Dopamine Transporter mRNA Expression Research Articles

Effects of Multiple High-Dose Methamphetamine Administration on Enteric Dopaminergic Neurons and Intestinal Motility in the Rat Model.

Several studies have identified the effects of methamphetamine (MA) on central dopaminergic neurons, but its effects on enteric dopaminergic neurons (EDNs) are unclear. The aim of this study was to investigate the effects of MA on EDNs and intestinal motility. Male Sprague-Dawley rats were randomly divided into MA group and saline group. The MA group received the multiple high-dose MA treatment paradigm, while the controls received the same saline treatment. After enteric motility was assessed, different intestinal segments (i.e., duodenum, jejunum, ileum, and colon) were taken for histopathological, molecular biological, and immunological analysis. The EDNs were assessed by measuring the expression of two dopaminergic neuronal markers, dopamine transporter (DAT) and tyrosine hydroxylase (TH), at the transcriptional and protein levels. We also used c-Fos protein, a marker of neural activity, to detect the activation of EDNs. MA resulted in a significant reduction in TH and DAT mRNA expression as well as in the number of EDNs in the duodenum and jejunum (p < 0.05). MA caused a dramatic increase in c-Fos expression of EDNs in the ileum (p < 0.001). The positional variability of MA effects on EDNs paralleled the positional variability of its effect on intestinal motility, as evidenced by the marked inhibitory effect of MA on small intestinal motility (p < 0.0001). This study found significant effects of MA on EDNs with locational variability, which might be relevant to locational variability in the potential effects of MA on intestinal functions, such as motility.

Analysis of neurotransmitters validates the importance of the dopaminergic system in autism spectrum disorder.

The reasons behind the cardinal symptoms of communication deficits and repetitive, stereotyped behaviors that characterize autism spectrum disorder (ASD) remain unknown. The dopamine (DA) system, which regulates motor activity, goal-directed behaviors, and reward function, is believed to play a crucial role in ASD, although the exact mechanism is still unclear. Investigations have shown an association of the dopamine receptorD4 (DRD4) with various neurobehavioral disorders. We analyzed the association between ASD and four DRD4 genetic polymorphisms, 5' flanking 120-bp duplication (rs4646984), rs1800955 in the promoter, exon 1 12bp duplication (rs4646983), and exon 3 48bp repeats. We also examined plasma DA and its metabolite levels, DRD4 mRNA expression, and correlations of the studied polymorphisms with these parameters by case-control comparative analyses. The expression of DA transporter (DAT), which is important in regulating the circulating DA level, was also evaluated. A significantly higher occurrence of rs1800955 "T/TT" was observed in the probands. ASD traits were affected by rs1800955 "T" and the higher repeat alleles of the exon 3 48bp repeats, rs4646983 and rs4646984. ASD probands exhibited lower DA and norepinephrine levels together with higher homovanillic acid levels than the control subjects. DAT and DRD4 mRNA expression were down-regulated in the probands, especially in the presence of DAT rs3836790 "6R" and rs27072 "CC" and DRD4 rs4646984 higher repeat allele and rs1800955 "T". This pioneering investigation revealed a positive correlation between genetic variants, hypodopaminergic state, and impairment in socio-emotional and communication reciprocity in Indian subjects with ASD, warranting further in-depth analysis.

Real time monitoring of dopamine release evoked by mitragynine (Kratom): An insight through electrochemical sensor

