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An improved, HPLC with electrochemical detection method for the isocratic separation and determination of amino acids from post-mortem brain tissue and from microdialysates of awake-behaving animals is described. Optimal conditions that maximize stability, resolution, and sensitivity were determined for the pre-column derivatization of amino acids using(More)
Kappa opioid agonists are known to inhibit dopamine release. We sought to determine the site of this action and the relationship of tolerance to this effect. Microdialysis perfusion of the nucleus accumbens in unanesthetized rats was used to monitor dopamine release, as well as DOPAC, HVA, and 5-HIAA efflux. Administration of the kappa agonist U-50488H(More)
In order to study the role of excitatory amino acids on motor function, the effects of kainic, quisqualic, and N-methyl-DL-aspartic acids on locomotor activity were determined after their direct injection into the nucleus accumbens. These three amino acids have been used in previous studies to classify receptors for excitatory amino acids in the mammalian(More)
In the lateral striatum of aged rats, dopamine D-2 receptor density is reduced and glutamate tissue content is elevated. D-2 receptor agonists have been shown to inhibit stimulated glutamate release. In the present study, microdialysis was used to investigate a potential role for D-2 receptors in the modulation of striatal glutamate efflux from 4-, 12-,(More)
Several compounds have been shown to antagonize the excitation of single neurons produced by excitatory amino acids. This study was designed to determine the effectiveness of these compounds in antagonizing the hypermotility response to excitatory amino acids after intra-accumbens administration. Of the putative antagonists tested, D-aminoadipic acid,(More)
The excitatory amino acids, N-methyl-aspartic acid, kainic acid and quisqualic acid have been shown to produce a marked increase in locomotor activity after bilateral injection into the rat nucleus accumbens. The intra-accumbens injection of magnesium inhibited the hypermotility response produced by N-methyl-aspartic acid in a dose-dependent manner.(More)
A rapid microassay is described for the measurement of biogenic amines using an isocratic HPLC system with electrochemical detection. Catecholamines, indoleamines and their major metabolites were extracted with 150 microliters of perchloric acid from brain tissue punches (less than 250 micrograms) using a simple one-step sample preparation method. These(More)
The effects of synthetic omega-grammotoxin SIA (omega-GsTxSIA) and synthetic omega-Aga-IVA were tested in in vitro and in vivo neurochemical assays that are reflective of voltage-sensitive calcium channel function. Synthetic omega-GsTx SIA inhibited K(+)-evoked rat and chick synaptosomal 45Ca2+ flux, K(+)-evoked release of [3H]D-aspartate and(More)
The topographical distribution of putative neurotransmitter amino acids in both 6- and 20-month-old Fischer 344 rats was studied in eight striatal subregions. Tissue levels of glutamate, aspartate, GABA, and taurine in the 20-month-old rats were elevated in virtually all of the anterior striatal subregions examined. In addition, aspartate levels were higher(More)
In vitro effects of d,l-methadone and morphine on [3H]serotonin (3H-5-HT) uptake in rat periaqueductal gray (PAG) slices were investigated. Only methadone had a significant inhibitory effect on 3H-5-HT uptake which was significantly enhanced by naloxone. The systemic administration of methadone did not affect 3H-5-HT uptake in vitro. These data further(More)
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