251
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Age-dependent maintenance of motor control and corticostriatal innervation by death receptor 3. J Neurosci 2010; 30:3782-92. [PMID: 20220013 DOI: 10.1523/jneurosci.1928-09.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Death receptor 3 is a proinflammatory member of the immunomodulatory tumor necrosis factor receptor superfamily, which has been implicated in several inflammatory diseases such as arthritis and inflammatory bowel disease. Intriguingly however, constitutive DR3 expression has been detected in the brains of mice, rats, and humans, although its neurological function remains unknown. By mapping the normal brain expression pattern of DR3, we found that DR3 is expressed specifically by cells of the neuron lineage in a developmentally regulated and region-specific pattern. Behavioral studies on DR3-deficient (DR3(ko)) mice showed that constitutive neuronal DR3 expression was required for stable motor control function in the aging adult. DR3(ko) mice progressively developed behavioral defects characterized by altered gait, dyskinesia, and hyperactivity, which were associated with elevated dopamine and lower serotonin levels in the striatum. Importantly, retrograde tracing showed that absence of DR3 expression led to the loss of corticostriatal innervation without significant neuronal loss in aged DR3(ko) mice. These studies indicate that DR3 plays a key nonredundant role in the retention of normal motor control function during aging in mice and implicate DR3 in progressive neurological disease.
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252
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Gal R, Libersat F. A wasp manipulates neuronal activity in the sub-esophageal ganglion to decrease the drive for walking in its cockroach prey. PLoS One 2010; 5:e10019. [PMID: 20383324 PMCID: PMC2850919 DOI: 10.1371/journal.pone.0010019] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Accepted: 03/11/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The parasitoid Jewel Wasp hunts cockroaches to serve as a live food supply for its offspring. The wasp stings the cockroach in the head and delivers a cocktail of neurotoxins directly inside the prey's cerebral ganglia. Although not paralyzed, the stung cockroach becomes a living yet docile 'zombie', incapable of self-initiating spontaneous or evoked walking. We show here that such neuro-chemical manipulation can be attributed to decreased neuronal activity in a small region of the cockroach cerebral nervous system, the sub-esophageal ganglion (SEG). A decrease in descending permissive inputs from this ganglion to thoracic central pattern generators decreases the propensity for walking-related behaviors. METHODOLOGY AND PRINCIPAL FINDINGS We have used behavioral, neuro-pharmacological and electrophysiological methods to show that: (1) Surgically removing the cockroach SEG prior to wasp stinging prolongs the duration of the sting 5-fold, suggesting that the wasp actively targets the SEG during the stinging sequence; (2) injecting a sodium channel blocker, procaine, into the SEG of non-stung cockroaches reversibly decreases spontaneous and evoked walking, suggesting that the SEG plays an important role in the up-regulation of locomotion; (3) artificial focal injection of crude milked venom into the SEG of non-stung cockroaches decreases spontaneous and evoked walking, as seen with naturally-stung cockroaches; and (4) spontaneous and evoked neuronal spiking activity in the SEG, recorded with an extracellular bipolar microelectrode, is markedly decreased in stung cockroaches versus non-stung controls. CONCLUSIONS AND SIGNIFICANCE We have identified the neuronal substrate responsible for the venom-induced manipulation of the cockroach's drive for walking. Our data strongly support previous findings suggesting a critical and permissive role for the SEG in the regulation of locomotion in insects. By injecting a venom cocktail directly into the SEG, the parasitoid Jewel Wasp selectively manipulates the cockroach's motivation to initiate walking without interfering with other non-related behaviors.
