To study the protective effects of oral sodium pyruvate on microstructural changes of L5 dorsal root ganglion in rats subjected to simulated weightlessness.

Forty male Sprague-Dawley rats were randomly divided into groups of normal control drinking regular water (group CON), tail-suspension drinking regular water (group SUS), tail-suspension drinking normal saline (group SAL) and tail-suspension drinking pyruvate saline (group PYR). After the microgravity for 8 weeks, both sides of L5 dorsal root ganglion were taken out. Cell morphology with hematoxylin eosin staining and Nissl body shape with toluidine blue staining examined by light microscopy and mitochondria observed by electron microscopy were carried out with dorsal root ganglion. Glial cell line-derived neurotrophic factor and glial fibrillary acidic protein protein expressions were measured by Western-blot. ATP contents and ATPase activities were also detected. Four groups of samples were compared using analysis of variance.

Compared with groups SUS and SAL, dorsal root ganglion cells showed no obvious swelling and gap widened. Their Nissl bodies were staining darker and mitochondrial structure was integral in group PYR. Western-blot determinations revealed that the glial cell line-derived neurotrophic factor expression in group PYR was increased with 223% and 212%, compared with group SUS and group SAL, respectively; the glial fibrillary acidic protein level was decreased in both group SUS and group SAL by 28% and 24% in comparison with group PYR, respectively, the differences were statistically significant (with P values below 0.05). In metabolic parameters, ATP contents in group PYR were enhanced by 35% and 38%, relative to groups SUS and SAL, respectively. ATPase activities in group PYR were improved with 42% and 51%, relative to groups SUS and SAL, respectively, the differences were statistically significant (with P values below 0.05). ATP contents and ATPase activities in group PYR were all preserved. All the parameters in group PYR were not statistically significant different from those in group CON(with P values above 0.05).

The dorsal root ganglion and its organelles in both structure and function were injured in rats subjected with 8-week simulated weightlessness; oral pyruvate could alleviate damage of dorsal root ganglion in the early stage of microgravity.