EGB761 ameliorates chronic cerebral hypoperfusion-induced cognitive dysfunction and synaptic plasticity impairment

miR-30a-5p mediates ferroptosis of hippocampal neurons in chronic cerebral hypoperfusion-induced cognitive dysfunction by modulating the SIRT1/NRF2 pathway

OBJECTIVE

Chronic cerebral hypoperfusion (CCH) is a common cause of brain dysfunction. As a microRNA (also known as miRNAs or miRs), miR-30a-5p participates in neuronal damage and relates to ferroptosis. We explored the in vivo and in vitro effects and functional mechanism of miR-30a-5p in CCH-triggered cognitive impairment through the silent information regulator 1 (SIRT1)/nuclear factor erythroid 2-related factor 2 (NRF2) pathway.

METHODS

After 1 month of CCH modeling through bilateral common carotid artery stenosis, mice were injected with 2 μL antagomir (also known as anti-miRNAs) miR-30a-5p, with cognitive function evaluated by Morris water maze and novel object recognition tests. In vitro HT-22 cell oxygen glucose deprivation (OGD) model was established, followed by miR-30a-5p inhibitor and/or si-SIRT1 transfections, with Fe2+ concentration, malonaldehyde (MDA) and glutathione (GSH) contents, reactive oxygen species (ROS), miR-30a-5p and SIRT1 and glutathione peroxidase 4 (GPX4) protein levels, NRF2 nuclear translocation, and miR-30a-5p-SIRT1 targeting relationship assessed.

RESULTS

CCH-induced mice showed obvious cognitive impairment, up-regulated miR-30a-5p, and down-regulated SIRT1. Ferroptosis occurred in hippocampal neurons, manifested by elevated Fe2+ concentration and ROS and MDA levels, mitochondrial atrophy, and diminished GSH content. Antagomir miR-30a-5p or miR-30a-5p inhibitor promoted SIRT1 expression and NRF2 nuclear translocation, increased GPX4, cell viability and GSH content, and reduced Fe2+ concentration and ROS and MDA levels. miR-30a-5p negatively regulated SIRT1. In vitro, miR-30a-5p knockout increased NRF2 nuclear translocation by up-regulating SIRT1, inhibiting OGD-induced ferroptosis in HT-22 cells.

CONCLUSION

miR-30a-5p induces hippocampal neuronal ferroptosis and exacerbates post-CCH cognitive dysfunction by targeting SIRT1 and reducing NRF2 nuclear translocation.

Impact of Codonopsis decoction on cerebral blood flow and cognitive function in rats with chronic cerebral ischemia

ETHNOPHARMACOLOGICAL RELEVANCE

Some species of Codonopsis (local name in Shanxi: Ludang) have long demonstrated high medicinal and economic value. Radix Codonopsis, the dried root of Codonopsis pilosula (Franch.) Nannf. (C. pilosula), Codonopsis pilosula var. modesta (Nannf.) L.D.Shen (C. pilosula var. modesta), or Codonopsis pilosula subsp. tangshen (Oliv.) D.Y.Hong (C. pilosula subsp. tangshen), was recorded as a traditional Chinese medicine back in the Qing Dynasty in Ben Cao Cong Xin. Radix Codonopsis, a valuable medicinal herb certified by the Chinese National Geographic Indication, is known for invigorating the spleen, nourishing the lungs, promoting blood circulation, and generating fluid properties. Given that chronic cerebral ischemia (CCI) is often associated with the symptoms of qi and blood deficiencies and fluid depletion, we explored the potential of Codonopsis decoction in the treatment of CCI.

STUDY AIMS

We investigated the effects of Codonopsis decoction on cerebral blood flow (CBF) and cognitive function in rats with bilateral carotid artery occlusion after surgery; explored whether Codonopsis decoction alleviates pathological injuries in brain tissue of rats after 2-VO surgery; and assessed the impact of Codonopsis decoction on the expression of chemokines, hypoxia-inducible factors, and inflammatory mediators in rats after 2-VO surgery.

