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  • 1
    Digitale Medien
    Digitale Medien
    Comparison of the In Vitro Receptor Binding Properties of N-[3H]Methylspiperone and [3H]Raclopride to Rat and Human Brain Membranes (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 55 (1990), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: The aim of the present investigation was to study and compare the in vitro binding properties of the two ra-dioligands N-[3H]methylspiperone ([3H]NMSP) and [3H]raclopride. These compounds, labeled with 11C, have been extensively used in positron emission tomography studies on central dopamine D2 receptors in schizophrenic patients, although with diverging results. One study (using [11C]NMSP) showed an increased dopamine receptor density in drug-naive schizophrenic patients, whereas in another study (using [11C]raclopride) the density in schizophrenic patients was no different from that in healthy controls. In the present study, using in vitro binding techniques, the density of the binding sites was found to be similar irrespective of which of the two radioligands was used (20 fmol/mg wet weight in rat striatum and 10 fmol/mg in human putamen; the 5-hydroxytryptamine2 receptors were blocked with 40 nM ketanserin). [3H]NMSP had a 10-fold higher affinity (KD, 0.3 nM in rat striatum and 0.2 nM in human putamen) than [3H]raclopride (KD, 2.1 nM in rat striatum and 3.9 nM in human putamen), which was consistent with the longer dissociation half-life of [3H]NMSP compared with [3H]raclopride (14.8 and 1.19 min, respectively). There was an approximate overall similarity between the inhibition constants for five dopamine antagonists, chlorpromazine, haloperidol, raclopride, remoxipride, and NMSP, when using either radioligand. The K1 values were, however, two- to fourfold higher when using [3H]NMSP as the radioligand, irrespective of inhibiting compound, except for chlorpromazine (and haloperidol in human putamen). NMSP was found to inhibit the binding of [3H]raclopride competitively, whereas raclopride inhibited the binding of [3H]NMSP both competitively and noncompetitively. This difference suggests that part of the binding site is exclusively used by NMSP and can only be allosterically interfered with by raclopride. It is proposed that [3H]NMSP binds to an additional set of accessory binding sites, presumably located more distantly from the agonist binding active site than the sites to which [3H]raclopride binds.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1471-4159.1990.tb05794.x
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  • 2
    Digitale Medien
    Digitale Medien
    Temperature Dependence of [3H]Ro 15–1788 Binding to Benzodiazepine Receptors in Human Postmortem Brain Homogenates (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 55 (1990), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: The temperature dependence of in vitro binding of [3H]Ro 15–1788 to benzodiazepine receptors in human postmortem neocortex and neocerebellum homogenates was studied. An increase of the equilibrium dissociation constants (KD) from 1.40 nmol/L and 1.04 nmol/L at 4°C to 6.10 nmol/L and 8.91 nmol/L at 37°C was found for neocortex and neocerebellum, respectively. In contrast, maximal binding (Bmax) remained in the range of 30–35 fmol/mg for neocortex and 24–27 fmol/mg of tissue (wet weight) for neocerebellum at all the temperatures. The KD of 6.10 nmol/L for neocortex at 37°C in vitro is of the same order as the KD of 10 nmol/L obtained by positron emission tomography for [11C]Ro 15–1788 binding to benzodiazepine receptors in the human neocortex in vivo. The differences in KD between in vitro and in vivo benzodiazepine receptor binding to human neocortex and cerebellum seem to be due at least partially to temperature differences of in vitro and in vivo studies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1471-4159.1990.tb03140.x
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  • 3
    Digitale Medien
    Digitale Medien
    Autoradiographic studies of 5-HT1A-receptor-stimulated [35S]GTPγS-binding responses in the human and monkey brain (1999)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 11 (1999), S. 0 
    Details
    ISSN: 1460-9568
