Garcinol Upregulates GABAA and GAD65 Expression, Modulates BDNF-TrkB Pathway to Reduce Seizures in Pentylenetetrazole (PTZ)-Induced Epilepsy

Pentylenetetrazole kindling induces dynamic changes in GAD65 expression in hippocampal somatostatin interneurons

INTRODUCTION

One of the mechanisms of epileptgenesis is impairment of inhibitory neural circuits. Several studies have compared neural changes among subtypes of gamma-aminobutyric acid-related (GABAergic) neurons after acquired epileptic seizure. However, it is unclear that GABAergic neural modifications that occur during acquisition process of epileptic seizure.

METHODS

Male rats were injected with pentylenetetrazole (PTZ kindling: n = 30) or saline (control: n = 15) every other day to observe the development of epileptic seizure stages. Two time points were identified: the point at which seizures were most difficult to induce, and the point at which seizures were most easy to induce. The expression of GABAergic neuron-related proteins in the hippocampus was immunohistochemically compared among GABAergic subtypes at each of these time points.

RESULTS

Bimodal changes in seizure stages were observed in response to PTZ kindling. The increase of seizure stage was transiently suppressed after 8 or 10 injections, and then progressed again by the 16th injection. Based on these results, we defined 10 injections as a short-term injection period during which seizures are less likely to occur, and 20 injections as a long-term injection period during which continuous seizures are likely to occur. The immunohistochemical analysis showed that hippocampal glutamic acid decarboxylase 65 (GAD65) expression was increased after short-term kindling but unchanged after long-term kindling. Increased GAD65 expression was limited to somatostatin-positive (SOM+) cells among several GABAergic subtypes. By contrast, GAD, GABA, GABAAR α1, GABABR1, and VGAT cells showed no change following short- or long-term PTZ kindling.

CONCLUSION

PTZ kindling induces bimodal changes in the epileptic seizure stage. Seizure stage is transiently suppressed after short-term PTZ injection with GAD65 upregulation in SOM+ cells. The seizure stage is progressed again after long-term PTZ injection with GAD65 reduction to baseline level.

Therapeutic Potential of Myricetin in the Treatment of Neurological, Neuropsychiatric, and Neurodegenerative Disorders

Myricetin (MC), 3,5,7,3',4',5'-hexahydroxyflavone, chemically belongs to a flavonoid category known to confer antioxidant, antimicrobial, antidiabetic, and neuroprotective effects. MC is known to suppress the generation of Reactive Oxygen Species (ROS), lipid peroxidation (MDA), and inflammatory markers. It has been reported to improve insulin function in the human brain and periphery. Besides this, it modulates several neurochemicals including glutamate, GABA, serotonin, etc. MC has been shown to reduce the expression of the enzyme Mono Amine Oxidase (MAO), which is responsible for the metabolism of monoamines. MC treatment reduces levels of plasma corticosterone and restores hippocampal BDNF (full form) protein in stressed animals. Further, MC has shown its protective effect against amyloid-beta, MPTP, rotenone, 6-OHDA, etc. suggesting its potential role against neurodegenerative disorders. The aim of the present review is to highlight the therapeutic potential of MC in the treatment of several neurological, neuropsychiatric, and neurodegenerative disorders.

Antidepressant effects of 70% ethanolic extract of Lonicerae japonicae flos and it contained chlorogenic acid via upregulation of BDNF-TrkB pathway in the hippocampus of mice

Lonicera japonica flos (LJF) is a common clinical herb with outstanding medicinal and nutritional value. This study aimed to evaluate the antidepressant effects of LJF's active extract and compound chlorogenic acid (CGA) around brain-derived neurotrophic factor(BDNF)-tropomyosin receptor kinase B (TrkB) pathway. The results showed that LJF's extracts and CGA had significant antidepressant effects, and the antidepressant effects of different extracts of LJF were highly positively correlated with the content of CGA (forced swimming test, r = 0.998; tail suspension test, r = 0.934). Moreover, LJF-70% ethanolic extract and CGA improved chronic unpredictable mild stress-induced depressive behavior, upregulated protein expression levels of BDNF and p-TrkB in the hippocampus, restored the damage of hippocampal neurons, and protected liver from damage. In summary, this study demonstrated for the first time that LJF-70% ethanolic extract was the active extract of LJF in antidepressant and CGA was its active compound, and the antidepressant mechanisms mainly involved the upregulation of BDNF-TrkB signaling pathway in the hippocampus of mice.

