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Gylys KH, Bilousova T. Flow Cytometry Analysis and Quantitative Characterization of Tau in Synaptosomes from Alzheimer's Disease Brains. Methods Mol Biol 2018; 1523:273-284. [PMID: 27975256 DOI: 10.1007/978-1-4939-6598-4_16] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
Synaptosomes, resealed nerve terminals that form when tissue is homogenized in isotonic medium, are a model system that has been a key source of knowledge about neurotransmission. Synaptosomes contain mitochondria, cytoskeletal proteins, and release neurotransmitters; many have postsynaptic elements. Cryopreservation at the time of autopsy makes it possible to prepare synaptosomes from human samples. Flow cytometry is a powerful analytic technique that precisely measures fluorescence on a cell-by-cell basis, and also indicates particle size and complexity with a routine parameter that measures light scattering. We describe here a procedure for flow cytometry analysis of tau in synaptosomes, a procedure that enables (1) "purification" of synaptosomes from the P-2 fraction (crude synaptosomes) by gating on particle size, and (2) quantitative measure of tau immunofluorescence in individual terminals. Application of flow cytometry to study of synaptosomes has yielded important information, not possible with routine biochemistry, about synaptic pathology in Alzheimer's disease.
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Affiliation(s)
- Karen Hoppens Gylys
- UCLA School of Nursing and Mary S. Easton Center for Alzheimer's Research at UCLA, Box 956919, Factor Building, Los Angeles, CA, 90095-6919, USA.
| | - Tina Bilousova
- UCLA School of Nursing and Mary S. Easton Center for Alzheimer's Research at UCLA, Box 956919, Factor Building, Los Angeles, CA, 90095-6919, USA
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2
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Administration of Dopamine to Rats Disorganizes the Rhythm of Protein Synthesis in Hepatocytes. Bull Exp Biol Med 2014; 157:220-3. [DOI: 10.1007/s10517-014-2529-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Indexed: 10/25/2022]
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Guez-Barber D, Fanous S, Harvey BK, Zhang Y, Lehrmann E, Becker KG, Picciotto MR, Hope BT. FACS purification of immunolabeled cell types from adult rat brain. J Neurosci Methods 2012; 203:10-8. [PMID: 21911005 PMCID: PMC3221768 DOI: 10.1016/j.jneumeth.2011.08.045] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 08/22/2011] [Accepted: 08/27/2011] [Indexed: 01/16/2023]
Abstract
Molecular analysis of brain tissue is greatly complicated by having many different classes of neurons and glia interspersed throughout the brain. Fluorescence-activated cell sorting (FACS) has been used to purify selected cell types from brain tissue. However, its use has been limited to brain tissue from embryos or transgenic mice with promoter-driven reporter genes. To overcome these limitations, we developed a FACS procedure for dissociating intact cell bodies from adult wild-type rat brains and sorting them using commercially available antibodies against intracellular and extracellular proteins. As an example, we isolated neurons using a NeuN antibody and confirmed their identity using microarray and real time PCR of mRNA from the sorted cells. Our FACS procedure allows rapid, high-throughput, quantitative assays of molecular alterations in identified cell types with widespread applications in neuroscience.
