fenfluramine

Summary

Summary: A centrally active drug that apparently both blocks serotonin uptake and provokes transport-mediated serotonin release.

Top Publications

  1. Siever L, Buchsbaum M, New A, Spiegel Cohen J, Wei T, Hazlett E, et al. d,l-fenfluramine response in impulsive personality disorder assessed with [18F]fluorodeoxyglucose positron emission tomography. Neuropsychopharmacology. 1999;20:413-23 pubmed
    ..for changes in regional glucose metabolism after administration of the serotonergic releasing agent d,l-fenfluramine (60 mg, p.o.) or placebo...
  2. Dahl C, Allen M, Urie P, Hopkins P. Valvular regurgitation and surgery associated with fenfluramine use: an analysis of 5743 individuals. BMC Med. 2008;6:34 pubmed publisher
    ..We performed an observational study of 5743 users of fenfluramines examined by echocardiography between July 1997 and February 2004 in a single large cardiology clinic...
  3. Correa H, Duval F, Mokrani M, Bailey P, Tremeau F, Staner L, et al. Prolactin response to D-fenfluramine and suicidal behavior in depressed patients. Psychiatry Res. 2000;93:189-99 pubmed
    Previous studies of the prolactin response to D-fenfluramine in depressed patients have yielded inconsistent results. This may be because they did not address the question of suicidality...
  4. New A, Trestman R, Mitropoulou V, Goodman M, Koenigsberg H, Silverman J, et al. Low prolactin response to fenfluramine in impulsive aggression. J Psychiatr Res. 2004;38:223-30 pubmed
    To examine the prolactin (prl) response to d,l-fenfluramine in a large sample of personality disorder patients with impulsive aggression...
  5. Evans J, Platts H, Lightman S, Nutt D. Impulsiveness and the prolactin response to d-fenfluramine. Psychopharmacology (Berl). 2000;149:147-52 pubmed
    ..It is unknown whether this is because serotonin function plays a part in determining the dimension of trait impulsiveness in the general population or whether this is restricted to these behaviourally extreme groups...
  6. Lucas J, Yamamoto A, Scearce Levie K, Saudou F, Hen R. Absence of fenfluramine-induced anorexia and reduced c-Fos induction in the hypothalamus and central amygdaloid complex of serotonin 1B receptor knock-out mice. J Neurosci. 1998;18:5537-44 pubmed
    b>Fenfluramine, a serotonin releaser and uptake inhibitor, has been widely prescribed as an appetite suppressant...
  7. Wee C, Phillips R, Aurigemma G, Erban S, Kriegel G, Riley M, et al. Risk for valvular heart disease among users of fenfluramine and dexfenfluramine who underwent echocardiography before use of medication. Ann Intern Med. 1998;129:870-4 pubmed
    Because uncontrolled echocardiographic surveys suggested that up to 30% to 38% of users of fenfluramine and dexfenfluramine had valvular disease, these drugs were withdrawn from the market.
  8. Pringle A, Jennings K, Line S, Bannerman D, Higgs S, Sharp T. Mice overexpressing the 5-hydroxytryptamine transporter show no alterations in feeding behaviour and increased non-feeding responses to fenfluramine. Psychopharmacology (Berl). 2008;200:291-300 pubmed publisher
    ..Expression of the 5-HTT varies in the human population, and this variation may determine both individual differences in feeding and abnormal feeding behaviours such as eating disorders...
  9. Blanpain C, Le Poul E, Parma J, Knoop C, Detheux M, Parmentier M, et al. Serotonin 5-HT(2B) receptor loss of function mutation in a patient with fenfluramine-associated primary pulmonary hypertension. Cardiovasc Res. 2003;60:518-28 pubmed
    Appetite-suppressant drug fenfluramine is implicated in primary pulmonary hypertension (PPH) but the molecular pathways that mediate this effect are unknown...

More Information

Publications62

  1. 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 pubmed
    ..Their actions were less profound than D-fenfluramine, but considerably greater than that of the selective 5-HT reuptake inhibitor, fluoxetine...
