Uptake of [3H]GABA by oligodendrocytes in dissociated brain cell culture: a combined autoradiographic and immunocytochemical study.

Uptake of [3H]GABA by dissociated mixed cell cultures of fetal mouse brain was studied using light microscopic autoradiography. Major cell types in the cultures were identified and quantified by immunocytochemical localization of reliable cell type-specific antigenic markers. In 12 days in vitro (DIV) cultures [3H]GABA uptake was predominantly into neurons and oligodendrocytes, whilst at 28 DIV the only surface cells labeled were oligodendrocytes. This was confirmed by complement-dependent antibody-mediated cytotoxicity against galactocerebroside-positive oligodendrocytes. There was a moderate labeling of almost all flat cells, the majority of which were glial fibrillary acidic protein (GFAP)-positive astrocytes. Heavily labeled astrocytes were only occasionally observed. Oligodendrocytes accumulated [3H]GABA more rapidly than astrocytes but slower than neurons. Oligodendroglial labeling was predominantly over the cell body, whereas neuronal labeling was more uniformly distributed over cell body and processes. The uptake was inhibited by diaminobutyric acid (DABA) and nipecotic acid, but not by beta-alanine, and thus had similar characteristics to neuronal rather than astroglial uptake. Oligodendrocytes did not accumulate [3H]beta-alanine, which labeled only astrocytes. Oligodendroglial [3H]GABA uptake was Na+-dependent and sensitive to ouabain, but was only slightly enhanced by aminooxyacetic acid (AOAA), whereas astroglial uptake was not sensitive to ouabain but was markedly enhanced by AOAA. The results indicate that oligodendrocytes, in addition to astrocytes, may also be involved in the modification of neuronal function by the uptake and inactivation of neuroactive substances.