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Brookshire BR, Jones SR. Direct and indirect 5-HT receptor agonists produce gender-specific effects on locomotor and vertical activities in C57 BL/6J mice. Pharmacol Biochem Behav 2009; 94:194-203. [PMID: 19698737 DOI: 10.1016/j.pbb.2009.08.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Revised: 07/31/2009] [Accepted: 08/06/2009] [Indexed: 11/19/2022]
Abstract
It is well established that the dopamine (DA) and serotonin (5-HT) systems have extensive and complex interactions. However, the effects of specific 5-HT receptor agonists on traditionally DA-related behaviors remain unclear. Our goal in these studies was to characterize the effects of 5-HT receptor agonists on measures of locomotor activity and vertical rearing. The SSRIs fluoxetine and citalopram produced significant decreases in locomotor activity and vertical rearing at the highest doses used with females significantly more sensitive to citalopram. The 5-HT(1A) agonist 8-OH-DPAT and the 5-HT(2C) agonist MK 212 significantly decreased activity in both male and female mice, with females more sensitive to 8-OH-DPAT. In contrast, the 5-HT(1B) agonist RU 24969 and the 5-HT(2A) agonist DOI both increased activity, with DOI exhibiting differential effects with regard to sex. Finally, the 5-HT(3) agonist SR 57227 produced significant locomotor increases only in female mice at the lowest dose. The results of these experiments define locomotor profiles of several 5-HT agonists in male and female C57BL/6J mice, providing a foundation for further explorations of 5-HT receptor effects on activity.
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Affiliation(s)
- Bethany R Brookshire
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA
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Alfinito PD, Chen X, Mastroeni R, Pawlyk AC, Deecher DC. Estradiol increases catecholamine levels in the hypothalamus of ovariectomized rats during the dark-phase. Eur J Pharmacol 2009; 616:334-9. [DOI: 10.1016/j.ejphar.2009.06.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 06/17/2009] [Accepted: 06/22/2009] [Indexed: 11/15/2022]
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Mueller D, Olivera-Figueroa LA, Pine DS, Quirk GJ. The effects of yohimbine and amphetamine on fear expression and extinction in rats. Psychopharmacology (Berl) 2009; 204:599-606. [PMID: 19242678 PMCID: PMC2692542 DOI: 10.1007/s00213-009-1491-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Accepted: 02/05/2009] [Indexed: 11/30/2022]
Abstract
RATIONALE Psychostimulants, such as yohimbine and amphetamine, can enhance learning and memory. Extinction of conditioned fear involves new learning, so we asked whether psychostimulants could enhance this learning. Previous work suggests that yohimbine facilitates extinction, using freezing as a fear measure. However, psychostimulant-induced alterations in locomotion can confound freezing measurements. Furthermore, the effects of amphetamine on fear extinction have never been examined. OBJECTIVE We evaluated the effectiveness of yohimbine and amphetamine in enhancing fear extinction. In addition to freezing, we measured bar-press suppression, which is less sensitive to changes in locomotion. We asked: Do psychostimulants reduce fear during extinction training when drug is present? Does learning extinction with psychostimulants result in better extinction retention? MATERIALS AND METHODS Rats received fear conditioning on day 1 followed by partial extinction training on days 2 and 3. Yohimbine (1.0, 2.0, or 5.0 mg/kg, i.p.), amphetamine (1.0 mg/kg, i.p.), or vehicle were injected prior to extinction on day 2. RESULTS Yohimbine dose-dependently reduced freezing during extinction training on day 2, whereas bar-press suppression was reduced at the highest dose only. When tested drug-free, yohimbine-treated rats showed equivalent levels of freezing and suppression to controls. Amphetamine also decreased freezing during extinction, but did not decrease suppression. During the drug-free test, there was no difference between amphetamine-treated rats and controls in either measure. CONCLUSIONS Although yohimbine and amphetamine are capable of decreasing freezing, neither drug strengthened retention of fear extinction. Based on these rodent findings, psychostimulants may not be suitable adjuncts to extinction-based therapies for the treatment of anxiety disorders.
