The role of rosemary extract in degeneration of hippocampal neurons induced by kainic acid in the rat: A behavioral and histochemical approach

Natural flavonoids as potential therapeutics in the management of Alzheimer's disease: a review

Alzheimer's disease (AD) is an age-dependent neurodegenerative disorder which is associated with the accumulation of proteotoxic Aβ peptides, and pathologically characterized by the deposition of Aβ-enriched plaques and neurofibrillary tangles. Given the social and economic burden caused by the rising frequency of AD, there is an urgent need for the development of appropriate therapeutics. Natural compounds are gaining popularity as alternatives to synthetic drugs due to their neuroprotective properties and higher biocompatibility. While natural compound's therapeutic effects for AD have been recently investigated in numerous in vitro and in vivo studies, only few have developed to clinical trials. The present review aims to provide a brief overview of the therapeutic effects, new insights, and upcoming perspectives of the preclinical and clinical trials of flavonoids for the treatment of Alzheimer's disease.

Role of Network Pharmacology in Prediction of Mechanism of Neuroprotective Compounds

Network pharmacology is an emerging pioneering approach in the drug discovery process, which is used to predict the therapeutic mechanism of compounds using various bioinformatic tools and databases. Emerging studies have indicated the use of network pharmacological approaches in various research fields, particularly in the identification of possible mechanisms of herbal compounds/ayurvedic formulations in the management of various diseases. These techniques could also play an important role in the prediction of the possible mechanisms of neuroprotective compounds. The first part of the chapter includes an introduction on neuroprotective compounds based on literature. Further, network pharmacological approaches are briefly discussed. The use of network pharmacology in the prediction of the neuroprotective mechanism of compounds is discussed in detail with suitable examples. Finally, the chapter concludes with the current challenges and future prospectives.

Effects of Rosmarinus officinalis L. Extract on Neurobehavioral and Neurobiological Changes in Male Rats with Pentylenetetrazol-Induced Epilepsy

This study investigated the effect of Rosmarinus officinalis L. (RO) extract on neurobehavioral and neurobiological changes in male rats with pentylenetetrazol (PTZ)-induced epilepsy. Rats were assigned into five groups: (1) control rats, (2) RO-treated rats, (3) PTZ-treated rats, (4) PTZ + RO-treated rats, and (5) PTZ + valproic acid (VA)-treated rats. The PTZ-treated rats required a significantly longer time and distance to find the platform in the Morris water maze test than the control and RO-treated rats. Additionally, PTZ-treated rats showed a decrease in tendency to cross over the platform compared to PTZ group. PTZ + RO-treated rats showed decreased swimming time and distance to find the platform compared to PTZ group. PTZ + RO-treated rats showed a significant decrease in seizure score, a reduced number of myoclonic jerks, and an increased onset of the first myoclonic jerk compared to PTZ group. PTZ reduced the time required to enter the dark room in the passive avoidance learning test, which was reversed by RO treatment. Biochemical results revealed that PTZ-treated rats had higher levels of oxidative stress markers. RO significantly increased the antioxidant markers levels and maintained normal rat brain histology. This study revealed that RO can shield the brain and neural tissues from PTZ.

Beneficial Effects of Rosmarinic Acid In Vitro and In Vivo Models of Epileptiform Activity Induced by Pilocarpine

Epilepsy is characterized by a predisposition to generate recurrent and spontaneous seizures; it affects millions of people worldwide. Status epilepticus (SE) is a severe type of seizure. In this context, screening potential treatments is very important. In the present study, we evaluated the beneficial effects of rosmarinic acid (RA) in pilocarpine-induced in vitro and in vivo models of epileptiform activity. Using an in vitro model in combined entorhinal cortex-hippocampal from Wistar rats we evaluated the effects of RA (10 µg/mL) on the lactate release and a glucose fluorescent analogue, 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NDBG), after incubation in high potassium aCSF supplemented or not with pilocarpine. In the in vivo model, SE was induced in male C57BL/6 mice by pilocarpine. At 1, 24, and 48 h after the end of SE mice were treated with RA (30 mg/kg/v.o.). We evaluated the neuromotor impairment by neuroscore tests and protein carbonyl levels in the cerebral cortex. In both in vitro models, RA was able to decrease the stimulated lactate release, while no effect on 2-NBDG uptake was found. RA has beneficial effects in models of epileptiform activity in vivo and in vitro. We found that RA treatment attenuated SE-induced neuromotor impairment at the 48 h timepoint. Moreover, post-SE treatment with RA decreased levels of protein carbonyls in the cerebral cortex of mice when compared to their vehicle-treated counterparts. Importantly, RA was effective in a model of SE which is relevant for the human condition. The present data add to the literature on the biological effects of RA, which could be a good candidate for add-on therapy in epilepsy.

