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Ghanbari R, El Mansari M, Blier P. Enhancement of serotonergic and noradrenergic neurotransmission in the rat hippocampus by sustained administration of bupropion. Psychopharmacology (Berl) 2011; 217:61-73. [PMID: 21445565 DOI: 10.1007/s00213-011-2260-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 03/06/2011] [Indexed: 12/31/2022]
Abstract
RATIONALE Previous studies reported that bupropion, an effective antidepressant, exerts modulatory actions on serotonin (5-HT) and norepinephrine (NE) neurons. OBJECTIVES This study examined effects of bupropion administration on 5-HT and NE neurotransmission in hippocampus. METHODS Electrophysiological recordings were obtained from anesthetized Sprague-Dawley rats. Subcutaneously implanted minipumps delivered saline or bupropion (30 mg/kg/day) for 2 and 14 days. RESULTS Although sustained bupropion administration did not alter the sensitivity of 5-HT(1A) and α₂-adrenergic receptors, the tonic activation of postsynaptic 5-HT(1A) receptors by endogenous 5-HT was enhanced in 14-day bupropion-treated rats to a greater extent than in the 2-day and control rats, as revealed by the greater disinhibitory action of the 5-HT(1A) antagonist WAY-100635 on hippocampus pyramidal neurons. The function of terminal 5-HT(1B) autoreceptors was not changed as determined by the unaltered effectiveness of different frequencies of stimulation of the ascending 5-HT fibers. The function of α₂-adrenergic receptors on 5-HT terminals was, however, diminished, as indicated by the lesser effect of the α₂-adrenoceptor agonist clonidine. Tonic activation of postsynaptic α₂- and α₁-adrenoceptors by endogenous NE was also increased in 14-day bupropion-treated rats, as indicated by the greater effect of the α₂- and α₁-adrenoceptor antagonists idazoxan and prazosin, respectively, on pyramidal firing. The function of terminal α₂-adrenergic autoreceptors was attenuated since increasing frequency of stimulation of the ascending NE pathway produced a lesser degree of suppression of pyramidal neurons in rats administered bupropion than the control. CONCLUSION Enhancement of 5-HT and NE transmissions in hippocampus by prolonged bupropion may account for its effectiveness in major depression.
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MESH Headings
- Action Potentials/drug effects
- Animals
- Antidepressive Agents, Second-Generation/administration & dosage
- Antidepressive Agents, Second-Generation/pharmacology
- Bupropion/administration & dosage
- Bupropion/pharmacology
- CA3 Region, Hippocampal/drug effects
- CA3 Region, Hippocampal/metabolism
- Electric Stimulation
- Infusion Pumps, Implantable
- Iontophoresis
- Male
- Neurons
- Norepinephrine/metabolism
- Pyramidal Cells/drug effects
- Pyramidal Cells/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT1A/metabolism
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Adrenergic, alpha-2/metabolism
- Synaptic Transmission/drug effects
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Affiliation(s)
- Ramez Ghanbari
- Institute of Mental Health Research, University of Ottawa, Room 6411, 1145 Carling Avenue, Ottawa, K1Z7K4 ON, Canada
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Paterson NE. Behavioural and pharmacological mechanisms of bupropion's anti-smoking effects: recent preclinical and clinical insights. Eur J Pharmacol 2008; 603:1-11. [PMID: 19101536 DOI: 10.1016/j.ejphar.2008.12.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Revised: 11/23/2008] [Accepted: 12/09/2008] [Indexed: 11/28/2022]
Abstract
Ongoing studies continue to explore the behavioural and pharmacological effects of bupropion in smoking cessation studies and animal models of nicotine dependence. In the present review, the components of nicotine dependence that form the most likely targets of bupropion are identified within the context of an expanding preclinical and clinical literature regarding the anti-addictive properties of bupropion. Second, preclinical and clinical data that implicate specific pharmacological modes of action of bupropion in mediating the anti-smoking effects of the compound are discussed. Third, it is suggested that the unique mixed pharmacological profile of bupropion provides (1) attenuation of the multiple negative consequences of withdrawal via blockade of dopamine and noradrenaline reuptake; (2) replacement of the reward-facilitating and subjective effects of nicotine via blockade of dopaminergic reuptake; (3) attenuation of the rewarding effects of acute nicotine by nicotinic acetylcholine receptor blockade. The importance of species differences in bupropion metabolism in the interpretation of preclinical studies is highlighted. Finally, future studies are suggested to address identified gaps in the knowledge: most importantly, to provide stronger evidence for the role of noradrenaline reuptake inhibition in bupropion-induced attenuation of nicotine withdrawal. Future studies aimed at providing more evidence for the three-fold nature of the anti-smoking effects of bupropion are also suggested, along with the possibility of utilizing adjunct therapies to improve smoking cessation rates.
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Affiliation(s)
- Neil E Paterson
- Behavioural Pharmacology, PsychoGenics, Inc, Tarrytown, NY 10591, USA.
