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  • 1
    Electronic Resource
    Electronic Resource
    Administration of 8-Hydroxy-2-(Di-n-Propylamino)tetralin in Raphe Nuclei Dorsalis and Medianus Reduces Serotonin Synthesis in the Rat Brain: Differences in Potency and Regional Sensitivity (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 56 (1991), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Following administration of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT; 0.04–5.0 μg/0.5 μl) in the raphe nucleus dorsalis (DR) or medianus (MR), the synthesis of serotonin (5-HT), as assessed by the accumulation of 5-hydroxytryptophan (5-HTP) after decarboxylase inhibition, was measured in various regions of the rat CNS. At all doses, 8-OH-DPAT in the DR significantly reduced 5-HTP accumulation in the striatum, nucleus accumbens, cortex, and prefrontal cortex, whereas even the highest dose had no effect in the hippocampus, hypothalamus, and spinal cord. One microgram of 8-OH-DPAT in the MR significantly reduced 5-HTP accumulation in the nucleus accumbens and prefrontal cortex, and 5 μg had an effect in all the areas except the striatum and spinal cord. One and 5 μg of 8-OH-DPAT, administered in either the DR or MR, did not significantly modify the accumulation of dihydroxyphenylalanine in the striatum and nucleus accumbens. The results confirm that DR and MR have different sensitivities to 5-HT1A receptor agonists, and that activation of 5-HT1A receptors in these nuclei produces different effects on 5-HT synthesis in different brain regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1991.tb02587.x
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  • 2
    Electronic Resource
    Electronic Resource
    Fluoxetine Increases Extracellular Dopamine in the Prefrontal Cortex by a Mechanism Not Dependent on Serotonin (1999)
    Oxford UK : Blackwell Science Ltd
    Journal of neurochemistry 73 (1999), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract : Fluoxetine at 10 and 25 mg/kg increased (167 and 205%, respectively) the extracellular dopamine concentration in the prefrontal cortex, whereas 25 (but not 10) mg/kg citalopram raised (216%) dialysate dopamine. No compound modified dialysate dopamine in the nucleus accumbens. The effect of 25 mg/kg of both compounds on cortical extracellular dopamine was not significantly affected by 300 mg/kg p-chlorophenylalanine (PCPA) (fluoxetine, saline, 235% ; PCPA, 230% ; citalopram, saline, 179% ; PCPA, 181%). PCPA depleted tissue and dialysate serotonin by ~90 and 50%, respectively, and prevented the effect of fluoxetine and citalopram on dialysate serotonin (fluoxetine, saline, 246% ; PCPA, 110% ; citalopram, saline, 155% ; PCPA, 96%). Citalopram significantly raised extracellular serotonin from 0.1 to 100 μM (251-520%), whereas only 10 and 100 μM increased dialysate dopamine (143-231%). Fluoxetine similarly increased extracellular serotonin (98-336%) and dopamine (117-318%). PCPA significnatly reduced basal serotonin and the effects of 100 μM fluoxetine (saline, 272% ; PCPA, 203%) and citalopram (saline, 345% ; PCPA 258%) on dialysate serotonin but did not modify their effect on dopamine (fluoxetine, saline, 220% ; PCPA, 202% ; citalopram, saline, 191% ; PCPA, 211%). The results clearly show that the effects of fluoxetine and of high concentrations of citalopram on extracellular dopamine do not depend on their effects on serotonin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1999.0731051.x
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  • 3
    Electronic Resource
    Electronic Resource
    The 5-HT2A receptor antagonist M100,907 prevents extracellular glutamate rising in response to NMDA receptor blockade in the mPFC (2004)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 91 (2004), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We recently found that intracortical injection of the selective and competitive N-methyl-d-aspartate (NMDA) receptor antagonist 3-(R)-2-carboxypiperazin-4-propyl-1-phosphonic acid (CPP) impaired attentional performance in rats and blockade of 5-hydroxytryptamine (5-HT)2A receptors antagonized this effect. Here, we used the microdialysis technique in conscious rats to study the effect of CPP on extracellular glutamate (GLU) in the medial prefrontal cortex (mPFC) and the regulation of this effect by 5-HT2A receptors. Intraperitoneal injection of 20 mg/kg CPP increased extracellular GLU