BackgroundMitragynine, the major indole alkaloid from Mitragyna speciosa has been reported previously to possess abuse liability. However, there are insufficient data suggesting the mechanism through which this pharmacological agent causes addiction. AimsIn this study, we investigated the effects of mitragynine on dopamine (DA) level and dopamine transporter (DAT) expression from the rat’s frontal cortex. MethodsDA level was recorded in the brain samples of animals treated with acute or repeated exposure for 4 consecutive days with either vehicle or mitragynine (1 and 30 mg/kg) using electrochemical sensor. Animals were then decapitated and the brain regions were removed, snap-frozen in liquid nitrogen and immediately stored at −80 °C. DA level was quantified using Enzyme linked immunosorbent assay (ELISA) kits and DAT gene expression was determined using quantitative real time polymerase chain reaction (RT-qPCR). Results/outcomeMitragynine (1 and 30 mg/kg) did not increase DA release following acute treatment, however, after repeated exposure at day 4, mitragynine significantly and dose dependently increased DA release in the frontal cortex. In this study, we also observed a significant increase in DAT mRNA expression at day 4 in group treated with mitragynine (30 mg/kg). Conclusion/interpretationData from this study indicates that mitragynine significantly increased DA release when administered repeatedly, increased in DAT mRNA expression with the highest tested dose (30 mg/kg). Therefore, the rewarding effects observed after mitragynine administration could be due to its ability to increase DA content in certain areas of the brain especially the frontal cortex.

Involvement of CB2 Receptors in the Neurobehavioral Effects of Catha Edulis (Vahl) Endl. (Khat) in Mice.

There is behavioral evidence for the interaction between crude khat extract and the endocannabinoid system, whereby the endocannabinoid system alters khat extract-mediated behavioral effects through modulation of the monoaminergic system. The objective of this study was to investigate the role of the endocannabinoid system on the neurobehavioral effect of khat extract in mice following concomitant administration of khat extract and the CB2R agonist, JWH133. Locomotor activity test, immunohistochemistry, and reverse transcriptase polymerase chain reaction technique were utilized to assess locomotor activity, tyrosine hydroxylase immunoreactivity, and expression of dopamine transporter mRNA gene. The results show sub-acute administration of khat extract alone increased locomotor activity in mice and co-administration of the CB2R agonist, JWH133, reduced khat extract induced hyperlocomotor activity. The data revealed that cell type specific deletion of CB2Rs on dopaminergic neurons increased the hyperlocomotor behavior of khat extract. Furthermore, the results revealed that khat extract attenuated MPTP induced motor deficits, which is enhanced by JWH133. Khat extract also increased expression of tyrosine hydroxylase positive cells and expression of dopamine transporter mRNA gene in wild type mice. Nevertheless, JWH133 did not alter the effect of khat extract on tyrosine hydroxylase immunoreactivity and dopamine transporter mRNA expression when given together with khat extract. Taken together, the results suggest that the CB2Rs selectively interact with khat extract-mediated locomotor effects and could be utilized as therapeutic target in central nervous system movement disorders associated with dopamine dysregulation.

Behavioral Changes and Neuronal Damage in Rhesus Monkeys after 10 Weeks of Ketamine Administration Involve Prefrontal Cortex Dopamine D2 Receptor and Dopamine Transporter

The dopamine D2 receptor (DRD2) and dopamine transporter (DAT) play a regulatory role in dopaminergic neurotransmission and thus play an important role in drug addiction. The prefrontal cortex (PFC), a critical part of the mesencephalic dopaminergic system, is thought to be involved in the development and maintenance of drug addiction. The addiction to ketamine is thought to induce behavioral effects primarily through actions on the central nervous system. However, the neural mechanism underlying the effects of ketamine addiction remains unclear. In this study, we investigate the involvement of PFC DRD2 and DAT in ketamine addiction effects after ketamine administration for 10 weeks in nonhuman primates. To this end, after administering ketamine to rhesus monkeys for 10 weeks, we assessed changes in body weight and behavior. Additionally, neuronal changes in the PFC were examined by hematoxylin and eosin (HE) staining; the DRD2 and DAT mRNA and protein expression levels in the PFC were determined by real-time PCR and Western blot analysis, respectively. After 10-week ketamine administration, the assessment of the manifestations of toxicity in rhesus monkeys revealed significant changes in body weight and behavior, decreased DRD2 and DAT mRNA and protein expression in the PFC, and histological abnormalities including neuronal eosinophilia, pyknosis and disorderly arrangement of neurons in the PFC. These results suggest that the reduced expression of DRD2 and DAT in PFC could be involved in the behavioral and the neurological changes induced by ketamine administration, which may play an important role in the molecular mechanisms of ketamine addiction.

