Cordycepin Ameliorates Synaptic Dysfunction and Dendrite Morphology Damage of Hippocampal CA1 via A1R in Cerebral Ischemia

Bioactive compounds from Cordyceps and their therapeutic potential

The Clavicipitaceae family's largest and most diverse genus is Cordyceps. They are most abundant and diverse in humid temperate and tropical forests and have a wide distribution in: Europe, North America, and East and Southeast Asian countries, particularly: Bhutan, China, Japan, Nepal, Korea, Thailand, Vietnam, Tibet, and the Himalayan region of India, and Sikkim. It is a well-known parasitic fungus that feeds on insects and other arthropods belonging to 10 different orders. Over 200 bioactive metabolites, that include: nucleotides and nucleosides, polysaccharides, proteins, polypeptides, amino acids, sterols, and fatty acids, among others have been extracted from Cordyceps spp. demonstrating the phytochemical richness of this genus. These components have been associated with a variety of pharmacological effects, including: anti-microbial, anti-apoptotic, anti-cancer, anti-inflammatory, antioxidant, and immunomodulatory activities. In this paper, the bioactivity of various classes of metabolites produced by Cordyceps spp., and their therapeutic properties have been reviewed in an attempt to update the existing literature. Furthermore, one of its nucleoside and a key bioactive compound, cordycepin has been critically elaborated with regard to its biosynthesis pathway and the recently proposed protector-protégé mechanism as well as various biological and pharmacological effects, such as: suppression of purine and nucleic acid biosynthesis, induction of apoptosis, and cell cycle regulation with their mechanism of action. This review provides current knowledge on the bioactive potential of Cordyceps spp.

Adenosine A2A receptor blockade attenuates excitotoxicity in rat striatal medium spiny neurons during an ischemic-like insult

During brain ischemia, excitotoxicity and peri-infarct depolarization injuries occur and cause cerebral tissue damage. Indeed, anoxic depolarization, consisting of massive neuronal depolarization due to the loss of membrane ion gradients, occurs in vivo or in vitro during an energy failure. The neuromodulator adenosine is released in huge amounts during cerebral ischemia and exerts its effects by activating specific metabotropic receptors, namely: A1, A2A, A2B, and A3. The A2A receptor subtype is highly expressed in striatal medium spiny neurons, which are particularly susceptible to ischemic damage. Evidence indicates that the A2A receptors are upregulated in the rat striatum after stroke and the selective antagonist SCH58261 protects from exaggerated glutamate release within the first 4 hours from the insult and alleviates neurological impairment and histological injury in the following 24 hours. We recently added new knowledge to the mechanisms by which the adenosine A2A receptor subtype participates in ischemia-induced neuronal death by performing patch-clamp recordings from medium spiny neurons in rat striatal brain slices exposed to oxygen and glucose deprivation. We demonstrated that the selective block of A2A receptors by SCH58261 significantly reduced ionic imbalance and delayed the anoxic depolarization in medium spiny neurons during oxygen and glucose deprivation and that the mechanism involves voltage-gated K+ channel modulation and a presynaptic inhibition of glutamate release by the A2A receptor antagonist. The present review summarizes the latest findings in the literature about the possibility of developing selective ligands of A2A receptors as advantageous therapeutic tools that may contribute to counteracting neurodegeneration after brain ischemia.

Rhynchophylline ameliorates cerebral ischemia by improving the synaptic plasticity in a middle cerebral artery occlusion induced stroke model

INTRODUCTION

Previous studies have documented that rhynchophylline exerts antioxidative and anti-inflammatory effects on ischemic neuronal damage in vitro or in vivo. There is a considerable lack of direct evidence for its role in neural function and neuroplasticity after ischemic stroke.

AIMS

This study aims to explore the role of rhynchophylline in middle cerebral artery occlusion (MCAO) induced ischemic stroke model and the potential mechanisms.

METHODS

Mice were randomly divided into the following three groups: Sham, MCAO + ddH2O, and MCAO + Rhy(40 mg/kg by oral gavage) groups. Cerebral ischemia was induced by MCAO. Cerebral blood flow was monitored to indicate the success of the ischemic model. The neurological severity score and a series of related behavior tests were performed(after MCAO 3d,7d,14d,21d,28d). Golgi staining and Sholl analysis were used to evaluate the complexity of dendrites and the density of dendritic spines. Immunohistochemistry was used to detect the expression of synapsin I and NeuN.

RESULTS

Administration of rhynchophylline for 7 consecutive days after the onset of cerebral ischemia alleviated the sensory-motor functional defects and ameliorated hippocampus-dependent spatial memory injury as well as reduced the infarct volume induced by MCAO. However, golgi staining and sholl analysis showed that rhynchophylline improved dendritic complexity and spine density as well as the synaptic plasticity. Furthermore,the expression of synapsin I and Neun was significantly reduced after cerebral ischemia and rhynchophylline administration ameliorated the loss of synapsin I.

