Daily acute intermittent hypoxia improves breathing function with acute and chronic spinal injury via distinct mechanisms

This study investigates how daily acute intermittent hypoxia (dAIH) can improve breathing after spinal cord injuries in rats. The researchers found that dAIH helps restore breathing function whether the injury is recent (2 weeks) or chronic (8 weeks), but it does so through different biological mechanisms. Specifically, they looked at the role of serotonin, a chemical messenger in the brain, and found that dAIH relies on serotonin-independent mechanisms shortly after the injury, but shifts to using serotonin-dependent mechanisms as the injury becomes chronic.

• 1
  dAIH-induced recovery of breathing capacity transitions from a serotonin-independent mechanism with acute C2Hs to a serotonin-dependent mechanism with chronic C2Hs.
• 2
  With acute C2Hs, dAIH-induced improvements in V̇E occurred through enhancement of respiratory frequency versus VT generating capacity.
• 3
  dAIH with chronic C2Hs appears to rely on serotonergic signaling mechanisms. dAIH treatment alone enhanced VT generating capacity to normal levels.