[Calcium-dependent liberation of gamma-hydroxybutyrate after depolarization of rat brain slices].

The release of gamma-hydroxybutyrate from preloaded Rat brain striatal slices was investigated. Potassium induced depolarisation caused an efflux of gamma-hydroxybutyrate in the incubation medium. This release is significantly decreased by a calcium free medium, containing magnesium salt and EGTA.

[Turnover of gamma-aminobutyric acid (GABA) in neurons and glial cells of the chick embryo in culture].

The turnover rates of gamma-aminobutyric acid (GABA) in cultured neurons and glial cells of Chicken embryo were measured by using a gas chromatography/mass spectrometric method. The method followed involved monitoring of the time course of changes in the enrichment of deuterium in GABA following incubation with pentadeuterated glutamate in the medium. The GABA turnover rate in neurons was found to be nearly eight fold greater than in glial cells.

A high-affinity, Na+-dependent uptake system for gamma-hydroxybutyrate in membrane vesicles prepared from rat brain.

gamma-Hydroxybutyrate (GHB) is a compared with numerous neuropharmacological properties. The discovery of its biosynthetic system, together with its endogenous repartition, have prompted its possible implication in neurotransmission. The role is also supported by the existence, reported here, of a high-affinity uptake system for GHB (Km = 46.

Ontogeny and distribution of specific succinic semialdehyde reductase apoenzyme in the rat brain.

The ontogeny and distribution in rat brain of specific succinic semialdehyde reductase is described. This enzyme is probably responsible for the synthesis of gamma-hydroxybutyrate in brain. The highest activities and levels of apoenzyme are found in cerebellum, olfactory bulb, septum and median hypothalamus.

High affinity binding sites for gamma-hydroxybutyric acid in rat brain.

The existence of a specific synthesizing enzyme for gamma-hydroxybutyric acid in rat brain has recently been reported. Here, for the first time, we demonstrate the presence of a high affinity, apparently specific binding site for this compound in the same tissue. This binding does not require Na+ and takes place optimally at pH 5.

Immunocytochemical evidence for the existence of GABAergic neurons in the nucleus raphe dorsalis. Possible existence of neurons containing serotonin and GABA.

It has been established that nerve cell bodies of the nucleus raphe dorsalis (NRD) belong to ascending 5-hydroxytryptamine systems. These neurons could be modulated by GABAergic interneurons or interposed GABA neurons. A high glutamate decarboxylase (GAD) activity in the NRD and a specific high-affinity uptake mechanism for GABA suggest the presence of GABA synthesizing elements in the NRD.

Immunocytochemical localization in rat brain of the enzyme that synthesizes ?-hydroxybutyric acid.

?-Hydroxybutyric acid, a reductive catabolite of GABA, has numerous neuropharmacological and neurophysiological properties when injected systematically to animals. Recently, a specific succinic semialdehyde reductase (SSR2) has been isolated from rat brain. This enzyme specifically produces [(3)H]?-hydroxybutyrate from [(3)H]GABA when incubated in vitro with rat brain tissue slices.

A radioautographic and immunocytochemical study of the GABA systems of the habenula complex in the rat.

Radioautography of [(3)H]GABA accumulation and immunocytochemistry of glutamate decarboxylase have been used to study anatomically and morphologically the GABA system of the rat habenular (Hb) complex. Radioautographic visualisation of GABA specific neurons show a very high innervation of the complex including both stria medullaris (SM), the habenular commissure and the periventricular thalamic fibers (FPVT). A massive labeled fiber system in the SM appears to divide into two branches when it reaches the Hb nuclei: a part of fibers continue their course dorsally to the nuclei up to the habenular commissure; other fibers enter the Hb lateralis or run along the ventral Hb medialis at the level of FPVT.

Regional and subcellular localization in rat brain of the enzymes that can synthesize gamma-hydroxybutyric acid.

Rat brain contains two major NADPH-linked aldehyde reductases that can reduce succinate semialdehyde to 4-hydroxybutyrate. One of these enzymes appears to be fairly specific for succinate semialdehyde and is not significantly inhibited by classic aldehyde reductase inhibitors such as barbiturates. The other enzyme can reduce several aromatic aldehydes and is strongly inhibited by barbiturates and branched-chain fatty acids.

Glutamate decarboxylase activity in brain regions of differentially-housed mice; a difference in the olfactory bulb.

Glutamate decarboxylase (GAD) activities were determined in homogenates of 8 brain regions of mice that had been differentially housed ("isolated" vs "grouped") for 4--9 weeks. GAD activity was lower in whole forebrains and in olfactory bulbs of isolated mice, changes which might be associated with their increased aggressiveness.

Brucella endocarditis on double valvular prosthesis.

The case is reported of a 48-year-old man suffering from Brucella endocarditis on a double prosthesis. The successful medical and surgical treatment is described. So far as the authors know, this is the first report of Brucella endocarditis from a heart valve prosthesis.