A Comparison of mRNA Expression of Dopamine Receptors, Tyrosine Hydroxylase, and Dopamine Transporter in the Mesolimbic System of Rats with Different Levels of Alcohol Consumption

Despite numerous studies, there is still no clear idea on the fine mechanisms of dysfunction of the brain dopamine system during the formation of alcohol dependence. In this work, we studied the expression of genes that encode tyrosine hydroxylase (TH), a key enzyme of dopamine synthesis, dopamine transporter (DAT), dopamine receptors of the second subtype (DRD2) in the midbrain, and dopamine receptors of the first and second subtypes (DRD1 and DRD2) in the striatum of rats that consumed alcohol from the 60th to 120th days of life in the “free choice” paradigm. The most pronounced changes, a decrease in mRNA expression of DRD1 and DRD2 in the striatum, as well as DAT and TH in the midbrain, were observed in animals with a growing preference for alcohol compared to a group of rats that controlled consumption at a constantly low level. In animals with initially stable high levels of alcohol preference, a decrease in the relative expression level of DRD1 and DRD2 mRNA in the striatum was found, while there was no difference in the expression of DAT and TH mRNA in the midbrain. The expression level of DRD2 mRNA in the midbrain did not differ in all the studied groups. These data suggest that changes in the expression of mRNA of DRD1 and DRD2 in the striatum do not depend on the initial alcohol preference and are determined by the level of alcohol intoxication, while the decrease in the level of TH and DAT mRNA in the midbrain may be one of the mech-anisms of loss of control over consumption.

No effect of sex on ethanol intake and preference after dopamine transporter (DAT) knockdown in adult mice.

Dopamine levels are controlled in part by transport across the cell membrane by the dopamine transporter (DAT), and recent evidence showed that a polymorphism in the gene encoding DAT is associated with alcoholism. However, research in animal models using DAT knockout mice has yielded conflicting results. The present study was planned to evaluate the effects of DAT knockdown in the nucleus accumbens (Nacc) on voluntary ethanol consumption and preference in male and female C57BL/6J mice. For this purpose, animals were stereotaxically injected with DAT siRNA-expressing lentiviral vectors in the Nacc, and using a voluntary, continuous access two-bottle choice model of alcohol, we investigated the importance of accumbal DAT expression in voluntary alcohol intake and preference. We also investigated the effects of DAT knockdown on saccharin and quinine consumption and ethanol metabolism. We show that females consumed more alcohol than males. Interestingly, DAT knockdown in the Nacc significantly decreased alcohol intake and preference in both groups, but no significant sex by group interaction was observed. Also, DAT knockdown did not alter total fluid consumption, saccharin or quinine consumption, or blood ethanol concentrations. Using Pearson correlation, results indicated a strong positive relationship between DAT mRNA expression and ethanol consumption and preference. Taken together, these data provide further evidence that DAT plays an important role in controlling ethanol intake and that accumbal DAT contributes in the modulation of the reinforcing effects of ethanol. Overall, the results suggest that DAT inhibitors may be valuable in the pharmacotherapy of alcoholism.

Tyrosine Hydroxylase, Vesicular Monoamine Transporter and Dopamine Transporter mRNA Expression in Nigrostriatal Tissue of Rats with Pedunculopontine Neurotoxic Lesion.

Background: The degeneration of the pedunculopontine nucleus (PPN) precedes the degeneration of the nigral cells in the pre-symptomatic stages of Parkinson’s disease (PD). Although the literature recognizes that a lesion of the PPN increases the vulnerability of dopaminergic cells, it is unknown if this risk is associated with the loss of capability of handling the dopaminergic function. Methods: In this paper, the effects of a unilateral neurotoxic lesion of the PPN in tyrosine hydroxylase (TH), vesicular monoamine transporter 2 (VMAT2) and dopamine transporter (DAT) mRNA expression in nigrostriatal tissue were evaluated. Three experimental groups were organized: non-treated rats, NMDA-lesioned rats and Sham-operated rats. Results: Seven days after the PPN lesion, in nigral tissue, TH mRNA expression was higher in comparison with control groups (p < 0.05); in contrast, VMAT2 mRNA expression showed a significant decrease (p < 0.01). DAT mRNA expression showed a significant decrease (p < 0.001) in the striatal tissue. Comparing nigral neuronal density of injured and control rats revealed no significant difference seven days post-PPN injury. Conclusions: Findings suggest that the PPN lesion modifies the mRNA expression of the proteins associated with dopaminergic homeostasis at nigrostriatal level. It could represent vulnerability signals for nigral dopaminergic cells and further increase the risk of degeneration of these cells.