  2. Simansky K, Nicklous D. Parabrachial infusion of D-fenfluramine reduces food intake. Blockade by the 5-HT(1B) antagonist SB-216641. Pharmacol Biochem Behav. 2002;71:681-90 pubmed
    Systemic administration of the serotonin (5-HT) releaser/reuptake inhibitor, D-fenfluramine decreases consumption of food in mammals. This hypophagic action involves loci at several levels of the neuraxis...
  3. Hopkins P, Polukoff G. Risk of valvular heart disease associated with use of fenfluramine. BMC Cardiovasc Disord. 2003;3:5 pubmed
    Estimates of excess risk of valvular heart disease among prior users of fenfluramine and dexfenfluramine have varied widely...
  4. Reist C, Mazzanti C, Vu R, Tran D, Goldman D. Serotonin transporter promoter polymorphism is associated with attenuated prolactin response to fenfluramine. Am J Med Genet. 2001;105:363-8 pubmed
    ..relationship between polymorphisms in the promoter region of the gene coding for the neuronal 5-HT transporter, fenfluramine-induced prolactin release, and aggressive impulsivity (as measured by Barratt Impulsivity Scale, Buss-Durkee ..
  5. Dahl C, Allen M. Regression and progression of valvulopathy associated with fenfluramine and phentermine. Ann Intern Med. 2002;136:489 pubmed
  6. Glatz A, Ehrlich M, Bae R, Clarke M, Quinlan P, Brown E, et al. Inhibition of cocaine self-administration by fluoxetine or D-fenfluramine combined with phentermine. Pharmacol Biochem Behav. 2002;71:197-204 pubmed
    ..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)...
  7. Jones K, Johnson K, Dick L, Felix R, Kao K, Chambers C. Pregnancy outcomes after first trimester exposure to phentermine/fenfluramine. Teratology. 2002;65:125-30 pubmed
    b>Fenfluramine was withdrawn from the U.S. market in 1997 because of its association with cardiac-valve abnormalities in adults...
  8. Palmieri V, Arnett D, Roman M, Liu J, Bella J, Oberman A, et al. Appetite suppressants and valvular heart disease in a population-based sample: the HyperGEN study. Am J Med. 2002;112:710-5 pubmed
    ..We assessed whether the use of the appetite suppressants fenfluramine/dexfenfluramine, either alone or with phentermine, was associated with aortic regurgitation while adjusting for ..
  9. Finnema S, Varrone A, Hwang T, Halldin C, Farde L. Confirmation of fenfluramine effect on 5-HT(1B) receptor binding of [(11)C]AZ10419369 using an equilibrium approach. J Cereb Blood Flow Metab. 2012;32:685-95 pubmed publisher
    ..We previously reported that fenfluramine caused a dose-dependent reduction in specific binding in monkeys using a classical displacement paradigm with ..
  10. Rocher C, Gardier A. Effects of repeated systemic administration of d-Fenfluramine on serotonin and glutamate release in rat ventral hippocampus: comparison with methamphetamine using in vivo microdialysis. Naunyn Schmiedebergs Arch Pharmacol. 2001;363:422-8 pubmed
    We compared the effects of three systemic injections of various doses of d-Fenfluramine, an indirect serotonergic agonist (1.3, 5 or 10 mg/kg), to those of a known neurotoxin, methamphetamine (METH, at a 7.5 mg/kg dose), given i.p...
  11. Connor T, Kelly J, Leonard B. An assessment of the acute effects of the serotonin releasers methylenedioxymethamphetamine, methylenedioxyamphetamine and fenfluramine on immunity in rats. Immunopharmacology. 2000;46:223-35 pubmed
    ..releasing amphetamine derivatives methylenedioxymethamphetamine (MDMA), methylenedioxyamphetamine (MDA) and fenfluramine (FEN) on immunity in rats...
  12. Wang Y, Bowersox S, Pettus M, Gao D. Antinociceptive properties of fenfluramine, a serotonin reuptake inhibitor, in a rat model of neuropathy. J Pharmacol Exp Ther. 1999;291:1008-16 pubmed
    b>Fenfluramine is an indirect agonist of 5-hydroxytryptamine (5-HT) receptors that acts by evoking 5-HT release and blocking 5-HT reuptake in neuronal cells...
