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-fi ring, fast-conducting neurons and from cholinergic slow-firing, slow-conduc ting neurons. With the combined immunofluorescence for parvalbumin/myelin b asic protein and choline acetyltransferase/myelin basic protein it was show n that the vast majority of parvalbumin-containing fibres are myelinated, b ut the choline acetyltransferase-containing fibres are not. Accordingly, ou r results confirm the expectation that conduction velocities and presence o r absence of myelin sheaths are also correlated in the septohippocampal pat hway. (C) 2000 Elsevier Science B.V. All rights reserved.