Morroniside improves microvascular functional integrity of the neurovascular unit after cerebral ischemia

Deep brain stimulation combined with morroniside promotes neural plasticity and motor functional recovery after ischemic stroke

Background and Objective

Until now, there has been an unmet need for treatments promoting chronic-phase post-stroke functional recovery. We previously found that morroniside promoted endogenous neurogenesis in ischemic stroke, but its therapeutic window was limited to the first 48 h. Here, we aimed to explore whether deep brain stimulation (DBS) combined with morroniside could enhance neurogenesis in rats subjected to focal ischemic stroke and contributes to functional recovery.

Methods

Beginning 2 weeks after the endothelin-1-induced stroke, rats were administered DBS of lateral cerebellar nucleus consecutively for 14 days, followed by morroniside for 7 consecutive days post-stimulation. Behavioral tests were used for assessing motor function. Local field potentials were recorded to evaluate neuronal excitability. Nissl staining was used to assess infarct volume. Immunofluorescence staining and Western blotting were carried out to uncover the stroke recovery mechanisms of DBS combined with morroniside treatment.

Results

The results showed that this combined treatment improved behavioral outcomes, enhanced cortical local field potentials, and diminished infarct volumes at 35 days post-stroke. Moreover, it notably amplified neurogenic responses post-stroke, evidenced by the proliferation of BrdU/SOX2 and BrdU/DCX in the subventricular zone, and their subsequent differentiation into BrdU/NeuN and BrdU/VgulT1 in the ischemic penumbra. Moreover, the combined treatment also elevated the amount of BrdU/Olig2 and the level of axonal sprouting-related proteins in the perilesional cortex.

Conclusion

Our results demonstrated that the combined treatment extended the neurorestorative efficacy of morroniside, reduced infarct size, enhanced neuronal excitability and accelerated sensorimotor function recovery. This therapeutic approach may emerge as a potential clinical intervention for chronic ischemic stroke.

A review of the sources and pharmacological research of morroniside

Introduction

Morroniside (Mor) is a bioactive compound found in Corni Fructus (CF) [Cornaceae; Cornus officinalis Siebold & Zucc.], which has been used as medicine and food in China, Korea, and Japan for over 2,000 years. This review summarizes recent progress on Mor, specifically focusing on its distribution, isolation, detection, and various pharmacological effects.

Methods

A literature survey on Mor was conducted using electronic databases such as PubMed, ScienceDirect, CNKI, and Google Scholar. After removing TCM prescription-related standards, medicinal herb processing-related research, and other irrelevant works of literature, we obtained relevant information on Mor's biological and pharmacological properties.

Results

The main conclusions are as follows: Mor is widely distributed in the plant kingdom; the methods for extracting and isolating Mor are well established; and the technology for detecting it is accurate. Mor exhibits numerous pharmacological effects. Along with CF, Mor has shown renoprotective effects against diabetes, hepatoprotective effects against diabetes, triptolide, and nonalcoholic steatohepatitis, and boneprotective effects against osteoporosis and osteoarthritis. In addition, researchers have also explored other pharmacological effects of Mor, including neuroprotective effects against focal cerebral ischemia, spinal cord injury, and Alzheimer's disease; cardioprotective effects against acute myocardial infarction; protection of the digestive system from gastritis, inflammatory bowel disease, and colitis; protection of the skin by promoting hair growth, wound healing, and flap survival; and protection of the lungs from acute lung injury and pulmonary fibrosis. Moreover, Mor has anti-obesity effects, anti-inflammatory effects in the eye, and improves follicular development.

Discussion

Overall, this review provides a comprehensive understanding of the pharmacological effects of Mor, from which the limitations of the current research can be understood, which will help facilitate future research.