Garcinia kola: a critical review on chemistry and pharmacology of an important West African medicinal plant

Garcinia kola Heckel (Clusiaceae) is a tree indigenous to West and Central Africa. All plant parts, but especially the seeds, are of value in local folklore medicine. Garcinia kola is used in treatment of numerous diseases, including gastric disorders, bronchial diseases, fever, malaria and is used to induce a stimulating and aphrodisiac effect. The plant is now attracting considerable interest as a possible source of pharmaceutically important drugs. Several different classes of compounds such as biflavonoids, benzophenones, benzofurans, benzopyran, vitamin E derivatives, xanthones, and phytosterols, have been isolated from G. kola, of which many appears to be found only in this species, such as garcinianin (found in seeds and roots), kolanone (fruit pulp, seeds, roots), gakolanone (stem bark), garcinoic acid, garcinal (both in seeds), garcifuran A and B, and garcipyran (all in roots). They showed a wide range of pharmacological activities (e.g. analgesic, anticancer, antidiabetic, anti-inflammatory, antimalarial, antimicrobial, hepatoprotective and neuroprotective effects), though this has only been confirmed in animal models. Kolaviron is the most studied compound and is perceived by many studies as the active principle of G. kola. However, its research is associated with significant flaws (e.g. too high doses tested, inappropriate positive control). Garcinol has been tested under better conditions and is perhaps showing more promising results and should attract deeper research interest (especially in the area of anticancer, antimicrobial, and neuroprotective activity). Human clinical trials and mechanism-of-action studies must be carried out to verify whether any of the compounds present in G. kola may be used as a lead in the drug development.

Garcinol acts as a novel integrin αIIbβ3 inhibitor in human platelets

AIMS

Platelet activation plays a central role in arterial thrombosis. Platelets are activated by adhesive proteins (i.e., collagen) or soluble agonists (i.e., thrombin), the respective receptor-specific signaling cause inside-out signaling, leading to the binding of fibrinogen to integrin α_IIbβ₃. This binding triggers outside-in signaling, resulting in platelet aggregation. Garcinol, a polyisoprenylated benzophenone, is extracted from the fruit rind of Garcinia indica. Although garcinol exhibits considerable bioactivities, few studies have investigated the effect of garcinol on platelet activation.

MAIN METHODS

Aggregometry, immunoblotting, flow cytometer, confocal microscopic analysis, fibrin clot retraction, animal studies such as fluorescein-induced platelet plug formation in mesenteric microvessels, acute pulmonary thromboembolism, and tail bleeding time were performed in this study.

KEY FINDINGS

This study indicates that garcinol inhibited platelet aggregation stimulated by collagen, thrombin, arachidonic acid, and U46619. Garcinol reduced integrin α_IIbβ₃ inside-out signaling, including ATP release; cytosolic Ca²⁺ mobilization; P-selectin expression; and Syk, PLCγ2/PKC, PI3K/Akt/GSK3β, MAPKs, and NF-κB activation stimulated by collagen. Garcinol directly inhibited integrin α_IIbβ₃ activation by interfering with FITC-PAC-1 and FITC-triflavin by collagen. Additionally, garcinol affected integrin α_IIbβ₃-mediated outside-in signaling, such as decreasing platelet adhesion and the single-platelet spreading area; suppressing integrin β₃, Src, FAK, and Syk phosphorylation on immobilized fibrinogen; and inhibiting thrombin-stimulated fibrin clot retraction. Garcinol substantially reduced mortality caused by pulmonary thromboembolism and prolonged the occlusion time of thrombotic platelet plug formation without extending bleeding time in mice.

SIGNIFICANCE

This study identified that garcinol, a novel antithrombotic agent, acts as a naturally occurring integrin α_IIbβ₃ inhibitor.

Brain-Derived Neurotrophic Factor: A Novel Dynamically Regulated Therapeutic Modulator in Neurological Disorders

The growth factor brain-derived neurotrophic factor (BDNF), and its receptor tropomyosin-related kinase receptor type B (TrkB) play an active role in numerous areas of the adult brain, where they regulate the neuronal activity, function, and survival. Upregulation and downregulation of BDNF expression are critical for the physiology of neuronal circuits and functioning in the brain. Loss of BDNF function has been reported in the brains of patients with neurodegenerative or psychiatric disorders. This article reviews the BDNF gene structure, transport, secretion, expression and functions in the brain. This article also implicates BDNF in several brain-related disorders, including Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, major depressive disorder, schizophrenia, epilepsy and bipolar disorder.

The Neuroprotective Effect Associated with Echinops spinosus in an Acute Seizure Model Induced by Pentylenetetrazole

Echinops spinosus (ES) is a medicinal plant with a wide range of pharmacological and biological effects. It is a medicinal herb having a variety of therapeutic characteristics, including antioxidant, anti-inflammatory, and antibacterial capabilities. The primary goal of this research is to investigate the neuroprotective and anticonvulsant characteristics of E. spinosa extract (ESE) against pentylenetetrazole (PTZ)-induced acute seizures. Negative control rats, ESE treatment rats, PTZ acute seizure model rats, ESE + PTZ rats, and Diazepam + PTZ rats were used in the study. The rats were given a 7-day treatment. ESE pretreatment elevated the latency to seizure onset and lowered seizure duration after PTZ injection. By reducing Bax levels and enhancing antiapoptotic Bcl-2 production, ESE prevented the release of interleukin-1β, tumor necrosis factor-α, and cyclooxygenase-2, as well as preventing hippocampal cell death after PTZ injection. ESE corrected the PTZ-induced imbalance in gamma-aminobutyric acid levels and increased the enzyme activity of Na⁺/K⁺-ATPase. Echinops spinosus is a potent neuromodulatory, antioxidant, antiinflammatory, and antiapoptotic plant that could be employed as a natural anticonvulsant in the future.

