1,8-cineole ameliorates ischaemic brain damage via TRPC6/CREB pathways in rats

Ethanol extracts of Cinnamomum migao H.W. Li attenuates neuroinflammation in cerebral ischemia-reperfusion injury via regulating TLR4-PI3K-Akt-NF-κB pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Cinnamomum migao H.W. Li, commonly known as migao (MG), is used in the Miao region of China for treating cardiovascular and cerebrovascular diseases, attributed to its detoxifying (Jiedu in Chinese), activating blood circulation (Huoxue in Chinese), and promoting Qi circulation (Tongqi in Chinese) properties. However, its therapeutic potential for ischemic stroke (IS) remains unexplored. Therefore, this study was to explore the protective effect of MG against cerebral ischemia-reperfusion injury caused by IS.

AIM OF THE STUDY

The aim of this study was to investigate whether ethanol extract of MG (EEMG) attenuates cerebral ischemia-reperfusion injury, and explored the underlying mechanisms.

MATERIALS AND METHODS

Middle cerebral artery occlusion and reperfusion (MCAO/R) was established, and the efficacy of EEMG was evaluated using triphenyltetrazolium chloride (TTC), immunofluorescence, hematoxylin-eosin (HE) staining, and real-time quantitative PCR (qRT-PCR). Qualitative analysis of EEMG was analyzed for chemical composition by liquid chromatography-mass spectrometry (LC-MS). The molecular mechanism of EEMG was explored by metabolomics, network pharmacology, immunoblotting, immunofluorescence staining, gene knockdown, and agonist treatment.

RESULTS

The results showed that EEMG alleviates ischemic injury in MCAO/R-operated rats and reduces neuronal damage of OGD/R-treated SH-SY5Y cells. Specifically, EEMG inhibited the release of inflammatory factors and reversed serum metabolic profile disorders of MCAO/R rats. Network pharmacology analysis showed that the PI3K-Akt and NF-κB signaling pathways play a role in the neuroprotective effects of EEMG against ischemic injury and in mitigating the inflammatory response. Consistent with our expectations, EEMG activated PI3K-AKT and suppressed NF-kB signaling pathways both in MCAO/R-operated rats and OGD/R-treated BV2 cells. The results showed that knockdown of TLR4 abolished the EEMG-mediated inhibition on neuroinflammation in OGD/R-treated BV2 cells. After treating BV2 cells with the TLR4 agonist neoseptin 3, EEMG showed a trend toward inhibiting neuroinflammation, though the effect was not statistically significant. Additionally, EEMG was found to improve liver injury caused by cerebral ischemia-reperfusion, which is associated with NF-κB signaling pathway in this study.

CONCLUSIONS

Collectively, this study demonstrated that EEMG attenuates neuroinflammation in cerebral ischemia-reperfusion injury via regulating TLR4-PI3K-Akt-NF-κB pathways.

NaturalEssential Oils: A Promising Therapy Way for Treating Ischemic Stroke

Stroke is an acute cerebrovascular disease with high morbidity, mortality, and disability, making it the second leading cause of death worldwide. Ischemic stroke (IS) accounts for the majority of strokes, and its pathogenesis is complex, often involving complications and sequelae. Currently, conventional clinical approaches are ineffective, with few drugs available for intravenous thrombolysis and mechanical thrombolysis limited by a short time window. With the poor efficacy of monotherapy, the search for new complementary or alternative therapies has become the focus of researchers. In traditional medicine, Chinese aromatherapy has a long history of using aromatic medicines to treat IS. Natural essential oils (EOs), as the main pharmacological substances in aromatic drugs, are composed of different ratios of active metabolites with multi-targets and multi-components, which makes EOs have a wide range of pharmacological effects. Modern studies have also shown that EOs extracts and isolated monomers are beneficial for pathologically complex CIS. Therefore, this paper summarizes the EOs and monomers obtained from EOs that can prevent and treat IS in the last 20 years, and finds that EOs exert their anti-CIS effects mainly through anti-oxidative stress, anti-inflammation, anti-apoptosis, and inhibition of excitotoxicity. The amelioration of IS complications by natural EOs and their active monomer components for the treatment of IS are further discussed.