Integrated Strategies for Targeting Arteriogenesis and Angiogenesis After Stroke

The interdependence between arteriogenesis and angiogenesis is crucial for enhancing perfusion by synchronously improving leptomeningeal collaterals (LMCs) and microvascular networks after stroke. However, current approaches often focus on promoting arteriogenesis and angiogenesis separately, neglecting the potential synergistic benefits of targeting both processes simultaneously. Therefore, it is imperative to consider both arteriogenesis and angiogenesis as integral and complementary strategies for post-stroke revascularization. To gain a deeper understanding of their relationships after stroke and to facilitate the development of targeted revascularization strategies, we compared them based on their timescale, space, and pathophysiology. The temporal differences in the occurrence of arteriogenesis and angiogenesis allow them to restore blood flow at different stages after stroke. The spatial differences in the effects of arteriogenesis and angiogenesis enable them to specifically target the ischemic penumbra and core infarct region. Additionally, the endothelial cell, as the primary effector cell in their pathophysiological processes, is promising target for enhancing both. Therefore, we provide an overview of key signals that regulate endothelium-mediated arteriogenesis and angiogenesis. Finally, we summarize current therapeutic strategies that involve these signals to promote both processes after stroke, with the aim of inspiring future therapeutic advances in revascularization.

Morroniside promotes skin wound re-epithelialization by facilitating epidermal stem cell proliferation through GLP-1R-mediated upregulation of β-catenin expression

Epidermal stem cells (EpSCs) play a vital role in skin wound healing through re-epithelialization. Identifying chemicals that can promote EpSC proliferation is helpful for treating skin wounds. This study investigates the effect of morroniside on cutaneous wound healing in mice and explores the underlying mechanisms. Application of 10‒50 μg/mL of morroniside to the skin wound promotes wound healing in mice. In vitro studies demonstrate that morroniside stimulates the proliferation of mouse and human EpSCs in a time- and dose-dependent manner. Mechanistic studies reveal that morroniside promotes the proliferation of EpSCs by facilitating the cell cycle transition from the G1 to S phase. Morroniside increases the expression of β-catenin via the glucagon-like peptide-1 receptor (GLP-1R)-mediated PKA, PKA/PI3K/AKT and PKA/ERK signaling pathways, resulting in an increase in cyclin D1 and cyclin E1 expression, either directly or by upregulating c-Myc expression. This process ultimately leads to EpSC proliferation. Administration of morroniside to mouse skin wounds increases the phosphorylation of AKT and ERK, the expressions of β-catenin, c-Myc, cyclin D1, and cyclin E1, as well as the proliferation of EpSCs, in periwound skin tissue, and accelerates wound re-epithelialization. These effects of morroniside are mediated by the GLP-1R. Overall, these results indicate that morroniside promotes skin wound healing by stimulating the proliferation of EpSCs via increasing β-catenin expression and subsequently upregulating c-Myc, cyclin D1, and cyclin E1 expressions through GLP-1R signaling pathways. Morroniside has clinical potential for treating skin wounds.

Cornus officinalis: a potential herb for treatment of osteoporosis

Osteoporosis (OP) is a systemic metabolic skeletal disorder characterized by a decline in bone mass, bone mineral density, and deterioration of bone microstructure. It is prevalent among the elderly, particularly postmenopausal women, and poses a substantial burden to patients and society due to the high incidence of fragility fractures. Kidney-tonifying Traditional Chinese medicine (TCM) has long been utilized for OP prevention and treatment. In contrast to conventional approaches such as hormone replacement therapy, TCM offers distinct advantages such as minimal side effects, low toxicity, excellent tolerability, and suitability for long-term administration. Extensive experimental evidence supports the efficacy of kidney-tonifying TCM, exemplified by formulations based on the renowned herb Cornus officinalis and its bioactive constituents, including morroniside, sweroside, flavonol kaempferol, Cornuside I, in OP treatment. In this review, we provide a comprehensive elucidation of the underlying pathological principles governing OP, with particular emphasis on bone marrow mesenchymal stem cells, the homeostasis of osteogenic and osteoclastic, and the regulation of vascular and immune systems, all of which critically influence bone homeostasis. Furthermore, the therapeutic mechanisms of Cornus officinalis-based TCM formulations and Cornus officinalis-derived active constituents are discussed. In conclusion, this review aims to enhance understanding of the pharmacological mechanisms responsible for the anti-OP effects of kidney-tonifying TCM, specifically focusing on Cornus officinalis, and seeks to explore more efficacious and safer treatment strategies for OP.

