration. Results suggest that 5-HTP/30 mg/kg carbidopa potentiates the anorectic effect of diethylpropion and phentermine with an acceptable safety profile, but further clinical studies are necessary to establish their therapeutic potential in the obesity treatment.
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Affiliation(s)
- Ernesto Limón-Bernal
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional
| | - José E Roa-Coria
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional
| | - Ángel Zúñiga-Romero
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional
| | - Juan C Huerta-Cruz
- Unidad de Investigación en Farmacología, Instituto Nacional de Enfermedades Respiratorias, Ismael Cosio Villegas
| | - Irma R C Ruíz-Velasco
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, Ciudad de México, Mexico
| | - Francisco J Flores-Murrieta
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional
- Unidad de Investigación en Farmacología, Instituto Nacional de Enfermedades Respiratorias, Ismael Cosio Villegas
| | - Eleazar Lara-Padilla
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional
| | - Juan G Reyes-García
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional
| | - Héctor I Rocha-González
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional
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Cortés-Moreno GY, Roa-Coria JE, Zúñiga-Romero Á, Huerta-Cruz JC, Lara-Padilla E, del Valle-Laisequilla CF, Rocha-González HI, Reyes-García JG. Anorectic efficacy and safety of the diethylpropion-topiramate combination in rats. Drug Dev Res 2018; 79:225-233. [DOI: 10.1002/ddr.21434] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 05/13/2018] [Indexed: 12/16/2022]
Affiliation(s)
- Gabriela Y. Cortés-Moreno
- Sección de Estudios de Posgrado e Investigación Escuela Superior de Medicina; Instituto Politécnico Nacional. Plan de San Luis y Díaz Mirón s/n, Col. Casco de Santo Tomas, Miguel Hidalgo; Ciudad de México 11340 Mexico
| | - José E. Roa-Coria
- Sección de Estudios de Posgrado e Investigación Escuela Superior de Medicina; Instituto Politécnico Nacional. Plan de San Luis y Díaz Mirón s/n, Col. Casco de Santo Tomas, Miguel Hidalgo; Ciudad de México 11340 Mexico
| | - Ángel Zúñiga-Romero
- Sección de Estudios de Posgrado e Investigación Escuela Superior de Medicina; Instituto Politécnico Nacional. Plan de San Luis y Díaz Mirón s/n, Col. Casco de Santo Tomas, Miguel Hidalgo; Ciudad de México 11340 Mexico
| | - Juan C. Huerta-Cruz
- Sección de Estudios de Posgrado e Investigación Escuela Superior de Medicina; Instituto Politécnico Nacional. Plan de San Luis y Díaz Mirón s/n, Col. Casco de Santo Tomas, Miguel Hidalgo; Ciudad de México 11340 Mexico
| | - Eleazar Lara-Padilla
- Sección de Estudios de Posgrado e Investigación Escuela Superior de Medicina; Instituto Politécnico Nacional. Plan de San Luis y Díaz Mirón s/n, Col. Casco de Santo Tomas, Miguel Hidalgo; Ciudad de México 11340 Mexico
| | - Cecilia F. del Valle-Laisequilla
- Laboratorios Medix S.A. de C.V. Calzada del Hueso 39, Ejido, Viejo, 04650, Col. de Santa, Úrsula Coapa, Coyoacán; Ciudad de México Mexico
| | - Héctor I. Rocha-González
- Sección de Estudios de Posgrado e Investigación Escuela Superior de Medicina; Instituto Politécnico Nacional. Plan de San Luis y Díaz Mirón s/n, Col. Casco de Santo Tomas, Miguel Hidalgo; Ciudad de México 11340 Mexico
| | - Juan G. Reyes-García
- Sección de Estudios de Posgrado e Investigación Escuela Superior de Medicina; Instituto Politécnico Nacional. Plan de San Luis y Díaz Mirón s/n, Col. Casco de Santo Tomas, Miguel Hidalgo; Ciudad de México 11340 Mexico
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Aznar S, Hervig MES. The 5-HT2A serotonin receptor in executive function: Implications for neuropsychiatric and neurodegenerative diseases. Neurosci Biobehav Rev 2016; 64:63-82. [DOI: 10.1016/j.neubiorev.2016.02.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 11/05/2015] [Accepted: 02/08/2016] [Indexed: 02/07/2023]
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Yoon YS, Lee JS, Lee HS. Retrograde study of CART- or NPY-neuronal projection from the hypothalamic arcuate nucleus to the dorsal raphe and/or the locus coeruleus in the rat. Brain Res 2013; 1519:40-52. [DOI: 10.1016/j.brainres.2013.04.039] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Revised: 04/08/2013] [Accepted: 04/19/2013] [Indexed: 11/16/2022]
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Abstract