Calpain: The regulatory point of cardiovascular and cerebrovascular diseases

Calpain, a key member of the Calpain cysteine protease superfamily, performs limited protein hydrolysis in a calcium-dependent manner. Its activity is tightly regulated due to the potential for non-specific cleavage of various intracellular proteins upon aberrant activation. A thorough review of the literature from 2010 to 2023 reveals 121 references discussing cardiovascular and cerebrovascular diseases. Dysregulation of the Calpain system is associated with various pathological phenomena, including lipid metabolism disorders, inflammation, apoptosis, and excitotoxicity. Although recent studies have revealed the significant role of Calpain in cardiovascular and cerebrovascular diseases, the precise mechanisms remain incompletely understood. Exploring the potential of Calpain inhibition as a therapeutic approach for the treatment of cardiovascular and cerebrovascular diseases may emerge as a compelling area of interest for future calpain research.

Neurotrophic Natural Products

Neurotrophins (NGF, BDNF, NT3, NT4) can decrease cell death, induce differentiation, as well as sustain the structure and function of neurons, which make them promising therapeutic agents for the treatment of neurodegenerative disorders. However, neurotrophins have not been very effective in clinical trials mostly because they cannot pass through the blood-brain barrier owing to being high-molecular-weight proteins. Thus, neurotrophin-mimic small molecules, which stimulate the synthesis of endogenous neurotrophins or enhance neurotrophic actions, may serve as promising alternatives to neurotrophins. Small-molecular-weight natural products, which have been used in dietary functional foods or in traditional medicines over the course of human history, have a great potential for the development of new therapeutic agents against neurodegenerative diseases such as Alzheimer's disease. In this contribution, a variety of natural products possessing neurotrophic properties such as neurogenesis, neurite outgrowth promotion (neuritogenesis), and neuroprotection are described, and a focus is made on the chemistry and biology of several neurotrophic natural products.

1,8-Cineole Alleviates OGD/R-Induced Oxidative Damage and Restores Mitochondrial Function by Promoting the Nrf2 Pathway

This study examined the effects of 1,8-cineole on reducing oxidative stress injury and restoring mitochondrial function in oxygen-glucose deprivation and reoxygenation (OGD/R) HT22 cells via the nuclear factor erythrocyte 2 related factor 2 (Nrf2) pathway. The optimal concentration of 1,8-cineole to reduce OGD/R injury was screened via cell morphology, cell survival rate, and lactate dehydrogenase (LDH) leakage rate. Oxidative damage was observed by measuring superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), catalase (CAT) activities, and reactive oxygen species (ROS), glutathione (GSH), protein carbonyl, malondialdehyde (MDA), lipid peroxidation (LPO) content, and 8-hydroxy-2 deoxyguanosine (8-OHDG) expression. Mitochondrial function was observed by mitochondrial membrane potential (MMP) and ATPase activity. Nrf2 pathways were observed by the expression levels of total Nrf2, nucleus Nrf2, reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H): quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1), the mRNA levels of HO-1 and NQO1. Among different concentrations of 1,8-cineole for promoting HT22 cell proliferation and attenuated OGD/R injury, 10 µmol/L 1,8-cineole was the best. After 1,8-cineole treatment, SOD, GSH-PX, and CAT activities and GSH content increased, while ROS, MDA, LPO, protein carbonyl, and 8-OHDG levels decreased. 1,8-Cineole could restore MMP and increase mitochondrial enzyme activity. It could also increase the total Nrf2, nucleus Nrf2, NQO1, and HO-1, and Nrf2 inhibitor brusatol reduced the effect of 1,8-cineole. Immunofluorescence assay showed that 1,8-cineole could facilitate the transfer of Nrf2 into the nucleus. 1,8-cineole increased the mRNA levels of NQO1 and HO-1. The above results showed that 1,8-cineole could alleviate OGD/R-induced oxidative damage and restores mitochondrial function by activating the Nrf2 signal pathway.