Neuroprotective strategies for neonatal hypoxic-ischemic brain damage: Current status and challenges

Neonatal hypoxic-ischemic brain damage (HIBD) is a prominent contributor to both immediate mortality and long-term impairment in newborns. The elusive nature of the underlying mechanisms responsible for neonatal HIBD presents a significant obstacle in the effective clinical application of numerous pharmaceutical interventions. This comprehensive review aims to concentrate on the potential neuroprotective agents that have demonstrated efficacy in addressing various pathogenic factors associated with neonatal HIBD, encompassing oxidative stress, calcium overload, mitochondrial dysfunction, endoplasmic reticulum stress, inflammatory response, and apoptosis. In this review, we conducted an analysis of the precise molecular pathways by which these drugs elicit neuroprotective effects in animal models of neonatal hypoxic-ischemic brain injury (HIBD). Our objective was to provide a comprehensive overview of potential neuroprotective agents for the treatment of neonatal HIBD in animal experiments, with the ultimate goal of enhancing the feasibility of clinical translation and establishing a solid theoretical foundation for the clinical management of neonatal HIBD.

Role of traditional Chinese medicine monomers in cerebral ischemia/reperfusion injury:a review of the mechanism

Ischemia/reperfusion (I/R) injury is a pathological process wherein reperfusion of an ischemic organ or tissue exacerbates the injury, posing a significant health threat and economic burden to patients and their families. I/R triggers a multitude of physiological and pathological events, such as inflammatory responses, oxidative stress, neuronal cell death, and disruption of the blood-brain barrier (BBB). Hence, the development of effective therapeutic strategies targeting the pathological processes resulting from I/R is crucial for the rehabilitation and long-term enhancement of the quality of life in patients with cerebral ischemia/reperfusion injury (CIRI). Traditional Chinese medicine (TCM) monomers refer to bioactive compounds extracted from Chinese herbal medicine, possessing anti-inflammatory and antioxidative effects, and the ability to modulate programmed cell death (PCD). TCM monomers have emerged as promising candidates for the treatment of CIRI and its subsequent complications. Preclinical studies have demonstrated that TCM monomers can enhance the recovery of neurological function following CIRI by mitigating oxidative stress, suppressing inflammatory responses, reducing neuronal cell death and functional impairment, as well as minimizing cerebral infarction volume. The neuroprotective effects of TCM monomers on CIRI have been extensively investigated, and a comprehensive understanding of their mechanisms can pave the way for novel approaches to I/R treatment. This review aims to update and summarize evidence of the protective effects of TCMs in CIRI, with a focus on their role in modulating oxidative stress, inflammation, PCD, glutamate excitotoxicity, Ca2+ overload, as well as promoting blood-brain barrier repairment and angiogenesis. The main objective is to underscore the significant contribution of TCM monomers in alleviating CIRI.

Cornuside, by regulating the AGEs-RAGE-IκBα-ERK1/2 signaling pathway, ameliorates cognitive impairment associated with brain aging

Anti-Alzheimer's disease (AD) drugs can only change the symptoms of cognitive impairment in a short time but cannot prevent or completely cure AD. Thus, a more effective drug is urgently needed. Cornuside is extracted from Corni Fructus, a traditional Chinese medicine that plays an important role in treating dementia and other age-related diseases. Thus, the study aimed to explore the effects and mechanisms of Cornuside on the D-galactose (D-Gal) induced aging mice accompanied by cognitive decline. Initially, we found that Cornuside improved the learning and memory abilities of D-Gal-treated mice in behavioral experiments. Pharmacological experiments indicated that Cornuside acted on anti-oxidant and anti-inflammatory effects. Cornuside also reversed acetylcholin esterase (AChE) activity. Meanwhile, pathology tests showed that Cornuside had a protective effect on neuron damage. Cornuside increased the expression of brain-derived neurotrophic factor (BDNF), and down-regulated the expression of receptor for advanced glycosylation end products (RAGE), ionized calcium binding adapter molecule 1 (Iba1), and glial fibrillary acidic protein (GFAP) respectively. Further studies claimed that Cornuside had important effects on the expression of IκBα and extracellular signal-regulated kinases 1/2 (ERK1/2). These effects might be achieved through regulating the AGEs-RAGE-IκBα-ERK1/2 signaling pathway, among which, ERK1/2 might be the key protein. The study provides direct preclinical evidence for the research of Cornuside, which may become an excellent candidate drug for the treatment of aging-related AD.

