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Author (up) Andersson, D.R.; Bjornsson, E.; Bergquist, F.; Nissbrandt, H.
Title Motor activity-induced dopamine release in the substantia nigra is regulated by muscarinic receptors Type Journal Article
Year 2010 Publication Experimental Neurology Abbreviated Journal Exp Neurol
Volume 221 Issue 1 Pages 251-259
Keywords Analysis of Variance; Animals; Area Under Curve; Brain Injuries/chemically induced/*pathology; Chromatography, High Pressure Liquid/methods; Dendrites/drug effects/metabolism; Disease Models, Animal; Dopamine/*metabolism; Dose-Response Relationship, Drug; Electrochemistry/methods; Female; Functional Laterality; Mecamylamine/pharmacology; Microdialysis/methods; Motor Activity/drug effects/*physiology; Muscarinic Antagonists/pharmacology; Nicotinic Antagonists/pharmacology; Oxidopamine; Rats; Rats, Sprague-Dawley; Receptors, Muscarinic/*physiology; Rotarod Performance Test/methods; Scopolamine Hydrobromide/pharmacology; Substantia Nigra/drug effects/*metabolism/pathology; gamma-Aminobutyric Acid/metabolism
Abstract Nigro-striatal neurons release dopamine not only from their axon terminals in the striatum, but also from somata and dendrites in the substantia nigra. Somatodendritic dopamine release in the substantia nigra can facilitate motor function by mechanisms that may act independently of axon terminal dopamine release in the striatum. The dopamine neurons in the substantia nigra receive a cholinergic input from the pedunculopontine nucleus. Despite recent efforts to introduce this nucleus as a potential target for deep brain stimulation to treat motor symptoms in Parkinson's disease; and the well-known antiparkinsonian effects of anticholinergic drugs; the cholinergic influence on somatodendritic dopamine release is not well understood. The aim of this study was to investigate the possible regulation of locomotor-induced dopamine release in the substantia nigra by endogenous acetylcholine release. In intact and 6-OHDA hemi-lesioned animals alike, the muscarinic antagonist scopolamine, when perfused in the substantia nigra, amplified the locomotor-induced somatodendritic dopamine release to approximately 200% of baseline, compared to 120-130% of baseline in vehicle-treated animals. A functional importance of nigral muscarinic receptor activation was demonstrated in hemi-lesioned animals, where motor performance was significantly improved by scopolamine to 82% of pre-lesion performance, as compared to 56% in vehicle-treated controls. The results indicate that muscarinic activity in the substantia nigra is of functional importance in an animal Parkinson's disease model, and strengthen the notion that nigral dopaminergic regulation of motor activity/performance is independent of striatal dopamine release.
Call Number Serial 308
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Author (up) Arimoto-Kobayashi, S.; Sakata, H.; Mitsu, K.; Tanoue, H.
Title A possible photosensitizer: Tobacco-specific nitrosamine, 4-(N-methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), induced mutations, DNA strand breaks and oxidative and methylative damage with UVA Type Journal Article
Year 2007 Publication Mutation Research Abbreviated Journal Mutat Res
Volume 632 Issue 1-2 Pages 111-120
Keywords Base Sequence; DNA Breaks; DNA Methylation--drug effects, radiation effects; Dose-Response Relationship, Drug; Models, Biological; Molecular Sequence Data; Mutation; Nitrosamines--toxicity; Oxidative Stress--drug effects, radiation effects; Photosensitizing Agents--toxicity; Salmonella typhimurium; Tobacco--chemistry; Ultraviolet Rays--adverse effects
Abstract We discovered the directly acting mutagenicity of the tobacco-specific nitrosamine, 4-(N-methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), with UVA light (320-400nm) in Ames bacteria and phage M13mp2 in the absence of metabolic activation. We have investigated the spectrum of mutations caused by UVA-activated NNK. The majority (57%) of induced sequence changes were comprised of GC to CG, GC to TA and GC to AT. This suggested that modification of guanine residues was responsible for these mutations. Hence, we explored the formation of 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxodG) and O(6)-methylguanine (O(6)meG) in the DNA. When calf thymus DNA was treated with NNK and UVA, the amount of 8-oxodG/dG and O(6)meG/G in the DNA increased up to 20-fold and 100-fold, respectively, compared with the untreated control. DNA strand breaks were observed following NNK and UVA treatment, and the strand breaks were suppressed in the presence of scavengers for oxygen and NO radical. The formation of NO was also observed in NNK solutions irradiated with UVA. We analyzed the photodynamic spectrum of mutation induction, 8-oxodG formation and NO formation using monochromatic radiation. The patterns of the action spectra were comparable to the absorption spectrum of NNK. We conclude that NNK may act as a photosensitizer in response to UVA to produce NO and other oxidative and alkylative intermediates following the formation of 8-oxodG and O(6)meG in DNA, which may lead to mutations and DNA strand breaks.
