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Evolution of the HIV-1 transgenic rat: utility in assessing the progression of HIV-1-associated neurocognitive disorders. J Neurovirol 2017; 24:229-245. [PMID: 28730408 DOI: 10.1007/s13365-017-0544-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 05/05/2017] [Accepted: 06/08/2017] [Indexed: 12/14/2022]
Abstract
Understanding the progression of HIV-1-associated neurocognitive disorders (HAND) is a critical need as the prevalence of HIV-1 in older individuals (>50 years) is markedly increasing due to the great success of combination antiretroviral therapy (cART). Longitudinal experimental designs, in comparison to cross-sectional studies, provide an opportunity to establish age-related disease progression in HAND. The HIV-1 transgenic (Tg) rat, which has been promoted for investigating the effect of long-term HIV-1 viral protein exposure, was used to examine two interrelated goals. First, to establish the integrity of sensory and motor systems through the majority of the animal's functional lifespan. Strong evidence for intact sensory and motor system function through advancing age in HIV-1 Tg and control animals was observed in cross-modal prepulse inhibition (PPI) and locomotor activity. The integrity of sensory and motor system function suggested the utility of the HIV-1 Tg rat in investigating the progression of HAND. Second, to assess the progression of neurocognitive impairment, including temporal processing and long-term episodic memory, in the HIV-1 Tg rat; the factor of biological sex was integral to the experimental design. Cross-modal PPI revealed significant alterations in the development of temporal processing in HIV-1 Tg animals relative to controls; alterations which were more pronounced in female HIV-1 Tg rats relative to male HIV-1 Tg rats. Locomotor activity revealed deficits in intrasession habituation, suggestive of a disruption in long-term episodic memory, in HIV-1 Tg animals. Understanding the progression of HAND heralds an opportunity for the development of an advantageous model of progressive neurocognitive deficits in HIV-1 and establishes fundamental groundwork for the development of neurorestorative treatments.
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Jiang L, O'Leary C, Kim HA, Parish CL, Massalas J, Waddington JL, Ehrlich ME, Schütz G, Gantois I, Lawrence AJ, Drago J. Motor and behavioral phenotype in conditional mutants with targeted ablation of cortical D1 dopamine receptor-expressing cells. Neurobiol Dis 2015; 76:137-158. [PMID: 25684539 DOI: 10.1016/j.nbd.2015.02.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 01/14/2015] [Accepted: 02/05/2015] [Indexed: 10/24/2022] Open
Abstract
D1-dopamine receptors (Drd1a) are highly expressed in the deep layers of the cerebral cortex and the striatum. A number of human diseases such as Huntington disease and schizophrenia are known to have cortical pathology involving dopamine receptor expressing neurons. To illuminate their functional role, we exploited a Cre/Lox molecular paradigm to generate Emx-1(tox) MUT mice, a transgenic line in which cortical Drd1a-expressing pyramidal neurons were selectively ablated. Emx-1(tox) MUT mice displayed prominent forelimb dystonia, hyperkinesia, ataxia on rotarod testing, heightened anxiety-like behavior, and age-dependent abnormalities in a test of social interaction. The latter occurred in the context of normal working memory on testing in the Y-maze and for novel object recognition. Some motor and behavioral abnormalities in Emx-1(tox) MUT mice overlapped with those in CamKIIα(tox) MUT transgenic mice, a line in which both striatal and cortical Drd1a-expressing cells were ablated. Although Emx-1(tox) MUT mice had normal striatal anatomy, both Emx-1(tox) MUT and CamKIIα(tox) MUT mice displayed selective neuronal loss in cortical layers V and VI. This study shows that loss of cortical Drd1a-expressing cells is sufficient to produce deficits in multiple motor and behavioral domains, independent of striatal mechanisms. Primary cortical changes in the D1 dopamine receptor compartment are therefore likely to model a number of core clinical features in disorders such as Huntington disease and schizophrenia.
