Intermittent fasting improves functional recovery after rat thoracic contusion spinal cord injury

Spinal cord injury (SCI) often results in a loss of motor and sensory function. Currently there are no validated effective clinical treatments. Previously we found in rats that dietary restriction, in the form of every-other-day fasting (EODF), started prior to (pre-EODF), or after (post-EODF) an incomplete cervical SCI was neuroprotective, increased plasticity, and promoted motor recovery. Here we examined if EODF initiated prior to, or after, a T10 thoracic contusion injury would similarly lead to enhanced functional recovery compared to ad libitum feeding. Additionally, we tested if a group fed every day (pair-fed), but with the same degree of restriction as the EODF animals (∼25% calorie restricted), would also promote functional recovery, to examine if EODF's effect is due to overall calorie restriction, or is specific to alternating sequences of 24-h fasts and ad libitum eating periods. Behaviorally, both pre- and post-EODF groups exhibited better functional recovery in the regularity indexed BBB ambulatory assessment, along with several parameters of their walking pattern measured with the CatWalk device, compared to both the ad-libitium-fed group as well as the pair-fed group. Several histological parameters (intensity and symmetry of serotonin immunostaining caudal to the injury and gray matter sparing) correlated with functional outcome; however, no group differences were observed. Thus besides the beneficial effects of EODF after a partial cervical SCI, we now report that alternating periods of fasting (but not pair-fed) also promotes improved hindlimb locomotion after thoracic spinal cord contusion, demonstrating its robust effect in two different injury models.