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Neuropsychopharmacology
2014 May 01;396:1355-65. doi: 10.1038/npp.2013.331.
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Evidence for a role of transporter-mediated currents in the depletion of brain serotonin induced by serotonin transporter substrates.
Baumann MH
,
Bulling S
,
Benaderet TS
,
Saha K
,
Ayestas MA
,
Partilla JS
,
Ali SF
,
Stockner T
,
Rothman RB
,
Sandtner W
,
Sitte HH
.
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Serotonin (5-HT) transporter (SERT) substrates like fenfluramine and 3,4-methylenedioxymethamphetamine cause long-term depletion of brain 5-HT, while certain other substrates do not. The 5-HT deficits produced by SERT substrates are dependent upon transporter proteins, but the exact mechanisms responsible are unclear. Here, we compared the pharmacology of several SERT substrates: fenfluramine, d-fenfluramine, 1-(m-chlorophenyl)piperazine (mCPP) and 1-(m-trifluoromethylphenyl)piperainze (TFMPP), to establish relationships between acute drug mechanisms and the propensity for long-term 5-HT depletions. In vivo microdialysis was carried out in rat nucleus accumbens to examine acute 5-HT release and long-term depletion in the same subjects. In vitro assays were performed to measure efflux of [(3)H]5-HT in rat brain synaptosomes and transporter-mediated ionic currents in SERT-expressing Xenopus oocytes. When administered repeatedly to rats (6 mg/kg, i.p., four doses), all drugs produce large sustained elevations in extracellular 5-HT (>5-fold) with minimal effects on dopamine. Importantly, 2 weeks after dosing, only rats exposed to fenfluramine and d-fenfluramine display depletion of brain 5-HT. All test drugs evoke fluoxetine-sensitive efflux of [(3)H]5-HT from synaptosomes, but d-fenfluramine and its bioactive metabolite d-norfenfluramine induce significantly greater SERT-mediated currents than phenylpiperazines. Our data confirm that drug-induced 5-HT release probably does not mediate 5-HT depletion. However, the magnitude of transporter-mediated inward current may be a critical factor in the cascade of events leading to 5-HT deficits. This hypothesis warrants further study, especially given the growing popularity of designer drugs that target SERT.
Figure 1. Effects of repeated i.p. administrations of saline, fenfluramine (fen), d-fenfluramine (d-fen), mCPP, and TFMPP on extracellular 5-HT and dopamine (DA) in rats undergoing microdialysis in nucleus accumbens. Panel a depicts the effects of fen, d-fen, and saline on dialysate 5-HT, whereas panel b shows dialysate dopamine. Panel c depicts effects of mCPP, TFMPP, and saline on dialysate 5-HT, whereas panel d shows dialysate dopamine. Arrows indicate time of injections. Data are mean±SEM expressed as % baseline for N=5 rats per group.
Figure 2. Effects of repeated doses of saline, fenfluramine (fen), d-fenfluramine (d-fen), mCPP, or TFMPP on post-mortem tissue levels of 5-HT and dopamine (DA) in rat nucleus accumbens, measured 2 weeks after injections. Panel a shows the effects of fenfluramines while panel c shows the effects of phenylpiperazines. Post-mortem tissue data (a, c) are mean±SEM expressed as % control amine N=5 rats per group. The relationship between dialysate 5-HT and post-mortem tissue 5-HT is illustrated for fenfluramines and phenylpiperazine in panels b and d, respectively. Pearson's correlation coefficient (r) was calculated for effects of fenfluramines (b) or piperazines (d), based on mean dialysate 5-HT during the sampling period (pg/5 μl) and post-mortem tissue levels of 5-HT (ng/100 mg) for individual subjects. N=15 rats per plot.
Figure 3. Release of preloaded [3H]5-HT from rat brain synaptosomes evoked by d-fenfluramine (d-fen), d-norfenfluramine (d-norfen), mCPP, and TFMPP. Drug-induced [3H]-5-HT release was measured in the presence or absence of 10 nM fluoxetine for d-fen (a), d-norfen (b), mCPP (c), and TFMPP (d). Data are mean±SD for N=3 separate experiments.