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: G-protein activation mediated by serotonin 5-HT1A receptors in human and monkey brain was investigated by using quantitative autoradiography of agonist-stimulated [35S]GTPγS binding to whole-hemisphere brain sections. [35S]GTPγS binding was stimulated by the mixed 5-HT1A/1B/1D agonist L 694247 (10 μm) in human brain regions enriched in 5-HT1A binding sites [e.g. hippocampus (132–137%), superficial layers of the neocortex (37–61%), and cingulate and entorhinal cortex (34 and 32%, respectively)]. L 694247 caused virtually no stimulation in regions with 5-HT1B/1D receptors, such as substantia nigra, caudate nucleus and putamen. Similar results were obtained with monkey brain sections. The L 694247-mediated [35S]GTPγS-binding responses in human and monkey brain sections were antagonized by the selective, silent 5-HT1A antagonist WAY 100635 (10 μm). The 5-HT1B inverse agonist SB 224289 (10 μm) did not affect the [35S]GTPγS-binding response of L 694247. The distribution pattern of the [35S]GTPγS-binding response and the antagonist profile suggest the L 694247-induced response in human and monkey brain is mediated by 5-HT1A receptors. A weak stimulation of [35S]GTPγS binding was also observed in human hippocampus with either 10 μm 8-OH-DPAT (25 ± 4%) or naratriptan (42 ± 2%) compared with that obtained with L 694247. In conclusion, G-protein activation by 5-HT1A receptors can be measured in human and monkey brain sections. L 694247 appears to possess higher efficacy at 5-HT1A receptors compared with 8-OH-DPAT and naratriptan.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1460-9568.1999.00600.x
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  • 4
    Digitale Medien
    Digitale Medien
    Autoradiographic mapping of dopamine-D2/D3 receptor stimulated [35S]GTPγS binding in the human brain (2005)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 22 (2005), S. 0 
    Details
    ISSN: 1460-9568
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Agonist stimulated [35S]guanosine 5′-γ-thiotriphosphate ([35S]GTPγS) binding autoradiography was established for the examination of dopamine-D2/D3 receptors in human brain sections. The distribution of G proteins activated by dopamine-D2/D3 receptors was studied in whole hemisphere cryosections. Dopamine stimulated [35S]GTPγS binding in brain regions with high densities of dopamine D2-like receptors, i.e. putamen (23 ± 2%, mean ± SEM,% stimulation over basal binding), caudate (20 ± 0%) and substantia nigra (22 ± 2%), but also in regions with lower receptor densities such as amygdala (17 ± 8%), hippocampus (16 ± 6%), anterior cingulate (13 ± 3%), and thalamus (12 ± 2%). Dopamine stimulated [35S]GTPγS binding to significantly higher levels in the dorsal than in the ventral part of the striatum. Dopamine caused low or very low stimulation in all cortical areas. Raclopride, a selective D2/D3 receptor antagonist, potently inhibited dopamine stimulated [35S]GTPγS binding, whereas R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH23390), a selective D1 antagonist, did not block the [35S]GTPγS binding response stimulated by dopamine. Hence, the stimulatory effect of dopamine was primarily mediated by D2/D3 receptors. Quinpirole stimulated [35S]GTPγS binding in the same regions as dopamine. The maximal level of stimulation induced by dopamine and quinpirole was not significantly different. The present study demonstrates that agonist stimulated [35S]GTPγS binding autoradiography could be a suitable technique for the examination of dopamine-D2/D3 receptors in the human brain. This functional assay could provide useful new information about dopamine receptor/G protein coupling in the postmortem human brain, and reveal possible disease related alterations of the interaction between D2/D3 receptors and G proteins.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1460-9568.2005.04192.x
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  • 5
    Digitale Medien
    Digitale Medien
    Binding affinity of levomepromazine and two of its major metabolites to central dopamine and α-adrenergic receptors in the rat (1981)
    Springer
    Psychopharmacology 74 (1981), S. 101-104 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Levomepromazine metabolites ; Dopamine receptor affinity ; α-Adrenergic receptor affinity ; Rat brain
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract N-Monodesmethyl levomepromazine and levmepromazine sulfoxide have previously been found in higher plasma concentrations than the parent drug in patients who received oral doses of levomepromazine. In the present study levomepromazine, N-monodesmethyl levomepromazine and levomepromazine sulfoxide have been assayed for their binding affinity to rat striatal dopamine receptors and to α-adrenergic receptors in rat cortex, and compared with the potency of chlorpromazine and some of its metabolites in the same systems. Levomepromazine sulfoxide was relatively inactive in the dopamine receptor binding test but much more active in the α-adrenergic receptor binding test, where it had a binding affinity similar to 7-hydroxy chlorpromazine. Levomepromazine and N-monodesmethyl levomepromazine were active in both systems, having a slightly higher potency than chlorpromazine in the α-adrenergic binding test, and a somewhat lower potency than chlorpromazine in the dopamine receptor binding test. The results indicate that N-monodesmethyl levomepromazine may significantly contribute to the antipsychotic effects of levomepromazine while the sulfoxide metabolite lacks neuroleptic potency, and that both metabolites may contribute to the autonomic side-effects of the drug.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00432672