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Affiliation(s)
- Luning Jiang
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia; St Vincent's Hospital, Melbourne, Victoria, Australia
| | - Claire O'Leary
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia; Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin 2, Ireland
| | - Hyun Ah Kim
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Clare L Parish
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Jim Massalas
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - John L Waddington
- Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin 2, Ireland
| | - Michelle E Ehrlich
- Department of Neurology, Mount Sinai School of Medicine, New York, NY, USA
| | - Günter Schütz
- Deutsches Krebsforschungszentrum, Heidelberg, Germany
| | - Ilse Gantois
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Andrew J Lawrence
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - John Drago
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia; St Vincent's Hospital, Melbourne, Victoria, Australia.
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Abstract
Relative to intravenous drug self-administration, locomotor activity is easier to measure with high throughput, particularly in mice. Therefore its potential to predict differences in self-administration between genotypes (e.g., targeted mutations, recombinant inbred strains) is appealing, but such predictive value is unverified. The main goal of this study was to evaluate the utility of the locomotor assay for accurately predicting differences in cocaine self-administration. A second goal was to evaluate any correlation between activity in a novel environment, and cocaine-induced hyperactivity, between strains. We evaluated locomotor activity in male and female Sprague-Dawley rats and 15 mouse strains (129S1/SvImJ, 129S6/SvEvTac, 129X1/SvJ, A/J, BALB/cByJ, BALB/cJ, C3H/HeJ, C57BL/6J, CAST/EiJ, DBA/2J, FVB/NJ, SJL/J, SPRET/EiJ, and outbred Swiss Webster and CD-1/ICR), as well as cocaine self-administration in BALB substrains. All but BALB/cJ mice showed locomotor habituation and significant cocaine-induced hyperactivity. BALB/cJ mice also failed to self-administer cocaine. BALB/cByJ mice showed modest locomotor habituation, cocaine-induced locomotion, and cocaine self-administration. As previously reported, female rats showed greater cocaine-induced locomotion than males, but this was only observed in one of 15 mouse strains (FVB/NJ), and the reverse was observed in two strains (129X1/SvJ, BALB/cByJ). The intriguing phenotype of the BALB/cJ strain may indicate some correlation between all-or-none locomotion in a novel environment, and stimulant and reinforcing effects of cocaine. However, neither novelty- nor cocaine-induced activity offered a clear prediction of relative reinforcing effects among strains. Additionally, these results should aid in selecting mouse strains for future studies in which relative locomotor responsiveness to psychostimulants is a necessary consideration.
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MESH Headings
- Animals
- Central Nervous System Stimulants/metabolism
- Central Nervous System Stimulants/pharmacology
- Cocaine/metabolism
- Cocaine/pharmacology
- Conditioning, Operant
- Dose-Response Relationship, Drug
- Female
- Hyperkinesis/chemically induced
- Locomotion/drug effects
- Male
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Mice, Inbred DBA
- Mice, Inbred Strains
- Models, Animal
- Motor Activity/drug effects
- Phenotype
- Predictive Value of Tests
- Rats
- Rats, Sprague-Dawley
- Reinforcement, Psychology
- Self Administration
- Sex Factors
- Substance-Related Disorders
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Affiliation(s)
- Morgane Thomsen
- Alcohol and Drug Abuse Research Center, Harvard Medical School and McLean Hospital, Mail Stop 214,115 Mill Street, Belmont, MA 02478, USA.
