| OBJECTIVES To study the effects of resveratrol ( Res ) on secondary spinal cord edema, ultrastuctural changes, lactic acid level ( LD ), lactic dehydrogenase ( LDH ) activity, Na+, K+-ATPase activity, lipid peroxidative production ( MDA ), reactive oxygen species ( ROS ), superoxide dismutase ( SOD ) activity, Ca2+ and Mg2+ levels, Ca2+, Mg2+-ATPase activities, neruofilament ( NTF ) , microtubule-associated protein 2 ( MAP2 ), microtubule-associated protein Tau ( Tau protein ) in experimental spinal cord injury ( SCI ) rats. At the same time, the mechanisms underlying the neuroprotection were investigated by H2C>2-induced spinal neuron damage model in vitro.METHODS In the experiments in vivo, the weight-dropping method was used to produce the experimental spinal cord injury model in adult rats. Res at the dosage of 50 mg -kg"1, 100 mg ?kg"1 and mythlprednisolone ( MPSS ) at the dosage of 100 mg ?kg"1 were given intraperitoneally immediately after the induction of SCI, respectively. And then, the effects of Res on H2O content in injured tissues, LD, LDH, Na+, K+-ATPase, MDA, ROS, SOD, Ca2+ and Mg2+ levels, Ca2+, Mg2+-ATPases were determined at 1 h, 24 h, and 48 h after SCI, with the comparison of MPSS. Furthermore, the ultrastructural observation and the disruption of NTF, MAP2 and Tau proteinwere carried out. Tissue H^O content was estimated by the dry-weight method. The special devised experimental kits were applied to assay LD, LDH activity, Na+, K+-ATPase, Ca2+-ATPase, Mg2+-ATPase, Ca2+, Mg2+-ATPase activity and ROS, MDA, SOD. The levels of Ca2+ and Mg2+ in the injured spinal tissues were surveyed by atomic absorption method. An electron microscope was employed to investigate the ultrastructural effects of Res on axons, neurons, and subcellular organelles after SCI. Western blotting was used for obsering the changes of some neuronal cytoskeleton proteins.In the experiments in vitro, H^Ch was successfully used to produce the peroxide damage model of spinal cord neuron. And then, the effects of Res ( 1 u mol/L-20 V- mol/L ) on neuron growth, [Ca2+]j, superoxide free radical, nitric oxide ( NO ), nitric oxide synthetase ( NOS ) were determined by the MTT method, flow cytometry, fluorospectrophotonetry, chemiluminescence, and spectrophotometry, respectively. And also, NOS was quantitatively estimated by Western blotting.RESULTS The experiments in vivo showed that weight-dropping method could successfully produce SCI model in adult rats, which not only induced secondary edema in the local injured spinal cord, but also brought about significant changes in morphology of injured spinal cord and statistically meaningful disturbances of energetic metabolic system, production of free oxygen radical, increase of peroxidation, disorders of Ca2+ and Mg2+, reduction of ATPase, especially Ca2+, Mg2+-ATPase, and disruption of neuronal cytoskeleton proteins. Therefore, the present SCI model could be used for the study of pharmacodynamics of Res on SCI.Res obviously inhibited the secondary spinal cord edema with the most remarkable suppressing rate of 11.5% at 48 h. Meantime, the ultra-structural findings suggested that SCI caused profound spinal cord damage, which could be protected or improved by injection of Res and MPSS. All rats in sham group showed normal ultrastructure with intact axons,neurons, and subcellular organelles such as mitochondrion and nucleus. In SCI group, similar ultra- structural morphological abnormities were seen in all rats at 1 h, 24 h, and 48 h after SCI, including sever cytoplasmic edema, empty appearance of the axons, lysosis and thin of myelin sheath, spare neurofilaments and vesicles and large vacuoles, nucleus membrane defect, loss of intracytoplasmic organelles such as edematous and emptymitochodria, which were not seen in Sham group. In MPSS-treated group, compared with SCI group, much more slight abnormal changes at post-trauma 1 h, 24 h, and 48 h were observed. All samples of MPSS-treated showed complete ultrastructures of axons, neurofilaments, myelin...
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