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Affiliation(s)
- Ram Gal
- Department of Life Sciences, Ben-Gurion University of the Negev, Be'er-Sheva, Israel
- * E-mail: (RG); (FL)
| | - Frederic Libersat
- Department of Life Sciences, Ben-Gurion University of the Negev, Be'er-Sheva, Israel
- Institut de Neurobiologie de la Méditerranée INSERM U901, Université de la Méditerranée, Parc Scientifique de Luminy, Marseille, France
- * E-mail: (RG); (FL)
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253
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Kiyatkin EA. Differential effects of dopamine and opioid receptor blockade on motivated Coca-Cola drinking behavior and associated changes in brain, skin and muscle temperatures. Neuroscience 2010; 167:439-55. [PMID: 20167257 DOI: 10.1016/j.neuroscience.2010.02.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 02/10/2010] [Accepted: 02/11/2010] [Indexed: 10/19/2022]
Abstract
Although pharmacological blockade of both dopamine (DA) and opiate receptors has an inhibiting effect on appetitive motivated behaviors, it is still unclear which physiological mechanisms affected by these treatments underlie the behavioral deficit. To clarify this issue, we examined how pharmacological blockade of either DA (SCH23390+eticlopride at 0.2 mg/kg each) or opioid receptors (naloxone 1 mg/kg) affects motor activity and temperature fluctuations in the nucleus accumbens (NAcc), temporal muscle, and facial skin associated with motivated Coca-Cola drinking behavior in rats. In drug-free conditions, presentation of a cup containing 5 ml of Coca-Cola induced locomotor activation and rapid NAcc temperature increases, which both transiently decreased during drinking, and phasically increased again after the cup was emptied. Muscle temperatures followed this pattern, but increases were weaker and more delayed than those in the NAcc. Skin temperature rapidly dropped after cup presentation, remained at low levels during consumption, and slowly restored during post-consumption behavioral activation. By itself, DA receptor blockade induced robust decrease in spontaneous locomotion, moderate increases in brain and muscle temperatures, and a relative increase in skin temperatures, suggesting metabolic activation coupled with adynamia. Following this treatment (approximately 180 min), motor activation to cup presentation and Coca-Cola consumption were absent, but rats showed NAcc and muscle temperature increases following cup presentation comparable to control. Therefore, DA receptor blockade does not affect significantly central and peripheral autonomic responses to appetitive stimuli, but eliminates their behavior-activating effects, thus disrupting appetitive behavior and blocking consumption. Naloxone alone slightly decreased brain and muscle temperatures and increased skin temperatures, pointing at the enhanced heat loss and possible minor inhibition of basal metabolic activity. This treatment (approximately 60 min) had minimal effects on the latencies of drinking, but increased its total duration, with licking interrupted by pauses and retreats. This behavioral attenuation was coupled with weaker than in control locomotor activation and diminished temperature fluctuations in each recording location. Therefore, attenuation of normal behavioral and physiological responses to appetitive stimuli appears to underlie modest inhibiting effects of opiate receptor blockade on motivated behavior and consumption.
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Affiliation(s)
- E A Kiyatkin
- Behavioral Neuroscience Branch, National Institute on Drug Abuse - Intramural Research Program, National Institutes of Health, DHHS, 333 Cassell Drive, Baltimore, MD 21224, USA.
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254
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Restricting dopaminergic signaling to either dorsolateral or medial striatum facilitates cognition. J Neurosci 2010; 30:1158-65. [PMID: 20089924 DOI: 10.1523/jneurosci.4576-09.2010] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Dopaminergic projections to the ventral and dorsomedial striatum are important for reward, motivation, and goal-directed learning, whereas projections to the dorsolateral striatum are implicated in motor control, habitual enactment of motor skills, visuospatial learning, and memory. These conclusions are derived from studies of rodents with lesions or pharmacological blockade of dopamine signaling to specific brain regions. In contrast, we investigated the behavioral abilities of dopamine-deficient mice in which dopamine signaling was restored to only the medial striatum by viral rescue. These mice displayed intact spatial memory, visuospatial and discriminatory learning. However, acquisition of operant behavior was delayed, and their motivation to obtain food rewards was blunted. We compare these behavioral results with our published results obtained from mice with dopamine signaling restored only to the dorsolateral striatum. We observe that most behaviors are restored with dopamine signaling restored to either brain region and conclude that the action of dopamine in either one of these nonoverlapping striatal areas can support cognitive processes independently of dopamine signaling in the other area.
