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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 10 (1998), S. 0 
    ISSN: 1460-9568
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The γ-aminobutyric acid (GABA) receptor ρ subunits recently cloned from rat and human retina are thought to form GABA receptor channels belonging to a pharmacologically distinct receptor class, termed GABAC. In this work we have examined the distribution of ρ1, ρ2 and ρ3 subunits, and found expression of all three transcripts in several regions of the rat nervous system. In situ hybridization revealed expression of ρ2 in the adult rat retina and some other parts of the visual pathways. A high local ρ2 expression was seen in the superficial grey layer of the superior colliculus, and in the dorsal lateral geniculate nucleus. Expression was also detected in the 6th layer of visual cortex and in the CA1 pyramidal cell layer of hippocampus. With reverse transcriptase–polymerase chain reaction, expression of ρ1 was mainly seen in the adult rat retina and dorsal root ganglia, as well as, at a significantly lower level, in the superior colliculus, hippocampus, brain stem, thalamus, postnatal day 8 (P8) superior colliculus and P8 hippocampus. Expression pattern of ρ3 mRNA was clearly different from that of ρ1 and ρ2, being strongest in the hippocampus, and significantly lower in the retina, dorsal root ganglia and cortex. No ρ3 expression was observed in adult or P8 superior colliculus or in P8 hippocampus.The present results clearly demonstrate that expression of GABA receptor ρ subunits is not restricted to the retina, but significant expression can also be detected in many other brain regions, especially in those belonging to the visual pathways. The expression pattern of the ρ subunits may be helpful in solving the functional significance of the receptors formed from these subunits.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1460-9568
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The localization of glial cell line-derived neurotrophic factor (GDNF) mRNA was studied by in situhybridization in rat from embryonic (E) day E10 to E15. At E10, GDNF mRNA is found in the urogenital field and the cranial part of the gut. At E11, the most abundant expression of GDNF mRNA is seen in the epithelial cells of the second, third and fourth pharyngeal pouches, the third and fourth pharyngeal arches and pharynx. Also mesenchymal cells of the gut and mesonephric tubules contain GDNF mRNA. At E13, expression is observed in the mesenchymal cell layers of the oesophagus, intestine and stomach, the mesenchymal cells around the condensing cartilages and metanephric kidney mesenchyme. Also, the epithelia of Rathke's pouch and pharynx are intensely labelled. High expression of GDNF mRNA continues at El5 in kidney, gastrointestinal tract and cartilage. At that stage, GDNF mRNA is seen also in whisker pad and skeletal muscles. The distribution of GDNF mRNA in embryonic rat suggests important roles for GDNF in the early differentiation of the kidney tubules, the innervation of the gastrointestinal tract and the differentiation process of the cartilage and muscle. Our results indicate novel functions for GDNF outside the nervous system.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1432-2072
    Schlagwort(e): Key words Alcoholism ; Dopamine transporter ; [123I]PE2I ; [123I]Epidepride ; SPECT
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Rationale: Late onset type 1 alcoholism has been suggested to be associated with an underlying dopaminergic defect. Therefore, it is relevant to study both postsynaptic D2-receptor and presynaptic dopamine transporter (DAT) densities among alcoholics. Objective: We investigated DAT densities, along with striatal and extrastriatal dopamine D2-receptor densities, in nine non-violent late-onset male alcoholics, who had no major mental disorder nor antisocial personality disorder (ASPD), and nine healthy controls. Methods: [123I]PE2I and [123I]epidepride were used in SPECT imaging. Results: DAT occupancy ratios (striatum/cerebellum) were significantly lower among alcoholics than in controls. Extrastriatal D2-receptor occupancy ratios (temporal pole/cerebellum) were not significantly different between the groups. Conclusions: Striatal presynaptic DAT densities are decreased among type 1 alcoholics, and this finding is not associated with recent alcohol abuse.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1432-0878