Valproate increases dopamine transporter expression through histone acetylation and enhanced promoter binding of Nurr1

The dopamine transporter (DAT) is the key regulator of dopaminergic transmission and is a target of several xenobiotics, including pesticides and pharmacological agents. Previously, we identified a prominent role for histone deacetylases in the regulation of DAT expression. Here, we utilized a rat dopaminergic cell line (N27) to probe the responsiveness of DAT mRNA expression to inhibitors of histone acetylation. Inhibition of histone deacetylases (HDACs) by valproate, butyrate and Trichostatin A led to a 3–10-fold increase in DAT mRNA expression, a 50% increase in protein levels, which were accompanied by increased H3 acetylation levels. To confirm the mechanism of valproate-mediated increase in DAT mRNA, chromatin immunoprecipitation (ChIP) assays were used and demonstrated a significant increase in enrichment of acetylation of histone 3 on lysines 9 and 14 (H3K9/K14ac) in the DAT promoter. Expression of Nurr1 and Pitx3, key regulators of DAT expression, were increased following valproate treatment and Nurr1 binding was enriched in the DAT promoter. Together, these results indicate that histone acetylation and subsequent enhancement of transcription factor binding are plausible mechanisms for DAT regulation by valproate and, perhaps, by other xenobiotics.

Epigenetic Regulation of Dopamine Transporter mRNA Expression in Human Neuroblastoma Cells.

The dopamine transporter (DAT) is a key regulator of dopaminergic neurotransmission. As such, proper regulation of DAT expression is important to maintain homeostasis, and disruption of DAT expression can lead to neurobehavioral dysfunction. Based on genomic features within the promoter of the DAT gene, there is potential for DAT expression to be regulated through epigenetic mechanisms, including DNA methylation and histone acetylation. However, the relative contribution of these mechanisms to DAT expression has not been empirically determined. Using pharmacologic and genetic approaches, we demonstrate that inhibition of DNA methyltransferase (DNMT) activity increased DAT mRNA approximately 1.5-2 fold. This effect was confirmed by siRNA knockdown of DNMT1. Likewise, the histone deacetylase (HDAC) inhibitors valproate and butyrate also increased DAT mRNA expression, but the response was much more robust with expression increasing over tenfold. Genetic knockdown of HDAC1 by siRNA also increased DAT expression, but not to the extent seen with pharmacological inhibition, suggesting additional isoforms of HDAC or other targets may contribute to the observed effect. Together, these data identify the relative contribution of DNMTs and HDACs in regulating expression. These finding may aid in understanding the mechanistic basis for changes in DAT expression in normal and pathophysiological states.

Dopaminergic activity and behaviour in SOCS2 transgenic mice: Revealing a potential drug target for schizophrenia.

Alterations in immune function have been implicated in the aetiopathogenesis of schizophrenia. Specifically, the induction of inflammatory cytokines, which are important immunological factors in infection or inflammation, may be critical factors altering the normal course of brain development and increasing schizophrenia risk. Suppressor of cytokine signalling 2 (SOCS2) can negatively regulate the signalling of cytokines. The present study aimed to determine the behavioural phenotype of transgenic mice over-expressing SOCS2 (SOCS2 Tg) in paradigms of relevance to schizophrenia. Both male and female SOCS2 Tg mice displayed reduced locomotor hyperactivity after the administration of the dopamine releaser, amphetamine, compared to wildtype controls (WT). However, only male SOCS2 Tg mice showed enhanced prepulse inhibition compared to WT. Dopamine D2 receptors mRNA expression was reduced and dopamine transporter mRNA expression was increased in the nucleus accumbens of female, but not male, SOCS2 Tg mice, compared to WT. The role of hyperdopaminergia has long been implicated in the aetiology of schizophrenia. This study shows that over-expression of SOCS2 reduces the psychostimulant effects of amphetamine, enhances PPI, and alters mesolimbic dopaminergic activity. SOCS2 may provide a novel target in the development of treatments for schizophrenia.