CONCLUSION

Rhynchophylline is a promising treatment for ischemic stroke via improving synaptic plasticity and ameliorating the sensory-motor function.

Cordycepin improved the cognitive function through regulating adenosine A2A receptors in MPTP induced Parkinson's disease mice model

BACKGROUND

Parkinson's disease (PD), the most common neurodegenerative disorder, primarily affects dopaminergic neurons in the substantia nigra (SN). In addition to severe motor dysfunction, PD patients appear apparent cognitive impairments in the late stage. Cognitive dysfunction is accompanied by synaptic transmission damage in the hippocampus. Cordycepin has been reported to alleviate cognitive impairments in neurodegenerative diseases.

PURPOSE

The study aimed to estimate the protection roles of cordycepin on cognitive dysfunction in PD model and explore the potential mechanisms.

METHODS

1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was used to establish the PD model in vivo and in vitro experiments. In the in vivo experiments, the C57BL / 6 mice were intraperitoneally injected with MPTP and intragastric administration with cordycepin. Open field test (OFT) was used to estimate the exercise ability. Spontaneous alternation behavioral (SAB) and morris water maze (MWM) tests were used to evaluate the learning and memory abilities. The hippocampal slices from C57BL / 6 and Kunming mice in the in vitro experiments were used to record field excitatory postsynaptic potential (fEPSP) by electrophysiological methods. Western blotting was used to examine the level of tyrosine hydroxylase (TH) in the in vivo experiments and the levels of adenosine A₁ and A_2A receptors (A₁R and A_2AR) in the in vitro experiments, respectively. The drugs of MPTP, cordycepin, DPCPX and SCH58261 were perfused through dissolving in artificial cerebrospinal fluid.

RESULTS

Cordycepin could significantly reduce the impairments on motor, exploration, spatial learning and memory induce by MPTP. MPTP reduced the amplitude of LTP in hippocampal CA1 area but cordycepin could improve LTP amplitudes. Cordycepin at dosage of 20 mg/kg also increased the TH level in SN. In the in vitro experiments, MPTP inhibited synaptic transmission in hippocampal Schaffer-CA1 pathway with a dose-dependent relationship, while cordycepin could reverse the inhibition of synaptic transmission. Furthermore, the roles of cordycepin on synaptic transmission could been attenuated in the presence of the antagonists of A₁R and A_2AR, DPCPX and SCH58261, respectively. Interestingly, the level of A_2AR rather than A₁R in hippocampus was significantly decreased in the cordycepin group as compared to the control.

CONCLUSION

The present study has showed that cordycepin could improve cognitive function in the PD model induced by MPTP through regulating the adenosine A_2A receptors. These findings were helpful to provide a new strategy for the dementia caused by Parkinson's disease.

Excitatory Synaptic Transmission in Ischemic Stroke: A New Outlet for Classical Neuroprotective Strategies

Stroke is one of the leading causes of death and disability in the world, of which ischemia accounts for the majority. There is growing evidence of changes in synaptic connections and neural network functions in the brain of stroke patients. Currently, the studies on these neurobiological alterations mainly focus on the principle of glutamate excitotoxicity, and the corresponding neuroprotective strategies are limited to blocking the overactivation of ionic glutamate receptors. Nevertheless, it is disappointing that these treatments often fail because of the unspecificity and serious side effects of the tested drugs in clinical trials. Thus, in the prevention and treatment of stroke, finding and developing new targets of neuroprotective intervention is still the focus and goal of research in this field. In this review, we focus on the whole processes of glutamatergic synaptic transmission and highlight the pathological changes underlying each link to help develop potential therapeutic strategies for ischemic brain damage. These strategies include: (1) controlling the synaptic or extra-synaptic release of glutamate, (2) selectively blocking the action of the glutamate receptor NMDAR subunit, (3) increasing glutamate metabolism, and reuptake in the brain and blood, and (4) regulating the glutamate system by GABA receptors and the microbiota–gut–brain axis. Based on these latest findings, it is expected to promote a substantial understanding of the complex glutamate signal transduction mechanism, thereby providing excellent neuroprotection research direction for human ischemic stroke (IS).

Bioactive natural products in COVID-19 therapy

The devastating COVID-19 pandemic has caused more than six million deaths worldwide during the last 2 years. Effective therapeutic agents are greatly needed, yet promising magic bullets still do not exist. Numerous natural products (cordycepin, gallinamide A, plitidepsin, telocinobufagin, and tylophorine) have been widely studied and play a potential function in treating COVID-19. In this paper, we reviewed published studies (from May 2021 to April 2022) relating closely to bioactive natural products (isolated from medicinal plants, animals products, and marine organisms) in COVID-19 therapy in vitro to provide some essential guidance for anti-SARS-CoV-2 drug research and development.