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Affiliation(s)
- Devin Mueller
- Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, P.O. Box 365067, San Juan, Puerto Rico 00936−5067
| | | | - Daniel S. Pine
- Section on Development and Affective Neuroscience, NIMH Intramural Research Program, Bethesda, MD, USA 20817−2670
| | - Gregory J. Quirk
- Departments of Psychiatry and Anatomy & Neurobiology, University of Puerto Rico School of Medicine, P.O. Box 365067, San Juan, Puerto Rico 00936−5067
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Abstract
AIMS To examine the literature regarding clinical pharmacokinetics, direct effects and adverse clinical outcomes associated with methamphetamine use. METHODS Relevant literature was identified through a PubMed search. Additional literature was obtained from relevant books and monographs. FINDINGS AND CONCLUSIONS The mean elimination half-life for methamphetamine is approximately 10 hours, with considerable inter-individual variability in pharmacokinetics. Direct effects at low-to-moderate methamphetamine doses (5-30 mg) include arousal, positive mood, cardiac stimulation and acute improvement in cognitive domains such as attention and psychomotor coordination. At higher doses used typically by illicit users (> or =50 mg), methamphetamine can produce psychosis. Its hypertensive effect can produce a number of acute and chronic cardiovascular complications. Repeated use may induce neurotoxicity, associated with prolonged psychiatric symptoms, cognitive impairment and an increased risk of developing Parkinson's disease. Abrupt cessation of repeated methamphetamine use leads to a withdrawal syndrome consisting of depressed mood, anxiety and sleep disturbance. Acute withdrawal lasts typically for 7-10 days, and residual symptoms associated with neurotoxicity may persist for several months.
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Affiliation(s)
- Christopher C Cruickshank
- Pharmacology and Anaesthesiology Unit (MBDP 510), School of Medicine and Pharmacology, TheUniversity of Western Australia, Crawley WA 6009, Australia.
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Sigma1 receptor antagonists determine the behavioral pattern of the methamphetamine-induced stereotypy in mice. Psychopharmacology (Berl) 2009; 203:781-92. [PMID: 19052726 PMCID: PMC3157915 DOI: 10.1007/s00213-008-1425-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Accepted: 11/20/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVE The effects of sigma receptor antagonists on methamphetamine (METH)-induced stereotypy have not been examined. We examined the effects of sigma antagonists on METH-induced stereotypy in mice. RESULTS The administration of METH (10 mg/kg) to male ddY mice induced stereotyped behavior consisting of biting (90.1%), sniffing (4.2%), head bobbing (4.1%), and circling (1.7%) during an observation period of 1 h. Pretreatment of the mice with BMY 14802 (alpha-(4-fluorophenyl)-4-(5-fluoro-2-pyrimidinyl)-1-piperazinebutanol; 1, 5, and 10 mg/kg), a non-specific sigma receptor antagonist, significantly increased METH-induced sniffing (19.2%, 30.5%, and 43.8% of total stereotypical behavior) but decreased biting (76.6%, 66.9%, and 49.3% of total stereotypical behavior) in a dose-dependent manner. This response was completely abolished by (+)-SKF 10,047 ([2S-(2alpha,6alpha,11R)]-1,2,3,4,5,6-hexahydro-6,11-dimethyl-3-(2-propenyl)-2,6-methano-3-benzazocin-8-ol; 4 and 10 mg/kg), a putative sigma(1) receptor agonist, and partially by PB 28 (1-cyclohexyl-4-[3-(1,2,3,4-tetrahydro-5-methoxy-1-naphthalen-1-yl)-n-propyl]piperazine; 1 and 10 mg/kg), a putative sigma(2) receptor agonist. The BMY 14802 action on METH-induced stereotypy was mimicked by BD 1047 (N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino)ethylamine; 10 mg/kg), a putative sigma(1) receptor antagonist, but not by SM-21 ((+/-)-tropanyl 2-(4-chlorophenoxy)butanoate; 1 mg/kg), a putative sigma(2) receptor antagonist. The BD 1047 effect on METH-induced stereotypy was also abolished completely by (+)-SKF 10,047 and partially by PB 28. The overall frequency of METH-induced stereotypical behavior was unchanged with these sigma receptor ligands, despite the alteration in particular behavioral patterns. The BMY 14802 action on METH-induced stereotypy was unaffected by pretreatment with centrally acting histamine H(1) receptor antagonists (pyrilamine or ketotifen, 10 mg/kg), suggesting that these effects are independent of histamine H(1) receptor signaling systems. CONCLUSION In summary, modulation of central sigma(1) receptors alters the pattern of METH-induced stereotypy, producing a shift from stereotypical biting to stereotypical sniffing, without affecting the overall frequency of stereotypical behavior.