MATERIALS AND METHODS

We used a 2-VO rat model to simulate CCI. We used a laser speckle imaging (LSI) system to observe changes in CBF before and after surgery. The goal was to examine variations in CBF at different time points after 2-VO surgery. For 4 weeks, the rats were orally administered Codonopsis decoction at doses of 2.7, 5.4, and 10.8 g/kg/day, or Ginaton at a dose of 43.2 mg/kg/day. To assess the effect of Codonopsis on cerebral hypoperfusion symptoms in rats, we conducted the Morris water maze (MWM), Barnes maze (BM), and forelimb grip strength tests. Additionally, pathological experiments including hematoxylin and eosin, Nissl, and Luxol fast blue staining were conducted. Furthermore, we used western blotting to detect changes in the levels of proteins such as the chemotactic factor CKLF1 and hypoxia-inducible actor 1-alpha (HIF-1α).

RESULTS

One week after 2-VO surgery, cerebral arterial blood supply in the rats rapidly reduced to approximately 43.39% ± 3.53% of the preoperative level. Cerebral cortex perfusion reached its nadir within 24 h of surgery, gradually recovering and stabilizing by the fourth week after surgery. An integration of the results from the BM, MWM, and grip strength tests, which assessed cognitive function and forelimb strength in rats after 2-VO surgery, unequivocally revealed that Codonopsis treatment significantly reduced the latency period and increased the number of platform crossings in the MWM test. Ginaton exhibited a comparable effect. Moreover, both Codonopsis and Ginaton decreased the number of errors and the time required to locate the target hole in the BM test. Histopathological staining revealed that Codonopsis and Ginaton could ameliorate pathological damage in rats after CCI and reduce the release of factors such as CKLF1 and HIF-1α.

CONCLUSION

Codonopsis decoction exerted its protective effects on CCI rats possibly by modulating the levels of chemokines, hypoxia-inducible factors, and neuroinflammatory mediators.

Volatile oil of Angelica sinensis Radix improves cognitive function by inhibiting miR-301a-3p targeting Ppp2ca in cerebral ischemia mice

ETHNOPHARMACOLOGICAL RELEVANCE

Angelica Sinensis Radix (ASR) is a commonly used Chinese medicine known for its effects on tonifying blood, promoting blood circulation, and alleviating pain associated with menstrual regulation. Additionally, it has been used in the treatment of vascular cognitive impairment (VCI). The primary pharmacodynamic agent within ASR is volatile oil of Angelica Sinensis Radix (VOASR), which has demonstrated efficacy in combating cognitive impairment, although its mechanism remains unclear.

OBJECTIVE

This study aimed to elucidate the potential molecular mechanisms underlying VOASR's improvement of cognitive function in cerebral ischemic mice.

METHODS

A model of cerebral ischemic mice was established through unilateral common carotid artery occlusion (UCCAO) surgery, followed by intervention with VOASR. Cognitive function was assessed using the Morris water maze (MWM) test, while RT-qPCR was utilized to measure the differential expression of miR-301a-3p in the hippocampus. To evaluate cognitive function and hippocampal protein differences, wild-type mice and miR-301a-3p knockout mice were subjected to the MWM test and iTRAQ protein profiling. The relationship between miR-301a-3p and potential target genes was validated through a Dual-Luciferase Reporter experiment. RT-qPCR and Western blot were employed to determine the differential expression of Ppp2ca and synaptic plasticity-related proteins in the mouse hippocampus.

RESULTS

Intervention with VOASR significantly improved cognitive impairment in cerebral ischemic mice and reduced the expression of miR-301a-3p in the hippocampus. Our findings suggest that miR-301a-3p may regulate cognitive function by targeting Ppp2ca. Furthermore, VOASR intervention led to an increase in the expression of Ppp2ca and synaptic plasticity-related proteins.

CONCLUSION

Our study indicates that VOASR may be involved in regulating cognitive function by inhibiting miR-301a-3p, consequently increasing the expression of Ppp2ca and synaptic plasticity proteins. These results provide a new target and direction for the treatment of cognitive dysfunction.