  13. Sher L, Oquendo M, Galfalvy H, Cooper T, Mann J. The number of previous depressive episodes is positively associated with cortisol response to fenfluramine administration. Ann N Y Acad Sci. 2004;1032:283-6 pubmed
    ..Measurement of cortisol levels after ingestion of fenfluramine, a specific serotonin releaser/uptake inhibitor agent, provides an index of HPA activity...
  14. Michelakis E, Weir E. Anorectic drugs and pulmonary hypertension from the bedside to the bench. Am J Med Sci. 2001;321:292-9 pubmed
    ..The use of fenfluramine and later dexfenfluramine [drugs that inhibit 5-hydroxytryptamine (5-HT) release and reuptake and increases 5-..
  15. Jollis J, Landolfo C, Kisslo J, Constantine G, Davis K, Ryan T. Fenfluramine and phentermine and cardiovascular findings: effect of treatment duration on prevalence of valve abnormalities. Circulation. 2000;101:2071-7 pubmed
    The combination of fenfluramine and phentermine was a widely used obesity treatment before the withdrawal of fenfluramine for an association with heart valve regurgitation...
  16. Seghatol F, Rigolin V. Appetite suppressants and valvular heart disease. Curr Opin Cardiol. 2002;17:486-92 pubmed
    Appetite suppressants fenfluramine, dexfenfluramine, and phentermine have been used alone or in combination as an alternative to diet and surgery in the management of obesity...
  17. Belohlavkova S, Simak J, Kokesov√° A, Hnilickova O, Hampl V. Fenfluramine-induced pulmonary vasoconstriction: role of serotonin receptors and potassium channels. J Appl Physiol (1985). 2001;91:755-61 pubmed
    The anorexic agent fenfluramine considerably increases the risk of primary pulmonary hypertension. The mechanism of this effect is unknown...
  18. Lee M, Somerville E, Kennett G, Dourish C, Clifton P. Reduced hypophagic effects of d-fenfluramine and the 5-HT2C receptor agonist mCPP in 5-HT1B receptor knockout mice. Psychopharmacology (Berl). 2004;176:39-49 pubmed
    The possible role of compensatory changes in 5-HT2C receptors in the reduced hypophagic action of d-fenfluramine in 5-HT1B knockout (KO) mice was assessed by comparing their response to d-fenfluramine and the 5-HT2C receptor agonist mCPP...
  19. Udo de Haes J, Harada N, Elsinga P, Maguire R, Tsukada H. Effect of fenfluramine-induced increases in serotonin release on [18F]MPPF binding: a continuous infusion PET study in conscious monkeys. Synapse. 2006;59:18-26 pubmed
    ..We used the 5-HT releasing agent and reuptake inhibitor fenfluramine (FEN) to increase the concentration of 5-HT...
  20. Choi S, Blake V, Cole S, Fernstrom J. Effects of chronic fenfluramine administration on hypothalamic neuropeptide mRNA expression. Brain Res. 2006;1087:83-6 pubmed
    ..We gave male rats once-daily dl-fenfluramine (dl-FEN, 5 mg/kg, i.p...
  21. Ledonne A, Sebastianelli L, Federici M, Bernardi G, Mercuri N. The anorexic agents, sibutramine and fenfluramine, depress GABA(B)-induced inhibitory postsynaptic potentials in rat mesencephalic dopaminergic cells. Br J Pharmacol. 2009;156:962-9 pubmed publisher
    ..For this reason, in the present study, we have investigated the electrophysiological effects of two centrally acting anorexic agents, fenfluramine and sibutramine, on these cells.
  22. Stocker S, Muldoon M, Sved A. Blunted fenfluramine-evoked prolactin secretion in hypertensive rats. Hypertension. 2003;42:719-24 pubmed
    Plasma prolactin (PRL) levels after acute administration of fenfluramine (FEN) have been used as a probe of brain serotonin activity...
  23. Soloff P, Kelly T, Strotmeyer S, Malone K, Mann J. Impulsivity, gender, and response to fenfluramine challenge in borderline personality disorder. Psychiatry Res. 2003;119:11-24 pubmed
    ..We studied gender differences in behavioral impulsivity and the prolactin response to D,L-fenfluramine (FEN) in BPD subjects in a community setting...
