Previously we have demonstrated that a Rhodiola crenulata extract (RCE), containing a potent antioxidant salidroside, promotes neurogenesis in the hippocampus of depressive rats. The current study was designed to further investigate the protective effect of the RCE on neurogenesis in a rat model of Alzheimer's disease (AD) induced by an intracerebroventricular injection of streptozotocin (STZ), and to determine whether this neuroprotective effect is induced by the antioxidative activity of salidroside. Our results showed that pretreatment with the RCE significantly improved the impaired neurogenesis and simultaneously reduced the oxidative stress in the hippocampus of AD rats. In vitro studies revealed that (1) exposure of neural stem cells (NSCs) from the hippocampus to STZ strikingly increased intracellular reactive oxygen species (ROS) levels, induced cell death and perturbed cell proliferation and differentiation, (2) hydrogen peroxide induced similar cellular activities as STZ, (3) pre-incubation of STZ-treated NSCs with catalase, an antioxidant, suppressed all these cellular activities induced by STZ, and (4) likewise, pre-incubation of STZ-treated NSCs with salidroside, also an antioxidant, suppressed all these activities as catalase: reduction of ROS levels and NSC death with simultaneous increases in proliferation and differentiation. Our findings indicated that the RCE improved the impaired hippocampal neurogenesis in the rat model of AD through protecting NSCs by its main ingredient salidroside which scavenged intracellular ROS.

Background: Bone marrow mesenchymal stem cells (MSCs) are one of the potential tools for treatment of the spinal cord injury; however, the survival and differentiation of MSCs in an injured spinal cord still need to be improved. In the present study, we investigated whether Governor Vessel electro-acupuncture (EA) could efficiently promote bone marrow mesenchymal stem cells (MSCs) survival and differentiation, axonal regeneration and finally, functional recovery in the transected spinal cord. Results: The spinal cords of adult Sprague-Dawley (SD) rats were completely transected at T10, five experimental groups were performed: 1. sham operated control (Sham-control); 2. operated control (Op-control); 3. electro-acupuncture treatment (EA); 4. MSCs transplantation (MSCs); and 5. MSCs transplantation combined with electro-acupuncture (MSCs+EA). After 2-8 weeks of MSCs transplantation plus EA treatment, we found that the neurotrophin-3 (NT-3), cAMP level, the differentiation of MSCs, the 5-HT positive and CGRP positive nerve fibers in the lesion site and nearby tissue of injured spinal cord were significantly increased in the MSCs+EA group as compared to the group of the MSCs transplantation or the EA treated alone. Furthermore, behavioral test and spinal cord evoked potentials detection demonstrated a significantly functional recovery in the MSCs +EA group. Conclusion: These results suggest that EA treatment may promote grafted MSCs survival and differentiation; MSCs transplantation combined with EA treatment could promote axonal regeneration and partial locomotor functional recovery in the transected spinal cord in rats and indicate a promising avenue of treatment of spinal cord injury.