Benzodiazepine binding sites: localization and characterization in the limbic system of the rat brain.

The distribution of benzodiazepine binding sites was analysed in limbic structures of rat brain by quantitative radioautography of brain sections incubated with 3H-flunitrazepam (3H-FLU). Quantitative estimation of the binding parameters was made in each range of postero-anterior sections taken. Distribution of 3H-FLU binding sites was found to be rather homogeneous in most of the structures examined but there were regional differences which resulted from variations in the densities of sites rather than in their affinities.

Evidence for the localization of 5HT1A binding sites on serotonin containing neurons in the raphe dorsalis and raphe centralis nuclei of the rat brain.

Precise anatomical distribution of 5HT1 binding sites has been investigated in the nuclei raphe dorsalis, raphe centralis and locus caeruleus of the rat brain. An original pattern of distribution was observed in the raphe nuclei, closely correlated to the already known distribution of 5HT containing elements. This pattern, more pronounced when 5HT1A sites were labelled, completely disappeared after lesioning by 5, 7DHT indicating the presence of this subtype of 5HT1 binding sites on 5HT containing neurons.

Immunocytochemical evidence for the presence of enzymes synthesizing GABA and GHB in the same neuron.

A specific and sensitive immunocytochemical double staining for visualization of glutamate decarboxylase (GAD) and semialdehyde succinate reductase (SSR(2)) in the same brain section has been developed. SSR(2) is the enzyme responsible for the transformation of succinic semialdehyde into ?-hydroxybutyrate (GHB). GAD was detected using specific rabbit GAD-antibodies and unlabeled antibody enzyme peroxidase antiperoxidase, and SSR(2) using specific guinea-pig SSR(2) antibodies conjugate to a fluorescein-labeled second antibody.

Depolarization-evoked release of gamma-hydroxybutyrate from rat brain slices.

The release of gamma-hydroxybutyrate from preloaded rat brain striatal slices was investigated. K+-induced depolarization caused an efflux of gamma-hydroxybutyrate of about 50 fmol min-1 mg-1 (wet weight), but in a Ca2+-free medium containing Mg2+, the evoked release was reduced by 50-60%. The release was higher when 100 microM veratridine was used as a depolarizing agent.

Immunohistochemical evidence for neuronal and non-neuronal synthesis of GABA in the rat subcommissural organ.

In the past few years, several studies have demonstrated in the rat subcommissural organ the presence of nerve endings and modified ependymocytes showing an uptake of [(3)H]GABA. The present work was performed to demonstrate in this cerebral zone the possibility of a GABA synthesis by the immunohistochemical localization of glutamate decarboxylase (GAD). GAD-positive reaction was detected with unlabelled antibody-enzyme peroxidase anti-peroxidase.