Figure 4. SERT-generated currents in Xenopus oocytes induced by increasing concentrations of d-fenfluramine, d-norfenfluramine, mCPP, TFMPP, or MTA in comparison with the physiological substrate 5-HT (10 μM). Sample traces are shown in panels a–e, and drug concentrations are given in μM.
Figure 5. (a) Concentration-response curves, pooled from different oocytes and (b) comparison of the maximal current (Cmax) for d-fenfluramine, d-norfenfluramine, mCPP, TFMPP, and MTA compared in the same oocyte. Maximal current for d-fenfluramine was measured at 10 μM and for d-norfenfluramine at 100 μM, whereas maximal current for mCPP, TFMPP, and MTA was measured at 3 μM. Statistical analysis revealed significant differences at a level of p<0.01 (***).
Adams,
Ionic currents in the human serotonin transporter reveal inconsistencies in the alternating access hypothesis.
2003, Pubmed,
Xenbase
Adams,
Ionic currents in the human serotonin transporter reveal inconsistencies in the alternating access hypothesis.
2003,
Pubmed
,
Xenbase
Appel,
Effects of high-dose fenfluramine treatment on monoamine uptake sites in rat brain: assessment using quantitative autoradiography.
1990,
Pubmed
Auerbach,
TFMPP and RU24969 enhance serotonin release from rat hippocampus.
1990,
Pubmed
Baumann,
N-substituted piperazines abused by humans mimic the molecular mechanism of 3,4-methylenedioxymethamphetamine (MDMA, or 'Ecstasy').
2005,
Pubmed
Baumann,
1-(m-chlorophenyl)piperazine (mCPP) dissociates in vivo serotonin release from long-term serotonin depletion in rat brain.
2001,
Pubmed
Baumann,
Intravenous administration of the serotonin agonist m-chlorophenylpiperazine (mCPP) increases extracellular serotonin in the diencephalon of awake rats.
1993,
Pubmed
Baumann,
The designer methcathinone analogs, mephedrone and methylone, are substrates for monoamine transporters in brain tissue.
2012,
Pubmed
Baumann,
Powerful cocaine-like actions of 3,4-methylenedioxypyrovalerone (MDPV), a principal constituent of psychoactive 'bath salts' products.
2013,
Pubmed
Berger,
The substituted amphetamines 3,4-methylenedioxymethamphetamine, methamphetamine, p-chloroamphetamine and fenfluramine induce 5-hydroxytryptamine release via a common mechanism blocked by fluoxetine and cocaine.
1992,
Pubmed
Bulling,
The mechanistic basis for noncompetitive ibogaine inhibition of serotonin and dopamine transporters.
2012,
Pubmed
,
Xenbase
Caccia,
The role of d-norfenfluramine in the indole-depleting effect of d-fenfluramine in the rat.
1993,
Pubmed
Cadet,
Free radicals and the pathobiology of brain dopamine systems.
1998,
Pubmed
Carvelli,
Dopamine transporters depolarize neurons by a channel mechanism.
2004,
Pubmed
Clineschmidt,
Fenfluramine and brain serotonin.
1978,
Pubmed
Colado,
In vivo evidence for free radical involvement in the degeneration of rat brain 5-HT following administration of MDMA ('ecstasy') and p-chloroamphetamine but not the degeneration following fenfluramine.
1997,
Pubmed
Commins,
Biochemical and histological evidence that methylenedioxymethylamphetamine (MDMA) is toxic to neurons in the rat brain.
1987,
Pubmed
Connolly,
Valvular heart disease associated with fenfluramine-phentermine.
1997,
Pubmed
Cryan,
Characterization of D-fenfluramine-induced hypothermia: evidence for multiple sites of action.
