Different myelination of rat septohippocampal fibres as revealed by immunofluorescence double-labelling

The present study focuses on the myelination of rat septohippocampal fibres that are known to originate from GABAergic parvalbumin-containing, fast-firing, fast-conducting neurons and from cholinergic slow-firing, slow-conducting neurons. With the combined immunofluorescence for parvalbumin/myelin basic protein and choline acetyltransferase/myelin basic protein it was shown that the vast majority of parvalbumin-containing fibres are myelinated, but the choline acetyltransferase-containing fibres are not. Accordingly, our results confirm the expectation that conduction velocities and presence or absence of myelin sheaths are also correlated in the septohippocampal pathway. (C) 2000 Elsevier Science B.V. All rights reserved.