Study suggests circadian rhythms may influence the neurotherapeutic potential of intermittent hypoxia

Mia Kelly

Rehabilitation Science doctoral student, Mia Kelly, published her article in the American Journal of Physiology- Regulatory Integrative and Comparative Physiology entitled, “Circadian clock genes and respiratory neuroplasticity genes oscillate in the phrenic motor system.”

Circadian rhythms are about 24-hour biological cycles that help anticipate changes throughout the day as well as adapt to changes in the environment. In this study, Mia found that genes that encode core components of the circadian clock are expressed rhythmically in the phrenic/diaphragm motor system. She and the Mitchell Lab hypothesize that clock genes may play important roles in circadian regulation of motor function (i.e. breathing) in addition to respiratory neuroplasticity elicited by rehabilitation.

The laboratory of Dr. Gordon Mitchell has pioneered research in a novel treatment to increase signals from the brain stem and spinal cord to respiratory muscles, called acute intermittent hypoxia (AIH). The molecules that increase following AIH treatment include neuromodulators like serotonin and growth factors like brain-derived neurotrophic factor (BDNF). This study also found that, in rats, just before bedtime, BDNF gene expression peaks – around 60% higher than its trough during the rest phase of the circadian cycle. Since new BDNF must be made for AIH to exert its neuroplastic effects, this study suggests that timing of treatment may be a valuable next step to harness the neurotherapeutic potential of AIH in situations where ventilation is compromised.