Mediterranean natural extracts improved cognitive behavior in zebrafish and healthy rats and ameliorated lps-induced cognitive impairment in a sex dependent manner

BACKGROUND

Several findings suggest neuroinflammation as a contributing factor for the onset of psychiatric disorders such as Alzheimer's disease, depression, and anxiety. There is increasing evidence pointing out that the Mediterranean diet influences brain and behavior. Mediterranean herbs and spices have been shown to be within those components of the Mediterranean diet involved in cognitive enhancement. Thus, we investigated the influence of Mediterranean natural extracts (MNE), Rosemary extract (RE) and Glycyrrhiza glabra root extract (GGRE), on cognitive behavior.

RESULTS

Adult zebrafish were exposed to RE or GGRE (100 and 250 mg/L) treatments. Both MNE improved memory retention during the T-maze test, although no improvements were observed during the novel object preference. Similarly, chronic administration of RE (150 mg/Kg) and GGRE (150 mg/Kg) improved, respectively, spatial and retention memory, as assessed by the Morris Water Maze (MWM), and the Elevated Plus Maze (EPM) in healthy male rats. However, no improvements were observed during the novel object recognition. Finally, male, and female rats were chronically treated with lipopolysaccharide [(LPS) 300 ug/kg] and orally administered with RE. Interestingly, RE reversed LPS-induced cognitive deficit during the MWM and EPM in female rats.

CONCLUSIONS

We found that MNE improved cognition in both zebrafish and rats. Moreover, MNE rescued LPS-induced cognitive impairment in a gender-specific manner. Therefore, our study supports the view that zebrafish represent a valuable preclinical model for drug discovery in neuroscience. These findings contribute to an exciting and growing body of research suggesting that MNE may play an important role in the prevention of cognitive impairment.

MicroRNA-451 Aggravates Kainic Acid-induced Seizure and Neuronal Apoptosis by Targeting GDNF

AIM

Epilepsy is a common and serious neurological disease that causes recurrent episodes, but its molecular mechanism remains unclear. Abnormal miRNA expression is associated with epilepsy, including miR-451. This research investigated the role of miR-451 in seizure and its detailed mechanism.

METHODS

The seizure mice model was induced by kainic acid (KA) injection to the right lateral cerebral ventricle. Behavioral changes in mice were observed and evaluated by the Racine Scale. The miR-451 knockout mice were established by adenovirus infection. The in vitro model was performed by miR-451 mimics transfected HEK-293 cells. The amount of neuronal death and morphological changes were evaluated by Nissl staining and H&E staining.

RESULTS

The results showed that miR-451 is up regulated in KA-induced seizure models and miR- 451 knockout decreased the behavior score and improved the pathological changes of the hippocampus. Besides, MiR-451 knockout inhibited the apoptosis of hippocampal neurons. Bioinformatics studies have shown that glial cell line-derived neurotrophic factor (GDNF) is a target gene of miR-451. MiR-451 could negatively regulate the expression of GDNF. GDNF overexpression could reverse the effect of miR-451 on KA induced brain injury and neuronal apoptosis.

CONCLUSION

This research demonstrates that miR-451 can affect the behavior of KA-induced epilepsy mice and hippocampal neuronal damage by regulating GDNF expression. The results would provide an experimental foundation for further research about the potential contribution of mi- RNAs to epilepsy pathophysiology.

