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Ulrich S, Lewitzka U. [Psychopharmacotherapy with the MAO-inhibitor Tranylcypromine Key Aspects and Trends in Theory and Practice]. FORTSCHRITTE DER NEUROLOGIE-PSYCHIATRIE 2023. [PMID: 37989204 DOI: 10.1055/a-2182-5365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2023]
Abstract
The irreversible monoamine oxidase inhibitor tranylcypromine has been known as an antidepressant drug for more than 60 years. The aim of this review was to make an assessment of the state of the art and therapy of tranylcypromine. The recent medical-scientific literature is analyzed and discussed with respect to key aspects of and general trends in practical psychopharmacotherapy. Meta-analyses of controlled clinical studies have shown that tranylcypromine is an established approach to treatment-resistant depression. Doses (maximum dose, maintenance dose) are increasingly adapted to the requirements of treatment-resistant depression. Monoamine oxidase is not only the primary pharmacological target of tranylcypromine but determines for the first doses also the pharmacokinetics of tranylcypromine because monoamine oxidase is also an enantioselective drug-metabolizing enzyme of the monoamine oxidase inhibitor. An increased diversity of the antidepressant pharmacotherapy suggests the need to rethink the continuing assessment of tranylcypromine as a therapeutic "ultima ratio" in depression. In conclusion, tranylcypromine as a drug of second choice remains a valuable option in antidepressant treatment. Criteria of a switch from other antidepressant drugs to tranylcypromine should be better defined.
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Affiliation(s)
- Sven Ulrich
- Med.-wiss. Abt., Aristo Pharma GmbH, Berlin, Germany
| | - Ute Lewitzka
- Klinik und Poliklinik für Psychiatrie und Psychotherapie, Universitätsklinikum Carl Gustav Carus, Dresden, Deutschland, Dresden, Germany
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Efficacy and Adverse Effects of Tranylcypromine and Tricyclic Antidepressants in the Treatment of Depression: A Systematic Review and Comprehensive Meta-analysis. J Clin Psychopharmacol 2020; 40:63-74. [PMID: 31834088 DOI: 10.1097/jcp.0000000000001153] [Citation(s) in RCA: 170] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
PURPOSE We conducted a comprehensive meta-analysis of the comparison of tranylcypromine (TCP) and tricyclic antidepressants (TCAs) in the treatment of depression because such work is lacking in medical scientific literature. METHODS Literature was searched for studies of TCP controlled by TCAs in multiple databases and in reviews of TCP and monoamine oxidase inhibitors. The natural logarithm of the odds ratio (logOR) and the pooled logOR according to a fixed effect model were calculated for the numbers of responders and nonresponders. RESULTS A total of 227 studies of TCP were found including 75 controlled studies of TCP-monotherapy. Twelve of 23 studies of TCP monotherapy and TCAs were excluded for several reasons (duplicates, safety studies, retrospective, cross-over), leaving 11 prospective and parallel controlled studies of TCP monotherapy versus TCAs (6 randomized double-blind). One study was excluded from the meta-analysis because of low quality of study design according to the Food and Drug Administration guidelines of studies of antidepressant drugs and high risk of bias according to the Cochrane's tool. Two studies with equal efficacy of TCP and TCAs in continuous endpoints did not provide dichotomous response data. A pooled logOR of 0.480 (95% confidence interval, 0.105-0.857, P = 0.01) resulted for the remaining eight studies in the primary meta-analysis, which favors TCP significantly over TCAs (test for heterogeneity: Х = 8.1, df = 7, P > 0.3, not heterogenous; I = 13.6%, heterogeneity not important). The result is robust with respect to inclusion of hypothetical response data of the 2 studies with continuous data only: pooled logOR, 0.350 (95% confidence interval, 0.028-0.672, P = 0.03). Visual inspection of forest plots and subgroup analysis suggest that superiority of TCP over TCAs is determined by 2 studies in psychomotor-retarded (anergic) depression. CONCLUSIONS Tranylcypromine and TCAs have an equal antidepressant effect in a mean sample of depressed patients with mixed psychomotor symptoms. Tranylcypromine might be superior to TCAs in depression with predominant psychomotor retardation.
