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 (SSR₂) in the same brain section has been developed. SSR₂ is the enzyme responsible for the transformation of succinic semialdehyde into γ-hydroxybutyrate (GHB). GAD was detected using specific rabbit GAD-antibodies and unlabeled antibody enzyme peroxidase antiperoxidase, and SSR₂ using specific guinea-pig SSR₂ antibodies conjugate to a fluorescein-labeled second antibody. The coexistence of GAD and SSR₂ in the same neuron was demonstrated by a peroxidase reaction superimposed on fluorescent compounds. Cell bodies containing both antigens were observed in the cerebellum, dorso-median hypothalamus and raphe nuclei. GHB is present in most GABA containing neurons. Some neurons contain only SSR₂; these neurons may synthesize GHB by an active uptake of GABA.