Analysis of the interactive effects of combinations of hormones or other manipulations with qualitatively similar individual effects is an important topic in basic and clinical endocrinology as well as other branches of basic and clinical research related to integrative physiology. Functional, as opposed to mechanistic, analyses of interactions rely on the concept of synergy, which can be defined qualitatively as a cooperative action or quantitatively as a supra-additive effect according to some metric for the addition of different dose-effect curves. Unfortunately, dose-effect curve addition is far from straightforward; rather, it requires the development of an axiomatic mathematical theory. I review the mathematical soundness, face validity, and utility of the most frequently used approaches to supra-additive synergy. These criteria highlight serious problems in the two most common synergy approaches, response additivity and Loewe additivity, which is the basis of the isobole and related response surface approaches. I conclude that there is no adequate, generally applicable, supra-additive synergy metric appropriate for endocrinology or any other field of basic and clinical integrative physiology. I recommend that these metrics be abandoned in favor of the simpler definition of synergy as a cooperative, i.e., nonantagonistic, effect. This simple definition avoids mathematical difficulties, is easily applicable, meets regulatory requirements for combination therapy development, and suffices to advance phenomenological basic research to mechanistic studies of interactions and clinical combination therapy research.
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Roth JD, Trevaskis JL, Turek VF, Parkes DG. “Weighing in” on synergy: Preclinical research on neurohormonal anti-obesity combinations. Brain Res 2010; 1350:86-94. [DOI: 10.1016/j.brainres.2010.01.027] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 01/08/2010] [Accepted: 01/11/2010] [Indexed: 01/01/2023]
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Whigham LD, Dhurandhar NV, Rahko PS, Atkinson RL. Comparison of combinations of drugs for treatment of obesity: body weight and echocardiographic status. Int J Obes (Lond) 2006; 31:850-7. [PMID: 17146452 DOI: 10.1038/sj.ijo.0803498] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Obesity treatment with single drugs produces weight losses of about 8-10% of initial body weight. Few studies of combinations of drugs for treating obesity have been published. The combination of phentermine, an adrenergic agent, and fenfluramine, a serotonergic agent, (phen-fen) produced weight losses of about 15% of initial body weight. Fenfluramine is no longer available because it was associated with cardiac valve lesions. Phentermine-fluoxetine (phen-flu) has been proposed as an alternative for phen-fen. OBJECTIVE To compare the efficacy of treatment and prevalence of cardiac valve abnormalities on phen-flu vs phen-fen. DESIGN Retrospective chart review of all patients treated for at least 3 months with phen-flu (N=97) to a random sample of patients treated with phen-fen (N=98) in the Clinical Nutrition Clinic at the University of Wisconsin. Comparison of echocardiograms in all patients treated solely with phen-flu (N=21) to a random sample of patients treated with phen-fen (N=47), and to a group of subjects never treated with obesity drugs (N=26). RESULTS With last observation carried forward analysis (LOCF), at 6 months of treatment the phen-fen patients lost 12.6+/-0.6% of baseline weight and phen-flu patients lost 9.0+/-0.6% (P<0.001). With completers analysis, there were no significant differences in weight loss as a percent of baseline weight at 6 months (14.4+/-0.6 vs 13.3+/-0.9%). LOCF decreases in body mass index (BMI) at 6 months were -5.3 and -3.6 kg/m(2) for phen-fen and phen-flu, respectively (P<0.001), and 6.2+/-0.3 vs 5.4+/-0.4 kg/m(2), respectively, for the completers analysis (P - NS). Dropout rate at 6 months was higher in phen-flu subjects (44 vs 28%). In subjects without atherosclerosis of valves (presumably pre-existing), cardiac valve lesions occurred in eight of 38 phen-fen subjects and in none of 15 phen-flu subjects or 25 control subjects who had not been treated with drugs. CONCLUSIONS The combination of phentermine and fluoxetine was not as effective as phen-fen, but was not associated with cardiac valve lesions. Longer term, larger scale studies of phen-flu are warranted.