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Bales JW, Wagner AK, Kline AE, Dixon CE. Persistent cognitive dysfunction after traumatic brain injury: A dopamine hypothesis. Neurosci Biobehav Rev 2009; 33:981-1003. [PMID: 19580914 DOI: 10.1016/j.neubiorev.2009.03.011] [Citation(s) in RCA: 187] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Revised: 03/10/2009] [Accepted: 03/23/2009] [Indexed: 12/12/2022]
Abstract
Traumatic brain injury (TBI) represents a significant cause of death and disability in industrialized countries. Of particular importance to patients the chronic effect that TBI has on cognitive function. Therapeutic strategies have been difficult to evaluate because of the complexity of injuries and variety of patient presentations within a TBI population. However, pharmacotherapies targeting dopamine (DA) have consistently shown benefits in attention, behavioral outcome, executive function, and memory. Still it remains unclear what aspect of TBI pathology is targeted by DA therapies and what time-course of treatment is most beneficial for patient outcomes. Fortunately, ongoing research in animal models has begun to elucidate the pathophysiology of DA alterations after TBI. The purpose of this review is to discuss clinical and experimental research examining DAergic therapies after TBI, which will in turn elucidate the importance of DA for cognitive function/dysfunction after TBI as well as highlight the areas that require further study.
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Affiliation(s)
- James W Bales
- Brain Trauma Research Center, University of Pittsburgh, PA 15260, USA
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Abstract
The arousing and motor-activating effects of psychostimulants are mediated by multiple systems. In Drosophila, dopaminergic transmission is involved in mediating the arousing effects of methamphetamine, although the neuronal mechanisms of caffeine (CAFF)-induced wakefulness remain unexplored. Here, we show that in Drosophila, as in mammals, the wake-promoting effect of CAFF involves both the adenosinergic and dopaminergic systems. By measuring behavioral responses in mutant and transgenic flies exposed to different drug-feeding regimens, we show that CAFF-induced wakefulness requires the Drosophila D1 dopamine receptor (dDA1) in the mushroom bodies. In WT flies, CAFF exposure leads to downregulation of dDA1 expression, whereas the transgenic overexpression of dDA1 leads to CAFF resistance. The wake-promoting effects of methamphetamine require a functional dopamine transporter as well as the dDA1, and they engage brain areas in addition to the mushroom bodies.
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Mitchell HA, Bogenpohl JW, Liles LC, Epstein MP, Bozyczko-Coyne D, Williams M, Weinshenker D. Behavioral responses of dopamine beta-hydroxylase knockout mice to modafinil suggest a dual noradrenergic-dopaminergic mechanism of action. Pharmacol Biochem Behav 2008; 91:217-22. [PMID: 18703079 DOI: 10.1016/j.pbb.2008.07.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2008] [Revised: 07/16/2008] [Accepted: 07/18/2008] [Indexed: 11/17/2022]
Abstract
Modafinil is approved for use in the treatment of excessive daytime sleepiness. The precise mechanism of modafinil action has not been elucidated, although both dopamine (DA) and norepinephrine (NE) systems have been implicated. To explore the roles of DA and NE in the mechanism of modafinil-induced arousal, dopamine beta-hydroxylase knockout (Dbh -/-) mice were examined in behavioral paradigms of arousal (photobeam breaks and behavioral scoring of sleep latency). Dbh -/- mice completely lack NE but have hypersensitive DA signaling. It was hypothesized that Dbh -/- mice would be unresponsive to modafinil if the compound acts primarily via NE, but would be hypersensitive to modafinil if it acts primarily via DA. Dbh -/- mice had increased sensitivity to the locomotor-activating and wake-promoting effects of modafinil. Paradoxically, the alpha1-adrenergic receptor antagonist, prazosin, attenuated the effects of modafinil in control mice, but not in Dbh -/- mice. Blockade of DA receptors with flupenthixol decreased modafinil-induced locomotion and wake in both control and Dbh -/- mice. These results suggest that both NE and DA are involved in the behavioral effects of modafinil in control mice, but the requirement for NE can be bypassed by hypersensitive DA signaling.