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Yarkov AV, Der TC, Joyce JN. Locomotor activity induced by MK-801 is enhanced in dopamine D3 receptor knockout mice but suppression by dopamine D3/D2 antagonists does not occur through the dopamine D3 receptor. Eur J Pharmacol 2010; 627:167-72. [DOI: 10.1016/j.ejphar.2009.10.068] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2009] [Revised: 09/21/2009] [Accepted: 10/14/2009] [Indexed: 11/28/2022]
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Iarkov AV, Der TC, Joyce JN. Age-related differences in MK-801 induced behaviors in dopamine D3 receptor knock out mice. Eur J Pharmacol 2010; 627:177-84. [DOI: 10.1016/j.ejphar.2009.11.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 10/16/2009] [Accepted: 11/03/2009] [Indexed: 11/16/2022]
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Harrison SJ, Nobrega JN. Differential susceptibility to ethanol and amphetamine sensitization in dopamine D3 receptor-deficient mice. Psychopharmacology (Berl) 2009; 204:49-59. [PMID: 19096829 DOI: 10.1007/s00213-008-1435-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Accepted: 12/02/2008] [Indexed: 11/30/2022]
Abstract
RATIONALE Dopamine D3 receptors (D3Rs) have been implicated in behavioral sensitization to various drugs of abuse, but their role in ethanol (EtOH) sensitization has not been directly examined. We used D3R knockout (D3 KO) mice to examine whether the D3R plays a permissive role in EtOH and amphetamine (AMPH) sensitization. We also investigated whether EtOH sensitization is accompanied by alterations in D3R mRNA expression or binding. MATERIALS AND METHODS After comparing EtOH sensitization in C57Bl/6 mice and DBA/2 mice, D3 KO, wild type (WT), and for comparison, D1 and D2 KOs received five biweekly injections of EtOH (2.2 g/kg, i.p.) or saline. Another group of D3 KOs and WT controls received six times AMPH (1.5 mg/kg, i.p.). D3R mRNA and binding were measured in EtOH-sensitized DBA/2 mice with in situ hybridization and [(125)I]-7-OH-PIPAT autoradiography, respectively. RESULTS C57Bl/6 mice expressed EtOH sensitization albeit to a lesser extent than DBA/2 mice. Compared to WT mice, D3 KOs were resistant to EtOH sensitization. The behavioral profile of D3 KOs was more similar to D1 KOs than D2 KOs, which also failed to develop EtOH sensitization. However, D3 KOs developed AMPH sensitization normally. EtOH sensitization was not accompanied by changes in either D3R mRNA or D3R binding in the islands of Calleja, nucleus accumbens, dorsal striatum, or cerebellum. CONCLUSIONS These results suggest a necessary role for the D3R in EtOH but not AMPH sensitization, possibly through postreceptor intracellular mechanisms. Results also suggest that different neurochemical mechanisms underlie sensitization to different drugs of abuse.
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Scalabrino GA, Hogan N, O'Boyle KM, Slator GR, Gregg DJ, Fitchett CM, Draper SM, Bennett GW, Hinkle PM, Bauer K, Williams CH, Tipton KF, Kelly JA. Discovery of a dual action first-in-class peptide that mimics and enhances CNS-mediated actions of thyrotropin-releasing hormone. Neuropharmacology 2007; 52:1472-81. [PMID: 17418282 DOI: 10.1016/j.neuropharm.2007.02.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 02/07/2007] [Accepted: 02/09/2007] [Indexed: 10/23/2022]
Abstract
Thyrotropin-releasing hormone (TRH) displays multiple CNS-mediated actions that have long been recognized to have therapeutic potential in treating a wide range of neurological disorders. Investigations of CNS functions and clinical use of TRH are hindered, however, due to its rapid degradation by TRH-degrading ectoenzyme (TRH-DE). We now report the discovery of a set of first-in-class compounds that display unique ability to both potently inhibit TRH-DE and bind to central TRH receptors with unparalleled affinity. This dual pharmacological activity within one molecular entity was found through selective manipulation of peptide stereochemistry. Notably, the lead compound of this set, L-pyroglutamyl-L-asparaginyl-L-prolyl-D-tyrosyl-D-tryptophan amide (Glp-Asn-Pro-D-Tyr-D-TrpNH(2)), is effective in vivo at producing and potentiating central actions of TRH without evoking release of thyroid-stimulating hormone (TSH). Specifically, this peptide displayed high plasma stability and combined potent inhibition of TRH-DE (K(i) 151 nM) with high affinity binding to central TRH receptors (K(i) 6.8 nM). Moreover, intraperitoneal injection of this peptide mimicked and augmented the effects of TRH on behavioural activity in rat. Analogous to TRH, it also antagonized pentobarbital-induced narcosis when administered intravenously. This discovery provides new opportunities for probing the role of TRH actions in the CNS and a basis for development of novel TRH-based neurotherapeutics.
