SUBPOPULATIONS OF PRIMARY SENSORY NEURONS SHOW COEXISTENCE OF NEUROPEPTIDES AND GLUCOCORTICOID RECEPTORS IN THE RAT SPINAL AND TRIGEMINAL GANGLIA

The coexistence of the neuropeptides substance P, calcitonin gene-rela ted peptide, galanin, somatostatin and neuropeptide Y with glucocortic oid receptors was studied in neurons of the rat lumbar dorsal root and trigeminal ganglia by means of the double immunofluorescence techniqu e. Based on analysis of microphotographs, about one-third of the popul ations of nerve cells (small and large) containing substance P or calc itonin gene-related peptide immunoreactivity (IR) showed nuclear gluco corticoid receptor IR. A similar pattern was observed within the dorsa l root and trigeminal ganglia. Furthermore, within the lumbar dorsal r oot ganglia 50% of the small neurons, containing galanin IR, possessed nuclear glucocorticoid receptor IR of moderate intensity. Glucocortic oid receptor IR was not observed in the galanin immunoreactive neurons of the trigeminal ganglion neither in the somatostatin and NPY immuno reactive neurons of both the dorsal root and the trigeminal ganglia. T he results provide a chemical anatomical basis for a direct regulation by glucocorticoids of distinct populations of substance P and calcito nin gene-related peptide immunoreactive nerve cells in the lumbar spin al and trigeminal ganglia and of galanin immunoreactive nerve cells of the spinal but not of the trigeminal ganglia.