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Neuroprotective effects of ginsenoside Rb1 on high glucose-induced neurotoxicity in primary cultured rat hippocampal neurons.

Liu D, Zhang H, Gu W, Liu Y, Zhang M - PLoS ONE (2013)

Bottom Line: Ginsenoside Rb1 is one of the main active principles in traditional herb ginseng and has been reported to have a wide variety of neuroprotective effects.In addition, the high glucose-induced cell apoptosis, activation of ER stress, ROS accumulation and mitochondrial dysfunction can also be attenuated by the inhibitor of ER stress 4-phenylbutyric acid (4-PBA) and anti-oxidant N-acetylcysteine(NAC).In conclusion, these results suggest that Rb1 may protect neurons against high glucose-induced cell injury through inhibiting CHOP signaling pathway as well as oxidative stress and mitochondrial dysfunction.

View Article: PubMed Central - PubMed

Affiliation: Department of Traditional Chinese Medicine, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China.

ABSTRACT
Ginsenoside Rb1 is one of the main active principles in traditional herb ginseng and has been reported to have a wide variety of neuroprotective effects. Endoplasmic reticulum (ER) stress has been implicated in neurodegenerative diseases, so the present study aimed to observe the effects of ginsenoside Rb1 on ER stress signaling pathways in high glucose-treated hippocampal neurons. The results from MTT, TUNEL labeling and Annexin V-FITC/PI/Hoechst assays showed that incubating neurons with 50 mM high glucose for 72 h decreased cell viability and increased the number of apoptotic cells whereas treating neurons with 1 μM Rb1 for 72 h protected the neurons against high glucose-induced cell damage. Further molecular mechanism study demonstrated that Rb1 suppressed the activation of ER stress-associated proteins including protein kinase RNA (PKR)-like ER kinase (PERK) and C/EBP homology protein (CHOP) and downregulation of Bcl-2 induced by high glucose. Moreover, Rb1 inhibited both the elevation of intracellular reactive oxygen species (ROS) and the disruption of mitochondrial membrane potential induced by high glucose. In addition, the high glucose-induced cell apoptosis, activation of ER stress, ROS accumulation and mitochondrial dysfunction can also be attenuated by the inhibitor of ER stress 4-phenylbutyric acid (4-PBA) and anti-oxidant N-acetylcysteine(NAC). In conclusion, these results suggest that Rb1 may protect neurons against high glucose-induced cell injury through inhibiting CHOP signaling pathway as well as oxidative stress and mitochondrial dysfunction.

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Effects of ginsenoside Rb1 on intracellular ROS accumulation induced by high glucose in hippocampal neurons.(A) Representative photographs of DCF staining in different groups. (a) control group; (b) high glucose group; (c) ginsenoside Rb1+high glucose group; (d) NAC + high glucose group;(e) 4-PBA + high glucose group. Magnification 400× ; Scale bar = 34μm. (B) DCF fluorescence intensity was quantitatively analyzed. All values are denoted as means ±S.D from six independent photographs shot in each group. Data are expressed as percentage of control group. The experiments were repeated three times independently. *P<0.05, as compared to the control group; **P<0.01, as compared to the control group; ##P<0.01, as compared to the high glucose group.
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pone-0079399-g004: Effects of ginsenoside Rb1 on intracellular ROS accumulation induced by high glucose in hippocampal neurons.(A) Representative photographs of DCF staining in different groups. (a) control group; (b) high glucose group; (c) ginsenoside Rb1+high glucose group; (d) NAC + high glucose group;(e) 4-PBA + high glucose group. Magnification 400× ; Scale bar = 34μm. (B) DCF fluorescence intensity was quantitatively analyzed. All values are denoted as means ±S.D from six independent photographs shot in each group. Data are expressed as percentage of control group. The experiments were repeated three times independently. *P<0.05, as compared to the control group; **P<0.01, as compared to the control group; ##P<0.01, as compared to the high glucose group.

Mentions: Recent studies have shown the involvement of ROS in ER stress-induced apoptosis[31]. Therefore, we examined the effects of ginsenoside Rb1 on the accumulation of ROS in high glucose-treated hippocampal neurons, using the DCFH-DA, which can be oxidized to the highly fluorescent compound DCF(Figure 4A). Compared with the control, incubating cells with 50mM high glucose for 24h significantly increased ROS levels (Figure 4A and 4B). However, treatment with ginsenoside Rb1 (1μM) for 24 h effectively attenuated this increase in ROS levels induced by high glucose. In addition, compared with the well-known anti-oxidant NAC, the anti-oxidative effect of ginsenoside Rb1 was similar to that of NAC (Figure 4B). These results suggest the involvement of oxidative stress in high glucose-induced cytotoxicity and the anti-oxidative activity of ginsenoside Rb1.