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Affiliation(s)
- Heather A Mitchell
- Department of Human Genetics, Emory University, Atlanta, GA 30322, United States
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Sizemore M, Perkel DJ. Noradrenergic and GABA B receptor activation differentially modulate inputs to the premotor nucleus RA in zebra finches. J Neurophysiol 2008; 100:8-18. [PMID: 18463188 DOI: 10.1152/jn.01212.2007] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Neuromodulators can rapidly modify neural circuits, altering behavior. Songbirds provide an excellent system for studying the role of neuromodulation in modifying circuits that underlie behavior because song learning and production are mediated by a discrete set of interconnected nuclei. We examined the neuromodulatory effects of noradrenergic and GABA B receptor activation on synaptic inputs to the premotor robust nucleus of the arcopallium (RA) in zebra finches using whole cell voltage-clamp recording in vitro. In adults, norepinephrine strongly reduced input from the lateral magnocellular nucleus of the anterior nidopallium (LMAN) but only slightly reduced the input from nucleus HVC (proper name), the excitatory input from axon collaterals of other RA neurons, and input from GABAergic interneurons. The effect of norepinephrine was mimicked by the alpha2 adrenoceptor agonist UK14,304 and blocked by the alpha2 antagonist yohimbine. Conversely, the GABA B receptor agonist baclofen strongly decreased HVC, collateral, and GABAergic inputs to RA neurons while causing little reduction in the LMAN input. In juveniles undergoing song learning, norepinephrine reduced the LMAN input, caused only a small reduction in the HVC input, and greatly reduced the collateral and GABAergic inputs. Baclofen caused similar results in juvenile and adult birds, reducing HVC, collateral, and GABAergic inputs significantly more than the LMAN input. Significant increases in paired-pulse ratio accompanied all reductions in synaptic transmission, suggesting a presynaptic locus. The reduction in the LMAN input by norepinephrine may be important for mediating changes in song elicited by different social contexts and is well-placed to play a role in song learning.
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Affiliation(s)
- Max Sizemore
- Graduate Program in Neurobiology and Behavior, University of Washington, Seattle, Washington, USA.
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60
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Keiflin R, Isingrini E, Cador M. Cocaine-induced reinstatement in rats: evidence for a critical role of cocaine stimulus properties. Psychopharmacology (Berl) 2008; 197:649-60. [PMID: 18311560 DOI: 10.1007/s00213-008-1083-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 01/18/2008] [Indexed: 10/22/2022]
Abstract
RATIONALE The exact behavioral nature of drug-induced reinstatement of drug seeking is still debated. As an incentive, the drug can have general facilitatory influences on appetitive behaviors. As an interoceptive stimulus, the drug can acquire discriminative properties and control behavior. OBJECTIVE This study assessed the relative contribution of the incentive versus discriminative properties of cocaine in food-seeking reinstatement. METHODS In Experiment 1, eight groups of rats were trained to press a lever for food pellets and experienced cocaine (0, 5, 10, or 15 mg/kg; i.p.), either during the operant conditioning sessions or 4 h after, in another environment without food access. In Experiment 2, to dissociate the role of the operant response per se from the consummatory response, two groups of rats experienced food consumption under cocaine (10 mg/kg; i.p.) either during operant conditioning sessions or during alternate sessions of free access to the food. Then, for both experiments, food pellets were withheld and cocaine injections ceased (extinction). The reinstating effects of noncontingent cocaine (10 mg/kg; i.p.) and food pellet delivery were assessed. Locomotor activity was recorded to probe expression of behavioral sensitization. RESULTS Cocaine reinstated lever pressing only in rats having previously performed the operant responses under cocaine. In contrast, food pellet delivery reinstated lever pressing independently of rats' history with cocaine. Locomotor sensitization was evidenced for all cocaine-pre-exposed rats, dissociating sensitization from reinstatement. CONCLUSIONS When present during operant conditioning, the stimulus "cocaine" acquires conditioned properties which can then promote reinstatement of the extinguished behavior.