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255
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Cav1.3 channel voltage dependence, not Ca2+ selectivity, drives pacemaker activity and amplifies bursts in nigral dopamine neurons. J Neurosci 2010; 29:15414-9. [PMID: 20007466 DOI: 10.1523/jneurosci.4742-09.2009] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Ca(v)1.3 (alpha 1D) L-type Ca(2+) channels have been implicated in substantia nigra (SN) dopamine (DA) neuron pacemaking and vulnerability to Parkinson's disease. These effects may arise from the depolarizing current and cytoplasmic Ca(2+) elevation produced by Ca(v)1.3 channels at subthreshold membrane potentials. However, the assumption that the Ca(2+) selectivity of Ca(v)1.3 channels is essential has not been tested. In this study the properties of SN DA neuron L-type Ca(2+) channels responsible for driving pacemaker activity in juvenile rat brain slices were probed by replacing native channels blocked with the dihydropyridine nimodipine with virtual channels generated by dynamic clamp. Surprisingly, virtual L-type channels that mimic native and recombinant Ca(v)1.3 channels supported pacemaker activity even though dynamic clamp currents are not carried by Ca(2+). This effect is specific because pacemaker activity could not be restored by tonic current injection, virtual nonselective leak channels or virtual NMDA receptors, which share with L-type channels a negative slope conductance region in their current-voltage (I-V) curve. Altering virtual channels showed that the production of pacemaker activity depended on the characteristic voltage dependence of DA neuron L-type channels, while activation kinetics and reversal potential were not critical parameters. Virtual L-type channels also supported slow oscillatory potentials and enhanced firing rate during evoked bursts. Thus, Ca(v)1.3 channel voltage dependence, rather than Ca(2+) selectivity, drives pacemaker activity and amplifies bursts in SN DA neurons.
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256
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Fulton S. Appetite and reward. Front Neuroendocrinol 2010; 31:85-103. [PMID: 19822167 DOI: 10.1016/j.yfrne.2009.10.003] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 10/06/2009] [Accepted: 10/06/2009] [Indexed: 12/14/2022]
Abstract
The tendency to engage in or maintain feeding behaviour is potently influenced by the rewarding properties of food. Affective and goal-directed behavioural responses for food have been assessed in response to various physiological, pharmacological and genetic manipulations to provide much insight into the neural mechanisms regulating motivation for food. In addition, several lines of evidence tie the actions of metabolic signals, neuropeptides and neurotransmitters to the modulation of the reward-relevant circuitry including midbrain dopamine neurons and corticolimbic nuclei that encode emotional and cognitive aspects of feeding. Along these lines, this review pulls together research describing the peripheral and central signalling molecules that modulate the rewarding effects of food and the underlying neural pathways.
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Affiliation(s)
- Stephanie Fulton
- CRCHUM and Montreal Diabetes Research Center, Department of Nutrition, Faculty of Medicine, University of Montreal, Montreal, QC, Canada.
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257
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Narayanan NS, Guarnieri DJ, DiLeone RJ. Metabolic hormones, dopamine circuits, and feeding. Front Neuroendocrinol 2010; 31:104-12. [PMID: 19836414 PMCID: PMC2813908 DOI: 10.1016/j.yfrne.2009.10.004] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 10/12/2009] [Accepted: 10/13/2009] [Indexed: 10/20/2022]
Abstract
Recent evidence has emerged demonstrating that metabolic hormones such as ghrelin and leptin can act on ventral tegmental area (VTA) midbrain dopamine neurons to influence feeding. The VTA is the origin of mesolimbic dopamine neurons that project to the nucleus accumbens (NAc) to influence behavior. While blockade of dopamine via systemic antagonists or targeted gene delete can impair food intake, local NAc dopamine manipulations have little effect on food intake. Notably, non-dopaminergic manipulations in the VTA and NAc produce more consistent effects on feeding and food choice. More recent genetic evidence supports a role for the substantia nigra-striatal dopamine pathways in food intake, while the VTA-NAc circuit is more likely involved in higher-order aspects of food acquisition, such as motivation and cue associations. This rich and complex literature should be considered in models of how peripheral hormones influence feeding behavior via action on the midbrain circuits.
