Ginsenoside Rd ameliorates high glucose-induced retinal endothelial injury through AMPK-STRT1 interdependence.

Diabetic retinopathy (DR) manifests as a complicated and blinding complication in diabetes mellitus. First-line treatments for advanced DR have shown ocular side-effects in some patients. Ginsenoside Rd (Rd), an active ingredient isolated from Panax notoginseng and P. ginseng, has demonstrated diverse and powerful activities on neuroprotection, anticancer and anti-inflammation, but its vascular protective effects have rarely been reported. Herein, this study aims to investigate the protective effects of Rd on retinal endothelial injury with emphasis on AMPK/SIRT1 interaction. The results indicated that Rd promoted AMPK activation and SIRT1 expression. Besides, Rd strengthened the interaction between AMPK and SIRT1 by increasing NAD+/NADH levels and LKB1 deacetylation in endothelial cells. Moreover, Rd reversed high glucose-induced activation of NOX2, oxidative stress, mitochondrial dysfunction, and endothelial apoptosis in an AMPK/SIRT1-interdependent manner. Hyperglycemia induced loss of endothelial cells and other retinal damage, which was restored by Rd via activating AMPK and SIRT1 in vivo. The enhancement of AMPK/SIRT1 interaction by Rd beneficially modulated oxidative stress and apoptosis, and ameliorated diabetes-driven vascular damage. These data also supported the evidence for Rd clinical development of pharmacological interventions and provided a novel potential vascular protective drug for early DR.

Ginsenoside Rg1 promotes neurite growth of retinal ganglion cells through cAMP/PKA/CREB pathways.

Background: Mechanisms of synaptic plasticity in retinal ganglion cells (RGCs) are complex and the current knowledge cannot explain. Growth and regeneration of dendrites together with synaptic formation are the most important parameters for evaluating the cellular protective effects of various molecules. The effect of ginsenoside Rg1 (Rg1) on the growth of retinal ganglion cell processes has been poorly understood. Therefore, we investigated the effect of ginsenoside Rg1 on the neurite growth of RGCs. Methods: Expression of proteins and mRNA were detected by Western blot and qPCR. cAMP levels were determined by ELISA. In vivo effects of Rg1 on RGCs were evaluated by hematoxylin and eosin, and immunohistochemistry staining. Results: This study found that Rg1 promoted the growth and synaptic plasticity of RGCs neurite by activating the cAMP/PKA/CREB pathways. Meanwhile, Rg1 upregulated the expression of GAP43, Rac1 and PAX6, which are closely related to the growth of neurons. Meantime, H89, an antagonist of PKA, could block this effect of Rg1. In addition, we preliminarily explored the effect of Rg1 on enhancing the glycolysis of RGCs, which could be one of the mechanisms for its neuroprotective effects. Conclusion: Rg1 promoted neurite growth of RGCs through cAMP/PKA/CREB pathways. This study may lay a foundation for its clinical use of optic nerve diseases in the future.

Simultaneous determination of Panax notoginseng total saponins in rabbit tears by UPLC-QqQ-MS/MS and its application to pharmacokinetic study.

Panax notoginseng total saponins (PNS), the main bioactive components of the radix and rhizome of Panax notoginseng (Burk.) F.H. Chen, could treat eye disorders. For the treatment of ocular diseases, eye drops are the first choice with the most common, economic and good compliance. So we proposed that PNS might be able to treat inflammatory ocular surface diseases by eye drops based on its anti-inflammatory and antioxidant activities. The short elimination half-life (t1/2) and rapid elimination of PNS after oral or intravenous administration may limit its application for eye disorders. Meanwhile, there is a lack of pharmacokinetic study on trace amount of tear samples with PNS eye drops. Therefore, a simple and sensitive ultra-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UPLC-QqQ-MS/MS) method by multiple reaction monitoring (MRM) in positive ion mode was firstly developed and applied in the pharmacokinetic study of PNS in rabbit tears. Tears samples were prepared by protein precipitation using methanol. The linearity, limit of detection, limit of quantification, specificity, precision, repeatability, stability, recovery, and matrix effect have been investigated and passed their validation criteria. Compared with prior methods, this method has the advantages of rapid analysis, high sensitivity, simple sample preparation and less sample demands. The pharmacokinetic results indicated that PNS eye drops had a slower elimination and a longer t1/2 by topical ocular administration, which is expected to improve the success rate of eye drops in the treatment of anterior segment diseases. The ocular pharmacokinetics of PNS provides an experimental guidance and feasibility basis for in vivo effect verification of PNS eye drops in the future investigation.