Long-term freewheel training in young animals decreases intestinal lymphocyte expression of inflammatory cytokines and apoptotic proteins. Little is known about these responses in older animals.
Purpose: This study aimed to evaluate the effect of training on intestinal lymphocyte expression of proinflammatory and anti-inflammatory cytokines and proapoptotic and anti-apoptotic proteins after an acute exercise challenge in older mice.
Methods: Eighty female C57BL/6 mice, aged 11 months at the start of the study, were randomized to two exercise training conditions for 4 months: access to in-cage running wheels (WR, n = 40) or to a no-running-wheel condition (NWR, n = 40). After 4 months of training, WR and NWR mice underwent a single bout of treadmill exercise with immediate sacrifice (n = 20 and n = 20, respectively) or were sedentary with exposure only to treadmill noise and vibrations without actual running (n = 20 and n = 20, respectively). Plasma 8-iso-PGF2α and corticosterone levels and intestinal lymphocyte cytokine (tumor necrosis factor (TNF)-α, interleukin (IL)-β, IL-10) and apoptotic protein (caspase-3, caspase-7, Bcl-2) expression were assessed by enzyme immunoassay and by Western blotting.
Results: Older (15–16 months) WR mice had greater intestinal lymphocyte expression of proinflammatory (TNF-α, IL-1β) and anti-inflammatory (IL-10) cytokines and proapoptotic (caspase-3, caspase-7) proteins and decreased expression of antiapoptotic (Bcl-2) proteins after acute treadmill challenge relative to older WR sedentary mice. Older NWR mice had few changes in intestinal lymphocyte cytokine or apoptotic protein expression after an acute treadmill exercise relative to NWR sedentary mice.
Conclusions: Long-term freewheel training preserves the intestinal lymphocyte cytokine and apoptotic protein responses in older mice similar to that previously reported for young animals. Older NWR (untrained) mice have blunted responsiveness (cytokines and apoptotic protein expression) after acute exercise suggestive of immunosenescence.