Exploration of Synergistic Pesticidal Activities, Control Effects and Toxicology Study of a Monoterpene Essential Oil with Two Natural Alkaloids

With the increasing development of pest resistances, it is not easy to achieve satisfactory control effects by using only one agrochemical. Additionally, although the alkaloid matrine (MT) isolated from Sophora flavescens is now utilized as a botanical pesticide in China, in fact, its pesticidal activities are much lower in magnitude than those of commercially agrochemicals. To improve its pesticidal activities, here, the joint pesticidal effects of MT with another alkaloid oxymatrine (OMT) (isolated from S. flavescens) and the monoterpene essential oil 1,8-cineole (CN) (isolated from the eucalyptus leaves) were investigated in the laboratory and greenhouse conditions. Moreover, their toxicological properties were also studied. Against Plutella xylostella, when the mass ratio of MT and OMT was 8/2, good larvicidal activity was obtained; against Tetranychus urticae, when the mass ratio of MT and OMT was 3/7, good acaricidal activity was obtained. Especially when MT and OMT were combined with CN, the significant synergistic effects were observed: against P. xylostella, the co-toxicity coefficient (CTC) of MT/OMT (8/2)/CN was 213; against T. urticae, the CTC of MT/OMT (3/7)/CN was 252. Moreover, the activity changes over time of two detoxification enzymes, carboxylesterase (CarE) and glutathione S-transferase (GST) of P. xylostella treated with MT/OMT (8/2)/CN, were observed. In addition, by scanning electron microscope (SEM), the toxicological study suggested that the acaricidal activity of MT/OMT (3/7)/CN may be related to the damage of the cuticle layer crest of T. urticae.

Calpain-TRPC6 signaling pathway contributes to propofol-induced developmental neurotoxicity in rats

Growing animal studies suggest a risk of neuronal damage following early childhood exposure to anesthesia and sedation drugs including propofol. Inhibition of transient receptor potential canonical 6 (TRPC6) degradation has been shown to protect neurons from neuronal damage induced by multiple brain injury models. Our aim was to investigate whether calpain-TRPC6 pathway is a target in propofol-induced neurotoxicity. Postnatal day (PND) 7 rats were exposed to five bolus injections of 25 mg/kg propofol or 10 % intralipid at hourly intervals. Neuronal injury was assessed by the expression pattern of TUNEL staining and cleaved-caspase-3. The Morris water maze test was used to evaluate learning and memory functions in later life. Pretreatments consisting of intracerebroventricular injections of a TRPC6 agonist, TRPC6 inhibitor, or calpain inhibitor were used to confirm the potential role of the calpain-TRPC6 pathway in propofol-induced neurotoxicity. Prolonged exposure to propofol induced neuronal injury, downregulation of TRPC6, and enhancement of calpain activity in the cerebral cortex up to 24 h after anesthesia. It also induced long-term behavioral disorders, manifesting as longer escape latency at PND40 and PND41 and as fewer platform-crossing times and less time spent in the target quadrant at PND42. These propofol-induced effects were attenuated by treatment with the TRPC6 agonist and exaggerated by the TRPC6 inhibitor. Pretreatment with the calpain inhibitor alleviated the propofol-induced TRPC6 downregulation and neuronal injury in the cerebral cortex. In conclusion, our data suggest that a calpain-TRPC6 signaling pathway contributes to propofol-induced acute cortical neuron injury and long-term behavioral disorders in rats.

Transient receptor potential ion channels and cerebral stroke

METHODS

The databases Pubmed, and the National Library of Medicine were searched for literature. All papers on celebral stroke and transient receptor potential ion channels were considered.

RESULTS

Stroke is the second leading cause of death and disability, with an increasing incidence in developing countries. About 75 per cent of strokes are caused by occlusion of cerebral arteries, and substantial advances have been made in elucidating mechanisms how stroke affects the brain. Transient receptor potential (TRP) ion channels are calcium-permeable channels highly expressed in brain that drives Ca²⁺ entry into multiple cellular compartments. TRPC1/3/4/6, TRPV1/2/4, and TRPM2/4/7 channels have been implicated in stroke pathophysiology.

CONCLUSIONS

Although the precise mechanism of transient receptor potential ion channels in cerebral stroke is still unclear, it has the potential to be a therapeutic target for patients with stroke if developed appropriately. Hence, more research is needed to prove its efficacy in this context.