Coexistence of Peptides in Primary Afferent Neurons

Abstract

Primary afferent neurons have been shown with immunohistochemistry to contain a variety of peptide-like substances. In fact, some neurons contain more than one peptide (Dalsgaard et al, 1982; Wiesenfeld-Hallin et al, 1984; Leah et al, 1985; Lee et al, 1985; Skofitsch and Jacobowitz, 1985; Tuchscherer and Seybold, 1985; Gibbins et al, 1987). We are interested in the possibility that particular peptides, alone or in combination, may be markers for functional categories of sensory neurons or targets of these neurons. Toward this end, we have studied the expression of peptide-immunoreactivity in dorsal root ganglion cells of cat and rat. Post-translational modification of amino acid sequences contained in the peptide precursor molecules, however, may alter the antigenic determinants expressed in a perikaryon. An antigenic determinant visualized in a neuronal perikaryon by immunohistochemistry may be cleaved or modified to an unrecognizable sequence, or the epitope recognized by an antibody may be created. For this reason we have also investigated the coexistence of peptide-immunoreactivities in axonal varicosities of primary afferent neurons in the spinal cord.