Distribution of protein gene product 9.5 (PGP 9.5) immunoreactivity in the dorsal root ganglia of adult rat.

The rat dorsal root ganglia (DRG) contain heterogeneous subpopulations of sensory neurons as demonstrated by ultrastructural, histochemical and immunohistochemical methods. In this study we investigated whether phenotypic heterogeneity occurs in the distribution of protein gene product 9.5 (PGP 9.5) in DRG neurons of adult rats by combined immunohistochemical and image analysis (neuron-size and intensity of immunostaining) techniques. Moreover, the effect of different fixatives on the expression of PGP 9.5 was analyzed. PGP 9.5 immunoreactivity (IR) was observed in all primary sensory neurons and in the axons of the ganglionic nerve fibres, but not in the satellite glial cells or Schwann cells. Data from a quantitative study demonstrated that DRG neurons displayed a homogeneous pattern of PGP 9.5 IR which was not affected by fixatives, and no correlation between neuron size and intensity of immunostaining was encountered. Thus, as reported for other neuronal and neuroendocrine cell proteins, no heterogeneity exists in the phenotypic expression of immunohistochemically demonstrable PGP 9.5 in sensory neurons of the adult rat DRG.