Fruits for Seizures? A Systematic Review on the Potential Anti-Convulsant Effects of Fruits and their Phytochemicals

Epilepsy is a devastating neurological disorder. Current anti-convulsant drugs are only effective in about 70% of patients, while the rest remain drug-resistant. Thus, alternative methods have been explored to control seizures in these drug-resistant patients. One such method may be through the utilization of fruit phytochemicals. These phytochemicals have been reported to have beneficial properties such as anti-convulsant, anti-oxidant, and anti-inflammatory activities. However, some fruits may also elicit harmful effects. This review aims to summarize and elucidate the anti- or pro-convulsant effects of fruits used in relation to seizures in hopes of providing a good therapeutic reference to epileptic patients and their carers. Three databases, SCOPUS, ScienceDirect, and PubMed, were utilized for the literature search. Based on the PRISMA guidelines, a total of 40 articles were selected for critical appraisal in this review. Overall, the extracts and phytochemicals of fruits managed to effectively reduce seizure activities in various preclinical seizure models, acting mainly through the activation of the inhibitory neurotransmission and blocking the excitatory neurotransmission. Only star fruit has been identified as a pro-convulsant fruit due to its caramboxin and oxalate compounds. Future studies should focus more on utilizing these fruits as possible treatment strategies for epilepsy.

Garcinol blocks motor behavioural deficits by providing dopaminergic neuroprotection in MPTP mouse model of Parkinson's disease: involvement of anti-inflammatory response

Although the etiology of Parkinson's disease (PD) is poorly understood, studies in animal models revealed loss of dopamine and the dopaminergic neurons harbouring the neurotransmitter to be the principal cause behind this neuro-motor disorder. Neuroinflammation with glial cell activation is suggested to play a significant role in dopaminergic neurodegeneration. Several biomolecules have been reported to confer dopaminergic neuroprotection in different animal models of PD, owing to their anti-inflammatory potentials. Garcinol is a tri-isoprenylated benzophenone isolated from Garcinia sp. and accumulating evidences suggest that this molecule could provide neuroprotection by modulating oxidative stress and inflammation. However, direct evidence of dopaminergic neuroprotection by garcinol in the pre-clinical model of PD is not yet reported. The present study aims to investigate whether administration of garcinol in the MPTP mouse model of PD may ameliorate the cardinal motor behavioural deficits and prevent the loss of dopaminergic neurons. As expected, garcinol blocked the parkinsonian motor behavioural deficits which include akinesia, catalepsy, and rearing anomalies in the mice model. Most importantly, the degeneration of dopaminergic cell bodies in the substantia nigra region was significantly prevented by garcinol. Furthermore, garcinol reduced the inflammatory marker, glial fibrillary acidic protein, in the substantia nigra region. Since glial hyperactivation-mediated inflammation is inevitably associated with the loss of dopaminergic neurons, our study suggests the anti-inflammatory role of garcinol in facilitating dopaminergic neuroprotection in PD mice. Hence, in the light of the present study, it is suggested that garcinol is an effective anti-parkinsonian agent to block motor behavioural deficits and dopaminergic neurodegeneration in PD.

Gamma-decanolactone attenuates acute and chronic seizures in mice: a possible role of adenosine A1 receptors

This study aimed to investigate the possible gamma-decanolactone mechanisms of action in the GABAergic and adenosine systems using the aminophylline-induced acute crisis model and the pentylenetetrazole-induced kindling model. In the acute model, male mice received administration of bicuculline (GABAA receptor antagonist), 8-cyclopentyl-1,3-dipropylxanthine (A1 receptor antagonist) or ZM241385 (A2A receptor antagonist), 15 min before the treatment with gamma-decanolactone (300 mg/kg). After a single dose of aminophylline was administered, the animals were observed for 60 min. In the chronic model of seizure, 30 min after the treatment with gamma-decanolactone, mice received pentylenetetrazole once every third day. On the last day of kindling, the animals received the same GABA and adenosine antagonists used in the acute model, 15 min before gamma-decanolactone administration. The protein expression of GABAA α1 receptor and adenosine A1 receptor was detected using western blotting technique in hippocampal samples. The results showed that gamma-decanolactone increased the latency to first seizure and decreased seizure occurrence in the acute and chronic models. The adenosine A2A receptor antagonist and GABAA receptor antagonist were not able to change gamma-decanolactone behavioral seizure induced by aminophylline or pentylenetetrazole. The administration of adenosine A1 receptor antagonist reversed the protective effect of gamma-decanolactone in both models. In addition, gamma-decanolactone promoted an increase in the expression GABAA α1 receptor, in the hippocampus. The results suggest that the neuroprotective effect of gamma-decanolactone observed during the investigation could have a straight connection to its action on A1 adenosine receptors.