Effect of morroniside on the transcriptome profiles of rat in injured spinal cords

We have previously reported that morroniside promoted motor activity after spinal cord injury (SCI) in rats. However, the mechanism by which morroniside induces recovery of injured spinal cord (SC) remains unknown. In the current study, RNA sequencing (RNA-seq) was employed to evaluate changes of gene expressions at the transcriptional level of the injured spinal cords in morroniside-administrated rats. Principal component analysis, analysis of enriched Gene Ontology (GO), enrichment analyses Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and other bioinformatics analyses were executed to distinguish differentially expressed genes (DEGs). The results of RNA-seq confirmed the anti-inflammatory and anti-apoptotic effects of morroniside on injured SC tissues, and provided the basis for additional research of the mechanisms involving the protective effects of morroniside on SCI.

Microglial M2 Polarization Mediated the Neuroprotective Effect of Morroniside in Transient MCAO-Induced Mice

Morroniside, a secoiridoid glycoside from Cornus officinalis, is a class of small molecule non-peptide glucagon-like peptide-1 receptor (GLP-1R) agonists and possess many important biomedical functions. Our previous studies reported that GLP-1R agonist exenatide promoted M2 polarization and the expression of cell-specific anti-inflammatory factor interleukin-10 in neuropathological pain model. In this study, we proved that morroniside not only induced M2 polarization and stimulated interleukin-10 expression specifically in cortical primary microglia by p38β mitogen-activated protein kinases pathway but also protected nerve cells against H₂O₂-induced cell oxidative damage and prohibited ischemic injury by reducing infarct size, which is at least in part mediated by enhanced expression of microglial interleukin-10. In the cortical penumbra area in middle cerebral artery occlusion (MCAO) mice. In general, our results indicated that GLP-1R agonist morroniside might play a neuroprotective effect by inducing M2 polarization, and cyclic-AMP/protein kinase A/p38β pathway might mediate morroniside-induced expression of interleukin-10 protein in M2 microglia.

Electrical stimulation of the lateral cerebellar nucleus promotes neurogenesis in rats after motor cortical ischemia

Deep brain stimulation (DBS) has been tentatively explored to promote motor recovery after stroke. Stroke could transiently activate endogenous self-repair processes, including neurogenesis in the subventricular zone (SVZ). In this regard, it is of considerable clinical interest to study whether DBS of the lateral cerebellar nucleus (LCN) could promote neurogenesis in the SVZ for functional recovery after stroke. In the present study, rats were trained on the pasta matrix reaching task and the ladder rung walking task before surgery. And then an electrode was implanted in the LCN following cortical ischemia induced by endothelin-1 injection. After 1 week of recovery, LCN DBS coupled with motor training for two weeks promoted motor function recovery, and reduced the infarct volumes post-ischemia. LCN DBS augmented poststroke neurogenetic responses, characterized by proliferation of neural progenitor cells (NPCs) and neuroblasts in the SVZ and subsequent differentiation into neurons in the ischemic penumbra at 21 days poststroke. DBS with the same stimulus parameters at 1 month after ischemia could also increase nascent neuroblasts in the SVZ and newly matured neurons in the perilesional cortex at 42 days poststroke. These results suggest that LCN DBS promotes endogenous neurogenesis for neurorestoration after cortical ischemia.

Morroniside enhances angiogenesis and improves cardiac function following acute myocardial infarction in rats

Angiogenesis is critical for re-establishing blood supply to the ischemic myocardium after acute myocardial infarction (AMI). This study aimed to investigate the effects of morroniside on angiogenesis after AMI and explored associated proangiogenic mechanisms. A rat model of AMI was established by ligation of the left anterior descending coronary artery followed by administration of three doses of morroniside. Immunofluorescence staining was performed to identify newly generated endothelial cells and arterioles. The protein expression levels associated with angiogenesis were examined by western blots. Echocardiography was used to examine cardiac function. Our data revealed that morroniside promoted angiogenesis and improved cardiac function in rats with AMI. The proangiogenic effect of morroniside might be mediated by the VEGFA/VEGF receptor 2 signaling pathway.