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Zabegalov KN, Kolesnikova TO, Khatsko SL, Volgin AD, Yakovlev OA, Amstislavskaya TG, Alekseeva PA, Meshalkina DA, Friend AJ, Bao W, Demin KA, Gainetdinov RR, Kalueff AV. Understanding antidepressant discontinuation syndrome (ADS) through preclinical experimental models. Eur J Pharmacol 2018; 829:129-140. [DOI: 10.1016/j.ejphar.2018.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 03/29/2018] [Accepted: 04/04/2018] [Indexed: 12/14/2022]
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Meshalkina DA, Kysil EV, Antonova KA, Demin KA, Kolesnikova TO, Khatsko SL, Gainetdinov RR, Alekseeva PA, Kalueff AV. The Effects of Chronic Amitriptyline on Zebrafish Behavior and Monoamine Neurochemistry. Neurochem Res 2018; 43:1191-1199. [DOI: 10.1007/s11064-018-2536-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 03/28/2018] [Accepted: 04/19/2018] [Indexed: 12/25/2022]
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Khlebnikova NN, Kushnareva EY, Kudrin VS, Krupina NA. The effects of imipramine and the inhibitor of prolylendopeptidase benzyloxycarbonyl-methionyl-2(S)-cyanopyrrolidine on the levels of monoamines and their metabolites in the brain of rats with an experimental anxious-depressive state. NEUROCHEM J+ 2014. [DOI: 10.1134/s1819712414040059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Ait-Belgnaoui A, Colom A, Braniste V, Ramalho L, Marrot A, Cartier C, Houdeau E, Theodorou V, Tompkins T. Probiotic gut effect prevents the chronic psychological stress-induced brain activity abnormality in mice. Neurogastroenterol Motil 2014; 26:510-20. [PMID: 24372793 DOI: 10.1111/nmo.12295] [Citation(s) in RCA: 275] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 11/29/2013] [Indexed: 12/14/2022]
Abstract
BACKGROUND A probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 combination, Probio'Stick(®) ) displays anxiolytic-like activity and reduces apoptosis in the lymbic system in animal models of depression. Based on the hypothesis that modulation of gut microbiota by this probiotic formulation has beneficial effects on brain activity in stress conditions, we report a set of probiotic-evoked physiological, cellular, and molecular events in the brain of Probio'Stick(®) pretreated mice submitted to chronic psychological stress. METHODS Water avoidance stress (WAS) was applied or not (sham). Hypothalamic-pituitary-adrenal (HPA) axis and autonomic nervous system (ANS) responses to the chronic stress were assessed through plasma corticosterone and catecholamine measurements. Specific markers for neuronal activity, neurogenesis, and synaptic plasticity were used to assess brain activity. In addition, gut permeability and tight junction (TJ) proteins levels were also determinated. KEY RESULTS We observed that a pretreatment with the probiotic formulation attenuated HPA axis and ANS activities in response to WAS, and reduced cFos expression in different brain areas but Lactobacillus salivarius (a negative control) treatment was ineffective on these parameters. Moreover, probiotic pretreatment prevented the WAS-induced decrease hippocampal neurogenesis and expression changes in hypothalamic genes involved in synaptic plasticity. These central effects were associated with restoration of TJ barrier integrity in stressed mice. CONCLUSIONS & INFERENCES These data suggest that chronic stress-induced abnormal brain plasticity and reduction in neurogenesis can be prevented by a pretreatment with the Probio'Stick(®) formulation, suggesting that probiotics modulate neuroregulatory factors and various signaling pathways in the central nervous system involved in stress response.
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Affiliation(s)
- A Ait-Belgnaoui
- Neuro-Gastroenterologie et Nutrition team, TOXALIM, UMR 1331-INRA/INP/UPS, Toulouse, France; Lallemand Health Solutions Inc., Montreal, QC, Canada
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Zheng M, Fan Y, Shi D, Liu C. Antidepressant-like effect of flavonoids extracted from Apocynum venetum leaves on brain monoamine levels and dopaminergic system. JOURNAL OF ETHNOPHARMACOLOGY 2013; 147:108-113. [PMID: 23453939 DOI: 10.1016/j.jep.2013.02.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 01/30/2013] [Accepted: 02/06/2013] [Indexed: 06/01/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Apocynum venetum L. (Apocynaceae), a traditional medicinal plant, has been used for the improvement of emotions in Asian countries. AIM OF THE STUDY We explored the antidepressant-like effect and monoaminergic mechanism of a flavonoids extract from Apocynum venetum leaves (AV-extract). MATERIALS AND METHODS Effect of AV-extract (25, 50 and 100 mg/kg, i.g.) on mice's immobility time was assessed in forced swim test (FST) and tail suspension test (TST). The locomotor activity was evaluated in the open-field test (OFT). Additionally, the main monoamine neurotransmitters serotonin (5-HT), noradrenaline (NA) and dopamine (DA) and their metabolites 5-hydroxyindole-3-acetic acid (5-HIAA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the mouse hippocampus involved in the antidepressant-like effect of AV-extract was also determined by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS). RESULTS AV-extract (50 and 100 mg/kg, i.g.) administration significantly reduced the immobility time in both the FST and TST without accompanying changes in locomotor activity in the OFT. It was also found that the AV-extract significantly increased the concentrations of the main neurotransmitters NE and DA along with their respective metabolites DOPAC, HVA in the hippocampus. The antidepressant-like effect of the AV-extract (50 mg/kg, i.g.) was prevented by the pretreatment of mice with SCH23390 (0.05 mg/kg, i.g., a dopamine D1 receptor antagonist) or sulpiride (50 mg/kg, i.g., a dopamine D2 receptor antagonist). CONCLUSION The AV-extract produced significant antidepressant-like effects, which likely attribute to increased NE and DA along with their respective metabolites DOPAC, HVA in the mouse hippocampus, and dependent on interaction with dopaminergic (D1 and D2 receptor) systems.