Rosmarinic Acid, a Bioactive Phenolic Compound, Inhibits Glutamate Release from Rat Cerebrocortical Synaptosomes through GABAA Receptor Activation

Rosmarinic acid, a major component of rosemary, is a polyphenolic compound with potential neuroprotective effects. Asreducing the synaptic release of glutamate is crucial to achieving neuroprotectant's pharmacotherapeutic effects, the effect of rosmarinic acid on glutamate release was investigated in rat cerebrocortical nerve terminals (synaptosomes). Rosmarinic acid depressed the 4-aminopyridine (4-AP)-induced glutamate release in a concentration-dependent manner. The removal of extracellular calcium and the blockade of vesicular transporters prevented the inhibition of glutamate release by rosmarinic acid. Rosmarinic acid reduced 4-AP-induced intrasynaptosomal Ca2+ elevation. The inhibition of N-, P/Q-type Ca2+ channels and the calcium/calmodulin-dependent kinase II (CaMKII) prevented rosmarinic acid from having effects on glutamate release. Rosmarinic acid also reduced the 4-AP-induced activation of CaMKII and the subsequent phosphorylation of synapsin I, the main presynaptic target of CaMKII. In addition, immunocytochemistry confirmed the presence of GABAA receptors. GABAA receptor agonist and antagonist blocked the inhibitory effect of rosmarinic acid on 4-AP-evoked glutamate release. Docking data also revealed that rosmarinic acid formed a hydrogen bond with the amino acid residues of GABAA receptor. These results suggested that rosmarinic acid activates GABAA receptors in cerebrocortical synaptosomes to decrease Ca2+ influx and CaMKII/synapsin I pathway to inhibit the evoked glutamate release.

Vagus nerve stimulation affects inflammatory response and anti-apoptosis reactions via regulating miR-210 in epilepsy rat model

BACKGROUND

Studies have shown that vagus nerve stimulation (VNS) significantly reduces the frequency of seizures. MicroRNAs (miRNAs) in cerebrospinal fluid are expected to become a new biomarker of epilepsy. Therefore, studying the interaction mechanism between the VNS and miRNAs is hopeful of bringing a new therapeutic direction for the treatment of epilepsy.

METHODS

Kainic acid was used to induce the Sprague-Dawley rat epilepsy model, and the rats were treated with VNS. The miR-210 expression was determined by quantitative reverse transcription PCR (qRT-PCR). Racine score was adopted to evaluate the performance of behavioral seizures, whereas qRT-PCR and ELISA were employed to test inflammatory factors. Western blotting was implemented to testify the inflammatory and apoptotic proteins.

RESULTS

Kainic acid-induced the Sprague-Dawley rat epilepsy model and upregulated the expression of miR-210, inflammatory response, inflammation and apoptosis-related proteins in brain tissues. In addition, compared with the epilepsy model group, miR-210 in the hippocampus of the epilepsy model rats treated with VNS was downregulated, and the expression of apoptosis-related proteins and inflammatory factors was reduced. Moreover, after further inhibiting the expression of miR-210, the inhibition of VNS on epilepsy, inflammation and apoptosis were significantly enhanced.

SUMMARY

VNS relieves the inflammatory response and apoptosis of epileptic rats via inhibiting miR-210.

MiR-125a-5p Alleviates Dysfunction and Inflammation of Pentylenetetrazol- induced Epilepsy Through Targeting Calmodulin-dependent Protein Kinase IV (CAMK4)

BACKGROUND

MicroRNAs (miRNA) are known to play a key role in the etiology and treatment of epilepsy through controlling the expression of gene. However, miR-125a-5p in the epilepsy is little known. Epilepsy in rat models was induced by Pentylenetetrazol (PTZ) and miR- 125a-5p profiles in the hippocampus were investigated in our experiment. Also, the relationship between miR-125a-5p and calmodulin-dependent protein kinase IV (CAMK4) was identified and the related mechanism was also illustrated.

METHODS

The miR-125a-5p mRNA expression levels were evaluated by quantitative real time polymerase chain reaction (qRT-PCR). Western Blot (WB) was used to analyze the CAMK4 protein expression levels. Seizure score, latency and duration were determined based on a Racine scale. The enzyme-linked immunosorbent assay (ELISA) was used to analyze the inflammatory factor expression. The relationship between miR-125a-5p and CAMK4 was detected through dual luciferase assay.

RESULTS

Downregulation of miR-125a-5p was observed in the hippocampus of PTZ-induced epilepsy rats. The overexpression of miR-125a-5p attenuated seizure and decreased inflammatory factor level in the hippocampus of PTZ-induced rats. The miR-125a-5p alleviated epileptic seizure and inflammation in PTZ-induced rats by suppressing its target gene, CAMK4.

CONCLUSION

miR-125a-5p may represent a novel therapeutic treatment for PTZ-induced epilepsy by preventing the activation of CAMK4.