2000,
Pubmed
Eriksson,
Effects of mCPP on the extracellular concentrations of serotonin and dopamine in rat brain.
1999,
Pubmed
Fuxe,
On the in vivo and in vitro actions of fenfluramine and its derivatives on central monoamine neurons, especially 5-hydroxytryptamine neurons, and their relation to the anorectic activity of fenfluramine.
1975,
Pubmed
Garattini,
The mechanism of action of fenfluramine.
1975,
Pubmed
Gobbi,
Down-regulation of rat brain 5-HT uptake carriers after treatment with high doses of D-fenfluramine.
1996,
Pubmed
Gobbi,
N,N-dimethyl-thioamphetamine and methyl-thioamphetamine, two non-neurotoxic substrates of 5-HT transporters, have scant in vitro efficacy for the induction of transporter-mediated 5-HT release and currents.
2008,
Pubmed
,
Xenbase
Halladay,
Role of monoamine oxidase inhibition and monoamine depletion in fenfluramine-induced neurotoxicity and serotonin release.
2001,
Pubmed
Hilber,
Serotonin-transporter mediated efflux: a pharmacological analysis of amphetamines and non-amphetamines.
2005,
Pubmed
Ingram,
Dopamine transporter-mediated conductances increase excitability of midbrain dopamine neurons.
2002,
Pubmed
Invernizzi,
Is receptor activation involved in the mechanism by which (+)-fenfluramine and (+)-norfenfluramine deplete 5-hydroxytryptamine in the rat brain?
1982,
Pubmed
Johnson,
Comparative serotonin neurotoxicity of the stereoisomers of fenfluramine and norfenfluramine.
1990,
Pubmed
Johnson,
Behavioral, biochemical and neurotoxicological actions of the alpha-ethyl homologue of p-chloroamphetamine.
1990,
Pubmed
Johnson,
[3H]monoamine releasing and uptake inhibition properties of 3,4-methylenedioxymethamphetamine and p-chloroamphetamine analogues.
1991,
Pubmed
Jones,
Serotonergic neurotoxic metabolites of ecstasy identified in rat brain.
2005,
Pubmed
Kleven,
D-, L- and DL-fenfluramine cause long-lasting depletions of serotonin in rat brain.
1989,
Pubmed
Lyles,
Methylenedioxymethamphetamine (MDMA, Ecstasy) neurotoxicity: cellular and molecular mechanisms.
2003,
Pubmed
Mager,
Conducting states of a mammalian serotonin transporter.
1994,
Pubmed
,
Xenbase
Malberg,
Administration of fenfluramine at different ambient temperatures produces different core temperature and 5-HT neurotoxicity profiles.
1997,
Pubmed
McCann,
Brain serotonin neurotoxicity and primary pulmonary hypertension from fenfluramine and dexfenfluramine. A systematic review of the evidence.
1997,
Pubmed
Meinild,
Zinc potentiates an uncoupled anion conductance associated with the dopamine transporter.
2004,
Pubmed
,
Xenbase
Murray,
The spin trap reagent PBN attenuates degeneration of 5-HT neurones in rat brain induced by p-chloroamphetamine but not fenfluramine.
1996,
Pubmed
Nichols,
Nonneurotoxic tetralin and indan analogues of 3,4-(methylenedioxy)amphetamine (MDA).
1990,
Pubmed
O'Callaghan,
Neurotoxicity profiles of substituted amphetamines in the C57BL/6J mouse.
1994,
Pubmed
Pettibone,
Serotonin-releasing effects of substituted piperazines in vitro.
1984,
Pubmed
Rosenauer,
A combined approach using transporter-flux assays and mass spectrometry to examine psychostimulant street drugs of unknown content.
2013,
Pubmed
Rothman,
Development of a rationally designed, low abuse potential, biogenic amine releaser that suppresses cocaine self-administration.
2005,
Pubmed
Rothman,
Amphetamine-type central nervous system stimulants release norepinephrine more potently than they release dopamine and serotonin.