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Affiliation(s)
- Meizhu Zheng
- The Central Laboratory, Changchun Normal University, Changchun, Jilin 130032, China.
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Desbonnet L, Garrett L, Clarke G, Bienenstock J, Dinan TG. The probiotic Bifidobacteria infantis: An assessment of potential antidepressant properties in the rat. J Psychiatr Res 2008; 43:164-74. [PMID: 18456279 DOI: 10.1016/j.jpsychires.2008.03.009] [Citation(s) in RCA: 612] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2008] [Revised: 03/20/2008] [Accepted: 03/20/2008] [Indexed: 12/14/2022]
Abstract
It is becoming increasingly apparent that probiotics are important to the health of the host. The absence of probiotic bacteria in the gut can have adverse effects not only locally in the gut, but has also been shown to affect central HPA and monoaminergic activity, features that have been implicated in the aetiology of depression. To evaluate the potential antidepressant properties of probiotics, we tested rats chronically treated with Bifidobacteria infantis in the forced swim test, and also assessed the effects on immune, neuroendocrine and central monoaminergic activity. Sprague-Dawley rats were treated for 14 days with B. infantis. Probiotic administration in naive rats had no effect on swim behaviours on day 3 or day 14 following the commencement of treatment. However, there was a significant attenuation of IFN-gamma, TNF-alpha and IL-6 cytokines following mitogen stimulation (p<0.05) in probiotic-treated rats relative to controls. Furthermore, there was a marked increase in plasma concentrations of tryptophan (p<0.005) and kynurenic acid (p<0.05) in the bifidobacteria-treated rats when compared to controls. Bifidobacteria treatment also resulted in a reduced 5-HIAA concentration in the frontal cortex and a decrease in DOPAC in the amygdaloid cortex. The attenuation of pro-inflammatory immune responses, and the elevation of the serotonergic precursor, tryptophan by bifidobacteria treatment, provides encouraging evidence in support of the proposition that this probiotic may possess antidepressant properties. However, these findings are preliminary and further investigation into the precise mechanisms involved, is warranted.
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Affiliation(s)
- Lieve Desbonnet
- Department of Psychiatry and Alimentary Pharmacobiotic Centre, Biosciences Institute, University College Cork, Cork, Ireland.
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Yalcin I, Aksu F, Bodard S, Chalon S, Belzung C. Antidepressant-like effect of tramadol in the unpredictable chronic mild stress procedure: possible involvement of the noradrenergic system. Behav Pharmacol 2008; 18:623-31. [PMID: 17912046 DOI: 10.1097/fbp.0b013e3282eff109] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Tramadol, which inhibits the reuptake of noradrenaline and serotonin, is effective in animal models of depression. Its antidepressant-like effects may be mediated mainly by the noradrenergic system. This study investigated the role of the noradrenergic system in the antidepressant-like effects of tramadol and desipramine in the unpredictable chronic mild stress model. We assessed the involvement of beta-adrenoreceptors, particularly beta2-receptors in the activity of these drugs. In addition, we measured the level of noradrenaline and its metabolite 3-methoxy-4-hydroxy-phenylglycol (MHPG) in the locus coeruleus, hypothalamus, hippocampus and cerebellum in stressed mice. Unpredictable chronic mild stress induced a degradation of coat state and decreased grooming behaviour in the splash test, which was reversed by the chronic administration of tramadol (20 mg/kg) and desipramine (10 mg/kg). The nonselective beta-adrenoreceptor antagonist propranolol (5 mg/kg, intraperitoneally) and the selective beta2-receptor antagonist ICI 118,551 (2 mg/kg, intraperitoneally) reversed the antidepressant-like effects of tramadol and desipramine. Moreover, chronic tramadol and desipramine treatment increased the level of noradrenaline (NA) and MHPG in the locus coeruleus but not in the cerebellum, whereas only MHPG level was increased in the hypothalamus. Tramadol, however, increased the levels of MHPG and NA in the hippocampus, whereas desipramine only increased NA level. These data support the view that the noradrenergic system plays an important role in the antidepressant-like action of tramadol.