  24. Halladay A, Kirschner E, Hesse K, Fisher H, Wagner G. Role of monoamine oxidase inhibition and monoamine depletion in fenfluramine-induced neurotoxicity and serotonin release. Pharmacol Toxicol. 2001;89:237-48 pubmed
    The role of both monoamine synthesis and monoamine oxidase inhibition in mediating the fenfluramine-induced damage to serotonin neurones was examined; as pretreatment agents, both alpha-methyl-para-tyrosine (AMPT) and ..
  25. Fitzgerald L, Burn T, Brown B, Patterson J, Corjay M, Valentine P, et al. Possible role of valvular serotonin 5-HT(2B) receptors in the cardiopathy associated with fenfluramine. Mol Pharmacol. 2000;57:75-81 pubmed
    ..To elucidate the mechanism of "fen-phen"-associated valvular lesions, we examined the interaction of fenfluramine and its metabolite norfenfluramine with 5-HT(2) receptor subtypes and examined the expression of these ..
  26. Rich S, Rubin L, Walker A, Schneeweiss S, Abenhaim L. Anorexigens and pulmonary hypertension in the United States: results from the surveillance of North American pulmonary hypertension. Chest. 2000;117:870-4 pubmed
    ..Recently, fenfluramine appetite suppressants became widely used in the United States but were withdrawn in September 1997 because of ..
  27. Callahan B, Cord B, Ricaurte G. Long-term impairment of anterograde axonal transport along fiber projections originating in the rostral raphe nuclei after treatment with fenfluramine or methylenedioxymethamphetamine. Synapse. 2001;40:113-21 pubmed
    ..axonal projections originating in the rostral raphe nuclei of animals treated 3 weeks previously with (+/-)fenfluramine (FEN, 10 mg/kg, every 2 h x 4 injections; i.p...
  28. van Amelsvoort T, Abel K, Robertson D, Daly E, Critchley H, Whitehead M, et al. Prolactin response to d-fenfluramine in postmenopausal women on and off ERT: comparison with young women. Psychoneuroendocrinology. 2001;26:493-502 pubmed
    ..Prolactin (PRL) responses to the specific 5-HT releasing and re-uptake inhibiting agent, d-fenfluramine, were measured in three groups of healthy women: 11 young, 11 postmenopausal on long-term ERT, and 11 ..
  29. Baumann M, Ayestas M, Rothman R. Functional consequences of central serotonin depletion produced by repeated fenfluramine administration in rats. J Neurosci. 1998;18:9069-77 pubmed
    Repeated administration of D,L-fenfluramine (FEN) is known to cause prolonged depletion of forebrain serotonin (5-HT) in animals. Ironically, few studies have evaluated functional consequences of such FEN-induced 5-HT loss...
  30. Kavoussi R, Kramer J, Hauger R, Coccaro E. Prolactin response to D-fenfluramine in outpatients with major depression. Psychiatry Res. 1998;79:199-205 pubmed
    ..20 outpatients with major depressive disorder to 20 normal control subjects using prolactin response to D-fenfluramine as a measure of central serotonergic (5-HT) functioning...
  31. Cherek D, Lane S. Acute effects of D-fenfluramine on simultaneous measures of aggressive escape and impulsive responses of adult males with and without a history of conduct disorder. Psychopharmacology (Berl). 2001;157:221-7 pubmed
    The role of serotonin in human aggression was evaluated by administering D-fenfluramine and comparing the effects on laboratory measures of aggression, escape and impulsivity among subjects with and without a history of conduct disorder.
  32. Setola V, Hufeisen S, Grande Allen K, Vesely I, Glennon R, Blough B, et al. 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") induces fenfluramine-like proliferative actions on human cardiac valvular interstitial cells in vitro. Mol Pharmacol. 2003;63:1223-9 pubmed
    ..VHD)] and primary pulmonary hypertension observed in patients taking the now-banned appetite suppressant fenfluramine (Pondimin, Redux)...
  33. Duval F, Mokrani M, Monreal J, Bailey P, Valdebenito M, Crocq M, et al. Dopamine and serotonin function in untreated schizophrenia: clinical correlates of the apomorphine and d-fenfluramine tests. Psychoneuroendocrinology. 2003;28:627-42 pubmed
    ..cortisol responses to the direct DA receptor agonist apomorphine (APO) and the selective 5HT-releasing agent d-fenfluramine (d-FEN) in 20 untreated inpatients with DSM-IV schizophrenia and without a history of suicide attempt, compared ..