Cornus mas and Cornus Officinalis-Analogies and Differences of Two Medicinal Plants Traditionally Used

Among 65 species belonging to the genus Cornus only two, Cornus mas L. and Cornus officinalis Sieb. et Zucc. (Cornaceae), have been traditionally used since ancient times. Cornus mas (cornelian cherry) is native to southern Europe and southwest Asia, whereas C. officinalis (Asiatic dogwood, cornel dogwood) is a deciduous tree distributed in eastern Asia, mainly in China, as well as Korea and Japan. Based on the different geographic distribution of the closely related species but clearly distinct taxa, the ethnopharmacological use of C. mas and C. officinalis seems to be independently originated. Many reports on the quality of C. mas fruits were performed due to their value as edible fruits, and few reports compared their physicochemical properties with other edible fruits. However, the detailed phytochemical profiles of C. mas and C. officinalis, in particular fruits, have never been compared. The aim of this review was highlighting the similarities and differences of phytochemicals found in fruits of C. mas and C. officinalis in relation to their biological effects as well as compare the therapeutic use of fruits from both traditional species. The fruits of C. mas and C. officinalis are characterized by the presence of secondary metabolites, in particular iridoids, anthocyanins, phenolic acids and flavonoids. However, much more not widely known iridoids, such as morroniside, as well as tannins were detected particularly in fruits of C. officinalis. The referred studies of biological activity of both species indicate their antidiabetic and hepatoprotective properties. Based on the available reports antihyperlipidemic and anticoagulant activity seems to be unique for extracts of C. mas fruits, whereas antiosteoporotic and immunomodulatory activities were assigned to preparations of C. officinalis fruits. In conclusion, the comparison of phytochemical composition of fruits from both species revealed a wide range of similarities as well as some constituents unique for cornelian cherry or Asiatic dogwood. Thus, these phytochemicals are considered the important factor determining the biological activity and justifying the use of C. mas and C. officinalis in the traditional European and Asiatic medicine.

Applications and development of permeability imaging in ischemic stroke

Brain permeability imaging techniques are specific for the assessment of blood-brain barrier integrity. The present review article primarily focuses on the application of permeability imaging in cases of ischemic stroke. The permeability maps may be used to predict future hemorrhagic transformation in patients following acute ischemic stroke, that have been treated with tissue plasminogen activator (tPA) or recanalization therapy. The permeability imaging would help make the clinical decision to administer tPA following acute ischemic stroke or not, which is not only due to the current 3-4.5 h time window. Additionally, permeability imaging may also be used to evaluate the collateral circulation in the perfusion and permeability of the ischemic area of the brain.

Morroniside on anti-inflammation activities in rats following acute myocardial infarction

Our previous studies have confirmed that morroniside has neuroprotective effects. However, the effects of morroniside on cardiac myocardium remain unknown. Rats were anaesthetized with 10% chloral hydrate (0.35~0.4 mL/kg) and an acute myocardial infarction (AMI) was induced by ligating the anterior descending coronary artery (LAD). Following AMI, morroniside was administered intragastrically for 3 consecutive days at doses of 45, 90 and 180 mg/kg, respectively. Lactate dehydrogenase (LDH) and cardiac troponin T (cTnT) activities in AMI rats in the serum were detected with commercial kits. The expression of IL-6, IL-1β and TNF-α in myocardium was detected by Western blotting analysis. We observed a significant decline in the Q(q) wave amplitude in morroniside-treated rats after 72 h. Additionally, treatment of morroniside decreased the levels of LDH and cTnT in AMI rats. We also observed that morroniside reduced the expression of IL-6, IL-1β and TNF-α in myocardium. Taken together, our findings demonstrate that morroniside had effective anti-inflammatory properties in AMI rats.

Repulsive guidance molecule a suppresses angiogenesis after ischemia/reperfusion injury of middle cerebral artery occlusion in rats