Exercise Improved the Anti-Epileptic Effect of Carbamazepine through GABA Enhancement in Epileptic Rats

Carbamazepine (CBZ) is an anticonvulsant drug that usually is used for the treatment of seizures. The anti-epileptic and the anti-epileptogenic effect of exercise has been reported, as well. This study was aimed to evaluate the synergic effect of combined therapy of exercise and CBZ in epileptic rats, as well as the alternation of the GABA pathway as a possible involved mechanism. The seizure was induced by pentylenetetrazol (PTZ) injection. Animals were divided into sham, seizure, exercise (EX), CBZ (25, 50 and 75), EX + CBZ (25, 50 and 75). Treadmill forced running for 30 min has been considered as the exercise 5 days per week for four weeks. CBZ was injected in doses of 25, 50 and 75 mg/kg, half an hour before seizure induction and 5 h after doing exercise in the animals forced to exercise. Seizure severity reduced and latency increased in the EX + CBZ (25) and EX + CBZ (50) groups compared to the seizure group. The distribution of GAD65 in both hippocampal CA1 and CA3 areas increased in the EX + CBZ (75) group. GABAA receptor α1 was up-regulated in the CA3 area of the EX + CBZ (75) group. The distribution of GAD65 in the cortical area increased in EX, EX + CBZ (50), CBZ (75) and EX + CBZ (75) groups. GABAA receptor α1 was up-regulated in the neocortex of EX + CBZ (50), CBZ (75) and EX + CBZ (75) groups. Our findings suggested that exercise has improved the efficacy of CBZ and reduced the anti-epileptic dose. The enhancement of GABA signaling might be involved in the synergistic effect of exercise and CBZ.

Pentylenetetrazol-induced seizures in adult rats are associated with plastic changes to the dendritic spines on hippocampal CA1 pyramidal neurons

Epilepsy is a chronic neurobehavioral disorder whereby an imbalance between neurochemical excitation and inhibition at the synaptic level provokes seizures. Various experimental models have been used to study epilepsy, including that based on acute or chronic administration of Pentylenetetrazol (PTZ). In this study, a single PTZ dose (60 mg/kg) was administered to adult male rats and 30 min later, various neurobiological parameters were studied related to the transmission and modulation of excitatory impulses in pyramidal neurons of the hippocampal CA1 field. Rats experienced generalized seizures 1-3 min after PTZ administration, accompanied by elevated levels of Synaptophysin and Glutaminase. This response suggests presynaptic glutamate release is exacerbated to toxic levels, which eventually provokes neuronal death as witnessed by the higher levels of Caspase-3, TUNEL and GFAP. Similarly, the increase in PSD-95 suggests that viable dendritic spines are functional. Indeed, the increase in stubby and wide spines is likely related to de novo spinogenesis, and the regulation of neuronal excitability, which could represent a plastic response to the synaptic over-excitation. Furthermore, the increase in mushroom spines could be associated with the storage of cognitive information and the potentiation of thin spines until they are transformed into mushroom spines. However, the reduction in BDNF suggests that the activity of these spines would be down-regulated, may in part be responsible for the cognitive decline related to hippocampal function in patients with epilepsy.

In Vivo Screening of Xanthones from Garcinia oligantha Identified Oliganthin H as a Novel Natural Inhibitor of Convulsions

Epilepsy is a chronic neurological disorder, characterized by recurrent, spontaneous, and transient seizures, and affects more than 70 million people worldwide. Although two dozen antiepileptic drugs (AEDs) are approved and available in the market, seizures remain poorly controlled in one-third of epileptic patients who are suffering from drug resistance or various adverse effects. Recently, the xanthone skeleton has been regarded as an attractive scaffold for the discovery and development of emerging anticonvulsants. We had isolated several dihydroxanthone derivatives previously, including oliganthin H, oliganthin I, and oliganthin N, whose structures were similar and delicately elucidated by spectrum analysis or X-ray crystallographic data, from extracts of leaves of Garcinia oligantha. These xanthone analogues were evaluated for anticonvulsant activity, and a novel xanthone, oliganthin H, has been identified as a sound and effective natural inhibitor of convulsions in zebrafish in vivo. A preliminary structure-activity relationship analysis on the relationship between structures of the xanthone analogues and their activities was also conducted. Oliganthin H significantly suppressed convulsant behavior and reduced to about 25% and 50% of PTZ-induced activity, in 12.5 and 25 μM treatment groups (P < 0.01 and 0.001), respectively. Meanwhile, it reduced seizure activity, velocity, seizure duration, and number of bursts in zebrafish larvae (P < 0.05). Pretreatment of oliganthin H significantly restored aberrant induction of gene expressions including npas4a, c-fos, pyya, and bdnf, as well as gabra1, gad1, glsa, and glula, upon PTZ treatment. In addition, in silico analysis revealed the stability of the oliganthin H-GABAA receptor complex and their detailed binding pattern. Therefore, direct interactions with the GABAA receptor and involvement of downstream GABA-glutamate pathways were possible mechanisms of the anticonvulsant action of oliganthin H. Our findings present the anticonvulsant activity of oliganthin H, provide a novel scaffold for further modifications, and highlight the xanthone skeleton as an attractive and reliable resource for the development of emerging AEDs.