Neuroprotective effects of ginsenoside Rb1 on high glucose-induced neurotoxicity in primary cultured rat hippocampal neurons.

Liu D, Zhang H, Gu W, Liu Y, Zhang M - PLoS ONE (2013)

Effects of ginsenoside Rb1 on intracellular ROS accumulation induced by high glucose in hippocampal neurons.(A) Representative photographs of DCF staining in different groups. (a) control group; (b) high glucose group; (c) ginsenoside Rb1+high glucose group; (d) NAC + high glucose group;(e) 4-PBA + high glucose group. Magnification 400× ; Scale bar = 34μm. (B) DCF fluorescence intensity was quantitatively analyzed. All values are denoted as means ±S.D from six independent photographs shot in each group. Data are expressed as percentage of control group. The experiments were repeated three times independently. *P<0.05, as compared to the control group; **P<0.01, as compared to the control group; ##P<0.01, as compared to the high glucose group.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3815219&req=5

pone-0079399-g004: Effects of ginsenoside Rb1 on intracellular ROS accumulation induced by high glucose in hippocampal neurons.(A) Representative photographs of DCF staining in different groups. (a) control group; (b) high glucose group; (c) ginsenoside Rb1+high glucose group; (d) NAC + high glucose group;(e) 4-PBA + high glucose group. Magnification 400× ; Scale bar = 34μm. (B) DCF fluorescence intensity was quantitatively analyzed. All values are denoted as means ±S.D from six independent photographs shot in each group. Data are expressed as percentage of control group. The experiments were repeated three times independently. *P<0.05, as compared to the control group; **P<0.01, as compared to the control group; ##P<0.01, as compared to the high glucose group.
Mentions: Recent studies have shown the involvement of ROS in ER stress-induced apoptosis[31]. Therefore, we examined the effects of ginsenoside Rb1 on the accumulation of ROS in high glucose-treated hippocampal neurons, using the DCFH-DA, which can be oxidized to the highly fluorescent compound DCF(Figure 4A). Compared with the control, incubating cells with 50mM high glucose for 24h significantly increased ROS levels (Figure 4A and 4B). However, treatment with ginsenoside Rb1 (1μM) for 24 h effectively attenuated this increase in ROS levels induced by high glucose. In addition, compared with the well-known anti-oxidant NAC, the anti-oxidative effect of ginsenoside Rb1 was similar to that of NAC (Figure 4B). These results suggest the involvement of oxidative stress in high glucose-induced cytotoxicity and the anti-oxidative activity of ginsenoside Rb1.

Bottom Line: Ginsenoside Rb1 is one of the main active principles in traditional herb ginseng and has been reported to have a wide variety of neuroprotective effects.In addition, the high glucose-induced cell apoptosis, activation of ER stress, ROS accumulation and mitochondrial dysfunction can also be attenuated by the inhibitor of ER stress 4-phenylbutyric acid (4-PBA) and anti-oxidant N-acetylcysteine(NAC).In conclusion, these results suggest that Rb1 may protect neurons against high glucose-induced cell injury through inhibiting CHOP signaling pathway as well as oxidative stress and mitochondrial dysfunction.

View Article: PubMed Central - PubMed

Affiliation: Department of Traditional Chinese Medicine, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China.

ABSTRACT
Ginsenoside Rb1 is one of the main active principles in traditional herb ginseng and has been reported to have a wide variety of neuroprotective effects. Endoplasmic reticulum (ER) stress has been implicated in neurodegenerative diseases, so the present study aimed to observe the effects of ginsenoside Rb1 on ER stress signaling pathways in high glucose-treated hippocampal neurons. The results from MTT, TUNEL labeling and Annexin V-FITC/PI/Hoechst assays showed that incubating neurons with 50 mM high glucose for 72 h decreased cell viability and increased the number of apoptotic cells whereas treating neurons with 1 μM Rb1 for 72 h protected the neurons against high glucose-induced cell damage. Further molecular mechanism study demonstrated that Rb1 suppressed the activation of ER stress-associated proteins including protein kinase RNA (PKR)-like ER kinase (PERK) and C/EBP homology protein (CHOP) and downregulation of Bcl-2 induced by high glucose. Moreover, Rb1 inhibited both the elevation of intracellular reactive oxygen species (ROS) and the disruption of mitochondrial membrane potential induced by high glucose. In addition, the high glucose-induced cell apoptosis, activation of ER stress, ROS accumulation and mitochondrial dysfunction can also be attenuated by the inhibitor of ER stress 4-phenylbutyric acid (4-PBA) and anti-oxidant N-acetylcysteine(NAC). In conclusion, these results suggest that Rb1 may protect neurons against high glucose-induced cell injury through inhibiting CHOP signaling pathway as well as oxidative stress and mitochondrial dysfunction.

Show MeSH
Related in: MedlinePlus