Call Number Serial 86
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Author (up) Arolfo, M.P.; Brioni, J.D.
Title Diazepam impairs place learning in the Morris water maze Type Journal Article
Year 1991 Publication Behavioral and Neural Biology Abbreviated Journal Behav Neural Biol
Volume 55 Issue 1 Pages 131-136
Keywords Animals; Diazepam/*pharmacology; Discrimination Learning/*drug effects; Dose-Response Relationship, Drug; Escape Reaction/*drug effects; Male; Mental Recall/drug effects; Orientation/*drug effects; Rats; Rats, Inbred Strains; Reaction Time/drug effects; Retention (Psychology)/*drug effects
Abstract The effect of diazepam (0.3, 1.0, and 3.0 mg/kg) on the acquisition and retention of place learning was evaluated. The analysis of escape latencies indicates that 1.0 and 3.0 mg/kg diazepam significantly impaired the retention of spatial information. When a free swim trial was carried out only control animals showed spatial bias to the target quadrant. The absence of spatial bias in the group that received 0.3 mg/kg suggests that the amnesic effect of diazepam can be seen at doses similar to or even lower than the anxiolytic ones, and that the GABA/benzodiazepine receptor complex is highly sensitive to the cognitive impairment induced by diazepam in spatial tasks.
Call Number Serial 249
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Author (up) Baselga, J.; Pfister, D.; Cooper, M.R.; Cohen, R.; Burtness, B.; Bos, M.; D'Andrea, G.; Seidman, A.; Norton, L.; Gunnett, K.; Falcey, J.; Anderson, V.; Waksal, H.; Mendelsohn, J.
Title Phase I studies of anti-epidermal growth factor receptor chimeric antibody C225 alone and in combination with cisplatin Type Journal Article
Year 2000 Publication Journal of Clinical Oncology : Official Journal of the American Society of Clinical Oncology Abbreviated Journal J Clin Oncol
Volume 18 Issue 4 Pages 904-914
Keywords Adult; Antibodies, Monoclonal/adverse effects/pharmacokinetics/*therapeutic use; Antibodies, Monoclonal, Humanized; Antineoplastic Agents/adverse effects/pharmacokinetics/*therapeutic use; Area Under Curve; Carcinoma, Non-Small-Cell Lung/drug therapy/therapy; Carcinoma, Squamous Cell/drug therapy/therapy; Cetuximab; Cisplatin/*therapeutic use; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Gene Expression Regulation, Neoplastic; Head and Neck Neoplasms/drug therapy/therapy; Humans; Infusions, Intravenous; Lung Neoplasms/drug therapy/therapy; Male; Neoplasms, Glandular and Epithelial/drug therapy/*therapy; Receptor, Epidermal Growth Factor/*antagonists & inhibitors/genetics; Recombinant Fusion Proteins/adverse effects/pharmacokinetics/*therapeutic use; Remission Induction; Safety
Abstract PURPOSE: The epidermal growth factor (EGF) receptor is frequently overexpressed in epithelial tumors. C225 is a human-to-murine chimeric monoclonal antibody that binds to the receptor and inhibits growth of cancer cells expressing the receptor. We evaluated the pharmacokinetics and toxicity of C225 in patients with advanced tumors overexpressing EGF receptors. PATIENTS AND METHODS: We treated 52 patients in three successive phase I clinical trials of C225 as a single dose (n = 13), weekly multiple dose (n = 17), and weekly multiple dose with cisplatin (n = 22). C225 dose levels were 5, 20, 50, and 100 mg/m(2). In the study combining C225 with cisplatin, limited to patients with either head and neck or non-small-cell lung cancer, C225 was further escalated to 200 and 400 mg/m(2). Cisplatin was given at a dose of 60 mg/m(2) once every 4 weeks, and treatment was