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Affiliation(s)
- Danielle Guez-Barber
- Behavioral Neuroscience Branch, IRP/NIDA/NIH/DHHS, 251 Bayview Boulevard, Baltimore, MD 21224, USA
- Department of Psychiatry, Yale University, 34 Park Street, New Haven, CT 06508, USA
| | - Sanya Fanous
- Behavioral Neuroscience Branch, IRP/NIDA/NIH/DHHS, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Brandon K Harvey
- Behavioral Neuroscience Branch, IRP/NIDA/NIH/DHHS, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Yongqing Zhang
- The Research Resources Branch, IRP/NIA/NIH/DHHS, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | | | - Kevin G Becker
- The Research Resources Branch, IRP/NIA/NIH/DHHS, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Marina R Picciotto
- Department of Psychiatry, Yale University, 34 Park Street, New Haven, CT 06508, USA
| | - Bruce T Hope
- Behavioral Neuroscience Branch, IRP/NIDA/NIH/DHHS, 251 Bayview Boulevard, Baltimore, MD 21224, USA
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Nakano M, Minagawa A, Hasunuma I, Okada R, Tonon MC, Vaudry H, Yamamoto K, Kikuyama S, Machida T, Kobayashi T. D2 Dopamine receptor subtype mediates the inhibitory effect of dopamine on TRH-induced prolactin release from the bullfrog pituitary. Gen Comp Endocrinol 2010; 168:287-92. [PMID: 20553721 DOI: 10.1016/j.ygcen.2010.05.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2009] [Revised: 05/13/2010] [Accepted: 05/24/2010] [Indexed: 11/23/2022]
Abstract
Dopamine receptors in mammals are known to consist of two D1-like receptors (D1 and D5) and three D2-like receptors (D2, D3 and D4). The aim of this study was to determine the dopamine receptor subtype that mediates the inhibitory action of dopamine on the release of prolactin (PRL) from the amphibian pituitary. Distal lobes of the bullfrog (Rana catesbeiana) were perifused and the amount of PRL released in the effluent medium was measured by means of a homologous enzyme-immunoassay. TRH stimulated the release of PRL from perifused pituitaries. Dopamine suppressed TRH-induced elevation of PRL release. Quinpirole (a D2 receptor agonist) also suppressed the stimulatory effect of TRH on the release of PRL, whereas SKF-38393 (a D1 receptor agonist) exhibited no such an effect. The inhibitory action of dopamine on TRH-induced PRL release from the pituitary was nullified by the addition of L-741,626 (a selective D2 receptor antagonist) to the medium, but not by the addition of SCH-23390 (a selective D1 receptor antagonist). These data indicate that the inhibitory effect of dopamine on TRH-evoked PRL release from the bullfrog pituitary gland is mediated through D2 dopamine receptors.
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Affiliation(s)
- Masaki Nakano
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
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Calcium homeostasis is dysregulated in parkinsonian patients with L-DOPA-induced dyskinesias. Clin Neuropharmacol 2009; 32:133-9. [PMID: 18978486 DOI: 10.1097/wnf.0b013e3181761466] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Long-term treatment of Parkinson disease (PD) is frequently associated with l-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesias (LIDs). L-DOPA-induced dyskinesias are likely due to changes in the signal transduction pathways, at the striatal level, related to pulsatile stimulation of dopamine receptors. We investigated whether markers of this phenomenon can also be detected peripherally. We analyzed mRNA expression for D5 (D1-like) and D3 (D2-like) receptors and levels of second messengers, such as cAMP and free intracellular Ca2+ ([Ca2+]i), in peripheral blood lymphocytes of PD patients with (LID+) or without LIDs (LID-). Patients with PD showed depressed [Ca2+]i rise in response to mitogen-induced activation. The defect was more pronounced in LID+ (-33% with respect to healthy controls) than in LID- patients (-20%). Peripheral blood lymphocyte levels of cAMP were decreased in both LID+ (3.8 +/- 2.9 pmol/10 cells) and LID- patients (4.2 +/- 2.4 pmol/10(6) cells), with respect to controls (6 +/- 2.6 pmol/10(6) cells). No differences were found in dopamine receptor mRNA expression. Our results demonstrate that second messenger levels are altered in the peripheral blood lymphocytes of PD patients treated with dopaminergic agents and that patients with LIDs show further alterations in the regulation of [Ca2+]i homeostasis. This may represent a distinctive trait of patients prone to develop dyskinetic movements.
