Serotonergic collateralized projections from Barrington's nucleus to the medial preoptic area and lumbo-sacral spinal cord

In this study, we employed triple fluorescent labelling to reveal the distribution of the direct serotonergic neurons within Barrington's nucleus (BN) that supply branching collateral input to the medial preoptic area (MPA) and to the lumbo-sacral spinal cord (LSC). Immunocytochemical detection of the monoclonal antibody raised against serotonin was used for identification of the neurons. The projections were defined by injections of two retrograde tracers: fluoro gold and rhodamine in the MPA and LSC, respectively. The aim of this study is to identify the direct projections to BN and MPA and/or LSC. The present study confirms findings of others describing BN-LSC projections and extends previous findings by demonstrating an single or collateralized fibers with MPA, and serotonergic immunoreactive fibers.