In vitro apoptosis of lymphocytes after exposure to levels of corticosterone observed following submaximal exercise.
BACKGROUND
To evaluate the in vitro effects of corticosterone, equivalent to blood levels measured after a single submaximal treadmill exercise, on apoptosis and necrosis of mouse thymic and peripheral lymphocytes.


METHODS



METHODS
analysis of variance with independent factors of time (0, 90, 210 minutes of incubation) and concentration of corticosterone (0, 150, 250, 450, 850 ng/ml).


METHODS
percentage of apoptotic, necrotic, and viable thymocytes and splenocytes determined by flow cytometry using Annexin V-FITC antibody and propidium iodide.


RESULTS
There was a significantly higher % of apoptotic thymocytes at 210 min at the higher corticosterone concentrations but not in % of apoptotic splenocytes at the same time point. For both lymphoid populations, corticosterone incubation was associated with a higher % of necrotic cells at 210 minutes but not at 0 or 90 minutes. For thymocytes, the interaction (time x concentration) was significant, with greater % necrosis observed at the lower (150 and 250 ng/ml) concentrations of corticosterone.


CONCLUSIONS
The data suggest that in vitro exposure to corticosterone, at physiological concentrations (< or = 450 ng/ml) observed after a moderate exercise stress, induces apoptosis in thymocytes and necrosis in both thymocytes and splenocytes. The implications for exercise-mediated glucocorticoid regulation of immune function remain to be investigated.
Hoffman-Goetz
L
L
Department of Health Studies and Gerontology, Faculty of Applied Health Sciences, University of Waterloo, Ontario, Canada.
Zajchowski
S
S
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D003345:Corticosterone / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D008214:Lymphocytes / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D010805:Physical Conditioning, Animal
D000893:Anti-Inflammatory Agents; D003345:Corticosterone