    Schlagwort(e): Glial cell line-derived neurotrophic factor (GDNF) GDNF family receptor-alpha Major pelvic ganglion Neurotrophic factor Penis Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Glial cell line-derived neurotrophic factor (GDNF), a member of the GDNF family of neurotrophic factors, promotes the survival and function of several neuronal populations in the peripheral and central nervous system. In the present study, expression of GDNF mRNA in the shaft of adult rat penis is demonstrated. In situ hybridization revealed GDNF mRNA expression in cells lying in the narrow zone between the tunica albuginea and the cavernous tissue. Most subtunical cells exhibited immunoreactivity for vimentin and S100beta, but they did not stain for smooth muscle alpha actin or PGP9.5. This suggests that the GDNF mRNA-expressing cells may have a mesenchymal origin. Also retrograde axonal transport of intracavernously injected 125I-labeled GDNF in penile parasympathetic and sensory neurons is shown. The transport was inhibited by excess unlabeled GDNF, whereas excess cytochrome c had no effect. This is in agreement with the view that the transport was mediated by binding to specific receptors located on axon terminals. In addition, this study demonstrates expression of GDNF family receptor-α3 (GFRα3) mRNA in most adrenergic, but only in a minor part (5.3%) of the penis-projecting adult rat major pelvic ganglion neurons, as well as in almost half (45.6%) of the penile S1 dorsal root ganglion neurons. In conclusion, the present data suggest that GDNF may act as a neurotrophic factor for subpopulations of adult rat penile parasympathetic and sensory neurons.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1619-7089
    Schlagwort(e): Benzodiazepine ; Dynamic single-photon emission tomography ; Iodine-123-3-(5-cyclopropyl1,2,4-oxadiazo-3-yl)-7-iodo-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]-benzodiazepine ; Receptors ; NNC 13-8241
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The iodine-123 labelled ligand 3-(5-cyclopropyl-1,2,4-oxadiazo-3-yl)-7-iodo-5,6-dihydro-5-methyl-6oxo-4H-imidazo[1,5-a][1,4]-benzodiazepine ([123I]NNC 13-8241) was evaluated as a probe for in vivo imaging of benzodiazepine receptor sites in the human brain. Four healthy volunteers were imaged with a high-resolution single-photon emission tomography (SPET) scanner. The metabolism of [123I]NNC 13-8241 in plasma was slow. The total brain uptake was about 1.5-fold higher than that of [123I]iomazenil. The specific binding in the cortical areas was high and less intense in the thalamus. The most intense uptake was seen in the occipital cortex. The peak cortical uptake of [123I]NNC 13-8241 was observed 6–10 h after the injection of tracer. The radiation burden to the patient was moderate, being 2.5·10−2 mSv/MBq (effective dose equivalent). A slow metabolism together with favourable kinetics indicates that [123I]NNC 13-8241 is a specific and promising SPET ligand for imaging benzodiazepine receptor sites in the living human brain.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    ISSN: 1619-7089
    Schlagwort(e): Dopamine D2 receptor ; Epidepride ; Extrastriatal ; Single-photon emission tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The iodine-123 labelled ligand benzamide epidepride was evaluated as a probe for in vivo imaging of striatal and extrastriatal dopamine D2 receptor sites in the human brain. Four healthy males were imaged with a high-resolution single-photon emission tomography scanner. Striatal radioactivity peaked at 3 h after injection. The specific binding in the striatum was 0.91±0.03 at 3 h and this ratio steadily increased with time. Extrastriatal radioactivity was highest in the thalamus, in the midbrain and in the temporal cortex, and peaked at 45–60 min after injection of tracer. A smaller amount of radioactivity was found in the parietal, frontal and occipital cortices. Two radioactive metabolites were observed, of which one was more lipophilic than the parent compound. The radiation burden to the patient was 0.035 mSv/MBq (effective dose equivalent). The preliminary results showed that [123I]epidepride can be used for imaging striatal and extrastriatal dopamine D2 receptor sites in the living human brain.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    ISSN: 1619-7089
    Schlagwort(e): Dopamine transporter ; Single-photon emission tomography ; 2β-carbomethoxy-3β-(4-iodophenyl)tropane ; N-(3-fluoropropyl)-2β-carbomethoxy-3β-(4-iodophenyl)nortropane ; N-(2-fluoroethyl)-2β-carbomethoxy-3β-(4-iodophenyl)nortropane