Changes in dopamine transporter expression in the midbrain following traumatic brain injury: an immunohistochemical and in situ hybridization study in a mouse model

Objectives: An association has been suggested between trauma and neurological degenerative diseases. Magnetic resonance imaging has revealed that traumatic brain injury (TBI) can cause primary lesions in the midbrain including the substantia nigra (SN). Dopamine transporter (DAT) is mainly expressed in the SN, ventral tegmental area (VTA), and retrorubral field (RRF) of the ventral midbrain. Previous western blot studies have examined DAT levels in the rat frontal cortex and striatum after a controlled cortical impact (CCI); however, no study has comprehensively examined DAT expression in the midbrain following TBI in an animal model.Methods: We used immunohistochemistry and in situ hybridization to examine the time-dependent changes in the expression of DAT in the midbrain during the first 14 days after TBI in a mouse CCI model.Results: The expression of DAT protein in the RRF on the side ipsilateral to the site of injury decreased in 14 days after injury. Dopamine transporter mRNA expression in the RRF on the ipsilateral side decreased in 1, 7, and 14 days and increased in 4 days after injury.Discussion: These findings indicated that TBI induced changes in DAT expression in the RRF. Because the DAT pumps dopamine (DA) out of the synapse back into the cytosol and maintains DA homeostasis, the decreased expression of DAT after TBI may result in decreased DA neurotransmission in the brain.

Dopamine Transporter Gene Variant Affecting Expression in Human Brain is Associated with Bipolar Disorder

The gene encoding the dopamine transporter (DAT) has been implicated in CNS disorders, but the responsible polymorphisms remain uncertain. To search for regulatory polymorphisms, we measured allelic DAT mRNA expression in substantia nigra of human autopsy brain tissues, using two marker SNPs (rs6347 in exon 9 and rs27072 in the 3'-UTR). Allelic mRNA expression imbalance (AEI), an indicator of cis-acting regulatory polymorphisms, was observed in all tissues heterozygous for either of the two marker SNPs. SNP scanning of the DAT locus with AEI ratios as the phenotype, followed by in vitro molecular genetics studies, demonstrated that rs27072 C>T affects mRNA expression and translation. Expression of the minor T allele was dynamically regulated in transfected cell cultures, possibly involving microRNA interactions. Both rs6347 and rs3836790 (intron8 5/6 VNTR) also seemed to affect DAT expression, but not the commonly tested 9/10 VNTR in the 3'UTR (rs28363170). All four polymorphisms (rs6347, intron8 5/6 VNTR, rs27072 and 3'UTR 9/10 VNTR) were genotyped in clinical cohorts, representing schizophrenia, bipolar disorder, depression, and controls. Only rs27072 was significantly associated with bipolar disorder (OR = 2.1, p = 0.03). This result was replicated in a second bipolar/control population (OR = 1.65, p = 0.01), supporting a critical role for DAT regulation in bipolar disorder.

Effect of maternal deprivation on emotion and expression of dopamine transporter in adult rats