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Affiliation(s)
- L D Whigham
- Department of Medicine, University of Wisconsin, Madison, WI, USA
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Abstract
Obesity is rapidly becoming an epidemic in developed countries. Currently available anti-obesity therapeutics are only modestly effective and are accompanied by significant adverse effects. In recent years, substantial advances have been made in the basic understanding of brain control of feeding behaviour and metabolism. As a result, several compounds have progressed to Phase III development, with additional compounds at various stages of Phase II development. Most of the late-stage development candidates are CNS agents, which reflects the consensus that the brain exerts a dominant control on feeding behaviour and peripheral metabolism through the autonomic nervous system. Homeostatic mechanisms encompassing hypothalamic/brainstem pathways have long been recognised in obesity research. In addition, non-homeostatic mechanisms encompassing the reward circuit and volitional control need to be targeted to control feeding behaviour and physical activity, especially in humans. While recognising the importance of CNS control, certain peripherally acting agents can affect mitochondrial metabolism, lipolysis, nutrient absorption or the vagal feedback pathway, such that these peripherally acting agents can potentially be combined with CNS agents to achieve maximal efficacy. It is expected that newer generations of anti-obesity therapeutics will be superior to existing agents and will facilitate lifestyle modification.
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Affiliation(s)
- Tung M Fong
- Department of Metabolic Disorders, Merck Research Laboratories, R80M-213, PO Box 2000, Rahway, NJ 07065, USA.
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Trifunovic R, Reilly S. Medial parabrachial nucleus neurons modulate d-fenfluramine-induced anorexia through 5HT2C receptors. Brain Res 2006; 1067:170-6. [PMID: 16343451 DOI: 10.1016/j.brainres.2005.10.092] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Revised: 10/20/2005] [Accepted: 10/20/2005] [Indexed: 12/31/2022]
Abstract
We previously reported that lesions of the medial parabrachial nucleus (PBN) enhanced d-fenfluramine (DFEN)-induced anorexia; a finding that suggests these lesions may potentiate the release of serotonin (5HT) or increase the postsynaptic action of 5HT. In the present study, we used SB 206553 (a 5HT2B/2C receptor antagonist) or m-CPP (a 5HT2C/1B receptor agonist) in a standard behavioral procedure (deprivation-induced feeding) to further explore the role of the medial PBN in drug-induced anorexia. In Experiment 1, DFEN (0 or 1.0 mg/kg) was given alone or in combination with SB 206553 (2.0 or 5.0 mg/kg). In Experiment 2, we investigated the food-suppressive effects of m-CPP (0.5, 1.0 or 2.0 mg/kg). The results of Experiment 1 show that SB 206553, while having no influence on the performance of control subjects, attenuated (2.0 mg/kg) or abolished (5 mg/kg) the potentiating effect of the lesions on DFEN-induced anorexia. In Experiment 2, m-CPP induced a suppression of food intake in nonlesioned animals that was significantly potentiated in rats with medial PBN lesions. These results are consistent with the hypothesis that medial PBN neurons mediate anorexia through 5HT2C receptors.