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258
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Salvatore MF, Pruett BS, Spann SL, Dempsey C. Aging reveals a role for nigral tyrosine hydroxylase ser31 phosphorylation in locomotor activity generation. PLoS One 2009; 4:e8466. [PMID: 20037632 PMCID: PMC2791868 DOI: 10.1371/journal.pone.0008466] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Accepted: 11/29/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Tyrosine hydroxylase (TH) regulates dopamine (DA) bioavailability. Its product, L-DOPA, is an established treatment for Parkinson's disease (PD), suggesting that TH regulation influences locomotion. Site-specific phosphorylation of TH at ser31 and ser40 regulates activity. No direct evidence shows that ser40 phosphorylation is the dominating mechanism of regulating TH activity in vivo, and physiologically-relevant stimuli increase L-DOPA biosynthesis independent of ser40 phosphorylation. Significant loss of locomotor activity occurs in aging as in PD, despite less loss of striatal DA or TH in aging compared to the loss associated with symptomatic PD. However, in the substantia nigra (SN), there is equivalent loss of DA or TH in aging and at the onset of PD symptoms. Growth factors increase locomotor activity in both PD and aging models and increase DA bioavailability and ser31 TH phosphorylation in SN, suggesting that ser31 TH phosphorylation status in the SN, not striatum, regulates DA bioavailability necessary for locomotor activity. METHODOLOGY AND PRINCIPAL FINDINGS We longitudinally characterized locomotor activity in young and older Brown-Norway Fischer 344 F(1) hybrid rats (18 months apart in age) at two time periods, eight months apart. The aged group served as an intact and pharmacologically-naïve source of deficient locomotor activity. Following locomotor testing, we analyzed DA tissue content, TH protein, and TH phosphorylation in striatum, SN, nucleus accumbens, and VTA. Levels of TH protein combined with ser31 phosphorylation alone reflected inherent differences in DA levels among the four regions. Measures strictly pertaining to locomotor activity initiation significantly correlated to DA content only in the SN. Nigral TH protein and ser31 phosphorylation together significantly correlated to test subject's maximum movement number, horizontal activity, and duration. CONCLUSIONS/SIGNIFICANCE Together, these results show ser31 TH phosphorylation regulates DA bioavailability in intact neuropil, its status in the SN may regulate locomotor activity generation, and it may represent an accurate target for treating locomotor deficiency. They also show that neurotransmitter regulation in cell body regions can mediate behavioral outcomes and that ser31 TH phosphorylation plays a role in behaviors dependent upon catecholamines, such as dopamine.
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Affiliation(s)
- Michael F Salvatore
- Department of Pharmacology, Toxicology, and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, Louisiana, USA.
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259
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Elman I, Lowen S, Frederick BB, Chi W, Becerra L, Pitman RK. Functional neuroimaging of reward circuitry responsivity to monetary gains and losses in posttraumatic stress disorder. Biol Psychiatry 2009; 66:1083-90. [PMID: 19640506 PMCID: PMC9446383 DOI: 10.1016/j.biopsych.2009.06.006] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2008] [Revised: 05/22/2009] [Accepted: 06/05/2009] [Indexed: 12/11/2022]
Abstract
BACKGROUND Clinical impressions and preclinical work suggest that posttraumatic stress disorder (PTSD) might be associated with dysfunctional reward processing. To pursue this issue, we administered a validated passive-viewing monetary reward task during functional magnetic resonance imaging (fMRI) to subjects with chronic PTSD and to mentally healthy individuals. METHODS The protocol evaluated fMRI signal changes that anticipated or accompanied monetary gains and losses under varying conditions of controlled expectation. The "expectancy phase" entailed presentation of a promising, unpromising, or intermediate Wheel of Fortune-type spinner, whereas the "outcome phase" was defined by the arrow landing on one of three sectors of that spinner, thereby determining the subjects' gain or loss for that trial. RESULTS Neuroimaging data from 20 PTSD and 26 healthy subjects withstood quality control procedures and were included. In voxelwise and anatomically defined region-of-interest analyses, when gains were contrasted to losses, between-group comparison revealed smaller bilateral striatal activations in the PTSD subjects. In the PTSD group, less striatal activation to gains versus losses was associated with more self-reported motivational and social deficits. CONCLUSIONS The present data support the hypothesis that PTSD is associated with abnormal processing of monetary outcomes and that this alteration might be related to some aspects of emotional numbing.