Natural Products and Their Bioactive Compounds: Neuroprotective Potentials against Neurodegenerative Diseases

In recent years, natural products, which originate from plants, animals, and fungi, together with their bioactive compounds have been intensively explored and studied for their therapeutic potentials for various diseases such as cardiovascular, diabetes, hypertension, reproductive, cancer, and neurodegenerative diseases. Neurodegenerative diseases, including Alzheimer's disease, Huntington's disease, Parkinson's disease, and amyotrophic lateral sclerosis are characterized by the progressive dysfunction and loss of neuronal structure and function that resulted in the neuronal cell death. Since the multifactorial pathological mechanisms are associated with neurodegeneration, targeting multiple mechanisms of actions and neuroprotection approach, which involves preventing cell death and restoring the function to damaged neurons, could be promising strategies for the prevention and therapeutic of neurodegenerative diseases. Natural products have emerged as potential neuroprotective agents for the treatment of neurodegenerative diseases. This review focused on the therapeutic potential of natural products and their bioactive compounds to exert a neuroprotective effect on the pathologies of neurodegenerative diseases.

Rosmarinus officinalis Essential Oil Improves Scopolamine-Induced Neurobehavioral Changes via Restoration of Cholinergic Function and Brain Antioxidant Status in Zebrafish (Danio rerio)

Rosmarinus officinalis L. is a traditional herb with various therapeutic applications such as antibacterial, antioxidant, anti-inflammatory, antidepressant, and anticholinesterase activities, and can be used for the prevention or treatment of dementia. In the present study, we tested whether Rosmarinus officinalis L. could counteract scopolamine-induced anxiety, dementia, and brain oxidative stress in the zebrafish model and tried to find the underlying mechanism. Rosmarinus officinalis L. essential oil (REO: 25, 150, and 300 µL/L) was administered by immersion to zebrafish (Danio rerio) once daily for eight days while scopolamine (100 µM) treatment was delivered 30 min before behavioral tests. The antidepressant and cognitive-enhancing actions of the essential oil in the scopolamine zebrafish model was measured in the novel tank diving test (NTT) and Y-maze test. The chemical composition was identified by Gas chromatograph–Mass spectrometry (GC-MS) analysis. The brain oxidative status and acetylcholinesterase (AChE) activity was also determined. REO reversed scopolamine-induced anxiety, memory impairment, and brain oxidative stress. In addition, a reduced brain AChE activity following the administration of REO in scopolamine-treated fish was observed. In conclusion, REO exerted antidepressant-like effect and cognitive-enhancing action and was able to abolish AChE alteration and brain oxidative stress induced by scopolamine.

Long non‑coding RNA LINC00473/miR‑195‑5p promotes glioma progression via YAP1‑TEAD1‑Hippo signaling

There is an urgent need to identify novel potential therapeutic targets for diagnosis and treatment of glioma, a common primary tumor in brain, due to its high-level invasiveness. Long non-coding RNA (lncRNA) LINC00473 has been reported as potentially critical regulators in various types of cancer tumorigenesis. However, the effects of LINC00473 on glioma cells is unclear. The present study aimed to investigate the clinical significance, effects and mechanism of LINC00437 on glioma tumorigenesis. In the present study, LINC00473 was significantly increased in glioma tissues and in cell models, and predicted a poor prognosis in patients with glioma. Notably, LINC00473 knockdown not only suppressed cell proliferation, invasion and migration of glioma cells, but also blocked cell cycle progression and induced apoptosis. Subcutaneous xenotransplanted tumor model experiments revealed that reduced LINC00473 expression was able to suppress in vivo glioma growth. Mechanistically, LINC00473 functioned as a competing endogenous (ce)RNA to decrease microRNA (miR)-195-5p expression. Moreover, Yes-associated protein 1 (YAP1) and TEA domain family member 1 (TEAD1) were identified as downstream targets of miR-195-5p, whose expression levels were inhibited by miR-195-5p. LINC00473 knockdown suppressed glioma progression through the decrease of miR-195-5p and subsequent increase of YAP1 and TEAD1 expression levels. These results indicated LINC00473 might act as a ceRNA to sponge miR-195-5p, thus promoting YAP1 and TEAD1 expressions, and shedding light on the underlying mechanisms of LINC00473-induced glioma progression.