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Affiliation(s)
- Radmila Trifunovic
- Department of Psychology, University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607, USA.
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Wellman PJ, Jones SL, Miller DK. Effects of preexposure to dexfenfluramine, phentermine, dexfenfluramine-phentermine, or fluoxetine on sibutramine-induced hypophagia in the adult rat. Pharmacol Biochem Behav 2003; 75:103-14. [PMID: 12759118 DOI: 10.1016/s0091-3057(03)00045-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The antiobesity drug sibutramine suppresses food intake via inhibition of reuptake of both norepinephrine (NE) and serotonin (5-HT) into brain terminals. The present study examined whether preexposure to other antiobesity drugs (fluoxetine [FLUOX], phentermine [PHEN], and dexfenfluramine [DEX]) that alter noradrenergic and/or serotonergic activity in brain induces tolerance or sensitization to the subsequent hypophagic action of sibutramine. Accordingly, adult male rats were treated (administered orally once per day for 21 days) with DEX (0, 1, or 3 mg/kg) and/or PHEN (0, 5, or 10 mg/kg), alone and in combination, or with the selective 5-HT reuptake inhibitor FLUOX (0, 15, or 30 mg/kg). Daily administration of PHEN persistently reduced food intake and body weight whereas tolerance developed to the hypophagic action of DEX or of FLUOX within the first week of daily administration. Moreover, low doses of DEX (1 mg/kg) and PHEN (5 mg/kg) interacted in a supra-additive manner to inhibit food intake and water intake and decrease body weight over the 21-day exposure period. After a recovery period of 9 days, a series of food intake trials were conducted to assess the hypophagic action of sibutramine (0, 1, 3, and 9 mg/kg po). Preexposure to PHEN (5 or 10 mg/kg), DEX (3 mg/kg), or FLUOX (30 mg/kg) resulted in a significant attenuation of the hypophagia induced by sibutramine over an 8-h, but not a 2-h, testing period. The pattern of cross-tolerance noted in this study is consistent with the observation that sibutramine inhibits eating via an interaction with noradrenergic and serotonergic mechanisms. Whether PHEN and DEX preexposure in humans alters subsequent sibutramine effectiveness is unknown.
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Affiliation(s)
- P J Wellman
- Department of Psychology, Texas A&M University, College Station, TX 77843-4235, USA.
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Svec F, Thompson H, Corll C, Porter J. Levels of hypothalamic neurotransmitters in lean and obese Zucker rats. Nutr Neurosci 2002; 5:321-6. [PMID: 12385594 DOI: 10.1080/1028415021000033785] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Hypothalamic neurotransmitter levels were compared between groups of Zucker rats. Animals were grouped by gender, phenotype and preference for dietary fat. Before sacrifice all animals consumed a standard rat chow diet and were fasted overnight. Five rats from each of eight groups were assayed. Hypothalamic regions (lateral, LH; ventromedial, VMH; paraventricular, PVN) and the raphe were isolated and analyzed for dopamine, norepinephrine, epinephrine, serotonin and 5-hydroxyindoleacetic acid. A factorial analysis of variance was used to compare the concentrations of these biogenic amines in the four regions across phenotypic, gender and fat preference profiles. No differences were demonstrated between groups based upon fat food preference. Epinephrine and 5-HIAA content varied between lean and obese animals but there were no differences in the content of serotonin, norepinephrine or dopamine. The results are consistent with the hypothesis that the obese animal eats more because it releases less of the satiety-inducing neurotransmitter serotonin in the hypothalamus.
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Affiliation(s)
- Frank Svec
- Obesity Research Program Department of Medicine, Louisiana State University Health Sciences Center, New Orleans 70112, USA.
