A search for immunoreactive substance P and other neural peptides in the limb regenerate of the newt Notophthalmus viridescens

Abstract

Immunochemical studies demonstrate that the undecapeptide substance P (SP) may be detected by radioimmunoassay in newt limb regenerates and that SP is localized in the blastemal epidermis by immunofluorescence and peroxidase-antiperoxidase staining. Immunoreactive SP is predominantly distributed at the periphery of epidermal cells, suggesting the presence of SP binding sites on the cell surface; the basal germinative layer of the epidermis and blastemal mesenchyme cells remain unreactive. The pattern of SP immunoreactivity in the blastema was compared with that of four other tachykinin-family peptides (eledoisin, kassinin, substance K, and neuromedin K) and with three non-tachykinin neural peptides (bombesin, neurotensin, and metenkephalin). With the exception of neurotensin, which showed weak staining in the basal layer but an absence in the peripheral layers of the epidermis, none of the peptides examined exhibited immunoreactivity in the blastema epidermis comparable to that of SP.