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Affiliation(s)
- Ronald Keiflin
- University of Bordeaux 2, CNRS, UMR 5227, Movement-Adaptation-Cognition, Team neuropsychopharmacology of addiction, 146 rue Leo Saignat, 33076 Bordeaux, France.
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Continuous stimulation of dopaminergic receptors by rotigotine does not interfere with the sleep–wake cycle in the rat. Eur J Pharmacol 2008; 584:111-7. [DOI: 10.1016/j.ejphar.2008.01.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2007] [Revised: 01/10/2008] [Accepted: 01/24/2008] [Indexed: 01/06/2023]
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Diller JW, Saunders BT, Anderson KG. Effects of acute and repeated administration of caffeine on temporal discounting in rats. Pharmacol Biochem Behav 2008; 89:546-55. [PMID: 18329086 DOI: 10.1016/j.pbb.2008.02.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Revised: 01/18/2008] [Accepted: 02/05/2008] [Indexed: 11/28/2022]
Abstract
Delay to presentation is one variable that can weaken the reinforcing efficacy of an outcome in a choice situation and drugs have been shown to modify such choices. A growing body of literature has examined effects of stimulant drugs on temporal (delay) discounting, but effects of caffeine, the most widely used stimulant in the world, have not previously been assessed. In the present experiment, effects of caffeine (administered acutely and repeatedly) on temporal discounting were analyzed. Male Sprague-Dawley rats (n=7) chose between a single food pellet delivered immediately after a lever press and three food pellets delivered after a delay. The delay to the three pellets increased within each session, from 0 to 16 s. High doses of caffeine increased large-reinforcer choice relative to control conditions. With repeated caffeine exposure, percent choice for the large reinforcer decreased relative to acute administration, but was still greater than pre-drug baseline. Following withdrawal of drug administration, choice returned to levels seen during pre-drug baseline. Reintroduction of caffeine increased the percent choice for a larger, delayed reinforcer to near acute levels. The results from the present study are consistent with previous research in which stimulant drugs have decreased temporal (delay) discounting.
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Affiliation(s)
- James W Diller
- West Virginia University, Morgantown. WV 26506, United States
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63
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Berridge CW. Noradrenergic modulation of arousal. ACTA ACUST UNITED AC 2007; 58:1-17. [PMID: 18199483 DOI: 10.1016/j.brainresrev.2007.10.013] [Citation(s) in RCA: 213] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 10/10/2007] [Accepted: 10/12/2007] [Indexed: 12/29/2022]
Abstract
Through a highly divergent efferent projection system, the locus coeruleus-noradrenergic system supplies norepinephrine throughout the central nervous system. State-dependent neuronal discharge activity of locus coeruleus neurons has long-suggested a role of this system in the induction of an alert waking state. More recent work supports this hypothesis, demonstrating robust wake-promoting actions of the locus coeruleus-noradrenergic system. Norepinephrine enhances arousal, in part, via actions of beta- and alpha1-receptors located within multiple subcortical structures, including the general regions of the medial septal area and the medial preoptic areas. Recent anatomical studies suggest that arousal-enhancing actions of norepinephrine are not limited to the locus coeruleus system and likely include the A1 and A2 noradrenergic cell groups. Thus, noradrenergic modulation of arousal state involves multiple noradrenergic systems acting within multiple subcortical regions. Pharmacological studies indicate that the combined actions of these systems are necessary for the sustained maintenance of arousal levels associated with spontaneous waking. Enhanced arousal state is a prominent aspect of both stress and psychostimulant drug action and evidence indicates that noradrenergic systems likely play an important role in both stress-related and psychostimulant-induced arousal. These and other observations suggest that the dysregulation of noradrenergic neurotransmission could well contribute to the dysregulation of arousal associated with a variety of behavioral disorders including insomnia and stress-related disorders.