in the mPFC (201% of basal levels) but had no effect on 5-HT. Intracortical infusion of 100 µm CPP increased extracellular GLU (230% of basal values) and 5-HT (150% of basal values) in the mPFC, whereas 30 µm had no significant effect. The effect of 100 µm CPP on extracellular GLU was abolished by tetrodotoxin, suggesting that neuronal activity is required. Subcutaneous injection of 40 µg/kg M100,907 completely antagonized the effect of 100 µm cpp on extracellular GLU, whereas 10 µg/kg caused only partial attenuation. Likewise, intracortical infusion of 0.1 µm M100,907 completely reversed the increase of extracellular GLU induced by CPP. These findings show that blockade of NMDA receptors in the mPFC is sufficient to increase extracellular GLU locally. The increase of cortical extracellular GLU may contribute to CPP-induced cognitive deficits and blockade of 5-HT2A receptors may provide a molecular mechanism for reversing these deficits caused by dysfunctional glutamatergic transmission in the mPFC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.2004.02704.x
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  • 4
    Electronic Resource
    Electronic Resource
    Proteasome inhibition and aggregation in Parkinson's disease: a comparative study in untransfected and transfected cells (2004)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 88 (2004), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Dysfunction of the ubiquitin-proteasome system (UPS) has been implicated in Parkinson's disease (PD) and other neurodegenerative disorders. We have investigated the effect of UPS inhibition on the metabolism of α-synuclein (SYN) and parkin, two proteins genetically and histopathologically associated to PD. Pharmacological inhibition of proteasome induced accumulation of both parkin and SYN in transfected PC12 cells. We found that this effect was caused by increased protein synthesis rather than impairment of protein degradation, suggesting that inhibition of the UPS might lead to non-specific up-regulation of cytomegalovirus (CMV)-driven transcription. To investigate whether endogenous parkin and SYN can be substrate of the UPS, untransfected PC12 cells and primary mesencephalic neurones were exposed to proteasome inhibitors, and parkin and SYN expression was evaluated at both protein and mRNA level. Under these conditions, we found that proteasome inhibitors did not affect the level of endogenous parkin and SYN. However, we confirmed that dopaminergic neurones were selectively vulnerable to the toxicity of proteasome inhibitors. Our results indicate that studies involving the use of proteasome inhibitors, particularly those in which proteins are expressed from a heterologous promoter, are subjected to potential artefacts that need to be considered for the interpretation of the role of UPS in PD pathogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2003.02152.x
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  • 5
    Electronic Resource
    Electronic Resource
    Stimulation of 5-hydroxytryptamine (5-HT2C) receptors in the ventrotegmental area inhibits stress-induced but not basal dopamine release in the rat prefrontal cortex (2002)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 82 (2002), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The present study investigated whether 5-HT2C receptors in the ventrotegmental area and prefrontal cortex regulate basal and stimulus-evoked dopamine release in the prefrontal cortex. Using the in vivo microdialysis technique in conscious rats, we studied the effect of a selective 5-HT2C receptor agonist, Ro60–0175, on basal and immobilization stress-induced dopamine release in the prefrontal cortex. Ro60–0175 intraperitoneally (2.5 mg/kg) and into the ventrotegmental area (10 µg/0.5 µL) completely antagonized the effect of stress on extracellular dopamine without altering basal levels. Infusion of 10 µm Ro60–0175 through the cortical probe had no significant effect on basal and stress-induced dopamine release. SB242084 (10 mg/kg), a selective antagonist of 5-HT2C receptors, significantly increased basal extracellular dopamine and completely prevented the effect of intraperitoneal and intraventrotegmental Ro60–0175 on the stress-induced rise of extracellular dopamine, but had no effect itself in stressed rats. The results show that Ro60–0175 suppresses cortical dopamine release induced by immobilization stress through the stimulation of 5-HT2C receptors in the ventrotegmental area. While confirming that endogenous 5-HT acting on 5-HT2C receptors tonically inhibit basal dopamine release in the prefrontal cortex, the present findings suggest that the stimulation of 5-HT2C receptors with an exogenous agonist preferentially inhibit stimulated release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2002.00947.x
