Neuroprotective effects of ginsenoside Rg1-induced neural stem cell transplantation on hypoxic-ischemic encephalopathy

Abstract

Ginsenoside Rg1 is the major pharmacologically active component of ginseng, and is reported to have various therapeutic actions. To determine whether it induces the differentiation of neural stem cells, and whether neural stem cell transplantation after induction has therapeutic effects on hypoxic-ischemic encephalopathy, we cultured neural stem cells in 10-80 μM ginsenoside Rg1. Immunohistochemistry revealed that of the concentrations tested, 20 mM ginsenoside Rg1 had the greatest differentiation-inducing effect and was the concentration used for subsequent experiments. Whole-cell patch clamp showed that neural stem cells induced by 20 μM ginsenoside Rg1 were more mature than non-induced cells. We then established neonatal rat models of hypoxic-ischemic encephalopathy using the suture method, and ginsenoside Rg1-induced neural stem cells were transplanted via intracerebroventricular injection. These tests confirmed that neural stem cells induced by ginsenoside had fewer pathological lesions and had a significantly better behavioral capacity than model rats that received saline. Transplanted neural stem cells expressed neuron-specific enolase, and were mainly distributed in the hippocampus and cerebral cortex. The present data suggest that ginsenoside Rg1-induced neural stem cells can promote the partial recovery of complicated brain functions in models of hypoxic-ischemic encephalopathy.

Keywords: cell differentiation; cell transplantation; cognition; ginsenoside Rg1; hypoxic-ischemic brain damage; nerve reconstruction; nerve regeneration; neural regeneration; neural stem cells.

Figure 1

Effect of ginsenoside Rg1 on the differentiation of neural stem cells. The percentage of cells expressing neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), or Gal-c (differentiated neurons) was determined by immunocytochemistry. Data are expressed as the mean ± SD (n = 5). One-way analysis of variance and paired t-tests were used to identify differences between groups. *P < 0.05, vs. control group.

Figure 2

Effect of ginsenoside Rg1 on membrane function of induced neural stem cells at 7 days after differentiation (whole-cell patch clamp recording). Cell activation was measured using the whole-cell patch clamp technique. Amplitudes in the 20 μM ginsenoside Rg1 group were notably greater than those in the control group.

Figure 3

Coronal brain sections in rat models of hypoxic-ischemic encephalopathy (TTC staining). (A) Control group; (B) model group. Red: Normal tissue; white: ischemic tissue.

Figure 4

Effects of NSC transplantation on rat behavior. Latency (A), distance (B) and (C) target quadrant time in the Morris water maze spatial probe test. Data are expressed as the mean ± SD (n = 5 rats per group). One-way analysis of variance and paired t-test were used to identify differences between groups. #P < 0.05, vs. III; †P < 0.05, vs. I. HIE: Hypoxic-ischemic encephalopathy; NSCs: neural stem cells. I: HIE + vehicle group; II: HIE + NSCs group; III: control group.

Figure 5

Effects of NSC transplantation on somatosensory evoked potential in HIE rats. (A) Latency of somatosensory evoked potential. (B) Amplitude of somatosensory evoked potential. Data are expressed as the mean ± SD (n = 5). One-way analysis of variance and paired t-tests were used to identify differences between groups. #P < 0.05, vs. III; †P < 0.05, vs. I. HIE: Hypoxic-ischemic encephalopathy; NSCs: neural stem cells. I: HIE + vehicle group; II: HIE + NSCs group; III: control group.

Figure 6

Changes in neuronal morphology in the brain of HIE rats 1 month after NSC transplantation. NSC transplantation increases the number of neurons and reduces tissue damage in HIE rats. The red arrows show vacuoles, and the black arrows show neuron-specific enolase-positive neurons. Scale bars: 20 μm (upper panel); and 10 μm (lower panel). HIE: Hypoxic-ischemic encephalopathy; NSCs: neural stem cells.