Notoginsenoside R1 Protects against Neonatal Cerebral Hypoxic-Ischemic Injury through Estrogen Receptor-Dependent Activation of Endoplasmic Reticulum Stress Pathways.

Notoginsenoside R1 (NGR1) is a phytoestrogen that is isolated from Panax notoginseng It is used in China to treat many diseases, including hypoxic-ischemic encephalopathy (HIE), and it has been shown to target estrogen receptors. Endoplasmic reticulum (ER) stress plays an important role in the development of cell apoptosis during ischemia, and ER stress is known to be regulated by estrogen; however, the neuroprotective mechanisms of NGR1 in neonatal HIE is unclear. In this study, oxygen-glucose deprivation/reoxygenation (OGD/R) in primary cortical neurons and unilateral ligation of the common carotid artery (CCL), followed by exposure to a hypoxic environment in 7-day-old postnatal Sprague-Dawley rats were used to mimic HIE episodes. Potential neuroprotective effects of NGR1 against neonatal HIE and its mechanisms were examined. After HIE conditions in vitro and in vivo, we administered NGR1 or the estrogen receptor inhibitor ICI-182780 and measured cell apoptosis, brain injury by MTT assay, TTC stain, and so forth. Expression of estrogen receptors α (ERα) and β (ERβ), ER stress-associated proteins was detected by Western blot upon stimulation with HIE, NGR1, or ICI-182780. Results showed that after HIE, ER chaperone GRP78 was activated, ER stress-associated proapoptotic proteins (CHOP, PERK, ERO1-α, and IRE1α) were increased, caspase-12 was increased, and BCL-2 was decreased. The ER stress response and neuronal apoptosis were attenuated by NGR1 treatment. However, neuroprotective properties of NGR1 against HIE-induced apoptosis and ER stress were attenuated by ICI-182780. These results suggest that NGR1 may be an effective treatment of HIE by reducing ER stress-induced neuronal apoptosis and brain injury via estrogen receptors.

Wang Y ，Tu L ，Li Y ，Chen D ，Wang S ... -  《-》

Protective Effects of Notoginsenoside R1 via Regulation of the PI3K-Akt-mTOR/JNK Pathway in Neonatal Cerebral Hypoxic-Ischemic Brain Injury.

Tu L ，Wang Y ，Chen D ，Xiang P ，Shen J ，Li Y ，Wang S ... -  《-》

Suppression of NADPH oxidase- and mitochondrion-derived superoxide by Notoginsenoside R1 protects against cerebral ischemia-reperfusion injury through estrogen receptor-dependent activation of Akt/Nrf2 pathways.

Meng X ，Wang M ，Wang X ，Sun G ，Ye J ，Xu H ，Sun X ... -  《-》

Notoginsenoside R1 Alleviates Oxygen-Glucose Deprivation/Reoxygenation Injury by Suppressing Endoplasmic Reticulum Calcium Release via PLC.

Wang Y ，Tu L ，Li Y ，Chen D ，Liu Z ，Hu X ，Wang S ... -  《Scientific Reports》

[Protective effect of notoginsenoside R1 on neuron injury induced by OGD/R through ATF6/Akt signaling pathway].

Notoginsenoside R1(NGR1),a critical compound in traditional herb Panax notoginseng, is a kind of estrogen receptor agonist.It is reported to exhibit anti-apoptotic,anti-oxidative and anti-inflammatory properties activity, so it is widely used for treatment of various diseases.In order to investigate the potential neuroprotective effect of NGR1 in hypoxic-ischemic brain damage(HIBD), primary cortical neurons were used in this study to establish oxygen-glucose deprivation/reoxygenation(OGD/R) injury models. They were treated with NGR1 and estrogen receptor inhibitor ICI-182780 respectively, then the neuronal survival, cell membrane integrity and apoptosis were assessed by MTT assay,lactate dehydrogenase test(LDH) and Hoechst 33342 stain respectively, while the protein expression levels of ATF6α,p-Akt,Akt,Bax and Cleaved Caspase-3 were measured by Western blotting. Results indicated that as compared with the blank control group,OGD/R could induce cell injury and apoptosis(P<0.05), reduce relative integrity of cell membrane(P<0.05), decrease protein expression of ATF6α,p-Akt(P<0.05), and increase protein expression of Bax and Cleaved Caspase-3(P<0.05) in the primary cortical cells. After NGR1 treatment, the expression levels of ATF6α,p-Akt were obviously increased, and the expression levels of Bax and Cleaved Caspase-3 and the apoptosis of neuron were decreased(P<0.05). However, these neuroprotective properties of NGR1 against ODG/R-induced cell damage could be blocked by ICI-182780. This finding indicated that NGR1 may protect the primary cortical neurons against OGD/R induced injury,and the mechanism may be associated with accelerating the activation of the ATF6/Akt signaling pathway via estrogen receptors.

Hou QL ，Wang Y ，Li YB ，Hu XL ，Wang SL ... -  《-》