title: Apoptotic and inflammatory cytokine protein expression in intestinal lymphocytes after acute treadmill exercise in young and old mice.
abstract: OBJECTIVE
  Gastrointestinal disturbances are common in athletes following intense exercise. Variations in apoptotic protein expression and cell death may contribute to acute exercise-induced intestinal inflammation. The effect of age on apoptotic protein response in the intestinal compartment in response to exercise is not known. Using a mouse model, we examined the effects of a single bout of treadmill running in young and old mice on intestinal lymphocyte (IL) expression of the apoptosis-inducing cytokine TNF-α, the pro-apoptotic proteins caspase-3 and 7, the anti-apoptotic protein Bcl-2, and IL apoptotic status (% AnnexinV+).
  
  
  METHODS
  Young (3-4 months, N.=44) and old (13-14 months, N.=45) female C57Bl/6 mice were randomized to treadmill exercise (10 min warm-up, 20 min at 22 m min-1, 30 min at 25 m min-1, 30 min at 28 m min-1, 2º slope) with sacrifice immediately (IMM) or 2hr after (2Hr), or to a non-exercised control (SED). IL were removed and prepared for analysis of % apoptosis (flow cytometry) and determination of apoptotic protein and cytokine expression (Western blotting). Plasma corticosterone and 8-iso-PGF2α were measured by EIA.
  
  
  RESULTS
  Exercise was associated with a higher IL expression of caspase-3 in IMM and 2Hr groups vs. SED (P<0.001), a higher expression of TNF-α in the IMM group vs. SED (P<0.001), and a lower Bcl-2 expression in the IMM and 2Hr groups vs. SED (P<0.01). There was a trend (P=0.07) for increased caspase-7 expression after exercise. IL caspase-3 and 7 and TNF-α expression did not differ by age whereas Bcl-2 expression was lower (P<0.001) and % Annexin V+ IL was higher (P<0.05) in old vs. young mice. Plasma corticosterone and 8-iso-PGF2α were higher (P<0.001 and P<0.05) in IMM vs. SED mice but did not differ by age.
  
  
  CONCLUSIONS
  The expression of the pro-apoptotic proteins, caspase-3 and caspase-7, and the apoptosis-inducing cytokine, TNF-α, in IL did not differ by age in this animal model in response to a single intense exercise challenge. However, Old mice had lower expression of the 'protective' anti-apoptotic protein Bcl-2 and a higher percentage of early apoptotic IL. Whether repeated exercise results in less IL resiliency in elderly individuals remains to be determined.
authors.affiliation: School of Public Health and Health Systems, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: N
authors.initials: N
authors.lastname: Packer
authors.forename: L
authors.initials: L
authors.lastname: Hoffman-Goetz
mesh_terms: D000367:Age Factors; D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D003345:Corticosterone / Q000097:blood; D015237:Dinoprost / Q000031:analogs & derivatives / Q000097:blood; D005260:Female; D008214:Lymphocytes / Q000378:metabolism*; D051379:Mice; D010581:Peyer's Patches; D005082:Physical Exertion / Q000276:immunology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D017304:Annexin A5; D019253:Proto-Oncogene Proteins c-bcl-2; D014409:Tumor Necrosis Factor-alpha; C075750:8-epi-prostaglandin F2alpha; D015237:Dinoprost; D053148:Caspase 3; D053179:Caspase 7; D003345:Corticosterone