Oral Pyruvate Protection of Dorsal Root Ganglia in Simulated Weightlessness Rats
Abstract Background: Previous studies demonstrate that long-tern microgravity induces multi-organ injury and dysfunction, including the dorsal root ganglia (DRG) damage. This study investigated oral pyruvate protective effects on lumbar 5 (L5) DRG nerve tissues in rats subjected to hindlimb unweighting (HU).Results: Male Sprague-Dawley rats were randomly assigned to four groups (n=10): control group (Group CON), suspension group (Group SUS), normal saline group (Group SAL) and sodium pyruvate group (Group PYR), respectively. The rats of SUS, SAL and PYR groups were simulated with microgravity by tail suspension of HU for 8 weeks. Rats in Groups SAL and PYR fed with normal saline and pyruvate saline, respectively. Histopathological and immunofluorescence examinations were conducted and levels of glial cell line-derived neurotrophic factor (GDNF), glial fibrillary acidic protein (GFAP), ATP and ATPase were measured in DRG tissues; L5 spinal cord scans were also carried out in rats following HU. Results showed that the HU resulted in significant alterations in DRG nerve tissues’ structure and function in Groups SUS and SAL, whereas morphological changes were not significantly distinguished between Group PYR and Group CON; GDNF, GFAP, ATP and ATPase levels were mostly preserved in Group PYR, but still worse than in Group CON. The significance of oral pyruvate protection against DRG injury following HU and the dose and formula of oral pyruvate solutions were discussed for use in astronauts’ spaceflight.Conclusions: oral pyruvate effectively protected L5 DRG from pathological alterations and dysfunction induced by the HU in rats. Further studies and clinical trials are warranted.