continued for up to 12 weeks if no disease progression occurred. RESULTS: C225 displayed nonlinear pharmacokinetics, with antibody doses in the range of 200 to 400 mg/m(2) being associated with complete saturation of systemic clearance. C225 clearance did not change with repeated administration or with coadministration of cisplatin. Antibodies against C225 were detected in only one patient, and C225-associated toxicity was minimal. Patients experiencing disease stabilization were seen in all studies. In the study combining C225 and cisplatin, nine (69%) of 13 patients treated with antibody doses >/= 50 mg/m(2) completed 12 weeks of therapy, and two partial responses were observed. CONCLUSION: C225 has dose-dependent pharmacokinetics, and doses that achieve saturation of systemic clearance are well tolerated. C225 given in combination with cisplatin has biologic activity at pharmacologically relevant doses.
Call Number Serial 2015
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Author (up) Bencan, Z.; Sledge, D.; Levin, E.D.
Title Buspirone, chlordiazepoxide and diazepam effects in a zebrafish model of anxiety Type Journal Article
Year 2009 Publication Pharmacology, Biochemistry, and Behavior Abbreviated Journal Pharmacol Biochem Behav
Volume 94 Issue 1 Pages 75-80
Keywords Animals; Anti-Anxiety Agents/*therapeutic use; Anxiety/*drug therapy; Behavior, Animal/drug effects; Benzodiazepines/administration & dosage/therapeutic use; Buspirone/administration & dosage/*therapeutic use; Chlordiazepoxide/administration & dosage/*therapeutic use; Cholinergic Agents/administration & dosage/therapeutic use; Diazepam/administration & dosage/*therapeutic use; *Disease Models, Animal; Diving; Dose-Response Relationship, Drug; Exploratory Behavior/drug effects; Imaging, Three-Dimensional/methods; Serotonin Agents/administration & dosage/therapeutic use; Stress, Psychological; Time Factors; *Zebrafish
Abstract Zebrafish are becoming more widely used to study neurobehavioral pharmacology. We have developed a method to assess novel environment diving behavior of zebrafish as a model of stress response and anxiolytic drug effects. In a novel tank, zebrafish dwell in the bottom of the tank initially and then increase their swimming exploration to higher levels over time. We previously found that nicotine, which has anxiolytic effects in rodents and humans, significantly lessens the novel tank diving response in zebrafish. The specificity of the diving effect was validated with a novel vs. non-novel test tank. The novel tank diving response of zebrafish was tested when given three anxiolytic drugs from two different chemical and pharmacological classes: buspirone, chlordiazepoxide and diazepam. When the test tank was novel the diving response was clearly seen whereas it was significantly reduced when the test tank was not novel. Buspirone, a serotonergic (5HT(1A) receptor agonist) anxiolytic drug with some D(2) dopaminergic effect, had a pronounced anxiolytic-like effect in the zebrafish diving model at doses that did not have sedative effects. In contrast, chlordiazepoxide, a benzodiazepine anxiolytic drug, which is an effective agonist at GABA-A receptors, did not produce signs of anxiolysis in zebrafish over a broad dose range up to those that caused sedation. Diazepam another benzodiazepine anxiolytic drug did produce an anxiolytic effect at doses that did not cause sedation. The zebrafish novel tank diving task can be useful in discriminating anxiolytic drugs of several classes (serotonergic, benzodiazepines and nicotinic).