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6
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Bazzini E, Samuele A, Granelli M, Levandis G, Armentero MT, Nappi G, Blandini F. Proteasomal inhibition and apoptosis regulatory changes in human isolated lymphocytes: The synergistic role of dopamine. J Cell Biochem 2008; 103:877-85. [PMID: 17647258 DOI: 10.1002/jcb.21457] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Abnormal deposition of protein aggregates and increased susceptibility to apoptotic cell death may result from defects in the activity of the ubiquitin-proteasome system (UPS); neurotoxicity related to UPS defects seems to require dopamine to be fully expressed. The aim of this study was to investigate the pro-apoptotic effects caused by proteasomal activity inhibition, as well as the synergistic effect of dopaminergic stimulation in human lymphocytes isolated from healthy volunteers. Cells were incubated 20 h at 37 degrees C, with: (1) lactacystin, (2) increasing concentrations of dopamine or (3) mixture of dopamine and lactacystin. Activities of proteasome 20S and pro-apoptotic caspases-3 and -9 and levels of anti-apoptotic Bcl-2 were measured with fluorimetric or immunochemical assays, while a "DNA diffusion" assay was used to determine the apoptosis. Incubation of lymphocytes with lactacystin, which caused reduction of proteasomal activity, was associated with activation of caspases. A clear, dose-dependent reduction of proteasomal activity was also seen in the presence of increasing doses of dopamine, which was accompanied by a slight dose-dependent increase of caspases activities and Bcl-2 levels. Both effects on proteasome and caspase activities were enhanced when cells were simultaneously exposed to lactacystin and elevated concentrations of dopamine. Apoptosis was detected in all treated samples, but not in controls, without significant differences among the treatment groups; however, the association of dopamine and lactacystin induced a clear reduction in the number of cells being analyzed, pointing to marked cytotoxicity. Our data confirm the potentiation of cytotoxicity related to proteasome inhibition, in the presence of dopaminergic stimulation.
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Affiliation(s)
- Eleonora Bazzini
- Laboratory of Functional Neurochemistry, Neurological Institute C. Mondino, Pavia, Italy
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Abstract
Flow cytometry, which definitively identifies each particle as positive or negative with respect to fluorescent markers, is used to characterize the P-2 fraction (crude synaptosomal fraction) with respect to primary components, size, and intactness. Particle size ranged from a few tenths of a microm to greater than 4.5 microm. The viable dye calcein AM labeled 90% of the preparation, indicating that the majority of particles were intact and esterase-positive. 66% of the P-2 fraction is neuronal in origin, as demonstrated by labeling with an antibody directed against SNAP-2. An antibody directed against glial fibrillary acidic protein (GFAP) labeled 35% of the particles in this preparation. The mitochondrial dye nonyl acridine orange (NAO) stained 74% of particles, indicating intra- and extrasynaptosomal mitochondria. Gating analysis reveals that SNAP-25 is enriched in the larger particles. These results suggest that flow cytometry may be used to take advantage of the increased viability, yield, and convenience of the P-2 fraction for studies of nerve terminal function.
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Affiliation(s)
- K H Gylys
- UCLA School of Nursing, Los Angeles, California 90095-6919, USA.
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Chang A, Shin SH. Relationships between dopamine-induced changes in cytosolic free calcium concentration ([Ca2+]i) and rate of prolactin secretion. Elevated [Ca2+]i does not indicate prolactin release. Endocrine 1997; 7:343-9. [PMID: 9657072 DOI: 10.1007/bf02801329] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study was undertaken to investigate the relationship between dopamine (DA) induced changes in the cytosolic calcium concentration ([Ca2+]i) and the rate of prolactin secretion using GH4ZR7, a rat pituitary cell line, which express only one subtype of D2 receptor. GH4ZR7 cells were loaded with Fluo-3, a fluorescent Ca2+ indicator, and then perifused with two different doses of DA (10(-7) mol/L and 5 x 10(-4) mol/L). We monitored changes in [Ca2+]i and rate of prolactin release simultaneously by attaching a spectrofluorometer to a dynamic perifusion system. DA has stimulatory and inhibitory effect on prolactin secretion in GH4ZR7 cells; 10(-7) mol/LDA slightly increased [Ca2+]i and stimulated prolactin release, whereas 5 x 10(-4) mol/LDA decreased [Ca2+]i and inhibited prolactin secretion. When the cells were pretreated with pertussis toxin (PTX), 10(-7) mol/L DA had no significant change in [Ca2+]i while stimulating prolactin release, and 5 x 10(-4) mol/L DA reduced [Ca2+]i without having any significant effect on the rate of prolactin secretion. The results of this study demonstrate that changes in [Ca2+]i do not always correlate with the rate of prolactin release from lactotrophs. The dissociation between [Ca2+]i and prolactin release is somewhat expected considering the diverse role of [Ca2+]i and post-[Ca2+]i events, which can change the rate of prolactin release.
