Immobilization stress-induced thymocyte apoptosis in rats

Immobilization of rats is a well known model of emotional stress. We studie d apoptosis in rat thymocytes during immobilization for 2-8 hours (h). Term inal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (T UNEL)-positive cells increased with time of immobilization. The positive ce lls increased significantly after 2 h and comprised about 33% of total cell s after 8 h. The apoptotic cells aggregated as scattered foci predominantly in the cortex of the thymus and diffusely distributed with time of the str ess. The DNA laddering also increased with time of immobilization, which wa s inhibited by a glucocorticoid receptor antagonist, RU-486. These results suggest that the emotional stress evoked by immobilization induces thymocyt e apoptosis through glucocorticoid overflow. (C) 2001 Elsevier Science Inc. All rights reserved.