Call Number Serial 209
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Author (up) Bertrand, D.; Gopalakrishnan, M.
Title Allosteric modulation of nicotinic acetylcholine receptors Type Journal Article
Year 2007 Publication Biochemical Pharmacology Abbreviated Journal Biochem Pharmacol
Volume 74 Issue 8 Pages 1155-1163
Keywords Allosteric Regulation; Animals; Binding Sites; Dose-Response Relationship, Drug; Humans; Receptors, Nicotinic/*chemistry/*drug effects; alpha7 Nicotinic Acetylcholine Receptor
Abstract Allosteric modulation refers to the concept that proteins could exist in multiple conformational states and that binding of allosteric ligands alters the energy barriers or “isomerization coefficients” between various states. In the context of ligand gated ion channels such as nicotinic acetylcholine receptors (nAChRs), it implies that endogenous ligand acetylcholine binds at the orthosteric site, and that molecules that bind elsewhere on the nAChR subunit(s) acts via allosteric interactions. For example, studies with the homomeric alpha7 nAChRs indicate that such ligand interactions can be well described by an allosteric model, and that positive allosteric effectors can affect energy transitions by (i) predominantly affecting the peak current response (Type I profile) or, (ii) both peak current responses and time course of agonist-evoked response (Type II profile). The recent discovery of chemically heterogeneous group of molecules capable of differentially modifying nAChR properties without interacting at the ligand binding site illustrates the adequacy of the allosteric model to predict functional consequences. In this review, we outline general principles of the allosteric concept and summarize the profiles of novel compounds that are emerging as allosteric modulators at the alpha7 and alpha4beta2 nAChR subtypes.
Call Number Serial 1877
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Author (up) Bertrand, D.; Gopalakrishnan, M.
Title Allosteric modulation of nicotinic acetylcholine receptors Type Journal Article
Year 2007 Publication Biochemical Pharmacology Abbreviated Journal Biochem Pharmacol
Volume 74 Issue 8 Pages 1155-1163
Keywords Allosteric Regulation; Animals; Binding Sites; Dose-Response Relationship, Drug; Humans; Receptors, Nicotinic/*chemistry/*drug effects; alpha7 Nicotinic Acetylcholine Receptor
Abstract Allosteric modulation refers to the concept that proteins could exist in multiple conformational states and that binding of allosteric ligands alters the energy barriers or “isomerization coefficients” between various states. In the context of ligand gated ion channels such as nicotinic acetylcholine receptors (nAChRs), it implies that endogenous ligand acetylcholine binds at the orthosteric site, and that molecules that bind elsewhere on the nAChR subunit(s) acts via allosteric interactions. For example, studies with the homomeric alpha7 nAChRs indicate that such ligand interactions can be well described by an allosteric model, and that positive allosteric effectors can affect energy transitions by (i) predominantly affecting the peak current response (Type I profile) or, (ii) both peak current responses and time course of agonist-evoked response (Type II profile). The recent discovery of chemically heterogeneous group of molecules capable of differentially modifying nAChR properties without interacting at the ligand binding site illustrates the adequacy of the allosteric model to predict functional consequences. In this review, we outline general principles of the allosteric concept and summarize the profiles of novel compounds that are emerging as allosteric modulators at the alpha7 and alpha4beta2 nAChR subtypes.
Call Number Serial 1887
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Author (up) Bhattacharya, R.; Beck, D.J.
