Molecular and genetic features of a labeled class of spinal substantia gelatinosa neurons in a transgenic mouse

Genetic incorporation in a mouse of a transgene containing the prion promoter and the green fluorescent protein (GFP) coding sequence labels a set of substantia gelatinosa (SG) neurons (SG-GFP) homogenous in morphology, electrophysiology, and gamma-amino-butyric acid expression. In the present analysis the SG-GFP neurons are established to have protein kinase C-beta II immunoreactivity and to lack evidence for the presence of calbindin D-28k, parvalbumin, and protein kinase C-gamma. These neurons were hyperpolarized by mediators of descending control, norepinephrine and serotonin. Sequential polymerase chain reactions established the insertion of the transgene to be in the receptor protein tyrosine phosphatase kappa (RPTP-K) and the laminin receptor 1 (ribosomal protein SA) pseudogene 1 locus. RPTP-K expression in both GFP-labeled dorsal root ganglia and SG neurons raises the possibility that homophilic interactions of RPTP-K contribute to establishment of connections between specific classes of primary afferent and SG neurons.