Inhibition of p300 by Garcinol Protects against Cisplatin-Induced Acute Kidney Injury through Suppression of Oxidative Stress, Inflammation, and Tubular Cell Death in Mice

Emerging evidence suggests that epigenetic mechanisms such as histone modification are crucially involved in the pathophysiology of acute kidney injury (AKI). The histone acetyltransferase p300 regulates several biological processes through the acetylation of histones or transcription factors. However, the role of p300 in cisplatin-induced AKI remains poorly understood. Therefore, we investigated the effects of garcinol, a potent p300 inhibitor, on cisplatin-induced AKI and explored the mechanisms. Administration of garcinol significantly reversed the upregulation of p300 and increased acetylation of histone H3, along with amelioration of renal dysfunction and histopathological injury in the kidneys of cisplatin-injected mice. Garcinol also attenuated oxidative stress and reduced expression of pro-oxidant enzymes. In addition, garcinol reduced the elevated production of cytokines and chemokines and suppressed immune cell accumulation together with downregulation of vascular adhesion molecules. These beneficial effects of garcinol were associated with a reduction in acetylation of the p65 subunit of nuclear factor kappa-B. Further, garcinol significantly inhibited apoptosis and caspase-3 activation, with a decrease in p53 acetylation in cisplatin-injected mice. Taken together, we demonstrated that the inhibition of p300 by garcinol ameliorated cisplatin-induced renal injury, presumably through epigenetic mechanisms. These results suggest that garcinol might be a potential preventive agent for cisplatin-induced AKI.

Experimental Models for the Discovery of Novel Anticonvulsant Drugs: Focus on Pentylenetetrazole-Induced Seizures and Associated Memory Deficits

Epilepsy is a chronic neurological disorder characterized by irregular, excessive neuronal excitability, and recurrent seizures that affect millions of patients worldwide. Currently, accessible antiepileptic drugs (AEDs) do not adequately support all epilepsy patients, with around 30% patients not responding to the existing therapies. As lifelong epilepsy treatment is essential, the search for new and more effective AEDs with an enhanced safety profile is a significant therapeutic goal. Seizures are a combination of electrical and behavioral events that can induce biochemical, molecular, and anatomic changes. Therefore, appropriate animal models are required to evaluate novel potential AEDs. Among the large number of available animal models of seizures, the acute pentylenetetrazole (PTZ)-induced myoclonic seizure model is the most widely used model assessing the anticonvulsant effect of prospective AEDs, whereas chronic PTZ-kindled seizure models represent chronic models in which the repeated administration of PTZ at subconvulsive doses leads to the intensification of seizure activity or enhanced seizure susceptibility similar to that in human epilepsy. In this review, we summarized the memory deficits accompanying acute or chronic PTZ seizure models and how these deficits were evaluated applying several behavioral animal models. Furthermore, major advantages and limitations of the PTZ seizure models in the discovery of new AEDs were highlighted. With a focus on PTZ seizures, the major biochemicals, as well as morphological alterations and the modulated brain neurotransmitter levels associated with memory deficits have been illustrated. Moreover, numerous medicinal compounds with concurrent anticonvulsant, procognitive, antioxidant effects, modulating effects on several brain neurotransmitters in rodents, and several newly developed classes of compounds applying computer-aided drug design (CADD) have been under development as potential AEDs. The article details the in-silico approach following CADD, which can be utilized for generating libraries of novel compounds for AED discovery. Additionally, in vivo studies could be useful in demonstrating efficacy, safety, and novel mode of action of AEDs for further clinical development.

Anti-convulsant effects of cultures bear bile powder in febrile seizure via regulation of neurotransmission and inhibition of neuroinflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Natural bear bile powder (NBBP) has been used to treat seizures for thousands of years, but its application is greatly restricted due to ethical reasons. Cultured bear bile powder (CBBP), which is produced by biotransformation, may be an appropriate substitute for NBBP. However, the anti-convulsant effects of CBBP and its mechanisms remain unclear.

AIM OF THE STUDY

This study aimed to investigate the anti-convulsant effects and possible mechanisms of CBBP in a febrile seizure (FS) rat model.

MATERIALS AND METHODS

FS was induced by placing the rats in a warm water bath (45.5 °C). The incidence rate and latency of FS, and hematoxylin-eosin staining (HE) were conducted for neurological damage. The levels of 4 bile acids and 8 main neurotransmitters in vivo were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The expression of bile acid related transports, neurotransmitter receptors, inflammatory factors, neurotrophic factors and glial fibrillary acidic protein (GFAP) in hippocampal tissues were detected by real-time PCR, western blotting, and immunohistochemistry.

RESULTS

Pre-treatments with CBBP and similarly, NBBP, significantly reduced the incidence rate and prolonged the latency of FS. Additionally, CBBP alleviated the histological injury induced by FS in the rat hippocampus tissue. LC-MS/MS analyses revealed that CBBP markedly increased the levels of tauroursodeoxycholic acid (TUDCA), taurochenodeoxycholic acid (TCDCA), ursodeoxycholic acid (UDCA), and chenodeoxycholic acid (CDCA) in FS rats. Furthermore, the content of gamma-aminobutyric acid (GABA) was up-regulated in rats pre-treated with CBBP whereas GFAP was down-regulated. CBBP also significantly suppressed the expression of interleukin -1β (IL-1β), tumor necrosis factor α (TNF-α), nuclear factor kappa B (NF-κB), and brain-derived neurotrophic factor (BDNF) and its TrkB receptors, and improved the expression of GABA type A receptors (GABA_AR) and farnesoid X receptors (FXR).