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Affiliation(s)
- Craig W Berridge
- Psychology Department, University of Wisconsin, Madison, WI 53706, USA.
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64
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White W, Sherrill LK, White IM. Time-dependent effects of amphetamine on feeding in rats. Brain Res 2007; 1171:75-82. [PMID: 17764665 PMCID: PMC2034444 DOI: 10.1016/j.brainres.2007.08.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2007] [Revised: 07/25/2007] [Accepted: 08/01/2007] [Indexed: 10/23/2022]
Abstract
Following administration of a moderate dose of amphetamine, rats appear to pass through a sequence of physiological/psychological states, including stimulant and depressant states. The present research evaluated whether these states could be inferred from time-dependent changes in feeding-related measures. Male rats were housed in individual stations (light-dark 12-12 h, free access to water) where, at 3-h intervals, they could respond for food for 1 h. The work requirement was fixed ratio 1, and each lever press produced six 94-mg food pellets. When the pattern of responding for food stabilized across the light-dark cycle, a series of 6 or 7 tests was run. During each test, rats received a saline treatment (1.0 ml/kg, subcutaneously) followed by a 48-h monitoring period, and then they received an amphetamine treatment (2.0 mg/kg, subcutaneously) followed by a 72-h monitoring period. Different groups were treated at either light onset or light offset. Lever presses and head-in-feeding-bin responses were monitored throughout these tests. Administration of amphetamine at light onset and at light offset produced cumulative food intake functions having four regions: post-treatment hours 1-6 (hypophagia), 7-12 (normal intake), 13-27 (hypophagia), and 28 and beyond (normal intake). The sequence, duration, and quality of the amphetamine-induced changes in food intake resembled those formerly seen in cue state and activity, and provided further evidence of a transient withdrawal state 20-24 h post-amphetamine treatment.
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Affiliation(s)
- Wesley White
- Psychology Department, 601 Ginger Hall, Morehead State University, Morehead, KY 40351, USA.
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Richards TL, Pazdernik TL, Levant B. Clorgyline-induced modification of behavioral sensitization to quinpirole: effects on local cerebral glucose utilization. Brain Res 2007; 1160:124-33. [PMID: 17573047 PMCID: PMC2099299 DOI: 10.1016/j.brainres.2007.05.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Revised: 05/15/2007] [Accepted: 05/17/2007] [Indexed: 11/18/2022]
Abstract
Sensitization refers to augmented behavioral responses produced by repeated, intermittent injections of dopaminergic psychostimulants. The locomotor manifestations observed after a sensitizing course of quinpirole, a D(2)/D(3) dopamine agonist, can be modified by the MAO(A) inhibitor clorgyline, by a mechanism apparently unrelated to its actions on MAO(A). Alterations in regional neuronal activity produced by quinpirole in quinpirole-sensitized rats with or without clorgyline pretreatment were assessed based on LCGU using the [(14)C]-2-deoxyglucose (2-DG) method. Adult, male Long-Evans rats (180-200 g, n=9-10/group) were subjected to an injection of either clorgyline (1.0 mg/kg, s.c.) or saline 90 min prior to an injection of quinpirole (0.5 mg/kg, s.c.) or saline, 1 set of injections administered every 3rd day for 10 sets. The 2-DG procedure was initiated 60 min after an 11th set of injections in freely moving rats. LCGU was determined by quantitative autoradiography. LCGU was decreased in a number of limbic (nucleus accumbens and ventral pallidum) and cortical (medial/ventral orbital and infralimbic) regions and in the raphe magnus nucleus in quinpirole-sensitized rats (P<0.05 vs. saline-saline). Quinpirole-sensitized rats pretreated with clorgyline had similar alterations in LCGU, but LCGU was higher in the locus coeruleus compared to quinpirole alone (P<0.05), was not decreased in the raphe magnus nucleus, and was decreased in the piriform cortex and septum. This implicates altered activity of the noradrenergic, serotonergic, olfactory, and limbic systems in the modified behavioral response to quinpirole with clorgyline pretreatment.
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Affiliation(s)
- Toni L Richards
- Department of Pharmacology, University of Kansas Medical Center, Kansas City, KS 66160-7417, USA
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