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Affiliation(s)
- Igor Elman
- Clinical Psychopathology Laboratory, McLean Hospital and Harvard Medical School, Boston, Massachusetts 02478-9106, USA.
| | - Steven Lowen
- Brain Imaging Center, McLean Hospital and Harvard Medical School
| | | | - Won Chi
- Clinical Psychopathology Laboratory, McLean Hospital and Harvard Medical School
| | - Lino Becerra
- Brain Imaging Center, McLean Hospital and Harvard Medical School
| | - Roger K. Pitman
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School
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260
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Cartier EA, Parra LA, Baust TB, Quiroz M, Salazar G, Faundez V, Egaña L, Torres GE. A biochemical and functional protein complex involving dopamine synthesis and transport into synaptic vesicles. J Biol Chem 2009; 285:1957-66. [PMID: 19903816 DOI: 10.1074/jbc.m109.054510] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Synaptic transmission depends on neurotransmitter pools stored within vesicles that undergo regulated exocytosis. In the brain, the vesicular monoamine transporter-2 (VMAT(2)) is responsible for the loading of dopamine (DA) and other monoamines into synaptic vesicles. Prior to storage within vesicles, DA synthesis occurs at the synaptic terminal in a two-step enzymatic process. First, the rate-limiting enzyme tyrosine hydroxylase (TH) converts tyrosine to di-OH-phenylalanine. Aromatic amino acid decarboxylase (AADC) then converts di-OH-phenylalanine into DA. Here, we provide evidence that VMAT(2) physically and functionally interacts with the enzymes responsible for DA synthesis. In rat striata, TH and AADC co-immunoprecipitate with VMAT(2), whereas in PC 12 cells, TH co-immunoprecipitates with the closely related VMAT(1) and with overexpressed VMAT(2). GST pull-down assays further identified three cytosolic domains of VMAT(2) involved in the interaction with TH and AADC. Furthermore, in vitro binding assays demonstrated that TH directly interacts with VMAT(2). Additionally, using fractionation and immunoisolation approaches, we demonstrate that TH and AADC associate with VMAT(2)-containing synaptic vesicles from rat brain. These vesicles exhibited specific TH activity. Finally, the coupling between synthesis and transport of DA into vesicles was impaired in the presence of fragments involved in the VMAT(2)/TH/AADC interaction. Taken together, our results indicate that DA synthesis can occur at the synaptic vesicle membrane, where it is physically and functionally coupled to VMAT(2)-mediated transport into vesicles.
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Affiliation(s)
- Etienne A Cartier
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
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261
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Restriction of dopamine signaling to the dorsolateral striatum is sufficient for many cognitive behaviors. Proc Natl Acad Sci U S A 2009; 106:14664-9. [PMID: 19667174 DOI: 10.1073/pnas.0907299106] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The striatum is a vital substrate for performance, procedural memory, and learning. The ventral and medial striatum are thought to be critical for acquisition of tasks while the dorsolateral striatum is important for performance and habitual enactment of skills. Evidence based on cortical, thalamic, and amygdaloid inputs to the striatum suggests a medio-lateral zonation imposed on the classical dorso-ventral distinction. We therefore investigated the functional significance of dopaminergic signaling in cognitive tasks by studying dopamine-deficient (DD) mice and mice with dopamine signaling restored to only the dorsolateral (DL) striatum by viral rescue (vrDD-DL mice). Whereas DD mice failed in all of the tasks examined here, vrDD-DL mice displayed intact discriminatory learning, object recognition, visuospatial learning and spatial memory. Acquisition of operant behavior for food rewards was delayed in vrDD-DL mice and their motivation in a progressive ratio experiments was reduced. Therefore, dopaminergic signaling in the dorsolateral striatum is sufficient for mice to learn several different cognitive tasks although the rate of learning some of them was reduced. These results indicate that dopaminergic signaling in the ventromedial striatum is not absolutely necessary for mastery of these behaviors, but may facilitate them.