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Affiliation(s)
- Ipek Yalcin
- EA 3248 Psychobiology of Emotions, Faculty of Science and Technics, Parc Grandmont, University François Rabelais Tours, France
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Marsteller DA, Barbarich-Marsteller NC, Patel VD, Dewey SL. Brain metabolic changes following 4-week citalopram infusion: increased 18FDG uptake and gamma-amino butyric acid levels. Synapse 2007; 61:877-81. [PMID: 17657806 DOI: 10.1002/syn.20428] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We used 2-week and 4-week citalopram infusion (10 mg/kg/day) to determine how this selective serotonin reuptake inhibitor (SSRI) would alter 2-deoxy-2-[18F]-fluoro-D-glucose (18FDG) uptake and neurotransmitter tissue levels in male Sprague-Dawley rodents. A weekly time course of 18FDG uptake altered by chronic citalopram treatment was determined in vivo with small animal positron emission tomography (microPET). Additionally, end of study monoamine levels were measured ex vivo using high pressure liquid chromatography (HPLC) and amino acid levels were determined ex vivo with proton nuclear magnetic resonance spectroscopy (1H-NMRS). We found increased striatal 18FDG uptake, reduced tissue levels of noradrenaline and serotonin in the striatum and prefrontal cortex, and increased striatal gamma-amino-butyric acid following 4-week citalopram infusion.
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Affiliation(s)
- Douglas A Marsteller
- Graduate Program in Molecular and Cellular Pharmacology, SUNY Stony Brook, Stony Brook, New York 11794, USA.
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Butterweck V, Simbrey K, Seo S, Sasaki T, Nishibe S. Long-term effects of an Apocynum venetum extract on brain monoamine levels and beta-AR density in rats. Pharmacol Biochem Behav 2003; 75:557-64. [PMID: 12895673 DOI: 10.1016/s0091-3057(03)00118-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The present study was designed to get further insight into the mode of antidepressant action of an extract prepared of the leaves of Apocynum venetum L. (AV). To evaluate biochemical changes, we used a high-performance liquid chromatography system to examine the effects of short-term (2 weeks) and long-term (8 weeks) administration of imipramine (15 mg/kg po) and an AV-extract (15, 60 and 250 mg/kg) on regional levels of serotonin (5-HT), norepinephrine (NE), dopamine (DA) and their metabolites in the rat hypothalamus, striatum and hippocampus. Pronounced changes in 5-HT, NE and DA levels were detected mainly after 8 weeks of daily imipramine treatment. Similar to imipramine, AV-extract reduced NE and DA concentrations after 8 weeks, whereas it failed to affect 5-HT levels. We speculate that the decrease in NE levels after chronic AV treatment might be based partly on the subsensitivity of presynaptic alpha(2)-receptors. In addition to the determination of central monoamine concentrations, quantitative radioligand receptor-binding studies were used to examine the effects of long-term administration of imipramine and AV-extract on beta-adrenergic binding in rat frontal cortex. [125I]CYP binding to beta-adrenergic receptors was found to be decreased after 8 weeks treatment with imipramine, whereas AV-extract had no effect on beta-receptor binding.
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Affiliation(s)
- Veronika Butterweck
- Institute of Pharmacology and Toxicology, Universitätsklinikum Muenster, Domagkstrasse 12, 48149 Münster, Germany.
