Dietary Restriction May Attenuate the Expression of Cell Death-Related Proteins in Rats with Acute Spinal Cord Injury

OBJECTIVE: There is currently no effective treatment for spinal cord injuries (SCIs). Previous studies have shown that every-other-day fasting (EODF), a dietary restriction method, can reduce SCI size and promote motor function recovery, making it a potential novel treatment. However, the mechanism that underlies the positive impact of EODF on SCI remains unclear. Caspase-dependent apoptosis and necroptosis, which involve receptor-interacting protein kinase (RIPK), drive the loss of nerve cells and restrict motor function recovery after SCI. Dietary restriction has a significant inhibitory effect on Caspase and RIPK expression. This study aimed to investigate whether the EODF diet achieves a neuroprotective effect by inhibiting Caspase-dependent apoptosis and RIPK-dependent necroptosis after SCI. METHODS: The model rats underwent EODF for 4 weeks before SCI or started EODF diet immediately after SCI. Immunoblotting and immunohistochemical analyses were used to assess the impact of the intervention on protein expression. Apoptosis in the spinal cord was detected by TdT-mediated dUTP nick-end labeling. RESULTS: Immunoblotting analysis results revealed that the levels of both RIPK1 and RIPK3 proteins in the injury zone were reduced at 6, 12, and 24 hours and at 3 and 7 days after SCI, respectively. Immunohistochemistry results showed that EODF reduced the expression of Caspase-3 and Bax proteins, while prophylactic EODF decreased the rate of apoptosis detected by TdT-mediated dUTP nick-end labeling within 3 days after SCI. CONCLUSIONS: These findings indicate that the mechanism by which EODF exerts neuroprotective effects may be related to the simultaneous inhibition of apoptosis and necroptosis in SCI.