Skin-visceral divergent projection of cholecystokinin — containing dorsal root ganglion neurons: A tri-labelling study with fluorescent tracers and immunohistochemistry

Abstract

Skin-visceral divergent projections of cholecystokinin (CCK)-containing dorsal root ganglion neurons were studied by combined technique of fluorescent double-labelling and immunohistochemistry. Fast blue (FB) and nuclear yellow (NY) were injected into the coeliac ganglion and the cutaneous branches of left 9th–11th intercostal nerves, respectively. Three kinds of neurons labelled with fluorescein were observed in T_9-11 dorsal root ganglia: FB-labelled neurons with blue-fluorescent cytoplasm; NY-labelled neurons with yellow-fluorescent nucleus and double-labelled neurons with blue cytoplasm and yellow nucleus. The double-labelled neurons were found to account for 2.8 % of total labelled neurons. The sections containing neurons labelled with fluorescein were stained by CCK-immunohistochemical procedure. Four kinds of neurons could be identified: NY-neurons with CCK-immunoreactivity (NY+CCK); FB-neurons with CCK-immunoreactivity (FB+CCK); NY+FB neurons with CCK-immunoreactivity (NY+FB+CCK); and neurons only CCK-positive. NY+FB+CCK tri-labelled neurons accounted for approximately 11.5 % of NY+FB double-labelled neurons, and for 0.4 % of all CCK-positive neurons. The findings clearly indicated that the peripheral processes of some sensory dorsal root ganglion neurons divergently project to both skin and visceral structure and contain CCK.

Keywords

fluorescent tracers / immunohistochemistry / cholecystokinin / dorsal root ganglion neurons / divergent projections

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