5-HT nerve terminals in the fourth ventricle of the rat brain: Their identification and distribution studied by fluorescence histochemistry and electron microscopy

摘要

The occurrence and distribution of supra-ependymal nerve terminals storing serotonin (5-HT) are described for the fourth ventricle of the rat brain. The nerve terminals were identified as monoaminergic 1) fluorescence-histochemically, by the presence of a varicose, formaldehyde-induced fluorescence (FIF) on the free surface of the ependyma, 2) electron microscopically, by the presence of electron dense (chromaffin) cores in small (50 nm) and large (100 nm) vesicles found within the varicose regions of supra-ependymal nerve fibres, and 3) by the absence of both the FIF and chromaffin dense cores after treatment with reserpine. Moreover, the serotonergic nature of these nerve fibres could be concluded from 1) the yellow colour of the FIF, 2) the increased FIF after treatment with nialamide or reserpine+nialamide, 3) the diminished FIF and absence of chromaffin dense cores after treatment with p-CPA, and finally 4) the persistence of the FIF and chromaffin dense cores after treatment withα-MPT