ChemR23 activation attenuates cognitive impairment in chronic cerebral hypoperfusion by inhibiting NLRP3 inflammasome-induced neuronal pyroptosis

Neuroinflammation plays critical roles in vascular dementia (VaD), the second leading cause of dementia, which can be induced by chronic cerebral hypoperfusion (CCH). NLRP3 inflammasome-induced pyroptosis, the inflammatory programmed cell death, has been reported to contribute to the development of VaD. ChemR23 is a G protein-coupled receptor that has emerging roles in regulating inflammation. However, the role of ChemR23 signalling in NLRP3 inflammasome-induced pyroptosis in CCH remains elusive. In this study, a CCH rat model was established by permanent bilateral common carotid artery occlusion (BCCAO) surgery. Eight weeks after the surgery, the rats were intraperitoneally injected with the ChemR23 agonist Resolvin E1 (RvE1) or chemerin-9 (C-9). Additionally, primary rat hippocampal neurons and SH-SY5Y cells were adopted to mimic CCH injury in vitro. Our results showed that the levels of ChemR23 expression were decreased from the 8th week after BCCAO, accompanied by significant cognitive impairment. Further analysis revealed that CCH induced neuronal damage, synaptic injury and NLRP3-related pyroptosis activation in hippocampal neurons. However, pharmacologic activation of ChemR23 with RvE1 or C-9 counteracted these changes. In vitro experiments also showed that ChemR23 activation prevented primary neuron pyroptosis induced by chronic hypoxia. In addition, manipulating ChemR23 expression markedly regulated NLRP3 inflammasome-induced neuronal pyroptosis through PI3K/AKT/Nrf2 signalling in SH-SY5Y cells under hypoglycaemic and hypoxic conditions. Collectively, our data demonstrated that ChemR23 activation inhibits NLRP3 inflammasome-induced neuronal pyroptosis and improves cognitive function via the PI3K/AKT/Nrf2 signalling pathway in CCH models. ChemR23 may serve as a potential novel therapeutic target to treat CCH-induced cognitive impairment.

Remote ischemic conditioning alleviates chronic cerebral hypoperfusion-induced cognitive decline and synaptic dysfunction via the miR-218a-5p/SHANK2 pathway

Vascular cognitive impairment (VCI) due to chronic cerebral hypoperfusion (CCH), is the second leading cause of dementia. Although synaptic impairment plays a critical role in VCI, its exact mechanism remains unknown. Our previous research revealed that remote ischemic conditioning (RIC) could alleviate cognitive decline resulting from CCH, however, its effects on synaptic impairment remain unclear. In this study, we confirmed that RIC alleviated both cognitive decline and its associated synaptic dysfunction caused by CCH. RNA sequencing revealed that CCH increased in miR-218a-5p expression, which was decreased by RIC. Elevated miR-218a-5p levels limited the benefits of RIC, however, inhibiting miR-218a-5p in hippocampal CA1 neurons rescued synaptic dysfunction. Additionally, we found that SHANK2 is a downstream target of miR-218a-5p, and inhibiting SHANK2 expression reduced the alleviation caused by hypoxic conditioning in synaptic impairment in vitro. In conclusion, our results suggested that RIC alleviated synaptic impairment via the miR-218a-5p/SHANK2 pathway, which could be a potential biomarker or therapeutic target for cognitive impairment caused by CCH.

