Caspase activation during spontaneous and radiation‐induced apoptosis in the murine intestine

The aim of this study was to characterize the activation of caspase‐3 along the crypt/villus axis in the normal and irradiated intestine and to compare active caspase‐3 expression with existing apoptosis detection techniques. Small and large intestine were removed from mice at various time points after exposure to 8 Gy γ‐radiation. Positive apoptotic cells stained with an antibody against active caspase‐3, haematoxylin and eosin (H&E) or TUNEL were scored in histological sections of small and large intestinal crypts and villi. In the control intestine, active caspase‐3 expression was rarely observed; however, expression was markedly increased following exposure to radiation and was predominantly confined to apoptotic bodies. Measurement of apoptosis in intestinal crypts using active caspase‐3 expression gave similar results to apoptosis detected from H&E‐stained sections. In the normal villus, active caspase‐3 expression was observed infrequently and did not significantly increase following radiation, consistent with a lack of apoptotic body formation from H&E sections. This study indicates that caspase‐3 is activated in intestinal crypts but not in villi following γ‐radiation. Active caspase‐3 detection compared favourably with existing immunological techniques, suggesting that it is a suitable alternative method for apoptosis quantification. Copyright © 2001 John Wiley & Sons, Ltd.