CONCLUSIONS

The present study demonstrated that CBBP had anti-convulsant effects in a FS rat model. CBBP may protect rats against FS, probably by up-regulating FXR, which was activated by increasing brain bile acids, up-regulating GABAergic transmission by inhibiting BDNF-TrkB signaling, and suppressing neuroinflammation by inhibiting the NF-κB pathway.

Effect of Curcuma zedoaria hydro-alcoholic extract on learning, memory deficits and oxidative damage of brain tissue following seizures induced by pentylenetetrazole in rat

BACKGROUND

Previous studies have shown that seizures can cause cognitive disorders. On the other hand, the Curcuma zedoaria (CZ) has beneficial effects on the nervous system. However, there is little information on the possible effects of the CZ extract on seizures. The aim of this study was to investigate the possible effects of CZ extract on cognitive impairment and oxidative stress induced by epilepsy in rats.

METHODS

Rats were randomly divided into different groups. In all rats (except the sham group), kindling was performed by intraperitoneal injection of pentylenetetrazol (PTZ) at a dose of 35 mg/kg every 48 h for 14 days. Positive group received 2 mg/kg diazepam + PTZ; treatment groups received 100, 200 or 400 mg/kg CZ extract + PTZ; and one group received 0.5 mg/kg flumazenil and CZ extract + PTZ. Shuttle box and Morris Water Maze tests were used to measure memory and learning. On the last day of treatments PTZ injection was at dose of 60 mg/kg, tonic seizure threshold and mortality rate were recorded in each group. After deep anesthesia, blood was drawn from the rats' hearts and the hippocampus of all rats was removed.

RESULTS

Statistical analysis of the data showed that the CZ extract significantly increased the tonic seizure threshold and reduced the pentylenetetrazol-induced mortality and the extract dose of 400 mg/kg was selected as the most effective dose compared to the other doses. It was also found that flumazenil (a GABA_A receptor antagonist) reduced the tonic seizure threshold compared to the effective dose of the extract. The results of shuttle box and Morris water maze behavioral tests showed that memory and learning decreased in the negative control group and the CZ extract treatment improved memory and learning in rats. The CZ extract also increased antioxidant capacity, decreased MDA and NO in the brain and serum of pre-treated groups in compared to the negative control group.

CONCLUSION

It is concluded that the CZ extract has beneficial effects on learning and memory impairment in PTZ-induced epilepsy model, which has been associated with antioxidant effects in the brain or possibly exerts its effects through the GABAergic system.

Ameliorative effect of curcumin on altered expression of CACNA1A and GABRD in the pathogenesis of FeCl3-induced epilepsy

The pivotal role played by ion-channel dysregulations in the pathogenesis of epilepsy has always garnered much attention. Since mutation of ion-channel proteins CACNA1A and GABRD have been associated with epilepsy, it is important to determine the post-traumatic epilepsy-associated changes in expression levels of these ion channel proteins. Additionally, curcumin is already known for its antiepileptic and neuroprotective potential in FeCl₃-induced model of post-traumatic epilepsy. Thus, we investigated FeCl₃-induced epilepsy mediated differential expression of CACNA1A and GABRD in the cortical region of the rat brain. Furthermore, we investigated the effect of curcumin on the expression of both proteins. For this, epilepsy was induced by intracortical FeCl₃ injection (5 μl of 100 mM). Additionally, curcumin (conc. 1000 ppm; 75 mg/kg of b.wt.; for 14 and 28 days) was administered, mixed with normal food pellets. Results obtained from EEG-MUA and Morris water maze assay demonstrate the progression of epilepsy after FeCl₃ injection. Additionally, western blotting and histological studies show the downregulation of CACNA1A and GABRD during epileptogenesis. It was observed that epilepsy-associated decline in learning and memory of animals might be linked with the dysregulation of both proteins. Results also demonstrated that curcumin administration ameliorated epilepsy-associated change in expression of both CACNA1A and GABRD proteins. In conclusion, the neuroprotective effect of curcumin against iron-induced epilepsy might be accompanied by the alleviated upregulation of these channel proteins.

Evaluation of Anti-Convulsive Properties of Aqueous Kava Extract on Zebrafish Using the PTZ-Induced Seizure Model

Kava roots have been extensively studied in clinical trials as potential candidate anti-anxiety drugs. However, anti-convulsive properties of various tissues of stems of Kava have not been reported to date. The objective of the study was to evaluate the anti-convulsive potential of aqueous extracts prepared from specific tissues of Kava (Piper methysticum) stems in zebrafish, using the PTZ-induced seizure model. The potency of each extract was compared in terms of the intensity of seizure scores and onset time after pre-treating the zebrafish before the PTZ challenge. The results indicate that aqueous extract of Kava stems without peel after 45 min of pre-treatment exhibited anti-convulsive potential at the dose of 50 mg/L. This study provides evidence to the anti-convulsive properties of peeled Kava stems and its potential for investigation and design of candidate anti-convulsive drugs.

