Calbindin D28k-containing splanchnic and cutaneous dorsal root ganglion neurons of the rat.

Calbindin D28k (CaBP)-containing splanchnic and cutaneous sensory neurons in the rat dorsal root ganglia (DRGs) were investigated immunocytochemically in combination with a fluorescent dye tracer (Fluoro gold). About 15% of the DRG neurons at Th9-10 levels showed CaBP-like immunoreactivity. Eighty-four % of the splanchnic sensory neurons were immunoreactive to CaBP, while only 3% of the cutaneous sensory neurons were. The diameters of the splanchnic and cutaneous sensory neurons containing CaBP were 23.4 +/- 6.3 microns and 38.4 +/- 8.8 microns, respectively. Splanchnic sensory neurons containing CaBP were sensitive to capsaicin while cutaneous ones were not. These findings suggest that CaBP-containing splanchnic and cutaneous sensory neurons constitute different subgroups among the DRG neurons at the lower thoracic level.