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Affiliation(s)
- A Chang
- Department of Physiology, Queen's University, Kingston, Ontario, Canada
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Onali P, Mosca E, Olianas MC. Presynaptic dopamine autoreceptors and second messengers controlling tyrosine hydroxylase activity in rat brain. Neurochem Int 1995; 20 Suppl:89S-93S. [PMID: 1365463 DOI: 10.1016/0197-0186(92)90217-f] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In brain areas enriched of dopaminergic nerve terminals presynaptic dopamine (DA) autoreceptors control the state of activation of tyrosine hydroxylase (TH) by regulating the extent of phosphorylation of the enzyme. Evidence is presented indicating that this autoinhibitory control may involve a decrease in the cyclic AMP-dependent activation of TH through an inhibitory coupling of presynaptic DA autoreceptors to adenylate cyclase. As indicated by the insensitivity of the DA inhibition of TH to changes in the extracellular concentrations of Ca++, to the addition of the Ca++ ionophore A 23187 and of different K+ channel blockers, a reduction of Ca++ influx and an increase in the K+ channel activity do not seem to be involved in the presynaptic regulation of TH activity by DA autoreceptors at least under basal conditions.
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Affiliation(s)
- P Onali
- Department of Neurosciences, University of Cagliari, Italy
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10
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Abstract
The aim of this study was to achieve a better understanding of the integration in striatal medium-sized spiny neurons (MSNs) of converging signals from glutamatergic and dopaminergic afferents. The review of the literature in the first section shows that these two types of afferents not only contact the same striatal cell type, but that individual MSNs receive both a corticostriatal and a dopaminergic terminal. The most common sites of convergence are dendritic shafts and spines of MSNs with a distance between the terminals of less than 1-2 microns. The second section focuses on synaptic transmission and second messenger activation. Glutamate, the candidate transmitter of corticostriatal terminals, via different types of glutamate receptors can evoke an increase in intracellular free calcium concentrations. The net effect of dopamine in the striatum is a stimulation of adenylate cyclase activity leading to an increase in cAMP. The subsequent sections present information on calcium- and cAMP-sensitive biochemical pathways and review the regional and subcellular distribution of the components in the striatum. The specific biochemical reaction steps were formalized as simplified equilibrium equations. Parameter values of the model were chosen from published experimental data. Major results of this analysis are: at intracellular free calcium concentrations below 1 microM the stimulation of adenylate cyclase by calcium and dopamine is at least additive in the steady state. Free calcium concentrations exceeding 1 microM inhibit adenylate cyclase, which is not overcome by dopaminergic stimulation. The kinases and phosphatases studied can be divided in those that are almost exclusively calcium-sensitive (PP2B and CaMPK), and others that are modulated by both calcium and dopamine (PKA and PP1). Maximal threonine-phosphorylation of the phosphoprotein DARPP requires optimal concentrations of calcium (about 0.3 microM) and dopamine (above 5 microM). It seems favourable if the glutamate signal precedes phasic dopamine release by approximately 100 msec. The phosphorylation of MAP2 is under essentially calcium-dependent control of at least five kinases and phosphatases, which differentially affect its heterogeneous phosphorylation sites. Therefore, MAP2 could respond specifically to the spatio-temporal characteristics of different intracellular calcium fluxes. The quantitative description of the calcium- and dopamine-dependent regulation of DARPP and MAP2 provides insights into the crosstalk between glutamatergic and dopaminergic signals in striatal MSNs. Such insights constitute an important step towards a better understanding of the links between biochemical pathways, physiological processes, and behavioural consequences connected with striatal function. The relevance to long-term potentiation, reinforcement learning, and Parkinson's disease is discussed.
