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In the central nervous system, two subtypes of sodium- and chloride-coupled GABA transporter exist. One is sensitive to ACHC, the other to beta-alanine. They are thought to be of neuronal and glial origin, respectively. GABA transport in membrane vesicles derived from astroglial cells was found to be sodium- and chloride-dependent, electrogenic and much more sensitive to beta-alanine than to ACHC. Immunoblotting with antibodies directed against a variety of sequences of the ACHC-sensitive transporter indicated that none of these epitopes was shared by the glial transporter.

Oligodendrocytes were isolated from the white matter of young trout by Percoll density centrifugation of enzymatically dissociated tissue and cultured on poly-D-lysine-coated petri dishes. Using antisera recognizing myelin-specific compounds of fish CNS (36K, IP2) up to 72% of the isolated cells could be identified as oligodendrocytes with an average yield of 4 x 10(6) cells per gram of wet tissue. Taken in culture, the cells rapidly regenerated their processes and soon acquired a morphology closely resembling mammalian oligodendrocytes in vitro. On the other hand, in terms of phenotypic expression, interesting parallels were revealed with the known in vitro behavior of Schwann cells: Galactocerebroside, which in mammalian oligodendrocytes is persistently expressed over longer periods of time in vitro, rapidly disappeared from the surface of cultured trout oligodendrocytes. In contrast, the fish CNS myelin glycoprotein IP2, which like IP1 is immunologically related to the major myelin product of Schwann cells, P0, was continuously expressed over several weeks in culture. Two other myelin protein constituents, 36K and IP1, transiently declined in vitro, but later on fully reappeared in the glial cells of trout. The present cell culture system offers an experimental model for studying in vitro the factors underlying oligodendroglial regeneration and remyelination in the fish CNS.