2001,
Pubmed
Rothman,
Evidence for possible involvement of 5-HT(2B) receptors in the cardiac valvulopathy associated with fenfluramine and other serotonergic medications.
2000,
Pubmed
Rothman,
Therapeutic and adverse actions of serotonin transporter substrates.
2002,
Pubmed
Rothman,
(+)-Fenfluramine and its major metabolite, (+)-norfenfluramine, are potent substrates for norepinephrine transporters.
2003,
Pubmed
Rothman,
Aminorex, fenfluramine, and chlorphentermine are serotonin transporter substrates. Implications for primary pulmonary hypertension.
1999,
Pubmed
Rothman,
Serotonergic drugs and valvular heart disease.
2009,
Pubmed
Sabol,
Fluoxetine attenuates the DL-fenfluramine-induced increase in extracellular serotonin as measured by in vivo dialysis.
1992,
Pubmed
Sanders-Bush,
Long-term effects of p-chloroamphetamine and related drugs on central serotonergic mechanisms.
1975,
Pubmed
Schicker,
Unifying concept of serotonin transporter-associated currents.
2012,
Pubmed
Schmidt,
Selective 5-hydroxytryptamine2 receptor antagonists protect against the neurotoxicity of methylenedioxymethamphetamine in rats.
1990,
Pubmed
Schoeffter,
Interaction of arylpiperazines with 5-HT1A, 5-HT1B, 5-HT1C and 5-HT1D receptors: do discriminatory 5-HT1B receptor ligands exist?
1989,
Pubmed
Schuldiner,
Amphetamine derivatives interact with both plasma membrane and secretory vesicle biogenic amine transporters.
1993,
Pubmed
Schwartz,
Fenfluramine administered systemically or locally increases extracellular serotonin in the lateral hypothalamus as measured by microdialysis.
1989,
Pubmed
Seiden,
Methamphetamine and methylenedioxymethamphetamine neurotoxicity: possible mechanisms of cell destruction.
1996,
Pubmed
Series,
p-Chloroamphetamine (PCA), 3,4-methylenedioxy-methamphetamine (MDMA) and d-fenfluramine pretreatment attenuates d-fenfluramine-evoked release of 5-HT in vivo.
1994,
Pubmed
Shi,
Dual effects of D-amphetamine on dopamine neurons mediated by dopamine and nondopamine receptors.
2000,
Pubmed
Sitte,
Characterization of carrier-mediated efflux in human embryonic kidney 293 cells stably expressing the rat serotonin transporter: a superfusion study.
2000,
Pubmed
Sprague,
An integrated hypothesis for the serotonergic axonal loss induced by 3,4-methylenedioxymethamphetamine.
1998,
Pubmed
Staack,
Cytochrome P450 dependent metabolism of the new designer drug 1-(3-trifluoromethylphenyl)piperazine (TFMPP). In vivo studies in Wistar and Dark Agouti rats as well as in vitro studies in human liver microsomes.
2004,
Pubmed
Steinkellner,
The ugly side of amphetamines: short- and long-term toxicity of 3,4-methylenedioxymethamphetamine (MDMA, 'Ecstasy'), methamphetamine and D-amphetamine.
2011,
Pubmed
Steranka,
Long-term effects of fenfluramine on central serotonergic mechanisms.
1979,
Pubmed
Sulzer,
How addictive drugs disrupt presynaptic dopamine neurotransmission.
2011,
Pubmed
Wrona,
A putative metabolite of serotonin, tryptamine-4,5-dione, is an irreversible inhibitor of tryptophan hydroxylase: possible relevance to the serotonergic neurotoxicity of methamphetamine.
2001,
Pubmed
Xie,
Loss of serotonin transporter protein after MDMA and other ring-substituted amphetamines.
2006,
Pubmed
Zaczek,
Effects of repeated fenfluramine administration on indices of monoamine function in rat brain: pharmacokinetic, dose response, regional specificity and time course data.
1990,
Pubmed