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Affiliation(s)
- Gaia A Scalabrino
- School of Biochemistry and Immunology and Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
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Waddington JL, O'Tuathaigh C, O'Sullivan G, Tomiyama K, Koshikawa N, Croke DT. Phenotypic studies on dopamine receptor subtype and associated signal transduction mutants: insights and challenges from 10 years at the psychopharmacology-molecular biology interface. Psychopharmacology (Berl) 2005; 181:611-38. [PMID: 16041535 DOI: 10.1007/s00213-005-0058-8] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2005] [Accepted: 04/27/2005] [Indexed: 10/25/2022]
Abstract
BACKGROUND Mutants with targeted gene deletion ('knockout') or insertion (transgenic) of D1, D2, D3, D4 and D5 dopamine (DA) receptor subtypes are complemented by an increasing variety of double knockout and transgenic-'knockout' models, together with knockout of critical components of DA receptor signalling cascades such as G alpha(olf)[G gamma7], adenylyl cyclase type 5, PKA [RIIbeta] and DARPP-32. However, it is increasingly recognised that these molecular techniques have a number of inherent limitations. Furthermore, there are poorly understood methodological factors that contribute to inconsistent phenotypic findings between laboratories. OBJECTIVE This review seeks to document the impact of DA receptor subtype and related transduction mutants on our understanding of the behavioural roles of these entities, primarily at the level of unconditioned psychomotor behaviour. METHODS It includes ethologically based and orofacial movement studies in our own laboratories, since these are the only studies to systematically compare each of the D1, D2, D3, D4 and D5 receptor and DARPP-32 signal transduction 'knockouts'. DISCUSSION There is a particular emphasis on identifying methodological factors that might influence phenotypic effects and account for inconsistencies. The findings are offered empirically to (1) specify the extent of phenotypic diversity among individual DA receptor subtypes and transduction components and (2) indicate relationships between D1, D2, D3, D4 and D5 receptor subtype proteins, associated G alpha(i)/G alpha(s)/G alpha(olf)[G gamma7]-adenylyl cyclase type 5-PKA [RIIbeta]-DARPP-32 signalling cascades and behaviour. The findings are also offered heuristically as a base for such phenotypic comparisons at additional levels of behaviour so that a yet more complete phenotypic profile might emerge.
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Affiliation(s)
- John L Waddington
- Institute of Biopharmaceutical Sciences, Royal College of Surgeons in Ireland, St. Stephen's Green, Dublin 2, Ireland.
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Holmes A, Lachowicz JE, Sibley DR. Phenotypic analysis of dopamine receptor knockout mice; recent insights into the functional specificity of dopamine receptor subtypes. Neuropharmacology 2005; 47:1117-34. [PMID: 15567422 DOI: 10.1016/j.neuropharm.2004.07.034] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Revised: 06/20/2004] [Accepted: 07/28/2004] [Indexed: 12/11/2022]
Abstract
The functional specificity of dopamine receptor subtypes remains incompletely understood, in part due to the absence of highly selective agonists and antagonists. Phenotypic analysis of dopamine receptor knockout mice has been instrumental in identifying the role of dopamine receptor subtypes in mediating dopamine's effects on motor function, cognition, reward, and emotional behaviors. In this article, we provide an update of recent studies in dopamine receptor knockout mice and discuss the limitations and future promise of this approach.
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Affiliation(s)
- Andrew Holmes
- Section on Behavioral Science and Genetics, National Institute of Alcoholism and Alcohol Abuse, National Institutes of Health, Bethesda, MD 20892, USA.