Bio-enhanced fraction from Clitoria ternatea root extract ameliorates cognitive functions and in vivo hippocampal neuroplasticity in chronic cerebral hypoperfusion rat model

Research employing a bio-enhanced fraction of Clitoria ternatea (CT) to treat cognitive decline in the animal model has not yet been found. This study aimed to determine the neuroprotective effect of CT root bioactive fraction (CTRF) in chronic cerebral hypoperfusion (CCH) rat model. CTRF and its major compound, clitorienolactones A (CLA), were obtained using column chromatography. A validated HPLC-UV method was employed for the standardization of CTRF. CCH rats were given orally either vehicle or fraction (10, 20 and 40 mg/kg). Behavioural and hippocampal neuroplasticity studies were conducted following 4 weeks post-surgery. The brain hippocampus was extracted for proteins and neurotransmitters analyses. HPLC analysis showed that CTRF contained 25% (w/w) of CLA. All tested doses of CTRF and CLA (10 mg/kg) significantly restored cognitive deficits and reversed the inhibition of neuroplasticity by CCH. However, only CTRF (40 mg/kg) and CLA (10 mg/kg) significantly reversed the elevation of amyloid-beta plaque. Subsequently, treatment with CTRF (40 mg/kg) and CLA (10 mg/kg) alleviated the downregulation of molecular synaptic signalling proteins levels caused by CCH. The neurotransmitters level was restored following treatment of CTRF and CLA. Our finding suggested that CTRF improves memory and neuroplasticity in CCH rats which was mainly contributed by CLA.

VEGF loaded nanofiber membranes inhibit chronic cerebral hypoperfusion-induced cognitive dysfunction by promoting HIF-1a/VEGF mediated angiogenesis

We investigated the potential effects and mechanisms of vascular endothelial growth factor (VEGF)-nanofiber membranes (NFMs) treatment in a rat model of chronic cerebral hypoperfusion (CCH). VEGF-NFMs treatment promoted angiogenesis in surgical temporal cortex and hippocampus, alleviating decreased CBF in these two cerebral regions. VEGF-NFMs application improved reduced NAA/Cr ratio, preventing neuronal loss. VEGF-NFMs sticking decreased the number of TUNEL-positive cells in surgical temporal cortex, ameliorated impaired synaptic plasticity, and inhibited the release of pro-inflammatory cytokines and the activation of microglia and astrocytes in surgical temporal cortex and hippocampus. Furthermore, BDNF-TrkB/PI3K/AKT, BDNF-TrkB/ERK and HIF-1a/VEGF/ERK pathways were involved in the treatment of VEGF-NFMs against CCH-induced neuronal injury. These results showed the neuroprotective effects of VEGF-NFMs sticking may initiate from neurovascular repairing followed by inhibition of neuronal apoptosis and neuronal and synaptic damage, eventually leading to the suppression of cognitive dysfunction, which provided theoretical foundation for further clinical transformation of VEGF-NFMs.

mTOR (Mammalian Target of Rapamycin): Hitting the Bull's Eye for Enhancing Neurogenesis After Cerebral Ischemia?

Ischemic stroke remains a leading cause of morbidity and disability around the world. The sequelae of serious neurological damage are irreversible due to body's own limited repair capacity. However, endogenous neurogenesis induced by cerebral ischemia plays a critical role in the repair and regeneration of impaired neural cells after ischemic brain injury. mTOR (mammalian target of rapamycin) kinase has been suggested to regulate neural stem cells ability to self-renew and differentiate into proliferative daughter cells, thus leading to improved cell growth, proliferation, and survival. In this review, we summarized the current evidence to support that mTOR signaling pathways may enhance neurogenesis, angiogenesis, and synaptic plasticity following cerebral ischemia, which could highlight the potential of mTOR to be a viable therapeutic target for the treatment of ischemic brain injury.

TiO2-Nanowired Delivery of Chinese Extract of Ginkgo biloba EGb-761 and Bilobalide BN-52021 Enhanced Neuroprotective Effects of Cerebrolysin Following Spinal Cord Injury at Cold Environment