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Butterweck V, Böckers T, Korte B, Wittkowski W, Winterhoff H. Long-term effects of St. John's wort and hypericin on monoamine levels in rat hypothalamus and hippocampus. Brain Res 2002; 930:21-9. [PMID: 11879791 DOI: 10.1016/s0006-8993(01)03394-7] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Hypericum perforatum L. (St. John's wort) is one of the leading psychotherapeutic phytomedicines and, because of this, great effort has been devoted to clarifying its mechanism of action. Chronic effects of St. John's wort and hypericin, one of its major active compounds, on regional brain amine metabolism have not been reported yet. We used a high-performance liquid chromatography system to examine the effects of short-term (2 weeks) and long-term (8 weeks) administration of imipramine, Hypericum extract or hypericin on regional levels of serotonin (5-HT), norepinephrine, dopamine and their metabolites in the rat brain. We focused our interest on the hypothalamus and hippocampus, as these brain regions are thought to be involved in antidepressant drug action. Imipramine (15 mg/kg, p.o.), Hypericum extract (500 mg/kg, p.o.), and hypericin (0.2 mg/kg, p.o.) given daily for 8 weeks significantly increased 5-HT levels in the hypothalamus (P<0.05). The 5-HT turnover was significantly lowered in both brain regions after 8 weeks of daily treatment with the Hypericum extract (both P<0.05). Consistent changes in catecholamine levels were only detected in hypothalamic tissues after long-term treatment. Comparable to imipramine, Hypericum extract as well as hypericin significantly decreased 3,4-dihydroxyphenylacetic acid and homovanillic acid levels in the hypothalamus (P<0.01). Our data clearly show that long-term, but not short-term administration of St. John's wort and its active constituent hypericin modify levels of neurotransmitters in brain regions involved in the pathophysiology of depression.
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Affiliation(s)
- Veronika Butterweck
- Institute of Pharmacology and Toxicology, Domagkstrasse 12, 48149 Muenster, Germany.
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Zangen A, Overstreet DH, Yadid G. Increased catecholamine levels in specific brain regions of a rat model of depression: normalization by chronic antidepressant treatment. Brain Res 1999; 824:243-50. [PMID: 10196455 DOI: 10.1016/s0006-8993(99)01214-7] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Alterations in catecholamine levels and neurotransmission have been shown in depressive disorders. However, the exact sites of alterations and the relation between these alterations to the etiology of the disease and the effectiveness of antidepressant therapy are poorly understood. In this study, catecholamine levels and metabolism were measured in specific brain regions of a genetic rat model of depression [Flinders Sensitive Line (FSL) rats], and compared to normal Sprague-Dawley rats. Norepinephrine levels were found to be two to threefold higher in the nucleus accumbens, prefrontal cortex, hippocampus and median raphe nucleus of FSL rats as compared with control Sprague-Dawley rats. Dopamine levels were sixfold higher in the nucleus accumbens and twofold higher in the striatum, hippocampus and hypothalamus of FSL rats as compared with control Sprague-Dawley rats. After chronic treatment with the antidepressant desipramine, the immobility score in a swim test, as a measure of a behavioral deficit, as well as catecholamine levels of the FSL rats became normalized, but these parameters in the control rats did not change. The results indicate that the behavioral deficits expressed in the FSL model for depression correlate with increased catecholamine levels in specific brain sites, and further suggest the FSL rats as a model for elucidation of the molecular mechanism of clinically used antidepressant drugs.
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Affiliation(s)
- A Zangen
- Faculty of Life Sciences, Bar Ilan University, Ramat-Gan, Israel
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Roffman JL, Raskin LA. Stereotyped behavior: effects of d-amphetamine and methylphenidate in the young rat. Pharmacol Biochem Behav 1997; 58:1095-102. [PMID: 9408219 DOI: 10.1016/s0091-3057(97)00321-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The proclivity of d-amphetamine and methylphenidate to induce perseverative motoric and vocal side effects detracts from the clinical efficacy of these stimulants in the treatment of Attention-Deficit Hyperactivity Disorder (ADHD). In an attempt to develop a model for these deleterious treatment effects, this study explored the behavioral influences exerted by d-amphetamine and methylphenidate in the young laboratory rat. This experiment revealed that doses of these stimulants that typically induce stereotypy provoke diverging behavioral profiles: while animals given 5 mg/kg d-amphetamine exhibited repetitive sniffing activity, rats treated with 30 mg/kg methyl-phenidate displayed perseverative gnawing behaviors. Although pretreatment with the serotonin synthesis inhibitor p-chlorophenylalanine (PCPA) significantly attenuated both stimulant-induced stereotypies, the effect of PCPA on d-amphetamine-induced sniffing was more profound than on methylphenidate-induced gnawing. High-performance liquid chromatography (HPLC) analysis of monoamine levels in the striatum, frontal cortex, and thalamus indicated that PCPA induced an overall 89% depletion of serotonin across all conditions. These findings shed some light on the neurochemical mechanisms that underlie the differential effects of d-amphetamine and methylphenidate on stereotyped motor activity in the rat, and suggest future experiments for understanding the role of serotonin in such effects. Further, these results have implications for the differential side effects observed from each of these stimulants when used clinically in children with ADHD.
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Affiliation(s)
- J L Roffman
- Neuroscience Program, Amherst College, MA 01002-5000, USA
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