[Regulatory mechanism of MS275 on the p38 MAPK signaling pathway in rats with convulsion in the developmental stage]

OBJECTIVE

To study the regulatory mechanism of MS275, a histone deacetylase inhibitor, on the p38 MAPK signaling pathway in rats with convulsion in the developmental stage.

METHODS

Thirty-two male rats were randomly divided into four groups: control, pentylenetetrazol (PTZ), PTZ+3 mg/kg MS275, and PTZ+6 mg/kg MS275 (n=8 each). A rat model of convulsion in the developmental stage was prepared by an intraperitoneal injection of PTZ. The rats in the control group were given an injection of normal saline alone. MS275 was given by an intraperitoneal injection at 2 hours before PTZ injection. At 24 hours after successful modeling, 6 rats were taken from each group. Western blot and qRT-PCR were used to measure the protein and mRNA expression of p38, MK2, cAMP response element-binding protein (CREB), and interleukin-6 (IL-6) in the hippocampus. Hematoxylin-eosin (HE) staining was used to observe brain pathological changes. Western blot was used to measure the expression of CD11b as a marker for the activation of microglial cells.

RESULTS

Compared with the control group, the PTZ group had significant increases in the mRNA and protein expression of p38, MK2, CREB, and IL-6 (P<0.05). MS275 significantly inhibited the mRNA and protein expression of the above markers in the rats with convulsion in the developmental stage (P<0.05), and 6 mg/kg MS275 had a significantly better inhibitory effect on the mRNA and protein expression of IL-6 and CREB than 3 mg/kg MS275 (P<0.05). HE staining showed that the PTZ group had marked neuron apoptosis, cellular edema, and inflammatory cell infiltration, while MS275 intervention alleviated neuron apoptosis and cellular edema and reduced inflammatory cell infiltration in the rats with convulsion. The PTZ group had a significant increase in the activation of microglial cells, while MS275 significantly inhibited the activation of microglial cells in the rats with convulsion (P<0.05); 6 mg/kg MS275 had a significantly better inhibitory effect than 3 mg/kg MS275 (P<0.05).

CONCLUSIONS

In rats with convulsion in the developmental stage, the histone deacetylase inhibitor MS275 can inhibit the p38 MAPK signaling pathway, the apoptosis of hippocampal neurons, and the activation of microglial cells and thus reduce inflammatory response and convulsion-induced brain injury in a dose-dependent manner.

[Regulatory mechanism of MS275 on the p38 MAPK signaling pathway in rats with convulsion in the developmental stage]

OBJECTIVE

To study the regulatory mechanism of MS275, a histone deacetylase inhibitor, on the p38 MAPK signaling pathway in rats with convulsion in the developmental stage.

METHODS

Thirty-two male rats were randomly divided into four groups: control, pentylenetetrazol (PTZ), PTZ+3 mg/kg MS275, and PTZ+6 mg/kg MS275 (n=8 each). A rat model of convulsion in the developmental stage was prepared by an intraperitoneal injection of PTZ. The rats in the control group were given an injection of normal saline alone. MS275 was given by an intraperitoneal injection at 2 hours before PTZ injection. At 24 hours after successful modeling, 6 rats were taken from each group. Western blot and qRT-PCR were used to measure the protein and mRNA expression of p38, MK2, cAMP response element-binding protein (CREB), and interleukin-6 (IL-6) in the hippocampus. Hematoxylin-eosin (HE) staining was used to observe brain pathological changes. Western blot was used to measure the expression of CD11b as a marker for the activation of microglial cells.

RESULTS

Compared with the control group, the PTZ group had significant increases in the mRNA and protein expression of p38, MK2, CREB, and IL-6 (P<0.05). MS275 significantly inhibited the mRNA and protein expression of the above markers in the rats with convulsion in the developmental stage (P<0.05), and 6 mg/kg MS275 had a significantly better inhibitory effect on the mRNA and protein expression of IL-6 and CREB than 3 mg/kg MS275 (P<0.05). HE staining showed that the PTZ group had marked neuron apoptosis, cellular edema, and inflammatory cell infiltration, while MS275 intervention alleviated neuron apoptosis and cellular edema and reduced inflammatory cell infiltration in the rats with convulsion. The PTZ group had a significant increase in the activation of microglial cells, while MS275 significantly inhibited the activation of microglial cells in the rats with convulsion (P<0.05); 6 mg/kg MS275 had a significantly better inhibitory effect than 3 mg/kg MS275 (P<0.05).

CONCLUSIONS

In rats with convulsion in the developmental stage, the histone deacetylase inhibitor MS275 can inhibit the p38 MAPK signaling pathway, the apoptosis of hippocampal neurons, and the activation of microglial cells and thus reduce inflammatory response and convulsion-induced brain injury in a dose-dependent manner.

