New indication of Chuankezhi injection for steroid-resistant focal segmental glomerulosclerosis and its mechanism of action.

Background: Chuankezhi (CKZ) injection is a traditional Chinese medicine (TCM) injection extracted from Chinese herbs Epimedium sagittatum (Yin Yang Huo) and Morinda officinalis (Bai Ji Tian). Studies have shown that CKZ has a positive effect on improving diabetic nephropathy and regulating immune function. Focal segmental glomerulosclerosis (FSGS) is a kind of refractory nephropathy, which has been confirmed as closely associated with immunity. Whether CKZ is effective against FSGS and how it works warrant further study. This study aimed to verify the efficacy of CKZ in rats with steroid-resistant (SR) FSGS and explore its mechanism of action. Methods: We established an SR FSGS model in male Sprague Dawley (SD) rats by injecting adriamycin into the tail vein. Based on group intervention and comparison, the primary efficacy parameters of FSGS were observed, including general condition, 24-hour urine protein, serum albumin, cholesterol, triglyceride, and renal pathological changes. Network pharmacological analysis and molecular docking were used to predict the mechanism of action of CKZ. Finally, we used quantitative polymerase chain reaction (qPCR) and western blot (WB) to detect messenger RNA (mRNA) expression and protein phosphorylation at specific targets in rat kidney tissue to validate the predicted results. Results: Intramuscular injection of CKZ had a dose-dependent effect in SR FSGS model rats, including lowering urine protein, increasing serum albumin, lowering cholesterol and triglyceride, and treating pathological lesions in the kidney. Network pharmacological analysis and Molecular docking revealed that 5 active components (Icariin, Icariside II, Epimedin C, Icaritin, and Noricaritin) might be the critical components. The findings also revealed that Akt was perhaps the critical target gene, the PI3K-Akt signaling pathway was perhaps the critical pathway, and reversible protein phosphorylation was probably the critical biological process. The qPCR and WB analyses showed that CKZ significantly increased the relative mRNA expression and protein phosphorylation of PI3K and Akt, respectively. Conclusions: This study showed that intramuscular injection of CKZ has a significant therapeutic effect in SR FSGS rats, which may be associated with the activation of PI3K-Akt signaling by CKZ.

Grape Seed Proanthocyanidin Extract Ameliorates Streptozotocin-induced Cognitive and Synaptic Plasticity Deficits by Inhibiting Oxidative Stress and Preserving AKT and ERK Activities.

Progressive memory loss and cognitive impairment are the main clinical manifestations of Alzheimer's disease (AD). Currently, there is no effective drug available for the treatment of AD. Previous studies have demonstrated that the cognitive impairment of AD is associated with oxidative stress and the inhibition of AKT and ERK phosphorylation. Grape seed proanthocyanidin extract (GSPE) has been shown to have strong antioxidant effect and can protect the nervous system from oxidative stress damage. This study aimed to investigate the protective effect of GSPE on the cognitive and synaptic impairments of AD using a sporadic AD rat model induced by intracerebroventricular (ICV) injection of streptozotocin (STZ) (ICV-STZ). Rats were treated with GSPE (50, 100, or 200 mg/kg every day) by intragastrical (ig.) administration for continuous 7 weeks, and ICV-STZ (3 mg/kg) was performed on the first day and third day of week 5. Learning and memory abilities were assessed by the Morris water maze (MWM) test at week 8. After behavioral test, hippocampal long-term potentiation (LTP) was recorded, and the levels of malondialdehyde (MDA), superoxide dismutases (SOD), glutathione (GSH) and the protein expression of AKT and ERK were measured in the hippocampus and cerebral cortex of rats. Our study revealed that ICV-STZ significantly impaired the working learning ability and hippocampal LTP of rats, significantly increased the levels of MDA, and decreased the activity of SOD and GSH in the hippocampus and cerebral cortex. In contrast, GSPE treatment prevented the impairment of cognitive function and hippocampal LTP induced by ICV-STZ, decreased the level of MDA, and increased the level of SOD and GSH. Furthermore, Western blot results showed that GSPE treatment could prevent the loss of AKT and ERK activities in the hippocampus and cerebral cortex induced by ICV-STZ. Our findings demonstrate that GSPE treatment could ameliorate the impairment of cognitive ability and hippocampal synaptic plasticity in a rat model of sporadic AD by inhibiting oxidative stress and preserving AKT and ERK activities. Therefore, GSPE may be an effective agent for the treatment of cognitive deficits associated with sporadic AD.

