Effects of an anxiogenic benzodiazepine receptor ligand on motor activity and dopamine release in nucleus accumbens and striatum in the rat

Abstract

The effects of the anxiogenic beta-carboline FG 7142 (N-methyl-beta-carboline-3-carboxylate) on motor activity and dopamine release in nucleus accumbens and striatum were measured in the rat. Changes in extracellular homovanillic acid (HVA) concentration, monitored by computer-controlled linear sweep voltammetry with carbon-paste electrodes, were used as an index of changes in dopamine release. An intraperitoneal injection of FG 7142 was followed by an inhibition of the nocturnal rise in motor activity and in dopamine release in nucleus accumbens, but not striatum. Two days after the drug injection, dopamine release in nucleus accumbens returned to control level and then increased on days 3-6 after the injection; there was no delayed change in motor activity or in striatal dopamine release. In parallel experiments using ex vivo changes in the ratio of 3,4-dihydroxyphenylacetic acid (DOPAC) to dopamine as an index of changes in dopamine turnover, a similar early depression and delayed increase of dopamine turnover in nucleus accumbens, with no change in striatum, was found after an intraperitoneal injection of FG 7142. Regression analysis of motor activity versus dopamine release showed a decrease in correlation between these 2 parameters for nucleus accumbens but not striatum after FG 7142 injection. These results suggest that the inverse benzodiazepine receptor agonist FG 7142 has a biphasic effect on dopamine release from mesolimbic neurons and support the hypothesis that dopamine release in nucleus accumbens and striatum has a modulatory effect on the control of motor activity but does not play a determining role in the regulation of movement.

Postpubertal Emergence of Hyperresponsiveness to Stress and to Amphetamine after Neonatal Excitotoxic Hippocampal Damage: A Potential Animal Model of Schizophrenia

“…The influence of other brain systems on locomotor behavior can be demonstrated under certain conditions. However, overwhelming expe rimental evi dence (Pijenburg et al 1975;Brose et al 1987;Sharp et al 1987;Piazza 1991) indicates that hyperlocomotion under the constellation of test conditions in our study (novelty, stress, and amphetamine administration) is highly suggestive of increased mesolimbic DA activity.…”

“…Both novelty and amphetamine-induced locomotion have been linked to mesolimbic DA transmission (Pijenburg et al 1975;Sharp et al 1987). Saline injections also are known to increase accumbens DA turnover/release (Brose et al 1987). Novelty, saline, and amphetamine may also have stresslike properties (Piazza et al 1989;Piazza et al 1991), which further implicate the limbic DA sys tem.…”

Effects of polymerization potential on the permselectivity of poly(o-phenylenediamine) coatings deposited on Pt–Ir electrodes for biosensor applications

“…Thus polymerization potential appears to determine of characteristics of the PoPD formed, rather than the subsequent calibration potential. However, the advantage of using lower applied potentials in this range for biosensor applications may be limited because many of the key interference species, such as AA, dopamine and its metabolites, oxidize at 0.4 V versus SCE on many electrode materials [38,54,64,91,101]. …”

Steps to a neurochemistry of personality

“…A direct relation exists between DA utilization in the NAS and level of spontaneous exploratory activity to novelty (Ahlenius et al 1987;Barnes et al 1987;Brose et al 1987). Additionally, extracellular concentration and release of DA in the NAS is greater and more prolonged in high than in low responders in both basal levels Hooks et al 1992a;Piazza et al 1991b), and levels induced by novelty (Piazza et al 1991b), stimulants (Bradberry et al 1991 Hooks et al 1991b;1992a), and stressors (Rouge-Pont et al 1993).…”