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Showing 2 results for Microdialysis.
THE EFFECT OF BENZODIA ZEPINES ON THE STRESS-INDUCED RESPONSES OF THE NORA DRENERGIC A ND SEROTONERGIC PROJECTIONS TO THE RAT HIPPOCAMPUS
A Vahabzadeh, M Fillenz,
Volume 12, Issue 3 (11-1998)
Abstract
Microdialysis was used to measure the effect of benzodiazepines (BDZs) on basal levels and on stress-induced increases of 5 -hydroxytryptamine (5 -HT), 5 - hydroxyind oleacetic acid (5 -HIAA) , noradrenaline (NA), and dihydroxyphenylacetic acid (DOP AC). The stressors used were a 5 min tail pinch or a 10 min period of restraint. A subcutaneous injection of 5 mg/kg diazepam decreased basal levels of 5 -HT, 5 -HIAA, and DOPAC, but not NA. There was no effect on the stress-induced increase in 5 -HT, NA, and 5 -HIAA, while the increase in DOPAC was completely abolished. Local infusion of 5 µM flurazepam decteased the basal level of 5 - HT but not 5 -HIAA and abolished the stress-induced increase of 5 -HIAA but not 5 -HT. These results suggest that the anxiolytic action of BDZs is unlikely to be attributable to the suppression of stress-induced increases in the release of NA or 5 -HT in the hippocampus.
MORPHINE RELE ASES GLUTAMATE THROUGH AMPA RECEPTORS IN THE VENTRAL TEGMENTAL AREA: A MICRODIALYSIS STUDY IN CONSCIOUS RATS
H Alaei, M Huotari, Pt Piepponen, L Ahtee, O Hanninen, Pt Mannisto,
Volume 17, Issue 3 (11-2003)
Abstract
In vivo microdialysis was used to study the effects of morphine on glutamate release from the ventral tegmentum area (VTA) in freely moving rats. Intraperitoneal (i.p.) injection of acute and repeated morphine at increasing doses significantly enhanced glutamate release. Only a minor tolerance developed to this dosage of morphine. AP-S (2-amino-5-phosphonovaleric acid, 0.5 mg/kg i.p.), a NMDA receptor antagonist, given 20 min before each repeated morphine injection, did not have a significant effect on the stimulated glutamate release . Conversely, injection of CNQX (6-cyano-7-nitroquinoxaline-2, 3-dione, 0.5 mg/kg i.p.), an AMPA receptor antagonist, 20 min before each morphine dose was found to markedly inhibit morphine-induced glutamate release in the VTA. In all experiments, glutamate release reduced by time. These results show for the first time that acute and repeated injection of morphine stimulates glutamate release in the conscious rat VTA via AMPA receptors.
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