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El Mansari M, Ghanbari R, Janssen S, Blier P. Sustained administration of bupropion alters the neuronal activity of serotonin, norepinephrine but not dopamine neurons in the rat brain. Neuropharmacology 2008; 55:1191-8. [PMID: 18708076 DOI: 10.1016/j.neuropharm.2008.07.028] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Revised: 06/13/2008] [Accepted: 07/21/2008] [Indexed: 11/28/2022]
Abstract
Bupropion is widely used in the treatment of depression. There are, however, limited data on its long-term effects on monoaminergic neurons and therefore the mechanism of its delayed onset of action is at present not well understood. The present study was conducted to examine the effects of prolonged bupropion administration on the firing activity of dorsal raphe nucleus (DRN), locus coeruleus (LC), and ventral tegmental area (VTA) neurons. Spontaneously firing neurons were recorded extracellularly in rats anesthetized with chloral hydrate. Bupropion (30 mg/kg/day) was administered using subcutaneously implanted minipumps. In the DRN, the firing rate of serotonin (5-HT) neurons was significantly increased after 2, 7 and 14 days of administration. The suppressant effect of LSD was significantly diminished after the two-day regimen, indicating a desensitization of 5-HT1A autoreceptors. In the LC, the firing rate of norepinephrine (NE) neurons was significantly attenuated after a 2-day regimen, but recovered progressively over 14 days of administration. The suppressant effect of clonidine on NE neuronal firing was significantly attenuated in rats treated with bupropion for 14 days, indicating a desensitization of alpha2-adrenoceptors. In the VTA, neither 2 nor 14 days of bupropion administration altered the firing and burst activity of dopamine neurons. These results indicate that bupropion, unlike 5-HT reuptake inhibitors, promptly increased 5-HT neuronal activity, due to early desensitization of the 5-HT1A autoreceptor. The gradual recovery of neuronal firing of NE neurons, due to the desensitization of alpha2-adrenoceptors, in the presence of the sustained increase in 5-HT neuronal firing, may explain in part the delayed onset of action of bupropion in major depression.
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Affiliation(s)
- Mostafa El Mansari
- University of Ottawa Institute of Mental Health Research, Room 7407, 1145 Carling Avenue, Ottawa, Ontario, Canada K1Z 7K4.
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Marshall RD, Johannet CM, Collins PY, Smith H, Kahn DA, Douglas CJ. Bupropion and sertraline combination treatment in refractory depression. J Psychopharmacol 1995; 9:284-6. [PMID: 22297770 DOI: 10.1177/026988119500900313] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A sizeable minority of depressed patients, estimated at 15-20%, suffer chronic symptoms which often persist despite appropriate treatment. The search for new, more efficacious pharmacotherapies has included testing existing medications for additional therapeutic effects, such as in combination treatment. Four treatment- refractory patients who presented to the authors for clinical care are described, in which the combination of bupropion and sertraline was effective for a major depressive episode. None of the patients experienced adverse effects. Two carried the diagnosis of unipolar depression, and two, bipolar disorder. All had prior adequate, but ineffective, separate trials of buproprion and a selective serotonin re-uptake inhibitor (SSRI), including sertraline. All had chronic depression with multiple failed medication treatments, arguing against the alternative explanation that their improvement represented a placebo response or spontaneous remission. The efficacious combination of sertraline and bupropion may be due to synergism of its two distinct antidepressant mechanisms involving serotonergic, dopaminergic and noradrenergic systems.
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Affiliation(s)
- R D Marshall
- New York State Psychiatric Institute, Columbia University College of Physicians and Surgeons, NY, USA
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Palazidou E, Papadopoulos A, Ratcliff H, Dawling S, Checkley SA. Noradrenaline uptake inhibition increases melatonin secretion, a measure of noradrenergic neurotransmission, in depressed patients. Psychol Med 1992; 22:309-315. [PMID: 1319597 DOI: 10.1017/s0033291700030257] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Eight patients with endogenous depression who had received no antidepressant treatment for the previous year were treated with the noradrenaline (NA) uptake inhibitor, desipramine (DMI). Pre-treatment plasma melatonin concentrations were normal. After one day of DMI treatment plasma melatonin concentrations were increased but the response was impaired compared to normal subjects. The acute effect of DMI on plasma melatonin persisted after six weeks of treatment. These findings question the hypothesis that beta adrenoceptors are supersensitive in depression and that antidepressant drugs act by down-regulating these receptors.
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Affiliation(s)
- E Palazidou
- Department of Psychiatry, New Cross Hospital, London
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Abstract
The effects of bupropion on core body temperature of intact or reserpinized mice were studied. Intraperitoneal (IP) administration of bupropion to mice induced a dose-dependent hypothermia. The response of bupropion was decreased by the D-2 antagonist sulpiride or pimozide, but not by the D-1 antagonist SCH 23390, antimuscarinic drug atropine, alpha-adrenergic blocker phenoxybenzimine, beta-adrenergic antagonist propranolol or antiserotonergic methergoline. Reserpine induced hypothermia, which was reversed by bupropion administration. The reversal response of bupropion was reduced by propranolol, but not sulpiride, SCH 23390, phenoxybenzamine, atropine or methergoline. It is concluded that bupropion-induced hypothermia may be mediated through D-2 receptor activation, while the reversal of reserpine-induced hypothermia by bupropion may be exerted through beta-adrenergic stimulation.
