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Blockade of NMDA/glutamate receptors induces altered behavior in humans and experimental animals. At the same time a differential activation of dopaminergic (DA) systems has been reported. To study the involvement of the medial prefrontal cortex (mPFC) in these effects, we used bilateral perfusions of the rat mPFC with the competitive NMDA-antagonist D-AP-5(More)
We report the effects of physiological stimuli on extracellular dopamine (DA) in the medial prefrontal cortex (PFC) of the rat determined on-line in dialysates obtained every 5.5 min. The detection limit for DA was 0.03-0.1 pg/5 microl injection using a conventional HPLC set-up. Basal levels in PFC were at the detection limit, therefore 3 microM nomifensine(More)
We used on-line microdialysis measurements of dopamine and noradrenaline extracellular concentrations in the medial prefrontal cortex of awake, freely moving rats during the dark and the light period of the day to study whether (i) basal efflux would be higher in the active, dark period than in the inactive, light period; (ii) the activation induced by(More)
On-line in vivo microdialysis was used to determine the effects of a 16-min handling period on release of dopamine (DA) in the nucleus accumbens and of DA and noradrenaline (NA) in the medial prefrontal cortex of awake, freely moving rats. DA and NA were determined in one HPLC run. Handling resulted in an immediate and strong increase of both catecholamines(More)
Using microdialysis, the glutamate agonist N-methyl-D-aspartate (NMDA) was perfused for 20 min through the medial prefrontal cortex of freely moving rats, and its effects on extracellular concentrations of dopamine (DA) were determined. NMDA (1 mM) increased DA to 170-1500%, depending on the intensity and duration of the clonic forelimb jerks and(More)
In Alzheimer's disease (AD) there is neuronal loss in the locus ceruleus (LC), and the noradrenergic system may be even more affected in depressed AD patients. However, this neuronal loss may go together with an increase in activity of the remaining noradrenergic neurons. We prospectively evaluated 16 AD patients (6 depressed, 5 transiently depressed, and 5(More)
We used bilateral microdialysis in the medial prefrontal cortex (PFC) of awake, freely moving rats to study aversive conditioning to an auditory cue in the controlled environment of the Skinner box. The presentation of the explicit conditioned stimuli (CS), previously associated with foot shocks, caused increased dopamine (DA) and noradrenaline (NA) efflux.(More)
Administration of non-competitive N-methyl-D-aspartate (NMDA) antagonists in rodents leads to a characteristic motor syndrome which has been related to changes in monoamine metabolism in a variety of brain regions. We examined the question whether chronic MK-801 treatment in neonatal rats from postnatal day 8 through 19, which has been shown previously to(More)
The effects of graded stressful conditions on extracellular concentrations of dopamine (DA) in the medial prefrontal cortex of rats were measured in vivo using microdialysis. Picking up the rat twice with a 20-min interval increased extracellular DA to 120%, exposure to a novel environment by placement in a clean cage for 20 min to 150% and holding the rat(More)
Early postnatal treatment with the antidepressant drug clomipramine has repeatedly been shown to lead to behavioural and physiological changes in adult rats. To provide some neurochemical correlates to these studies we have measured a number of monoaminergic parameters in the brains of adult (one year old) rats that were treated twice daily with 15 mg/kg(More)