Synergistic neuroprotective effect of microglial-conditioned media treated with geniposide and ginsenoside Rg1 on hypoxia injured neurons

The synergistic mechanism underlying the effects of multi-component combined drug use for complex diseases remains to be fully elucidated. Microglial activation following ischemia can either affect neural survival or cause neuronal injury. The aim of the present study was to determine the synergistic effect of geniposide and ginsenoside Rg1, based on microglial-neuronal communication. N2a neuronal cells were divided into the following seven groups: Control group; normal cultured microglial cells in conditioned medium (N-MG-CM) group; oxygen-glucose deprivation (OGD) model group; OGD-injured MG-CM (I-MG-CM) group; geniposide-treated MG-CM (G-MG-CM) group; ginsenoside Rg1-treated MG-CM (R-MG-CM) group; and combination-treated MG-CM (C-MG-CM) group. A series of assays were used to detect the effects of the different MG-CM on neurons in terms of: (i) cell viability, determined using a Cell Counting Kit-8; (ii) lactate dehydrogenase (LDH) leakage rate; (iii) expression of NMDAR1 and activated caspase-3, detected using western blotting; (iv) mitochondrial transmembrane potential, determined by JC-1; and (v) mitochondrial ultrastructural features, determined using electron microscopy. The experimental results demonstrated that MG-CM including the integrated use of geniposide and ginsenoside Rg1 significantly protected neuronal cell viability and inhibited LDH leakage, suppressed the expression of N-methyl-D-aspartate receptor subunit 1 and activated caspase-3, increased the mitochondrial transmembrane potential and improved the mitochondrial ultrastructure. MG-CM from separately used geniposide or ginsenoside Rg1 demonstrated differential neuroprotection at different levels. These findings revealed that the synergistic drug combination of geniposide and ginsenoside Rg1 in the treatment of stroke is a feasible approach for use.