  34. Sher L, Oquendo M, Li S, Ellis S, Brodsky B, Malone K, et al. Prolactin response to fenfluramine administration in patients with unipolar and bipolar depression and healthy controls. Psychoneuroendocrinology. 2003;28:559-73 pubmed
    The hormonal response to the serotonin releasing agent/uptake inhibitor fenfluramine has been used as an indicator of central serotonin system function...
  35. Sachdev M, Miller W, Ryan T, Jollis J. Effect of fenfluramine-derivative diet pills on cardiac valves: a meta-analysis of observational studies. Am Heart J. 2002;144:1065-73 pubmed
    b>Fenfluramine-derivative diet pills were withdrawn from the market in 1997 because of an association with valvular regurgitation, but subsequent estimates of the prevalence of this condition have varied widely...
  36. Finnema S, Varrone A, Hwang T, Gulyas B, Pierson M, Halldin C, et al. Fenfluramine-induced serotonin release decreases [11C]AZ10419369 binding to 5-HT1B-receptors in the primate brain. Synapse. 2010;64:573-7 pubmed publisher
    ..b>Fenfluramine-induced 5-HT release decreased radioligand binding in a dose-dependent fashion with a regional average of 27% ..
  37. Davidoff R, McTiernan A, Constantine G, Davis K, Balady G, Mendes L, et al. Echocardiographic examination of women previously treated with fenfluramine: long-term follow-up of a randomized, double-blind, placebo-controlled trial. Arch Intern Med. 2001;161:1429-36 pubmed
    b>Fenfluramine hydrochloride was withdrawn from the market in September 1997 after reports of heart valve abnormalities in patients who used it...
  38. Pickens C, Cifani C, Navarre B, Eichenbaum H, Theberge F, Baumann M, et al. Effect of fenfluramine on reinstatement of food seeking in female and male rats: implications for the predictive validity of the reinstatement model. Psychopharmacology (Berl). 2012;221:341-53 pubmed publisher
    ..Here, we assessed the predictive validity of the food reinstatement model by studying the effects of fenfluramine, a serotonin releaser with known anorectic effects, on reinstatement of food seeking...
  39. Wellman P, Maher T. Synergistic interactions between fenfluramine and phentermine. Int J Obes Relat Metab Disord. 1999;23:723-32 pubmed
    Fen-phen' refers to the off-label combination of the appetite suppressants fenfluramine and phentermine...
  40. Souza R, Humbert M, Sztrymf B, Jais X, Yaici A, Le Pavec J, et al. Pulmonary arterial hypertension associated with fenfluramine exposure: report of 109 cases. Eur Respir J. 2008;31:343-8 pubmed
    The aim of the present study was to describe a large cohort of fenfluramine-associated pulmonary arterial hypertension (fen-PAH) and its possible prognostic markers...
  41. Subramanian S, Vollmer R. Fenfluramine-induced hypothermia is associated with cutaneous dilation in conscious rats. Pharmacol Biochem Behav. 2004;77:351-9 pubmed
    The antiobesity agent, fenfluramine, produces hypothermia in rodents by an, as yet, uncharacterized mechanism...
  42. Rothman R, Ayestas M, Dersch C, Baumann M. Aminorex, fenfluramine, and chlorphentermine are serotonin transporter substrates. Implications for primary pulmonary hypertension. Circulation. 1999;100:869-75 pubmed
    Coadministration of phentermine and fenfluramine (phen/fen) effectively treats obesity and possibly addictive disorders...
  43. Li R, Serdula M, Williamson D, Bowman B, Graham D, Green L. Dose-effect of fenfluramine use on the severity of valvular heart disease among fen-phen patients with valvulopathy. Int J Obes Relat Metab Disord. 1999;23:926-8 pubmed
    To determine whether the severity of valvulopathy was associated with the dosage of fenfluramine taken by fenfluramine-phentermine users with valvulopathy.
  44. Burger A, Sherman H, Charlamb M, Kim J, Asinas L, Flickner S, et al. Low prevalence of valvular heart disease in 226 phentermine-fenfluramine protocol subjects prospectively followed for up to 30 months. J Am Coll Cardiol. 1999;34:1153-8 pubmed
    This investigation sought to determine the effect of phentermine-fenfluramine (phen-fen) on the prevalence of valvular heart disease in 226 obese subjects enrolled in a prospective, strict weight loss, research protocol.