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Kalueff AV, Tuohimaa P. Contrasting grooming phenotypes in C57Bl/6 and 129S1/SvImJ mice. Brain Res 2005; 1028:75-82. [PMID: 15518644 DOI: 10.1016/j.brainres.2004.09.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/08/2004] [Indexed: 11/23/2022]
Abstract
Since C57 and 129 mice are the commonly used background strains, a better knowledge of all their behavioural characteristics is important in neuroscience research. Grooming is a complex and essential ritual in the rodent behavioural repertoire, normally proceeding in a cephalocaudal progression (paws-nose-face-body-legs-tail and genitals). Various stressors as well as genetic manipulations have been reported to alter mouse grooming and its patterning, underlying the importance of analysis of grooming behaviours in detail. Although strain differences between C57BL/6 and 129S1/SvImJ substrains have been assessed in many studies, no ethological analyses of their grooming have been performed. Here we show strain differences between these mice in spontaneous (novelty-induced) and artificial (water-induced) grooming. Overall, 129S1/SvImJ mice demonstrated less grooming activity, more interrupted and incomplete bouts, and more incorrect transitions (contrary to the cephalocaudal rule) between patterns, accompanied by lower vertical activity and higher defecation/urination in both tests. These results are consistent with general hypoactive anxious phenotype in 129S1/SvImJ mice and suggest that ethological analysis of mouse grooming may be used in neurobehavioural stress research, including behavioural phenotyping of both mutant and background mice.
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Affiliation(s)
- Allan V Kalueff
- Department of Anatomy, Medical School, University of Tampere, Tampere 33014, Finland.
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Murphy DL, Uhl GR, Holmes A, Ren-Patterson R, Hall FS, Sora I, Detera-Wadleigh S, Lesch KP. Experimental gene interaction studies with SERT mutant mice as models for human polygenic and epistatic traits and disorders. GENES BRAIN AND BEHAVIOR 2004; 2:350-64. [PMID: 14653307 DOI: 10.1046/j.1601-1848.2003.00049.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Current evidence indicates that virtually all neuropsychiatric disorders, like many other common medical disorders, are genetically complex, with combined influences from multiple interacting genes, as well as from the environment. However, additive or epistatic gene interactions have proved quite difficult to detect and evaluate in human studies. Mouse phenotypes, including behaviors and drug responses, can provide relevant models for human disorders. Studies of gene-gene interactions in mice could thus help efforts to understand the molecular genetic bases of complex human disorders. The serotonin transporter (SERT, 5-HTT, SLC6A4) provides a relevant model for studying such interactions for several reasons: human variants in SERT have been associated with several neuropsychiatric and other medical disorders and quantitative traits; SERT blockers are effective treatments for a number of neuropsychiatric disorders; there is a good initial understanding of the phenotypic features of heterozygous and homozygous SERT knockout mice; and there is an expanding understanding of the interactions between variations in SERT expression and variations in the expression of a number of other genes of interest for neuropsychiatry and neuropharmacology. This paper provides examples of experimentally-obtained interactions between quantitative variations in SERT gene expression and variations in the expression of five other mouse genes: DAT, NET, MAOA, 5-HT(1B) and BDNF. In humans, all six of these genes possess polymorphisms that have been independently investigated as candidates for neuropsychiatric and other disorders in a total of > 500 reports. In the experimental studies in mice reviewed here, gene-gene interactions resulted in either synergistic, antagonistic (including 'rescue' or 'complementation') or more complex, quantitative alterations. These were identified in comparisons of the behavioral, physiological and neurochemical phenotypes of wildtype mice vs. mice with single allele or single gene targeted disruptions and mice with partial or complete disruptions of multiple genes. Several of the descriptive phenotypes could be best understood on the basis of intermediate, quantitative alterations such as brain serotonin differences. We discuss the ways in which these interactions could provide models for studies of gene-gene interactions in complex human neuropsychiatric and other disorders to which SERT may contribute, including developmental disorders, obesity, polysubstance abuse and others.
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Affiliation(s)
- D L Murphy
- Laboratory of Clinical Science, Building 10, Room 3D41, 10 Center Drive, NIMH, NIH/ DHHS, Bethesda, MD 20892-1264, USA.