Repulsive guidance molecule a (RGMa) has now emerged as a molecule with pleiotropic roles, including repulsion, adhesion, migration and differentiation in the nervous system. In this study, adult male Sprague-Dawley (SD) rats received 90-min middle cerebral artery occlusion (MCAO) to observe RGMa/neogenin expression sites after ischemia/reperfusion injury and changes in angiogenesis after treatment with RNA interference using RGMa-specific recombinant adenovirus rAd5-shRNA-RGMa (rAd-shRGMa). To clarify how RGMa mediates angiogenesis, the RGMa function-blocking peptide six fibronectin type III (6FNIII) was also administered, and corresponding changes in vascular endothelial growth factor (VEGF), angiopoietin-2 (Ang2), angiopoietin-1 (Ang1), and brain derived neurotrophic factor (BDNF) were determined by western blotting. Both RGMa and its receptor neogenin were expressed in neurons and vessel endothelial cells after ischemia/reperfusion injury, and angiogenesis, coupled with functional recovery, was enhanced after RNA interference against RGMa compared with the vehicle groups. VEGF, Ang2, Ang1 and BDNF expression levels were significantly increased after intervention with rAd-shRGMa or 6FNIII. Thus, RGMa might suppress angiogenesis via VEGF, Ang2, Ang1 and BDNF after cerebral ischemia/reperfusion injury, which has therapeutic potential by reducing these endogenous detrimental mechanisms.

Effects of intra-arterial transplantation of adipose-derived stem cells on the expression of netrin-1 and its receptor DCC in the peri-infarct cortex after experimental stroke

Background

Stem cell transplantation has been documented to promote functional recovery in animal models of stroke; however, the underlying mechanisms are not yet fully understood. As netrin-1 and its receptor deleted in colorectal cancer (DCC) are important regulators in neuronal and vascular activities, the present study attempted to explore whether netrin-1 and DCC are involved in the neuroprotection of stem cell-based therapies in a rat ischemic stroke model.

Methods

Adult male Sprague–Dawley rats were subjected to a transient middle cerebral artery occlusion (MCAO) and subsequently received an intra-arterial injection of 2 × 10⁶ PKH26-labeled adipose-derived stem cells (ADSCs) or saline 24 h later. Neurological function was evaluated by behavioral tests before the rats were sacrificed at days 7 and 14 after MCAO. The migration of ADSCs and regeneration of neuronal fibers and blood vessels were determined by immunofluorescence staining. The expression of netrin-1 and DCC was analyzed by Western blot and immunofluorescence staining.

Results

ADSC transplantation significantly improved the neurological recovery at days 7 and 14, and noticeably promoted the regeneration of neuronal fibers and blood vessels in the peri-infarct cortex at day 14. PKH26-labeled ADSCs located mainly in the peri-infarct area at days 7 and 14. In ADSC-treated rats, the expression of netrin-1 and DCC significantly increased in the peri-infarct cortex at days 7 and 14. Immunofluorescence staining showed that netrin-1 was mainly expressed by neuronal perikaryal in the peri-infarct cortex, and DCC was mainly expressed by neuronal fibers and was present around the blood vessels in the peri-infarct cortex.

Conclusions

These findings suggest that ADSC transplantation facilitates the regeneration of neuronal fibers and blood vessels in the peri-infarct cortex and improves neurological functions, which may be attributed, at least in part, to the involvement of upregulated netrin-1 and DCC in the remodeling of neuronal and vascular networks in the peri-infarct cortex.

Anti-Inflammation of Natural Components from Medicinal Plants at Low Concentrations in Brain via Inhibiting Neutrophil Infiltration after Stroke

Inflammation after stroke consists of activation of microglia/astrocytes in situ and infiltration of blood-borne leukocytes, resulting in brain damage and neurological deficits. Mounting data demonstrated that most natural components from medicinal plants had anti-inflammatory effects after ischemic stroke through inhibiting activation of resident microglia/astrocytes within ischemic area. However, it is speculated that this classical activity cannot account for the anti-inflammatory function of these natural components in the cerebral parenchyma, where they are detected at very low concentrations due to their poor membrane permeability and slight leakage of BBB. Could these drugs exert anti-inflammatory effects peripherally without being delivered across the BBB? Factually, ameliorating blood-borne neutrophil recruitment in peripheral circulatory system has been proved to reduce ischemic damage and improve outcomes. Thus, it is concluded that if drugs could achieve effective concentrations in the cerebral parenchyma, they can function via crippling resident microglia/astrocytes activation and inhibiting neutrophil infiltration, whereas the latter will be dominating when these drugs localize in the brain at a low concentration. In this review, the availability of some natural components crossing the BBB in stroke will be discussed, and how these drugs lead to improvements in stroke through inhibition of neutrophil rolling, adhesion, and transmigration will be illustrated.