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  • 6
    Electronic Resource
    Electronic Resource
    Neurochemical and behavioural studies with RU-24969 in the rat (1988)
    Springer
    Psychopharmacology 94 (1988), S. 359-364 
    Details
    ISSN: 1432-2072
    Keywords: Serotonin synthesis ; Dopamine synthesis ; RU-24969 ; Anxiety ; Antidepressant activity ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The regional brain synthesis of serotonin (5-HT) and dopamine (DA) was studied in rats after various doses of 5-methoxy-3(1,2,3,6-tetrahydro-4-pyridinyl)-1H-indole (RU-24969), a 5-HT1 receptor agonist. The potential anxiolytic and antidepressant properties of the compound were examined as well. RU-24969 0.62 mg/kg significantly reduced 5-HT synthesis in the nucleus accumbens and hypothalamus, while with 1.25 and 2.5 mg/kg the effect was also seen in striatum, hippocampus, brainstem and cortex. RU-24969 2.5 and 5 mg/kg had no effect on DA synthesis in the striatum, while 5.0 mg/kg significantly increased it in the nucleus accumbens. At doses of 2.5 and 5.0 mg/kg the drug increased the motor activity of rats measured during 1 h in activity cages while 0.625 and 1.25 mg/kg had no effect. Doses ranging from 0.62 to 2.5 mg/kg RU-24969 significantly reduced unpunished responding in a test of conditioned suppression of drinking. Doses of 1.25 and 2.5 mg/kg also reduced punished responding. Finally, of various doses only 2.5 mg/kg RU-24969 significantly reduced the duration of immobility of rats in the forced swimming test but the effects were due to running around the cylinder rather than to escape attempts. In conclusion, RU-24969 reduced 5-HT synthesis in all brain areas examined, with a preferential effect for the nucleus accumbens and the hypothalamus. At higher doses, there was also a specific increase in DA synthesis in the nucleus accumbens. The compound raised the level of activity of rats but no clear evidence of any potential anxiolytic or antidepressant properties has been obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00174690
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  • 7
    Electronic Resource
    Electronic Resource
    Tissue distribution of monoamine neurotransmitters in normal and regenerating arms of the feather star Antedon mediterranea (1996)
    Springer
    Cell & tissue research 285 (1996), S. 341-352 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Dopamine ; Serotonin ; Nervous system ; Arm regeneration ; Antedon mediterranea (Echinodermata)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Crinoid echinoderms can completely and rapidly regenerate arms lost following self-induced or traumatic amputation. Arm regeneration in these animals therefore provides a valuable experimental model for studying all aspects of regenerative processes, particularly with respect to the nervous system and its specific contribution to regenerative phenomena. Taking into account the primary role of the nervous system in regeneration in other invertebrates, we have investigated the specific involvement of neural factors, viz. the monoamine neurotransmitters dopamine and serotonin, in arm regeneration of Antedon mediterranea. In the present work, the presence of classical monoamines has been revealed by employing specific immunocytochemical and histofluorescence tests in association with biochemical detection by means of high pressure liquid chromatography. The distribution pattern of these neurohumoral molecules at standard regenerative stages has been compared with that of normal non-regenerating arms. Results indicate that both dopamine and serotonin dramatically change in both their distribution and concentration during the repair and regenerative processes. Their remarkably enhanced pattern during regeneration and widespread presence at the level of both nervous and non-nervous tissues indicates that they are important neural growth-promoting factors in crinoid arm regeneration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050651
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