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  • 6
    Digitale Medien
    Digitale Medien
    Effects of zimelidine on serotoninergic and noradrenergic neurons after repeated administration in the rat (1981)
    Springer
    Psychopharmacology 72 (1981), S. 219-225 
    Details
    ISSN: 1432-2072
    Schlagwort(e): 5-Hydroxytryptamine ; Noradrenaline ; Zimelidine ; Norzimelidine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effects of prolonged treatment of rats with zimelidine, 5, 12.5, and 25 μmol/kg PO twice daily for 2 weeks, on the accumulation of 14C-5-hydroxytryptamine (14C-5-HT) and 3H-noradrenaline (3H-NA) in hypothalamic slices were studied. The concentrations of 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) in whole brain, the concentration of 5-HT in whole blood and the in vitro labelling of receptors in cerebral cortex with 3H-5-HT, 3H-dihydroalprenolol (3H-DHA) and striatum with 3H-spiroperidol were also determined, and the concentrations of zimelidine and its demethylated metabolite norzimelidine in plasma and hypothalamus were analysed. The degree of inhibition of the accumulation of 14C-5-HT and 3H-NA was not changed or only slightly increased by prolonged treatment as compared to acute treatment with zimelidine, i.e. the 5-HT accumulation was more inhibited than the NA accumulation. The inhibition of 14C-5-HT accumulation was significantly correlated to the plasma and hypothalamic concentration of norzimelidine 14 h after the last repeated administration. The 5-HT concentration in whole blood was markedly reduced at the same doses which produced inhibition of 5-HT uptake in brain, which indicates that the inhibition of 5-HT uptake in platelets and in neurons are similarly affected. The concentration of 5-HIAA in whole brain was reduced by both single and repeated administration of zimelidine, whereas the concentration of 5-HT was decreased only after prolonged treatment. The density of β-adrenoceptors (binding of 3H-DHA) was significantly reduced by zimelidine, whereas 5-HT receptor binding (3H-5-HT) and dopamine receptor binding (3H-spiroperidol) were unchanged. It is concluded that the effects on 5-HIAA and 5-HT levels in brain and on the β-adrenoceptors in cerebral cortex reflect pre-and post-synaptic regulation resulting from the uptake inhibition.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00431820
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  • 7
    Digitale Medien
    Digitale Medien
    11C-SCH 39166, a selective ligand for visualization of dopamine-D1 receptor binding in the monkey brain using PET (1991)
    Springer
    Psychopharmacology 103 (1991), S. 150-153 
    Details
    ISSN: 1432-2072
    Schlagwort(e): D1-dopamine receptors ; Positron emission tomography ; Monkey brain ; Dopamine receptor antagonist ; Antipsychotic drugs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The new selective D1-dopamine receptor antagonist SCH 39166 was labelled with the positron emitting isotope11C and used as ligand for visualization of dopamine-D1 receptor binding in Cynomolgus monkeys by PET. After intravenous administration of the ligand a marked uptake of radioactivity was recorded in the D1-dopamine receptor-rich striatum and neocortex but not in the dopamine receptor-poor cerebellum. The uptake of radioactivity in striatum and neocortex was markedly displaced after the intravenous injection of a high dose of the D1-dopamine receptor antagonist SCH 23390 but not after the 5-HT2 receptor antagonist ketanserine.11C-SCH 39166 should be a useful tool to explore D1-dopamine receptor characteristics in the living human brain by PET.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02244195
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  • 8
    Digitale Medien
    Digitale Medien
    [11C]Ro 15-4513, a ligand for visualization of benzodiazepine receptor binding (1992)
    Springer
    Psychopharmacology 108 (1992), S. 16-22 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Benzodiazepine receptors ; Ro 15-4513 ; 11C ; Positron emission tomography ; PET ; In vitro autoradiography ; Monkey brain ; Human brain