  45. Fava M, Vuolo R, Wright E, Nierenberg A, Alpert J, Rosenbaum J. Fenfluramine challenge in unipolar depression with and without anger attacks. Psychiatry Res. 2000;94:9-18 pubmed
    ..We wanted to compare the prolactin response to fenfluramine challenge, as an indirect measure of central serotonergic function, in depressed patients with and without ..
  46. Rothman R, Jayanthi S, Wang X, Dersch C, Cadet J, Prisinzano T, et al. High-dose fenfluramine administration decreases serotonin transporter binding, but not serotonin transporter protein levels, in rat forebrain. Synapse. 2003;50:233-9 pubmed
    Administration of D-fenfluramine (D-FEN) or parachloroamphetamine (PCA) can produce long-lasting decreases in serotonin transporter (SERT) binding and tissue levels of serotonin (5-HT) in rat forebrain...
  47. Duval F, Mokrani M, Correa H, Bailey P, Valdebenito M, Monreal J, et al. Lack of effect of HPA axis hyperactivity on hormonal responses to d-fenfluramine in major depressed patients: implications for pathogenesis of suicidal behaviour. Psychoneuroendocrinology. 2001;26:521-37 pubmed
    ..the dexamethasone suppression test (DST, 1 mg PO) and prolactin, corticotropin and cortisol responses to the d-fenfluramine test (d-FEN, 45 mg PO) - a specific 5-HT releaser/uptake inhibitor - were measured in 71 drug-free DSM-IV major ..
  48. Fleming R, Boyd L. The longitudinal effects of fenfluramine-phentermine use. Angiology. 2007;58:353-9 pubmed
    The use of previous anorectic medications and the combined use of the anorectic medications fenfluramine and phentermine (Fen-Phen) have been associated with varying degrees of valvular regurgitation and pulmonary hypertension...
  49. Ryan D, Bray G, Helmcke F, Sander G, Volaufova J, Greenway F, et al. Serial echocardiographic and clinical evaluation of valvular regurgitation before, during, and after treatment with fenfluramine or dexfenfluramine and mazindol or phentermine. Obes Res. 1999;7:313-22 pubmed
    ..We studied 86 patients who had echocardiograms before treatment with appetite suppressants to determine the incidence of new cases and to evaluate the clinical implication of the echocardiographic findings...
  50. Connolly J, Bakay M, Fulmer J, Gorman R, Gorman J, Oyama M, et al. Fenfluramine disrupts the mitral valve interstitial cell response to serotonin. Am J Pathol. 2009;175:988-97 pubmed publisher
    Serotonin (5HT) receptor signaling and 5HT-related agents, such as the anorexogen fenfluramine (Fen), have been associated with heart valve disease...
  51. Humbert M, Deng Z, Simonneau G, Barst R, Sitbon O, Wolf M, et al. BMPR2 germline mutations in pulmonary hypertension associated with fenfluramine derivatives. Eur Respir J. 2002;20:518-23 pubmed
    ..whether patients developing pulmonary arterial hypertension (PAH) after exposure to the appetite suppressants fenfluramine and dexfenfluramine have mutations in the bone morphogenetic protein receptor 2 (BMPR2) gene, as reported in ..
  52. Burger A, Charlamb M, Singh S, Notarianni M, Blackburn G, Sherman H. Low risk of significant echocardiographic valvulopathy in patients treated with anorectic drugs. Int J Cardiol. 2001;79:159-65 pubmed
    Phentermine--fenfluramine and dexfenfluramine use for weight loss has been previously associated with increased prevalence of valvular heart disease...
  53. Vickers S, Dourish C, Kennett G. Evidence that hypophagia induced by d-fenfluramine and d-norfenfluramine in the rat is mediated by 5-HT2C receptors. Neuropharmacology. 2001;41:200-9 pubmed
    The present series of studies is the first to investigate the pharmacological mechanisms underlying d-fenfluramine- and d-norfenfluramine-induced hypophagia in the rat using highly selective serotonin 5-HT2 receptor antagonists...