Effect of Naojian Tablet on cerebral ischemic injury and its prevention mechanism

OBJECTIVE To investigate the prevention and its mechanism of Naojian Tablet,the adjusted prescription from Buyang Huanwu Decoction,during focal ischemic brain injury condition,and study on the main bioactive substance for this function.METHODS To apply the modified middle cerebral artery occlusion(MCAO)model in rats,immunohistochemistry,RT-PCR and Western blotting were applied to determine the expression of CDK5,CDK4/cyclinD1 in the hippocampus tissues in MCAO rat by treating with Naojian Tablet.On the other hand,the processes of metabolism and disposition of several active components in Naojian Tablet and Buyang Huanwu Decoction were analyzed and characterized by using HPLC-Q-TOF method.RESULTS Naojian Tablet(ig,2.41g·kg-1)could significantly decrease the levels of CDK5,CDK4/cyclinD1 in hippocampus tissues in MACO rat after treated by 3d,7d,14 d,28d(P<0.05).The similar mechanism was observed in the Buyang Huanwu Decoction treated MACO rat.Calycosin,fermononetin,senkyunolide and ligustilide in Naojian Tablet was determined simultaneously as the main active ingredient of Naojian Tablet.CONCLUSION The above-mentioned in vivo studies suggested that Naojian Tablet maybe play its prevention effect on nerve cells via its acting on CDK5 signaling and cell cycle pathway,which verified the multi-target and multi active pathways efficiency of tradition Chinese medicine in treating diverse disease.

Structural and functional damage to the hippocampal neurovascular unit in diabetes-related depression

Previous studies have shown that models of depression exhibit structural and functional changes to the neurovascular unit. Thus, we hypothesized that diabetes-related depression might be associated with damage to the hippocampal neurovascular unit. To test this hypothesis, neurons, astrocytes and endothelial cells were isolated from the brain tissues of rat embryos and newborn rats. Hippocampal neurovascular unit co-cultures were produced using the Transwell chamber co-culture system. A model of diabetes-related depression was generated by adding 150 mM glucose and 200 μM corticosterone to the culture system and compared with the neuron + astrocyte and astrocyte + endothelial cell co-culture systems. Western blot assay was used to measure levels of structural proteins in the hippocampal neurovascular unit co-culture system. Levels of basic fibroblast growth factor, angiogenic factor 1, glial cell line–derived neurotrophic factor, transforming growth factor β1, leukemia inhibitory factor and 5-hydroxytryptamine in the hippocampal neurovascular unit co-culture system were measured by enzyme-linked immunosorbent assay. Flow cytometry and terminal deoxynucleotidyl transferase(TdT)-mediated dUTP nick end labeling staining was used to assess neuronal apoptosis in the hippocampal neurovascular unit. The neurovascular unit triple cell co-culture system had better barrier function and higher levels of structural and secretory proteins than the double cell co-culture systems. In comparison, in the model of diabetes-related depression, the neurovascular unit was damaged with decreased barrier function, poor structural integrity and impaired secretory function. Moreover, neuronal apoptosis was markedly increased, and 5-hydroxytryptamine levels were reduced. These results suggest that diabetes-related depression is associated with structural and functional damage to the neurovascular unit. Our findings provide a foundation for further studies on the pathogenesis of diabetes-related depression.

Abnormal Glu/mGluR2/3/PI3K pathway in the hippocampal neurovascular unit leads to diabetesrelated depression

Our previous studies have shown that glutamate and hippocampal neuron apoptosis are key signals and direct factors associated with diabetes-related depression,and structural and functional damage to the hippocampal neurovascular unit has been associated with diabetesrelated depression.However,the underlying mechanism remains unclear.We hypothesized that diabetes-related depression might be associated with the glutamate(Glu)/metabotropic glutamate receptor2/3(mGluR2/3)/phosphoinositide 3-kinase(PI3K)pathway,activated by glucocorticoid receptors in the hippocampal neurovascular unit.To test this hypothesis,rat hippocampal neurovascular unit models,containing hippocampal neurons,astrocytes,and brain microvascular endothelial cells,were treated with 150 mM glucose and 200μM corticosterone,to induce diabetes-related depression.Our results showed that under conditions of diabetes complicated by depression,hippocampal neurovascular units were damaged,leading to decreased barrier function;elevated Glu levels;upregulated glucocorticoid receptor,vesicular glutamate transporter 3(VGLUT-3),and metabotropic glutamate receptor 2/3(mGluR2/3)expression;downregulated excitatory amino acid transporter 1(EAAT-1)expression;and alteration of the balance of key proteins associated with the extracellular signal-regulated kinase(ERK)/glial cell-derived neurotrophic factor(GDNF)/PI3K signaling pathway.Moreover,the viability of neurons was dramatically reduced in the model of diabetes-related depression,and neuronal apoptosis,and caspase-3 and caspase-9 expression levels,were increased.Our results suggest that the Glu/mGluR2/3/PI3K pathway,induced by glucocorticoid receptor activation in the hippocampal neurovascular unit,may be associated with diabetes-related depression.This study was approved by the Laboratory Animal Ethics Committee of The First Hospital of Hunan University of Chinese Medicine,China(approval No.HN-ZYFY-2019-11-12)on November 12,2019.