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262
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Wassum KM, Cely IC, Maidment NT, Balleine BW. Disruption of endogenous opioid activity during instrumental learning enhances habit acquisition. Neuroscience 2009; 163:770-80. [PMID: 19619616 DOI: 10.1016/j.neuroscience.2009.06.071] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 06/24/2009] [Accepted: 06/30/2009] [Indexed: 10/20/2022]
Abstract
Considerable evidence suggests that in instrumental conditioning rats learn the relationship between actions and their consequences, or outcomes. Such goal-directed actions are sensitive to changes in outcome value. The present study assessed the role of the endogenous opioid system in goal-directed reward learning. In two experiments, rats were trained to lever press for food pellets either under vehicle or naloxone-induced opioid receptor blockade. Specific satiety procedures were used for outcome devaluation, and the effect of this devaluation on instrumental responding was then tested in extinction. In Experiment 1 outcome devaluation resulted in a reduction in lever pressing in rats that were trained after vehicle injections, indicating that actions in these rats were goal-directed. In contrast, actions in rats trained under naloxone were insensitive to outcome devaluation when tested off drug, suggesting that lever pressing had become habitual in these rats. Interestingly, in Experiment 2 naloxone-induced habitual behavior was shown to be specific to the context in which the training occurred under naloxone; rats showed normal sensitivity to outcome devaluation when tested in an alternate vehicle-trained context. Additionally, in Experiment 2 we found that the acute administration of naloxone on test had no effect in itself, indicating that opioid receptor-related processes contribute to the acquisition of goal-directed actions and not to their general performance. These data suggest that an intact endogenous opioid system is necessary for normal goal-directed learning and more importantly, reveal that a compromised endogenous opioid system during learning enhances the habitual control of actions.
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Affiliation(s)
- K M Wassum
- Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, CA 90024, USA.
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263
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Requena DF, Parra LA, Baust TB, Quiroz M, Leak RK, Garcia-Olivares J, Torres GE. The molecular chaperone Hsc70 interacts with the vesicular monoamine transporter-2. J Neurochem 2009; 110:581-94. [DOI: 10.1111/j.1471-4159.2009.06135.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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264
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Disruption of NMDAR-dependent burst firing by dopamine neurons provides selective assessment of phasic dopamine-dependent behavior. Proc Natl Acad Sci U S A 2009; 106:7281-8. [PMID: 19342487 DOI: 10.1073/pnas.0813415106] [Citation(s) in RCA: 309] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Midbrain dopamine (DA) neurons fire in 2 characteristic modes, tonic and phasic, which are thought to modulate distinct aspects of behavior. However, the inability to selectively disrupt these patterns of activity has hampered the precise definition of the function of these modes of signaling. Here, we addressed the role of phasic DA in learning and other DA-dependent behaviors by attenuating DA neuron burst firing and subsequent DA release, without altering tonic neural activity. Disruption of phasic DA was achieved by selective genetic inactivation of NMDA-type, ionotropic glutamate receptors in DA neurons. Disruption of phasic DA neuron activity impaired the acquisition of numerous conditioned behavioral responses, and dramatically attenuated learning about cues that predicted rewarding and aversive events while leaving many other DA-dependent behaviors unaffected.