Title Survival and SOS induction in cisplatin-treated Escherichia coli deficient in Pol II, RecBCD and RecFOR functions Type Journal Article
Year 2002 Publication DNA Repair Abbreviated Journal DNA Repair (Amst)
Volume 1 Issue 11 Pages 955-966
Keywords Antineoplastic Agents/*pharmacology; Bacterial Proteins/physiology; Cell Division/drug effects/genetics/radiation effects; Cisplatin/*pharmacology; DNA Damage/drug effects/radiation effects; DNA Polymerase II/*physiology; DNA Polymerase III/physiology; DNA Repair/drug effects/radiation effects; DNA-Binding Proteins/physiology; Dose-Response Relationship, Drug; Drug Resistance, Bacterial/physiology; Escherichia coli/*drug effects/enzymology; Escherichia coli Proteins/pharmacology/*physiology; Exodeoxyribonuclease V; Exodeoxyribonucleases/*physiology; Lac Operon; SOS Response (Genetics)/*physiology; beta-Galactosidase/metabolism
Abstract Cisplatin is a potent anticancer agent forming intrastrand-crosslinks in DNA. The efficacy of cisplatin in chemotherapy can be limited by the development of tumor resistances such as elevated DNA repair or damage tolerance. In Escherichia coli, cisplatin treatment causes induction of the SOS regulon resulting in elevated levels of DNA Pol II, DNA Pol IV, DNA Pol V, the cell division inhibitor SfiA (SulA), homologous recombination (HR) and DNA repair. In this work, the roles of Pol II and HR in facilitating resistance of E. coli to cisplatin are studied. SOS induction levels were measured by beta-galactosidase assays in cisplatin-treated and untreated E. coli PQ30 that has the lacZ gene fused to the sfiA promoter. Comparative studies were carried out with derivatives of PQ30 constructed by P1 transduction that have transposon insertions in the polB gene, the recB gene blocking the RecBCD pathway of HR and genes of the RecFOR pathway of HR. Resistance of E. coli strains to cisplatin as determined by plating experiments decreased in the following order: parent PQ30 strain, polB > recO, recR, recF > recB. Both the RecBCD and RecFOR pathways of HR are important for survival when E. coli is exposed to cisplatin, because treatment of double mutants deficient in both pathways reduced colony forming ability to 37% in 6-9min in comparison to 39-120min for single mutants. Pol II and RecF appear to function in two distinct pathways to initiate replication blocked due to damage caused by cisplatin because function of Pol II was required for survival in mutants deficient in the RecFOR pathway after 2h of cisplatin treatment. In contrast, Pol II was not required for survival in recB mutants. SOS induction was delayed in RecFOR deficient mutants but occurred at high levels in the recB mutant soon after cisplatin treatment in a RecFOR-dependent way. An SfiA independent, DNA damage dependent pathway is apparently responsible for the filamentous cells observed after cisplatin or MMC treatments of these SfiA defective strains.
Call Number Serial 407
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Author (up) Briggs, C.A.; Gronlien, J.H.; Curzon, P.; Timmermann, D.B.; Ween, H.; Thorin-Hagene, K.; Kerr, P.; Anderson, D.J.; Malysz, J.; Dyhring, T.; Olsen, G.M.; Peters, D.; Bunnelle, W.H.; Gopalakrishnan, M.