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Affiliation(s)
- M R Zarrindast
- Department of Pharmacology, Medical Faculty, University of Tehran, Iran
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Cohen BM, Stramentinoli G, Sosa AL, Babb SM, Olgiati V. Effects of the novel antidepressant S-adenosyl-methionine on alpha 1- and beta-adrenoceptors in rat brain. Eur J Pharmacol 1989; 170:201-7. [PMID: 2559855 DOI: 10.1016/0014-2999(89)90540-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
alpha 1- and beta-adrenoceptors were studied ex vivo in the brains of rats receiving repeated daily treatment with the standard antidepressant imipramine or the atypical antidepressant S-adenosyl-L-methionine (SAM), which has minimal effects on monoamine reuptake or turnover. Consistent with past studies, a decrease in the density of beta receptors at three weeks and an increase in the affinity of alpha 1 receptors for the agonist phenylephrine at one week of treatment was observed with imipramine. By comparison, an increase in the density of beta receptors and a decrease in the affinity of alpha 1 receptors for phenylephrine was observed at one week of treatment with SAM. These changes were no longer apparent at three weeks of treatment. The results suggest that treatment with SAM does lead to changes in adrenergic neurotransmission, but that down regulation of beta receptors or increased agonist affinity of alpha 1 receptors may not be necessary for the production of antidepressant effects.
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Affiliation(s)
- B M Cohen
- Laboratories for Psychiatric Research, McLean Hospital, Belmont, MA 02178
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Sulser F. New perspectives on the molecular pharmacology of affective disorders. EUROPEAN ARCHIVES OF PSYCHIATRY AND NEUROLOGICAL SCIENCES 1989; 238:231-9. [PMID: 2548868 DOI: 10.1007/bf00449803] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Research with antidepressants has emphasized the importance of a delayed deamplification of the linked serotonin (5HT)/norepinephrine (NE) receptor coupled adenylate cyclase system in brain. The basic phenomena of regulation of receptor number and function of the beta adrenoceptor linked adenylate cyclase system in brain are well established, with NE regulating beta adrenoceptors in the high agonist affinity conformation (linked to adenylate cyclase and down-regulated by antidepressants), and with 5HT regulating those receptors in the low agonist affinity conformation. The biochemical effector systems of NE and 5HT are discussed and it is concluded that the final common pathway of signal transduction is protein kinase mediated phosphorylation of cellular proteins. Glucocorticoid receptors are located in the perikarya of aminergic cell bodies and may exert their effects by modifying the genomic expression of the diffusely projecting stress-responsive monoamine systems. The molecular neurobiology of beta adrenoceptors, with its implication for genetic and immunologic investigations, is briefly discussed and further research on stimulus-transcription coupling and regulation of gene expression in brain is suggested as an exciting new direction in central receptor research relevant to the psychopharmacology of affective and other disorders.
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Affiliation(s)
- F Sulser
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232
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Krijzer FN, Schipper J, Tulp MT, Koopman PA. Relationship between electrocortical activity and beta-adrenergic receptor function in the rat after chronic desimipramine treatment. J Neural Transm (Vienna) 1989; 78:73-87. [PMID: 2547025 DOI: 10.1007/bf01247115] [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: 01/01/2023]
Abstract
The aim of this study was to investigate the effects of chronic administration of desimipramine (DMI) after 2, 7 or 20 mg/kg per day, administered by osmotic minipumps, on electrocortical activity and beta-adrenergic receptors in rat brain. Rats receiving DMI chronically show a dose- and time-dependent increase of electrocortical activity above 15 Hz as well as a dose- and time-dependent decrease below 15 Hz. Already after 3 days of treatment a clear effect on the electrocorticogram (ECoG) was seen. The maximal change in the ECoG was reached at the end of the study, after 24 days of treatment. After acute treatment (20 and 45 minutes after 2, 4 or 10 mg/kg i.p.) with DMI, a decrease of electrocortical activity is seen above 15 Hz. Thus the effect of acute DMI treatment on the ECoG is different from that of chronic treatment. In the same group of rats the effect of chronic DMI treatment on the beta-adrenergic receptor number was determined 24 hours after the last ECoG recording. The number of beta-adrenergic receptors was dose dependently reduced in the DMI-treated rats as determined by [3H]-dihydroalprenolol binding. There was no change in affinity (KD) of the ligand for the beta-receptor. This finding was corroborated by a decrease in the functional activity of the beta-adrenergic receptors, as determined by isoprenaline stimulated efflux of cyclic-AMP in cortex slices. These data indicate that chronic treatment with DMI, resulting in a down-regulation of the cortical beta-adrenergic system, is paralleled by pronounced effects on the ECoG of rats. The different ECoG profiles after chronic DMI treatment compared with acute treatment suggest that adaptive changes in the electrical brain activity continually develop during the chronic treatment with this antidepressant drug.
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Affiliation(s)
- F N Krijzer
- Department of Pharmacology, Duphar B.V., Weesp, The Netherlands
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