MODULATION OF APOPTOSIS BY STARVATION - MORPHOLOGICAL AND BIOCHEMICAL-STUDY OF RAT INTESTINAL-MUCOSA

Morphology at light and electron microscopic levels, expression and ac tivation of transglutaminase and DNA fragmentation at internucleosomal sites were used as markers to study the effect of starvation on the a poptosis of small intestinal epithelial cells, The cells entering apop totic programme in well-fed animals undergo many morphological changes in apical cytoplasm involving alterations in actin cytoskeleton organ isation which may cause a discharge of microvilli, Some free floating cells in the intestinal lumen show characteristics of apoptotic cell d eath, e.g. shrinkage of cell and peripheral condensation of chromatin, while mitochondria and lysosomes remain unchanged, Apoptotic bodies a re also seen in scanning electron micrographs, During progressive star vation, epithelial cells do not enter the apoptotic cell death program me, Biochemical markers for apoptosis such as increased transglutamina se activity and DNA fragmentation are clearly discernible in normally fed animals, The percentage of cells labelled immunohistochemically by antibody against transglutaminase decreased during starvation while D NA fragmentation was absent, The exact mechanism for suppressing apopt osis in intestinal cells under starvation is not known, However, the d ata presented here support the existence of such a regulatory process.