To investigate the change of emotion and striatum dopamine transporter(DAT) expression in adult male rats experiencing maternal deprivation, and to explore whether DNA methylation is involved in the regulatory mechanism of DAT expression. Newborn rats were randomly divided into 2 groups: a maternal separation group (n=16) and a control group (n=14). The maternal deprivation group were separated from their mother for 6 hours (09:00-15:00) per day from postnatal day 1 to 14, while the controls (n=14) without the deprivation. When the rats in the 2 groups were 12 week, their spontaneous anxiety levels and exploratory ability in novel environments were assessed by an elevated plus maze and an open field test. DAT mRNA expression in the striatum was detected by reverse transcription-PCR, and its DNA methylation level was measured by bisulfated DNA sequencing. Maternally-deprived rats showed lower ability of exploring in a new environment and lower levels of anxiety than the controls. The expression of DAT mRNA in the striatum of the maternal separation group (0.236+/-0.043) was significantly lower than that in the control group (0.480+/-0.107) (P<0.05). However the DNA methylation level in the promoter region of DAT was not significantly different between the 2 groups. Maternal deprivation influenced the emotion and expression of dopamine transporter in adult rats and DNA methylation may not be involved.

Epigenetic dysregulation of dopaminergic genes in eating disorders

The pathophysiology of eating disorders such as anorexia nervosa (AN) and bulimia nervosa (BN) has been linked to an impaired dopaminergic neurotransmission, still the origin of this disturbance remains unknown. The aim of the present study was, therefore, to evaluate whether the expression of dopaminergic genes is altered in the blood of patients suffering from eating disorders and if these alterations can be explained by changes in the promoter specific DNA methylation of the genes. We used quantitative real-time PCR to measure both the expression and the promoter specific DNA methylation of the dopamine transporter (DAT), and the D2 (DRD2) and D4 receptor (DRD4) gene in the blood of 46 patients (22 AN, 24 BN) and 30 healthy controls. Patients showed an elevated expression of DAT mRNA when compared with the controls and a downregulation of the DRD₂ expression. The upregulation of the DAT gene was accompanied by a hypermethylation of the gene's promoter in the AN and BN group while a significant hypermethylation of the DRD₂ promoter was only present in the AN group. No differences in expression or methylation were found for the other dopamine receptors investigated. Our study shows a disturbed expression of dopaminergic genes that is accompanied by a dysregulation of the epigenetic DNA methylation. Further studies are necessary to provide more insight into the epigenetic dysregulation of the dopaminergic neurotransmission in the pathophysiology of eating disorders.

Neuroprotective effects of enriched environment in MPTP-treated SAMP8 mice

Neuroprotective effects of enriched environment (EE) have been well established. Recent study suggests that exposure to EE can protect dopaminergic neurons against MPTP-induced Parkinsonism. After 64 female SAMP8 mice were reared in EE and standard environment (SE) for 3 months, the effects of EE and SE were compared on behavioural change, tyrosine hydroxylase (TH) immunoreaction positive neuron and dopaminetransporter (DAT) expression in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)-treated SAMP8. EE mice showed decreased spontaneous activity compared with SE mice. But EE + MPTP mice showed less decreased spontaneous activity compared with SE + MPTP mice. Otherwise, EE mice showed increased percentage of entries into the open arms and percentage of time spent in the open arms. Furthermore, EE mice demonstrated reduced neurotoxicity, with less decreased TH mRNA and protein expression in Substantia Nigra (SN) after MPTP administration compared with SE mice. SE mice showed a 53.77% loss of TH-positive neurons, whereas EE mice only showed a 42.28% loss. Moreover, EE mice showed decreased DAT mRNA and protein expression compared with SE mice. These data demonstrate that EE can protect dopaminergic neurons against MPTP-induced neuronal damage, which suggest that the probability of developing Parkinson's disease (PD) may be related to life environment.

Ectopic expression of the TrkA receptor in substantia nigra and enhanced synthesis of NGF in striatum modulate dopaminergic neurotransmission of adult rat basal ganglia

