Figure 9.

Incidence of D_1–5 receptor cell labeling in various spinal laminae in comparison to that of the selective neuronal marker NeuN. A. Histograms represent mean number of NeuN⁺ cells per entire spinal hemisegment as a whole (all) or in separate laminae. Values represent averages from 2 animals ± S.E., and values from each animal were obtained as the mean value from 4 separate 10 μm sections. Image at right is a representative section with counted neurons indicated by white dots. Note that laminae I–III contain the greatest neuron density. B. Incidence and distribution of cells labeled with D₁ through D₅ receptor antisense probes expressed relative to the mean number of NeuN⁺ cells obtained in the same 2 animals in A. Percentage of labeled cells are shown for all spinal regions combined. Significant differences were observed between D₂ and D₁, D₂ and D₃, D₂ and D₄, between D₁ and D₅, and D₃ and D₅ (all p<0.001). Differences were also found between D₃ and D₄ (p=0.013) and D₄ and D₅ (p=0.002; all tests: One-Way-ANOVA with All-Pairwise Bonferroni Comparison). C. Incidence and distribution of cells labeled with D₁ through D₅ receptor antisense probes expressed relative to the mean number of NeuN⁺ cells obtained in the same 2 animals in A. Percentage of labeled cells are shown for the separated laminae. Note that D₂ and D₅ receptors appear to be expressed in the largest number of cells throughout the spinal gray matter. Note also that the incidence of labeling in lamina IX (gray bar) is the highest among all laminae for all five receptor subtypes.