Title Role of channel activation in cognitive enhancement mediated by alpha7 nicotinic acetylcholine receptors Type Journal Article
Year 2009 Publication British Journal of Pharmacology Abbreviated Journal Br J Pharmacol
Volume 158 Issue 6 Pages 1486-1494
Keywords Allosteric Regulation; Animals; Avoidance Learning/drug effects; Azabicyclo Compounds/administration & dosage/*pharmacology; Behavior, Animal/drug effects; Cell Line; Cognition Disorders/drug therapy/physiopathology; Dose-Response Relationship, Drug; Furans/administration & dosage/*pharmacology; Humans; Male; Mice; Nicotinic Agonists/*pharmacology; Oocytes/drug effects/metabolism; Oxadiazoles/administration & dosage/*pharmacology; Pyridazines/pharmacology; Pyrroles/pharmacology; Rats; Receptors, Nicotinic/*drug effects/metabolism; Xenopus laevis; alpha7 Nicotinic Acetylcholine Receptor
Abstract BACKGROUND AND PURPOSE: Several agonists of the alpha7 nicotinic acetylcholine receptor (nAChR) have been developed for treatment of cognitive deficits. However, agonist efficacy in vivo is difficult to reconcile with rapid alpha7 nAChR desensitization in vitro; and furthermore, the correlation between in vitro receptor efficacy and in vivo behavioural efficacy is not well delineated. The possibility that agonists of this receptor actually function in vivo as inhibitors via desensitization has not been finally resolved. EXPERIMENTAL APPROACH: Two structurally related alpha7 nAChR agonists were characterized and used to assess the degree of efficacy required in a behavioural paradigm. KEY RESULTS: NS6784 activated human and rat alpha7 nAChR with EC(50)s of 0.72 and 0.88 microM, and apparent efficacies of 77 and 97% respectively. NS6740, in contrast, displayed little efficacy at alpha7 nAChR (<2% in oocytes, < or =8% in GH4C1 cells), although its agonist-like properties were revealed by adding a positive allosteric modulator of alpha7 nAChRs or using the slowly desensitizing alpha7V274T receptor. In mouse inhibitory avoidance (IA) memory retention, NS6784 enhanced performance as did the 60% partial agonist A-582941. In contrast, NS6740 did not enhance performance, but blocked effects of A-582941. CONCLUSIONS AND IMPLICATIONS: Collectively, these findings suggest that a degree of alpha7 nAChR agonist efficacy is required for behavioural effects in the IA paradigm, and that such behavioural efficacy is not due to alpha7 nAChR desensitization. Also, a partial agonist of very low efficacy for this receptor could be used as an inhibitor, in the absence of alpha7 nAChR antagonists with favourable CNS penetration.
Call Number Serial 1881
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Author (up) Decamp, E.; Clark, K.; Schneider, J.S.
Title Effects of the alpha-2 adrenoceptor agonist guanfacine on attention and working memory in aged non-human primates Type Journal Article
Year 2011 Publication The European Journal of Neuroscience Abbreviated Journal Eur J Neurosci
Volume 34 Issue 6 Pages 1018-1022
Keywords Adrenergic alpha-2 Receptor Agonists--pharmacology; Adrenergic alpha-Antagonists--pharmacology; Aging--psychology; Animals; Attention--drug effects; Cognition--physiology; Dose-Response Relationship, Drug; Guanfacine--pharmacology; Idazoxan--pharmacology; Macaca mulatta; Male; Memory, Short-Term--drug effects; Psychomotor Performance--drug effects; Reaction Time--physiology; Space Perception--physiology
Abstract Alpha-2 adrenergic receptors are potential targets for ameliorating cognitive deficits associated with aging as well as certain pathologies such as attention deficit disorder, schizophrenia and Parkinson's disease. Although the alpha-2 agonist guanfacine has been reported to improve working memory in aged primates, it has been difficult to assess the extent to which these improvements may be related to drug effects on attention and/or memory processes involved in task performance. The present study investigated effects of guanfacine on specific attention and memory tasks in aged monkeys. Four Rhesus monkeys (18-21 years old) performed a sustained attention (continuous performance) task and spatial working memory task (self-ordered spatial search) that has minimal demands on attention. Effects of a low (0.0015 mg/kg) and high (0.5 mg/kg) dose of gunafacine were examined. Low-dose guanfacine improved performance on the attention task [i.e. decreased omission errors by 50.8 +/- 4.3% (P = 0.001) without an effect on commission errors] but failed to improve performance on the spatial working memory task. The high dose of guanfacine had no effects on either task. Guanfacine may have a preferential effect on some aspects of attention in normal aged monkeys and in doing so may also improve performance on other tasks, including some working memory tasks that have relatively high attention demands.
Call Number Serial 67
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