Event Abstract Back to Event Ectopic expression of the TrkA receptor in substantia nigra and enhanced synthesis of NGF in striatum modulate dopaminergic neurotransmission of adult rat basal ganglia Dimitra Giannakopoulou1*, Veronique Daguin-Nerriere2, Philippe Brachet2, Elias D. Kouvelas3, Adamantia Mitsacos3 and Panagiotis Giompres1 1 University of Patras, Laboratory of human and animal physiology, Department of Biology, Greece 2 University of Nantes, INSERM 643, France 3 University of Patras, Department of Physiology, Medical School, Greece Nerve growth factor (NGF) is a neurotrophic factor belonging to the neurotrophin family. The neurotrophic effects of NGF are mediated by the high affinity receptor, TrkA, which is a membrane tyrosine-kinase. In the present study we investigated whether the ectopic synthesis of TrkA in subtantia nigra cells and enhanced synthesis of NGF in striatal cells modulate the dopaminergic and GABAergic system of adult basal ganglia. For this purpose, we used two recombinant adeno-associated viruses, rAAV-CMV-TrkA and rAAV-CBA-NGF. Three separate experimental groups were used: rats stereotaxically injected with rAAV-TrkA in the right substantia nigra (SN); with rAAV-NGF in the right striatum; with rAAV-TrkA in the right SN and rAAV-NGF in the right striatum. The effects of TrkA and NGF gene delivery on locomotor activity were assessed using the open field and rotarod tests. TrkA and NGF immunoreactivities were detected in SN pars compacta and striatum, respectively. Receptor binding autoradiography, in situ hybridization and immunohistochemistry were performed. An increase in choline acetyltransferase and TrkA mRNA expression indicates that striatal cholinergic neurons respond to NGF. To reveal co-localization of TH with TrkA, double immunolabeling was performed. In striatum, we studied the dopamine transporter (DAT) by measuring binding levels of [3H]WIN35428 and DAT immunoreactivity. D1, D2 dopamine receptors and GABAA were studied by measuring binding levels of [3H]SCH23390, [3H]raclopride, and [3H]SR95531, respectively. In SN, DAT was studied by measuring binding levels of [3H]WIN35428, DAT mRNA expression and immunoreactivity. We observed selective neurochemical changes in DAT and dopamine receptors, as well as in GABAA in the viral treated right hemisphere. These data suggest that neuron-specific genetic modification of TrkA and NGF expression can induce plasticity to adult basal ganglia neurons.Supported by Socrates/Erasmus program and Polebros shipping limited. Conference: 41st European Brain and Behaviour Society Meeting, Rhodes Island, Greece, 13 Sep - 18 Sep, 2009. Presentation Type: Poster Presentation Topic: Poster presentations Citation: Giannakopoulou D, Daguin-Nerriere V, Brachet P, Kouvelas ED, Mitsacos A and Giompres P (2009). Ectopic expression of the TrkA receptor in substantia nigra and enhanced synthesis of NGF in striatum modulate dopaminergic neurotransmission of adult rat basal ganglia. Conference Abstract: 41st European Brain and Behaviour Society Meeting. doi: 10.3389/conf.neuro.08.2009.09.163 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 09 Jun 2009; Published Online: 09 Jun 2009. * Correspondence: Dimitra Giannakopoulou, University of Patras, Laboratory of human and animal physiology, Department of Biology, Patras, Greece, dimitragian@yahoo.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Dimitra Giannakopoulou Veronique Daguin-Nerriere Philippe Brachet Elias D Kouvelas Adamantia Mitsacos Panagiotis Giompres Google Dimitra Giannakopoulou Veronique Daguin-Nerriere Philippe Brachet Elias D Kouvelas Adamantia Mitsacos Panagiotis Giompres Google Scholar Dimitra Giannakopoulou Veronique Daguin-Nerriere Philippe Brachet Elias D Kouvelas Adamantia Mitsacos Panagiotis Giompres PubMed Dimitra Giannakopoulou Veronique Daguin-Nerriere Philippe Brachet Elias D Kouvelas Adamantia Mitsacos Panagiotis Giompres Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

The role of dopamine D2 receptor and transporter in the different susceptibility of morphine-induced conditioned place preference in rats

