Electron microscopic demonstration of nick end-labeled DNA fragments during capsaicin-induced apoptosis of trigeminal primary neurons in neonatal rats

DNA fragmentation was induced in the trigeminal ganglion of newborn rats by subcutaneous capsaicin injection (50 mg/kg). Twenty-four hours later, nume rous roundish profiles were intensely labeled by both a DNA polymerase I-me diated nick translation method and a terminal transferase-mediated tailing method. Direct electron microscopic examination of labeled profiles indicat ed that the labeled profiles were neurons at earlier stages of apoptosis. D NA fragmentation signal was first detected in the nucleoplasm and later spr ead to the cytoplasm. The cell finally disintegrated forming many small apo ptotic bodies. DNA fragmentation signal in the apoptotic bodies was readily labeled by the tailing but not the translation method. (C) 1999 Elsevier S cience B.V. All rights reserved.