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Yarkov AV, Hanger D, Reploge M, Joyce JN. Behavioral effects of dopamine agonists and antagonists in MPTP-lesioned D3 receptor knockout mice. Pharmacol Biochem Behav 2003; 76:551-62. [PMID: 14643855 DOI: 10.1016/j.pbb.2003.09.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To test the modulatory role of D(3) receptors in normal and dopamine-depleted mice, D(3) receptor KO mice and wild-type (WT) littermates were administered saline, L-dopa/carbidopa (20/2 mg/kg ip), a preferential D(3)>D(2) agonist S32504, a D1+D(2)/D(3) agonist apomorphine, a selective D(3) antagonist S33084, or apomorphine with S33084 prior to and after administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We monitored lines crossed in a 55-min session, average number of rears, and average number of grooming bouts. MPTP treatment produced equivalent 70% losses of dopamine fibers in the caudate putamen (CPu) and nucleus accumbens (NAC) of WT and D(3) KO mice as compared to their control (vehicle injected) counterparts. D(3) receptors were absent in KO mice, and the number of D(3) receptors was unaffected by MPTP-induced loss of DA terminals in WT mice. The results support a lack of involvement of the D(3) receptor for D1:D2 receptor-mediated behavioral activity (synergy). First, S32504 inhibited all behaviors and to a similar degree in D(3) KO and WT mice. Second, S33084 at the higher concentration increased number of lines crossed in response to high dose apomorphine in both D(3) KO and WT mice. Third, in nonlesioned mice, apomorphine-induced gnawing stereotypies were inhibited by S33084 in both D(3) KO and WT mice. Interestingly, the inhibition of apomorphine-induced gnawing was not apparent in MPTP-lesioned mice, and this stereotypy was elevated in D(3) KO-MPTP-lesioned mice. Thus, the suppressive effects of S32504 could be via D2 autoreceptor inhibition of DA release, and D2 receptor blockade by S33084 leads to release of that inhibition. This may be more apparent in MPTP-lesioned partially DA denervated mice.
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Affiliation(s)
- Alex V Yarkov
- Thomas H. Christopher Center for Parkinson's Disease Research, Sun Health Research Institute, 10515 West Santa Fe Drive, Sun City, AZ 85351, USA.
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Viggiano D, Ruocco LA, Sadile AG. Dopamine phenotype and behaviour in animal models: in relation to attention deficit hyperactivity disorder. Neurosci Biobehav Rev 2003; 27:623-37. [PMID: 14624807 DOI: 10.1016/j.neubiorev.2003.08.006] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The phenotypic expression of behaviour is the outcome of interacting neuronal networks and is modulated by different subcortical systems. In the present paper the role of a major subcortical neurochemical system, dopamine (DA), is reviewed. In particular, knockout (KO) technology has given an overwhelming insight into the effects of specific component of the dopaminergic system. Therefore, the behavioural profile of dopamine transporter (DAT), tyrosine hydroxylase (TH), DA and cAMP-regulated phosphoprotein (DARPP 32), and D1, D2, D3, D4 and D5 dopamine receptors knockouts (and their combination) is reviewed.TH, D1, D2, D4 KO mice exhibit decreased locomotor activity, perhaps due to decreased motivational level. D3 KO and DAT KO mice show an increase in basal and novelty-induced activity respectively. It is possible that the increased dopamine levels in DAT KO mice enhance motivation. These observations support the hyperDA hypothesis in hyperactive phenotypes. Moreover, they suggest that the inhibitory effect of psychostimulant drugs, such as methylphenidate and amphetamines, in Attention Deficit Hyperactivity Disorder may be the outcome of an altered balance between auto- and hetero-receptors. However, since KO technology is hampered by blockade of the target at early stages of development, some alternatives have been proposed, such as inducible mutagenesis and inhibitory small RNAs conveyed to target by viral vectors in adulthood.
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Affiliation(s)
- Davide Viggiano
- Department of Experimental Medicine, Second University of Naples, Naples, Italy
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