Chronic administration tetrahydroxystilbene glucoside promotes hippocampal memory and synaptic plasticity and activates ERKs, CaMKII and SIRT1/miR-134 in vivo.

ETHNOPHARMACOLOGICAL RELEVANCE: Polygonum multiflorum Thunb is a traditional Chinese medicine with anti-aging effect. 2,3,5,4'-tetrahydroxystilbene-2-O-ß-D-glucoside (TSG) is generally considered as the main active component in Polygonum multiflorum Thunb. However, the effect of TSG on memory in adult is unclear till now. AIM OF STUDY: 2,3,5,4'-tetrahydroxystilbene-2-O-ß-D-glucoside (TSG) is a polyphenols compound from Polygonum multiflorum Thunb. The present study aimed to evaluate the effect of chronic administration of TSG on hippocampal memory in normal mice. MATERIALS AND METHODS: Behavioral test, electrophysiology and golgi staining were used to evaluate the effect of TSG on hippocampus-dependent memory and synaptic plasticity. Western blotting was used to determine the expression of ERK1/2, CaMKII, and SIRT1. Real-time quantitative PCR was explored to measure miR-134. RESULTS: It was found that TSG enhanced hippocampus-dependent contextual fear memory and novel object recognition, facilitated hippocampal LTP and increased dendrite spine density in the CA1 region of hippocampus. TSG obviously promoted the phosphorylations of ERK1/2, CaMKII, CREB and the expression of BDNF in the hippocampus, with upregulation of silent information regulator 1 (SIRT1) and downregulation of miR-134. CONCLUSIONS: Chronic administration of TSG promotes hippocampal memory in normal mice, suggesting that supplementary of TSG might serve as an enhancement of memory.

Leptin: a potential anxiolytic by facilitation of fear extinction.

AIMS: Anxiety disorders are characterized by a deficient extinction of fear memory. Evidence is growing that leptin influences numerous neuronal functions. The aims of this study were to investigate the effects and the mechanism of leptin on fear extinction. METHODS AND RESULTS: Leptin (1 mg/kg, i.p) was applied to evaluate the anxiolytic effect in rat behavioral tests. Field potentials recording were used to investigate the changes in synaptic transmission in the thalamic-lateral amygadala (LA) pathway of rat. We found that leptin produced strong anxiolytic effects under basal condition and after acute stress. Systemic administration and intra-LA infusions of leptin facilitated extinction of conditioned fear responses. The antagonist of NMDA receptor, MK-801, blocked the effect of leptin on fear extinction completely. Furthermore, these effects of leptin on fear extinction were accompanied by a reversal of conditioning-induced synaptic potentiation in the LA. Leptin facilitated NMDA receptor-mediated synaptic transmission, and reversed amygdala long-term potentiation (LTP) in a dose-dependent manner in vitro, and this LTP depotentiation effect was mediated by NMDA receptor and MAPK signaling pathway. CONCLUSIONS: These results identify a key role of leptin in dampening fear conditioning-induced synaptic potentiation in the LA through NMDA receptor and indicate a new strategy for treating anxiety disorders.

Aquaporin-4 deficiency impairs synaptic plasticity and associative fear memory in the lateral amygdala: involvement of downregulation of glutamate transporter-1 expression.

Astrocytes are implicated in information processing, signal transmission, and regulation of synaptic plasticity. Aquaporin-4 (AQP4) is the major water channel in adult brain and is primarily expressed in astrocytes. A growing body of evidence indicates that AQP4 is a potential molecular target for the regulation of astrocytic function. However, little is known about the role of AQP4 in synaptic plasticity in the amygdala. Therefore, we evaluated long-term potentiation (LTP) in the lateral amygdala (LA) and associative fear memory of AQP4 knockout (KO) and wild-type mice. We found that AQP4 deficiency impaired LTP in the thalamo-LA pathway and associative fear memory. Furthermore, AQP4 deficiency significantly downregulated glutamate transporter-1 (GLT-1) expression and selectively increased NMDA receptor (NMDAR)-mediated EPSCs in the LA. However, low concentration of NMDAR antagonist reversed the impairment of LTP in KO mice. Upregulating GLT-1 expression by chronic treatment with ceftriaxone also reversed the impairment of LTP and fear memory in KO mice. These findings imply a role for AQP4 in synaptic plasticity and associative fear memory in the amygdala by regulating GLT-1 expression.