Elsevier

Brain Research Bulletin

Volume 20, Issue 2, February 1988, Pages 233-240
Brain Research Bulletin

Article
Serotonergic and nonserotonergic projections from the rat interpeduncular nucleus to the septum, hippocampal formation and raphe: A combined immunocytochemical and fluorescent retrograde labelling study of neurons in the apical subnucleus

https://doi.org/10.1016/0361-9230(88)90183-9Get rights and content

Abstract

This study examined the subnuclear distribution and transmitter content of neurons in the interpeduncular nucleus (IPN) that projected to the septum, dorsal hippocampal formation, and/or raphe. Following the injection of fast blue into the medial septum/diagonal band nucleus and rhodamine-conjugated microspheres into the dorsal hippocampal formation (or vice versa), retrogradely-labelled cells were found throughout the apical subnucleus of the IPN. Incubation of these sections with 5-hydroxytryptamine antiserum indicated that a small number of fast blue- or rhodamine-positive cells also contained serotonin. Occasional apical cells contained both fast blue and rhodamine, indicating a dual projection via collaterals to both the septum and hippocampus. Injection of either dye into the raphe also retrogradely labelled cells in the apical subnucleus, none of which contained serotonin. These results suggest that the IPN may function to integrate the activity within subcortical limbic nuclei via widespread Serotonergic and nonserotonergic projections.

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    This study was supported by grants from The Pennsylvania State University (G.S.H.) and the Medical Research Committee, University of Louisville Medical School (B.F.).

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