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Tao R, Fray A, Aspley S, Brammer R, Heal D, Auerbach S. Effects on serotonin in rat hypothalamus of D-fenfluramine, aminorex, phentermine and fluoxetine. Eur J Pharmacol 2002; 445:69-81. [PMID: 12065196 DOI: 10.1016/s0014-2999(02)01751-x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Hypothalamic 5-HT (serotonin) regulates food intake, energy expenditure and bodyweight. Using in vivo microdialysis, we determined the effects of various anorectic drugs on hypothalamic extracellular 5-HT levels during the dark phase when rats predominantly feed. Phentermine and aminorex, which were originally considered to be catecholaminergic drugs, markedly increased 5-HT efflux in rat hypothalamus. Their actions were less profound than D-fenfluramine, but considerably greater than that of the selective 5-HT reuptake inhibitor, fluoxetine. This suggests that enhanced hypothalamic 5-HT function could be involved in their anorectic actions. Pharmacological characterization revealed that D-fenfluramine, aminorex and probably also phentermine potentiate synaptic 5-HT function predominantly by release, whereas fluoxetine acts exclusively by reuptake inhibition. The results also revealed that the combined actions of phentermine and D-fenfluramine on hypothalamic extracellular 5-HT levels were additive, but not synergistic. In contrast, there was a significant negative cooperative effect on extraneuronal 5-HT of combining phentermine with fluoxetine.
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Affiliation(s)
- Rui Tao
- Nelson Laboratories, Department of Cell Biology and Neuroscience, Rutgers University, 604 Allison Road, Piscataway, NJ 08854-8082, USA
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Glatz AC, Ehrlich M, Bae RS, Clarke MJ, Quinlan PA, Brown EC, Rada P, Hoebel BG. Inhibition of cocaine self-administration by fluoxetine or D-fenfluramine combined with phentermine. Pharmacol Biochem Behav 2002; 71:197-204. [PMID: 11812523 DOI: 10.1016/s0091-3057(01)00657-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Instrumental responding for intravenous cocaine in rats at 85% of free-feeding weight was significantly decreased 50% by D-fenfluramine plus phentermine (D-Fen/Phen, 5 mg/kg of each for 1 day). A similar effect was obtained in normal-weight rats self-administering a cocaine-heroin mixture. Treating normal-weight animals with fluoxetine (5 mg/kg) for 4 days also significantly decreased cocaine self-administration by half, and then adding phentermine caused an additional decrease in cocaine intake. Animals that were well trained to self-administer drug did not self-administer intravenous D-Fen/Phen or Flu/Phen. The present results confirm that serotonergic drugs can decrease cocaine, or cocaine/heroin, self-administration in rats, and that phentermine adds to the effect. Based on related research with the same dose of D-Fen/Phen, it is suggested that effectiveness in reducing cocaine reinforcement is due in part to a satiating effect in which dopamine and acetylcholine are released in the nucleus accumbens.
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Affiliation(s)
- Andrew C Glatz
- Department of Psychology, Princeton University, Princeton, NJ 08544, USA
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Rowland NE, Marshall M, Robertson K. Anorectic effect of dehydroepiandrosterone combined with dexfenfluramine or thionisoxetine. Eur J Pharmacol 2001; 419:61-4. [PMID: 11348631 DOI: 10.1016/s0014-2999(01)00958-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Free feeding rats given supplementary 1 h access per day to a palatable dessert test meal were tested for the anorectic effect of dehydroepiandrosterone alone or in combination with either the serotonin releasing agent dexfenfluramine or the norepinephrine uptake inhibitor thionisoxetine (LY 368975). Isobolographic analysis showed that the effect of dehydroepiandrosterone combined with either dexfenfluramine or thionisoxetine was within the range predicted for additivity of action.
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Affiliation(s)
- N E Rowland
- Department of Psychology, University of Florida, P.O. Box 112250, Center Drive, Gainesville, FL 32611-2250, USA.
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