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265
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Dwyer JB, McQuown SC, Leslie FM. The dynamic effects of nicotine on the developing brain. Pharmacol Ther 2009; 122:125-39. [PMID: 19268688 DOI: 10.1016/j.pharmthera.2009.02.003] [Citation(s) in RCA: 420] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Accepted: 02/05/2009] [Indexed: 12/25/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) regulate critical aspects of brain maturation during the prenatal, early postnatal, and adolescent periods. During these developmental windows, nAChRs are often transiently upregulated or change subunit composition in those neural structures that are undergoing major phases of differentiation and synaptogenesis, and are sensitive to environmental stimuli. Nicotine exposure, most often via tobacco smoke, but increasingly via nicotine replacement therapy, has been shown to have unique effects on the developing human brain. Consistent with a dynamic developmental role for acetylcholine, exogenous nicotine produces effects that are unique to the period of exposure and that impact the developing structures regulated by acetylcholine at that time. Here we present a review of the evidence, available from both the clinical literature and preclinical animal models, which suggests that the diverse effects of nicotine exposure are best evaluated in the context of regional and temporal expression patterns of nAChRs during sensitive maturational periods, and disruption of the normal developmental influences of acetylcholine. We present evidence that nicotine interferes with catecholamine and brainstem autonomic nuclei development during the prenatal period of the rodent (equivalent to first and second trimester of the human), alters the neocortex, hippocampus, and cerebellum during the early postnatal period (third trimester of the human), and influences limbic system and late monoamine maturation during adolescence.
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Affiliation(s)
- Jennifer B Dwyer
- Department of Pharmacology, Med Surge II, School of Medicine, University of California, Irvine, CA 92697, USA.
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266
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Fetissov SO, Meguid MM. On dopamine, D2 receptor, and Taq1A polymorphism in obesity and anorexia. Nutrition 2009; 25:132-3. [DOI: 10.1016/j.nut.2008.12.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Accepted: 12/01/2008] [Indexed: 11/29/2022]
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267
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Ettenberg A. The runway model of drug self-administration. Pharmacol Biochem Behav 2008; 91:271-7. [PMID: 19032964 DOI: 10.1016/j.pbb.2008.11.003] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 11/06/2008] [Accepted: 11/08/2008] [Indexed: 01/01/2023]
Abstract
Behavioral scientists have employed operant runways as a means of investigating the motivational impact of incentive stimuli for the better part of the past 100 years. In this task, the speed with which a trained animal traverses a long straight alley for positive incentive stimuli, like food or water, provides a reliable index of the subject's motivation to seek those stimuli. The runway is therefore a particularly appropriate tool for investigating the drug-seeking behavior of animals working for drugs of abuse. The current review describes our laboratory's work over the past twenty years developing and implementing an operant runway model of drug self-administration. Procedures are described that methodologically dissociate the antecedent motivational processes that induce an animal to seek a drug, from the positive reinforcing consequences of actually earning the drug. Additional work is reviewed on the use of the runway method as a means of modeling the factors that often result in a "relapse" of drug self-administration after a period of abstinence (i.e., a response reinstatement test), as are runway studies that revealed the presence of opposing positive and negative consequences of self-administered cocaine. This body of work suggests that the runway method has served as a powerful behavioral tool for the study of the behavioral and neurobiological basis of drug self-administration.
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Affiliation(s)
- Aaron Ettenberg
- Behavioral Pharmacology Laboratory, Department of Psychology, University of California, Santa Barbara, CA 93106-9660, United States.
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268
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Gonon F. The dopaminergic hypothesis of attention-deficit/hyperactivity disorder needs re-examining. Trends Neurosci 2008; 32:2-8. [PMID: 18986716 DOI: 10.1016/j.tins.2008.09.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Revised: 09/24/2008] [Accepted: 09/26/2008] [Indexed: 11/16/2022]
Abstract
Although psychostimulants alleviate the core symptoms of attention-deficit/hyperactivity disorder (ADHD), recent studies confirm that their impact on the long-term outcomes of ADHD children is null. Psychostimulants enhance extracellular dopamine. Numerous review articles assert that they correct an underlying dopaminergic deficit of genetic origin. This dopamine-deficit theory of ADHD is often based upon an overly simplistic dopaminergic theory of reward. Here, I question the relevance of this theory regarding ADHD. I underline the weaknesses of the neurochemical, genetic, neuropharmacological and imaging data put forward to support the dopamine-deficit hypothesis of ADHD. Therefore, this hypothesis should not be put forward to bias ADHD management towards psychostimulants.
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Affiliation(s)
- Francois Gonon
- University of Bordeaux, Centre National de la Recherche Scientifique UMR 5227, 146 rue Leo Saignat, Bordeaux, F-33076, France.
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