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Affiliation(s)
- R Kötter
- Department of Anatomy and Structural Biology, University of Otago, Medical School, Dunedin, New Zealand
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Tissari AH, Lillgäls MS. Reduction of dopamine synthesis inhibition by dopamine autoreceptor activation in striatal synaptosomes with in vivo reserpine administration. J Neurochem 1993; 61:231-8. [PMID: 8099951 DOI: 10.1111/j.1471-4159.1993.tb03559.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In an attempt to clarify the mechanisms by which dopamine (DA) autoreceptor activation inhibits DA synthesis, the efficacy and potency of the D2 DA agonists bromocriptine, lisuride, and pergolide, and the D1-D2 DA agonist apomorphine were studied in rat striatal synaptosomes, in which the rate of DA synthesis (formation of 14CO2 from L-[1-14C]tyrosine) was increased 103% by treating the animals from which the synaptosomes were obtained with reserpine (5 mg/kg i.p. twice, 24 and 2 h before they were killed), using the striatal total homogenate as the standard synaptosomal preparation. The increase in DA synthesis evoked by reserpine was additive with that produced by treatment of the synaptosomes with dibutyryl cyclic AMP, suggesting that, not a cyclic AMP-dependent, but possibly a Ca(2+)-dependent mechanism was involved. The DA agonists showed a concentration-dependent inhibition of DA synthesis in the control synaptosomes, which was antagonized by the selective D2 DA antagonist (-)-sulpiride. In the synaptosomes with increased rate of DA synthesis obtained from the rats treated with reserpine, the concentration-response curves of DA synthesis inhibition for the other DA agonists were shifted to the right, and the effect of bromocriptine was completely eliminated, whereas bromocriptine antagonized the effect of apomorphine. The increased rate of DA synthesis was not preserved in the striatal P1 + P2 fraction obtained from the reserpine-treated rats, but the effects of the DA agonists were still reduced to the same degree as those in the total homogenate. (-)-Sulpiride did not enhance DA synthesis in synaptosomes from the reserpine-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A H Tissari
- Department of Pharmacology and Toxicology, University of Kuopio, Finland
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12
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Wang HY, Zhou LW, Friedman E, Weiss B. Differential regulation of release of acetylcholine in the striatum in mice following continuous exposure to selective D1 and D2 dopaminergic agonists. Neuropharmacology 1993; 32:85-91. [PMID: 8094235 DOI: 10.1016/0028-3908(93)90133-n] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The effect of continuously infusing the selective D1 and D2 dopamine receptor agonists, SKF 38393 and quinpirole, on the release of [3H]acetylcholine from prelabeled striatal slices was investigated. These biochemical parameters were correlated with the behavioral effects of these agonists. Acute injections of SKF 38393 or quinpirole did not affect either K(+)-stimulated or spontaneous release of [3H]acetylcholine. Chronic exposure to quinpirole reduced the K(+)-evoked release of [3H]acetylcholine by 25.7%; long-term treatment with SKF 38393 did not alter the release of [3H]acetylcholine, induced by K+ stimulation. Added in vitro, SKF 38393 increased the release of [3H]acetylcholine from striatal slices. The effect of the D1 dopamine receptor agonist, SKF 38393 was reduced after 7-days of infusion of SKF 38393 but was enhanced by 7-days of infusion of quinpirole. Activation of D2 dopamine receptors with quinpirole or of muscarinic receptors with carbachol induced an inhibition of release of [3H]acetylcholine. Chronic treatment with quinpirole diminished the response to the in vitro addition of quinpirole. The ability of carbachol to inhibit release of acetylcholine was not altered by continuous treatment with either SKF 38393 or quinpirole. Continuous infusion of SKF 38393 produced an initial grooming behavior; this behavior disappeared by 2 hr and remained absent during the 7 days of infusion of SKF 38393. Similarly, continuous administration of quinpirole produced stereotyped behavior, which peaked at 1 hr and disappeared by 4 hr and remained absent for the duration of the infusion. These findings demonstrate that continuous exposure to D1 or D2 agonists caused receptor-selective functional desensitization of D1 or D2 dopamine receptors.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- H Y Wang
- Department of Psychiatry, Medical College of Pennsylvania, Philadelphia 19129
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Ochsner M, Fleck T, Waldmeier P. Simultaneous measurement of Ca2+ transients and of membrane depolarizations in synaptosomes. Biochem Biophys Res Commun 1991; 181:797-803. [PMID: 1755858 DOI: 10.1016/0006-291x(91)91260-j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Calcium and membrane potential sensitive dyes have been widely used to study the biochemical effects of the intracellular calcium concentration and of the membrane potential on diverse biochemical processes. However, due to the discontinuous measurement techniques applied, it was until now impossible to get an insight into the sequence and dynamics of the induced biological reactions. In order to study the relationship between the intracellular calcium concentration and the membrane potential, an apparatus was developed capable of measuring both biological processes simultaneously. Potassium chloride induced changes of the synaptosomal membrane potential and of the intracellular calcium concentration are presented.