Objective To investigate the expression of dopamine D2 receptor(D2 R)and dopamine transporter(DAT)located in the medial prefrontal contex(mPFC)in high and low CPP rats,thus to unveil the possible mechanism lead to the different CPP susceptibility.Methods 160 male Sprague-Dawley rats were randomly assigned into experiment group (n=130)and control group(n=30).The experiment group were re-classified into two groups according to the numerical value of the CPP(Conditioned place preference):high preference group(HP group)and low preference group(LP group).Further,according to the executed time-points after the last administration.each the HP and LP group was classified into 3-holly group(3H),72-hour group(JD3)and 14-day group (JD14)respectively.At the time of 3 hours,72 hours and 14 days after the final injection,rats were scarified and cardio-perfused,and the brains were removed and sliced up coronarily.The mRNA levels of D2R and DAT in mPFC were estimated with in situ hybridization.Results No significant difference of pretest scores staying at the non-preference chamber exist among the three groups(P＞0.05),however,the test scores of the CPP minus the time stayed at pretest natural preference in the HP group was significantly higher than the LP group(P＜0.01).In 3H,J3D and J14D group,the expression of D2R mRNA in HP group(125.43±2.90～142.92±3.32)were lower that of in LP group(122.25±2.20～136.67±5.39),and the difference between the HP and LP group was significant(P＜0.01).In 3H and J3D,the expression of DAT mRNA in HP group(157.00±3.55～145.15±3.69)were significantly lower than that of in LP group(150.69±3.12～138.84±3.99)(P＜0.01).In J14D,there were no difference between 3 groups in mPFC(P＞0.05).Conclusions It can be inferred that D2R and DAT maybe correlated closely and underlie the different susceptibility to morphine induced CPP. Key words: Morphine; Psychological dependence; Conditioned place preference; Susceptibility; Dopamine D2 receptor; Dopamine transporter

The role of gamma‐synuclein in cocaine‐induced behaviour in rats

The aim of this study was to investigate the role of gamma-synuclein in the rewarding effects of chronic cocaine administration and its putative interaction with the dopamine transporter (DAT). For this purpose, regulatable lentiviruses driving overexpression of the rat gamma-synuclein or DAT have been prepared, as well as lentiviruses expressing siRNAs, aimed at silencing either DAT or gamma-synuclein mRNA expression. Overexpression of DAT in the nucleus accumbens (NAc) induced a 35% decrease in locomotor activity, which could be abolished when the same animal was fed doxycycline. Furthermore, local inhibition of DAT in the NAc, using lentiviruses expressing siRNAs targeted against DAT, resulted in significant hyperlocomotion activity (72% increase over controls). By contrast, overexpression of gamma-synuclein in the NAc alone had no effect, while local silencing lead to a significant decrease in cocaine-induced locomotor activity (47% decrease compared with controls). Surprisingly, coinjection lentiviruses expressing DAT and gamma-synuclein - leading to overexpression of both proteins in the NAc - resulted in a strong increase in cocaine-induced rat locomotor activity (52% increase compared with controls), which was abolished upon locally silencing these genes, suggesting a synergetic role of both proteins, possibly mediated through a direct interaction.

Gender differences in zebrafish responses to cocaine withdrawal

The acute responses to cocaine and its withdrawal contribute to cocaine dependence and potentiate relapse, with gender being one of the genetic factors affecting the outcome. Here we report that in both male and female zebrafish ( Danio rerio, AB strain), an initial low-dose cocaine treatment (1.5 μM, immersion) does not acutely change their behavior. The cocaine withdrawal, however, is associated with an anxiety-like state that develops earlier in female zebrafish but is more robust and persistent in males, and can be acutely attenuated by cocaine administration. This is not a result of gender differences in the expression of anxiety-like state, since behavioral responses to an anxiogenic drug, FG-7142, are similar in male and female zebrafish. The basal brain dopamine (DA) levels and the expression of dopamine transporter mRNA ( zDAT) show no significant sexual dimorphism. Acute cocaine exposure does not significantly change DA or zDAT. Withdrawal from repeated cocaine administration results in an overall reduction in zDAT, as well as an increase in DA levels. Neither treatment leads to significant gender differences in brain DA or zDAT. The common and gender-specific effects of cocaine on zebrafish, a well-characterized model of vertebrate development and genetics, should help in understanding the mechanisms involved in the anxiety associated with cocaine withdrawal and provide new opportunities in search for therapeutic solutions.