Substance P-like immunoreactivity in neurons in dissociated cell cultures of mammalian spinal cord and dorsal root ganglia.

Dissociated cell cultures prepared from fetal mouse spinal cords and dorsal root ganglia were stained for endogenous substance P using the peroxidase-antiperoxidase technique. Substance P-like immunoreactivity was localized within a small percentage of rounded or multipolar neuronal somata and in varicose processes. The substance P-positive multipolar neurons were derived from spinal cord, while the small rounded neurons were possibly of spinal cord and/or sensory ganglion origin. Large dorsal root ganglion neurons were unreactive. These results are consistent with in vivo findings and indicate the feasibility of electrophysiologic studies in culture to analyze the synaptic connections between substance P neurons and their target cells.