Military personnel during combat or peacekeeping operations are exposed to extreme climates of hot or cold environments for longer durations. Spinal cord injury is quite common in military personnel following central nervous system (CNS) trauma indicating a possibility of altered pathophysiological responses at different ambient temperatures. Our previous studies show that the pathophysiology of brain injury is exacerbated in animals acclimated to cold (5 °C) or hot (30 °C) environments. In these diverse ambient temperature zones, trauma exacerbated oxidative stress generation inducing greater blood-brain barrier (BBB) permeability and cell damage. Extracts of Ginkgo biloba EGb-761 and BN-52021 treatment reduces brain pathology following heat stress. This effect is further improved following TiO₂ nanowired delivery in heat stress in animal models. Several studies indicate the role of EGb-761 in attenuating spinal cord induced neuronal damages and improved functional deficit. This is quite likely that these effects are further improved following nanowired delivery of EGb-761 and BN-52021 with cerebrolysin-a balanced composition of several neurotrophic factors and peptide fragments in spinal cord trauma. In this review, TiO₂ nanowired delivery of EGb-761 and BN-52021 with nanowired cerebrolysin is examined in a rat model of spinal cord injury at cold environment. Our results show that spinal cord injury aggravates cord pathology in cold-acclimated rats and nanowired delivery of EGb-761 and BN-52021 with cerebrolysin significantly induced superior neuroprotection, not reported earlier.

Inflammatory mechanisms of Ginkgo Biloba extract in improving memory functions through lncRNA-COX2/NF-κB pathway in mice with status epilepticus

PURPOSE

This study was to explore whether Ginkgo biloba extract (GBE) improve memory impairment by alleviating neuroinflammation signaling in mice with status epilepticus.

METHODS

The status epilepticus (SE) mice model was established by pilocarpine and treated with 100 mg / kg of GBE for 14 days. Spontaneous alternation of Y-maze and new object recognition were used to explore memory impairment. To examine glial cell activation, we performed immunohistochemistry and immunofluorescence staining. The activation of NF-κB signaling and the expression level of lncRNA-COX2 were detected by Western blot and qRT-PCR, respectively. Adeno-associated virus lncRNA-COX2 was injected into mice for overexpression of lncRNA-COX2.

RESULTS

After GBE treatment, the spontaneous alternation rate and the recognition coefficient in SE mice were both increased. Moreover, activation of glial cells, NF-κB signaling and lncRNA-COX2 were significantly decreased in SE mice. In the GBE-treated SE mice with lncRNA-COX2 overexpression, NF-κB signaling was up-regulated again; the reduced level of inflammation factors was reversed; the GBE-rescued spontaneous alternation rate of Y-maze was eliminated.

CONCLUSION

Our results suggested that GBE reduces the hippocampal inflammation by down-regulating lncRNA-COX2 / NF-κB signaling in the SE mice, leading to the decrease of neuronal damage and the improvement of memory functions.

Electroacupuncture Increases the Hippocampal Synaptic Transmission Efficiency and Long-Term Plasticity to Improve Vascular Cognitive Impairment

Studies have shown that electroacupuncture (EA) can effectively improve vascular cognitive impairment (VCI), but its mechanisms have not been clearly elucidated. This study is aimed at investigating the mechanisms underlying the effects of EA treatment on hippocampal synaptic transmission efficiency and plasticity in rats with VCI. Methods. Sprague–Dawley rats were subjected to VCI with bilateral common carotid occlusion (2VO). EA stimulation was applied to Baihui (GV20) and Shenting (GV24) acupoints for 30 min once a day, five times a week, for four weeks. Our study also included nonacupoint groups to confirm the specificity of EA therapy. The Morris water maze (MWM) was used to assess cognitive function. Electrophysiological techniques were used to detect the field characteristics of the hippocampal CA3–CA1 circuit in each group of rats, including input-output (I/O), paired-pulse facilitation ratios (PPR), field excitatory postsynaptic potential (fEPSP), and excitatory postsynaptic current (EPSC). The expression of synapse- and calcium-mediated signal transduction associated proteins was detected through western blotting. Results. The MWM behavioural results showed that EA significantly improved cognitive function in VCI model rats. EA increased the I/O curve of VCI model rats from 20 to 90 μA. No significant differences were observed in hippocampal PPR. The fEPSP of the hippocampal CA3–CA1 circuit was significantly increased after EA treatment compared with that after nonacupuncture treatment. We found that EA led to an increase in the EPSC amplitude and frequency, especially in the decay and rise times. In addition, the protein expression and phosphorylation levels of N-methyl-D-aspartate receptor 2B, α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor 1, and Ca²⁺-calmodulin-dependent protein kinase II increased to varying degrees in the hippocampus of VCI model rats. Conclusion. EA at GV20 and GV24 acupoints increased the basic synaptic transmission efficiency and synaptic plasticity of the hippocampal CA3–CA1 circuit, thereby improving learning and memory ability in rats with VCI.