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Affiliation(s)
- M Ochsner
- CIBA-GEIGY Ltd., Physics Department, Basle, Switzerland
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Deutch AY, Moghaddam B, Innis RB, Krystal JH, Aghajanian GK, Bunney BS, Charney DS. Mechanisms of action of atypical antipsychotic drugs. Implications for novel therapeutic strategies for schizophrenia. Schizophr Res 1991; 4:121-56. [PMID: 1674882 DOI: 10.1016/0920-9964(91)90030-u] [Citation(s) in RCA: 161] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The mechanisms which contribute to the actions of atypical antipsychotic drugs, such as clozapine and the putative atypical agents remoxipride and raclopride, are reviewed. Examination of available preclinical and clinical data leads to two hypotheses concerning the mode of action of atypical antipsychotic drugs. The first hypothesis is that antagonism of the dopamine D2 receptor is both necessary and sufficient for the atypical profile, but that interaction with subtypes of the D2 receptor differentiates typical from atypical antipsychotic drugs. The second hypothesis has been previously advanced, and suggests that a relatively high ratio of serotonin 5-HT2:dopamine D2 receptor antagonism may subserve the atypical profile. It seems likely that the atypical antipsychotic drug profile may be achieved in more than one way.
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Affiliation(s)
- A Y Deutch
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510
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England BP, Ackerman MS, Barrett RW. A chimeric D2 dopamine/m1 muscarinic receptor with D2 binding specificity mobilizes intracellular calcium in response to dopamine. FEBS Lett 1991; 279:87-90. [PMID: 1995348 DOI: 10.1016/0014-5793(91)80257-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Using PCR methodology, a chimeric receptor cDNA was constructed in which the entire third cytoplasmic loop of the human D2 dopamine receptor was replaced by the analogous portion of the human m1 muscarinic receptor. When expressed in CHO cells, the chimeric D2/m1 receptor bound dopaminergic ligands with affinities similar to the native D2(414) receptor. Intracellular calcium levels (measured with Fura-2) were not altered when CHO cells expressing the D2(414) receptor were exposed to dopamine. In contrast, dopamine elevated intracellular calcium levels in cells expressing the D2/m1 chimeric receptor in a dose-dependent manner which was blocked by the D2 antagonist, fluphenazine. The ability to construct G-protein-linked receptor chimeras which mobilize calcium with nearly unaltered pharmacologic specificity raises the possibility of a generic strategy for creating non-radioisotopic reporter systems for use in drug discovery.
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Affiliation(s)
- B P England
- Affymax Research Institute, Palo Alto, CA 94304
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WOLF MARINAE, KAPATOS GREGORY. Stimulation of D2 Dopamine Receptors Decreases Intracellular Calcium Levels in Rat Anterior Pituitary Cells but Not Striatal Synaptosomes: A Flow Cytometric Study Using Indo-1. Ann N Y Acad Sci 1990. [DOI: 10.1111/j.1749-6632.1990.tb32053.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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17
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Affiliation(s)
- M E Wolf
- Department of Psychiatry, Wayne State University School of Medicine, Lafayette Clinic, Detroit, Michigan 48207
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