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Ro 15-4513, a partial inverse agonist at the benzodiazepine (BZ) receptor site was labelled with11C and used for in vitro autoradiography on human post mortem brain sections and for positron emission tomography (PET) on Cynomolgus monkeys. The total radiochemical yield of [11C]Ro 15-4513 was 30–40% with an overall synthesis time of 40 min. The specific radioactivity was about 1000 Ci/mmol at end of synthesis. In vitro autoradiography showed that [11C]Ro 15-4513 bound specifically predominately in the neocortex of the human brain. Specific binding was also demonstrated in the basal ganglia and the cerebellar cortex. Flumazenil (Ro 15-1788) and clonazepam inhibited the binding in cerebral regions, but a significant proportion in the cerebellum was not inhibited by these agents. This proportion may represent α6-containing BZ receptors. PET examination of [11C]Ro 15-4513 binding in Cynomolgus monkeys demonstrated high uptake of radioactivity in neocortex. The uptake of radioactivity was markedly displaced by high doses of Ro 15-4513 or clonazepam. [11C]Ro 15-4513 should be a useful ligand to examine BZ receptor characteristics in the living human brain by PET.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02245279
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  • 9
    Digitale Medien
    Digitale Medien
    Preparation of a potential positron emission tomographic radioligand for the dopamine transporter (1994)
    Springer
    European journal of nuclear medicine 21 (1994), S. 131-137 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Dopamine transporter ; NNC 12-0722 ; Carbon-11 ; Positron emission tomography ; In vitro autoradiography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract NNC 12-0722 (1-[2-(bis(4-fluorophenyl)methoxy)ethyl]-4-methyl piperazine) is a new selective inhibitor of the dopamine transporter. [11C]NNC 12-0722 was prepared by N-methylation of the desmethyl compound with [11C]methyl iodide. The total radiochemical yield of [11C]NNC 12-0722 was 40%–50% with an overall synthesis time of 30–35 min. The radiochemical purity was higher than 99% and the specific radioactivity about 1500 Ci/mmol (55 GBq/μmol). Autoradiographic examination of [11C]NNC 12-0722 binding on whole hemisphere cryosections from human brain post mortem demonstrated specific binding in the caudate nucleus and putamen. In a positron emission tomographic examination of [11C]NNC 12-0722 in a cynomolgus monkey there was a rapid uptake of radioactivity in the brain. In the striatum, a region with a high density of dopamine transporters, the radioactivity was two times higher than in the cerebellum. These results indicate that [11C]NNC 12-0722 may be a useful radioligand for labelling of the dopamine transporter in man.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00175760
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  • 10
    Digitale Medien
    Digitale Medien
    In vitro and in vivo characterisation of nor-β-CIT: a potential radioligand for visualisation of the serotonin transporter in the brain (1997)
    Springer
    European journal of nuclear medicine 24 (1997), S. 596-601 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Key words: 2β-Carbomethoxy-3β-(4-iodophenyl)nortropane ; Serotonin transporter ; Brain ; Positron emission tomography ; Autoradiography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Radiolabelled 2β-carbomethoxy-3β-(4-iodophenyl)tropane (β-CIT) has been used in clinical studies for the imaging of dopamine and serotonin transporters with single-photon emission tomography (SPET). 2β-Carbomethoxy-3β-(4-iodophenyl)nortropane (nor-β-CIT) is a des-methyl analogue of β-CIT, which in vitro has tenfold higher affinity (IC50=0.36 nM) to the serotonin transporter than β-CIT (IC50=4.2 nM). Nor-β-CIT may thus be a useful radioligand for imaging of the serotonin transporter. In the present study iodine-125 and carbon-11 labelled nor-β-CIT were prepared for in vitro autoradiographic studies on post-mortem human brain cryosections and for in vivo positron emission tomography (PET) studies in Cynomolgus monkeys. Whole hemisphere autoradiography with [125I]nor-β-CIT demonstrated high binding in the striatum, the thalamus and cortical regions of the human brain. Addition of a high concentration (1 μM) of citalopram inhibited binding in the thalamus and the neocortex, but not in the striatum. In PET studies with [11C]nor-β-CIT there was rapid uptake of radioactivity in the monkey brain (6% of injected dose at 15 min) and high accumulation of radioactivity in the striatum, thalamus and neocortex. Thalamus to cerebellum and cortex to cerebellum ratios were 2.5 and 1.8 at 60 min, respectively. The ratios obtained with [11C]nor-β-CIT were 20%–40% higher than those previously obtained with [11C]β-CIT. Radioactivity in the thalamus and the neocortex but not in the striatum was displaceable with citalopram (5 mg/kg). In conclusion, nor-β-CIT binds to the serotonin transporter in the primate brain in vitro and in vivo and has potential for PET and SPET imaging of the serotonin transporter in human brain.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00841395
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