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C A Marsden

Publications and source records attributed to C A Marsden.

At least 235 records · Page 13Linked to original sources
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Participation of the glutamatergic input of the nucleus accumbens in the regulation of the synaptic release of dopamine during associative learning.

The changes in the synaptic release of dopamine in the medial division of the nucleus accumbens in the course of a conditioned emotional response and the influence on this process of the blockade of N-methyl-D-aspartate (NMDA) receptors of this structure were investigated in awake Lister-hooded rats, using the method of intravital intracerebral dialysis in combination with high-pressure liquid chromatography and electrochemical detection. It was established that situational stimuli, previously combined with painful reinforcement, but not acoustic conditional signals, lead to a slow increase in the level of dopamine in the extracellular space of the nucleus accumbens. This process reaches a maximum 40 min after the beginning of testing and lasts 80 min. Dialysis perfusion of the nucleus accumbens with a solution of MK-801 (50 mumole/liter) does not alter the magnitude of the slow rise in the synaptic release of dopamine in this structure in the course of the conditioned emotional response, but completely blocks the late components of the release. It is concluded that the glutamatergic input of the nucleus accumbens participates in the regulation of the late components of the synaptic release of dopamine, governed by the conditioned emotional response, in this structure through NMDA receptors.

Acoustic Stimulation↗
PubMedDate not supplied

gamma-Aminobutyric acid levels in the intercellular space in the nucleus accumbens of the rat brain during a nociceptive conditioned response.

Studies on Lister rats, using intracerebral dialysis in behaving animals combined with high-performance liquid chromatography with electrochemical detection, showed that the development and realization of an emotional conditioned response were accompanied by increases in the gamma-aminobutyric acid (GABA) levels in the extracellular space of the medial part of the nucleus accumbens. Regression analysis demonstrated that measures of investigative behavior (horizontal movements, rearings, and sniffing and grooming times) during quenching of the emotional conditioned response (but not on presentation of the experimental chamber to control rats) correlated with individual changes in the extracellular GABA levels in the nucleus accumbens. Thus, this is the first report of in vivo recording of changes in GABA levels in the extracellular space of the brain during realization of normal behavior.

Animals↗
PubMedDate not supplied

Acute administration of clozapine, thioridazine and metoclopramide increases extracellular DOPAC and decreases extracellular 5-HIAA, measured in the nucleus accumbens and striatum of the rat using in vivo voltammetry.

Changes in the extracellular levels of dihydroxyphenylacetic acid (DOPAC) and 5-hydroxy-indoleacetic acid (5-HIAA) after acute administration of clozapine (50 mg/kg s.c.), thioridazine (20 mg/kg s.c.) and metoclopramide (5 mg/kg s.c.), were monitored using in vivo voltammetry with micro-carbon electrodes implanted in the nucleus accumbens and striatum of the rat anaesthetised with halothane/N2O. Both clozapine and thioridazine increased extracellular levels of DOPAC in the striatum and the nucleus accumbens. The maximum increases with clozapine were 60% and 86% in the nucleus accumbens and striatum and 44% and 55% with thioridazine. Both neuroleptics also decreased the extracellular level of 5-HIAA in these regions of the brain. Metoclopramide increased the extracellular level of DOPAC in the nucleus accumbens (42%) and the striatum (57%) and significantly decreased the level of 5-HIAA in the nucleus accumbens. These results suggest that the two so-called atypical neuroleptics, clozapine and thioridazine, do not have selective effects on the metabolism of dopamine in vivo in the nucleus accumbens after acute administration. Furthermore, neuroleptic-induced increases in dopamine metabolism are accompanied by reciprocal decreases in 5-hydroxytryptamine metabolism in vivo.

3,4-Dihydroxyphenylacetic Acid↗