Ginkgo Biloba Extract Ameliorates Scopolamine-induced Memory Deficits via Rescuing Synaptic Damage

Objective

Alzheimer’s disease (AD) is the most common age-related neurodegenerative disorder. Emerging evidence suggests that synaptic dysfunction is associated with the onset and progression of AD. Interestingly, Ginkgo biloba extract (EGb) is one of the most frequently investigated herbal medicines for enhancing cognition and alleviating neurodegenerative dementia. This study aimed to investigate the effect and the mechanism of EGb on AD-like synaptic disorders.

Methods

Scopolamine (SCO)-induced rats were used to mimic AD-like memory deficits. Morris water maze test and fear conditioning test were conducted to evaluate the memory status of rats in response to different treatments. Then, the synapse alterations were assessed by Golgi staining, and Western blotting was conducted to assess the protein expression of PSD95, GluN2B, synapsin-1, and synaptophysin. Reverse transcription quantitative polymerase chain reaction was applied to detect the mRNA expression of PSD95 and the levels of miR-1-3p/miR-206-3p.

Results

EGb supplement alleviated the learning and memory deficits induced by SCO in behavioral experiments. Moreover, EGb treatment attenuated synaptic damage elicited by SCO, manifested as increased dendritic spine density and the proportion of mushroom-type spines in hippocampal neurons. Further investigation indicated that EGb rescued the expression of synaptic-related proteins, especially PSD95, and decreased the levels of miR-1-3p/miR-206-3p in the rat hippocampus.

Conclusion

The application of EGb effectively treats SCO-induced memory impairments probably by suppressing miR-1-3p/miR-206-3p and elevating the expression of PSD95.

The microbiota-gut-brain axis participates in chronic cerebral hypoperfusion by disrupting the metabolism of short-chain fatty acids

BACKGROUND

Chronic cerebral hypoperfusion (CCH) underlies secondary brain injury following certain metabolic disorders and central nervous system (CNS) diseases. Dysregulation of the microbiota-gut-brain axis can exacerbate various CNS disorders through aberrantly expressed metabolites such as short-chain fatty acids (SCFAs). Yet, its relationship with CCH remains to be demonstrated. And if so, it is of interest to explore whether restoring gut microbiota to maintain SCFA metabolism could protect against CCH.

RESULTS

Rats subjected to bilateral common carotid artery occlusion (BCCAO) as a model of CCH exhibited cognitive impairment, depressive-like behaviors, decreased gut motility, and compromised gut barrier functions. The 16S ribosomal RNA gene sequencing revealed an abnormal gut microbiota profile and decreased relative abundance of some representative SCFA producers, with the decreased hippocampal SCFAs as the further evidence. Using fecal microbiota transplantation (FMT), rats recolonized with a balanced gut microbiome acquired a higher level of hippocampal SCFAs, as well as decreased neuroinflammation when exposed to lipopolysaccharide. Healthy FMT promoted gut motility and gut barrier functions, and improved cognitive decline and depressive-like behaviors by inhibiting hippocampal neuronal apoptosis in BCCAO rats. Long-term SCFA supplementation further confirmed its neuroprotective effect in terms of relieving inflammatory response and hippocampal neuronal apoptosis following BCCAO.

CONCLUSION

Our results demonstrate that modulating the gut microbiome via FMT can ameliorate BCCAO-induced gut dysbiosis, cognitive decline, and depressive-like behaviors, possibly by enhancing the relative abundance of SCFA-producing floras and subsequently increasing SCFA levels. Video abstract.