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract There are several cocaine analogs which have potential for imaging the dopamine transporters (DAT). Earlier studies have shown that iodine-123 labelled 2β-carbomethoxy-3β-(4-iodophenyl)tropane ([123I]β-CIT) andN-(3-fluoropropyl)-2β-carbomethoxy-3β-(4-iodo-phenyl)nortropane ([123I]β-CIT-FP) are promising DAT imaging agents in the living human brain with single-photon emission tomography (SPET). Here we report a pilot comparison of [123I]β-CIT and [123I]β-CIT-FP with a new tropane derivative, [123I]N-(2-fluoroethyl)-2β-carbomethoxy-3β-(4-iodophenyl)nortropane ([123I]β-CITFE), using SPET imaging in four healthy male subjects. Peak uptake of [123I]β-CIT-FE into the basal ganglia occurred very rapidly (0.5 h after injection of tracer), after which the striatal washout obeyed a bi-exponential form. The specific DAT binding of [[123I]β-CIT FE into the basal ganglia was somewhat less (0.785 ± 0.117) than that of [123I]β-CIT (0.922 ± 0.004) or [123I]β-CIT-FP (0.813 ± 0.047). All these tracers have excellent imaging quality in healthy control subjects. However, the relatively fast washout of [123I]β-CIT-FE and low temporal resolution of older SPET cameras may limit the use of this tracer to the measurement of the DAT density.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    ISSN: 1619-7089
    Schlagwort(e): Key words: Dopamine D2 receptor ; Epidepride ; Extrastriatal ; Single-photon emission tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. The iodine-123 labelled ligand benzamide epidepride was evaluated as a probe for in vivo imaging of striatal and extrastriatal dopamine D2 receptor sites in the human brain. Four healthy males were imaged with a high-resolution single-photon emission tomography scanner. Striatal radioactivity peaked at 3 h after injection. The specific binding in the striatum was 0.91±0.03 at 3 h and this ratio steadily increased with time. Extrastriatal radioactivity was highest in the thalamus, in the midbrain and in the temporal cortex, and peaked at 45–60 min after injection of tracer. A smaller amount of radioactivity was found in the parietal, frontal and occipital cortices. Two radioactive metabolites were observed, of which one was more lipophilic than the parent compound. The radiation burden to the patient was 0.035 mSv/MBq (effective dose equivalent). The preliminary results showed that [123I]epidepride can be used for imaging striatal and extrastriatal dopamine D2 receptor sites in the living human brain.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    ISSN: 1619-7089
    Schlagwort(e): Key words:Z-(R ; R)-IQNP ; Muscarinic acetylcholine receptors ; Brain ; Single-photon emission tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Z-(R)-1-Azabicyclo[2.2.2]oct-3-yl (R)-α-hydroxy-α-(1-iodo-1-propen-3-yl)-α-phenylacetate (Z-IQNP) has high affinity to the M1 and M2 muscarinic acetylcholine receptor (mAChR) subtypes according to previous in vitro and in vivo studies in rats. In the present study iodine-123 labelled Z-IQNP was prepared for in vivo single-photon emission tomography (SPET) studies in cynomolgus monkeys. SPET studies with Z-[123I]IQNP demonstrated high accumulation in monkey brain (〉5% of injected dose at 70 min p.i.) and marked accumulation in brain regions such as the thalamus, the neocortex, the striatum and the cerebellum. Pretreatment with the non-selective mAChR antagonist scopolamine (0.2 mg/kg) inhibited Z-[123I]IQNP binding in all these regions. The percentage of unchanged Z-[123I]IQNP measured in plasma was less than 10% at 10 min after injection, which may be due to rapid hydrolysis, as has been demonstrated previously with the E-isomer of IQNP. Z-[123I]IQNP showed higher uptake in M2-rich regions, compared with previously obtained results with E-[123I]IQNP. In conclusion, the radioactivity distribution from Z-[123I]IQNP in monkey brain indicates that Z-[123I]IQNP binds to the M1- and M2-rich areas and provides a high signal for specific binding, and is thus a potential ligand for mAChR imaging with SPET.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    European journal of nuclear medicine 26 (1999), S. 1486-1488 
    ISSN: 1619-7089
    Schlagwort(e): Key words: Age ; Dopamine transporter ; Human brain ; Single-photon emission tomography ; Striatum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. The iodine-123 labelled selective ligand N-(3-iodoprop-2E-enyl)-2β-carbomethoxy-3β-(4-methylphenyl)nortropane ([123I]PE2I) has been developed and has been shown to be suitable for single-photon emission tomography imaging of the dopamine transporter. In this study the influence of age on ligand binding was investigated in 16 healthy males with an age range of 23– 75 years. Single-photon emission tomography (SPET) imaging was performed with a triple-headed gamma camera. A simplified reference region model, in which the input function was derived from the non-displaceable cerebellar compartment, was used to calculate the volume of distribution in the striatum. The volume of distribution was shown to decline with age (–0.4%/year; P〈0.005). The results were in agreement with in vivo and in vitro findings of a decline in dopamine transporter binding with age. The findings confirm the suitability of [123I]PE2I for SPET imaging in clinical routine but emphasize the necessity of using age-matched controls in patient studies.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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