Bicyclic polyprenylated acylphloroglucinols and their derivatives: structural modification, structure-activity relationship, biological activity and mechanism of action

Bicyclic polyprenylated acylphloroglucinols (BPAPs), the principal bioactive benzophenone products isolated from plants of genera Garcinia and Hypericum, have attracted noticeable attention from the synthetic and biological communities due to their fascinating chemical structures and promising biological activities. However, the potential drug interaction, undesired physiochemical properties and toxicity have limited their potential use and development. In the last decade, pharmaceutical research on the structural modifications, structure-activity relationships (SARs) and mechanisms of action of BPAPs has been greatly developed to overcome the challenges. A comprehensive review of these scientific literature is extremely needed to give an overview of the rapidly emerging area and facilitate research related to BPAPs. This review, containing over 226 references, covers the progress made in the chemical synthesis-based structure modifications, SARs and the mechanism of action of BPAPs in vivo and vitro. The most relevant articles will focus on the discovery of lead compounds via synthetic modifications and the important BPAPs for which the direct targets have been deciphered. From this review, several key points of the SARs and mode of actions of this novel class of compounds have been summarized. The perspective and future direction of the research on BPAPs are concluded. This review would be helpful to get a better grasp of medicinal research of BPAPs and become a compelling guide for chemists dedicated to the synthesis of these compounds.

MS275 reduces seizure-induced brain damage in developing rats by regulating p38 MAPK signaling pathways and epigenetic modification

Seizure is a common acute and severe disease in infants and children. Recurrent seizures or persistent seizures may cause irreversible brain damage. Mitogen activated protein kinase (MAPK) signaling pathway is associated with an inflammatory response, however it's involvement in the pathological process of seizures is not clear. Histone deacetylase inhibitors (HDACi) have promising neuroprotective effects through epigenetic regulation. Therefore, this study aimed to investigate the mechanism of HDACi MS275 on p38 MAPK signaling pathway and p38 histone modifications in developing rats post-seizure. Intraperitoneal administration of Pentylenetetrazole (PTZ) was used to induce developing rat seizures, and MS275 (5 or 10 mg/kg) was injected intraperitoneally 2 h before PTZ injection. Hippocampal tissues were sampled at 24 h post-seizures for protein and mRNA levels of p38、MK2、CREB and IL-6. Neuronal apoptosis and microglia activation significantly increased after PTZ treatment. However, pretreatment with MS275 attenuated these effects as well as increased seizure latency and decreased seizure scores. Furthermore, MS275 was found to inhibit the expression of p38 by increasing histone H3 and H4 acetylation and decreasing histone H3 and H4 methylation. This study thereby demonstrates that HDACi MS275 can reduce the inflammatory response associated with seizure-induced brain injury through inhibiting the p38 MAPK signaling pathway and p38 gene expression.

Chemical and Biological Aspects of Garcinol and Isogarcinol: Recent Developments

The natural polyisoprenylated benzophenone derivatives garcinol and isogarcinol are secondary plant metabolites isolated from various Garcinia species including Garcinia indica. This review takes stock of the recent chemical and biological research into these interesting natural compounds over the last five years. New biological sources and chemical syntheses are discussed followed by new insights into the activity of garcinol and isogarcinol against cancer, pathogenic bacteria, parasite infections and various inflammatory diseases.

The effect of exercise on GABA signaling pathway in the model of chemically induced seizures

AIMS

Gamma amino butyric acid (GABA) imbalance plays a critical role in most neurological disorders including epilepsy. This study assessed the involvement of mild exercise on GABA imbalance following by seizure induction in rats.

MAIN METHODS

Seizure was induced by pentylentetrazole (PTZ) injection. Animals were divided into sham, seizure, exercise (EX), co-seizure-induced exercise (Co-SI EX) and Pre-SI EX groups. In the Co-SI EX group, doing exercise and seizure induction was carried out during four weeks. Animals in the Pre-SI EX group exercised in week 1 to week 8 and seizures were induced in week 5 to week 8. Seizure properties, neural viability and expressions of glutamic acid decarboxylase 65 (GAD65) and GABA_A receptor α1 in the hippocampus were assessed.

KEY FINDINGS

Seizure severity reduced and latency increased in the Co-SI EX and Pre-SI EX groups compared to seizure group. The mean number of dark neurons decreased in all exercise groups compared to seizure group in both CA1 and CA3 areas. The gene level of GAD65 and GABA_A receptor α1 was highly expressed in the Co-SI EX group in the hippocampal area. Distribution of GAD65 in the both CA1 and CA3 areas increased in the EX and Co-SI EX groups. GABA_A receptor α1 was up-regulated in the CA3 area of Co-SI EX group and down-regulated in the CA1 and CA3 areas of Pre-SI EX group.

SIGNIFICANCE

These findings suggest that exercise develop anti-epileptic as well as neuroprotective effects by modulating of GABA disinhibition.

Garcinol A Novel Inhibitor of Platelet Activation and Apoptosis

Garcinol, an anti-inflammatory and anti-carcinogenic polyisoprenylated benzophenone isolated from Garcinia plants, stimulates tumor cell apoptosis and suicidal erythrocyte death, but supports the survival of hepatocytes and neurons. The present study explored whether the substance influences platelet function and/or apoptosis. To this end, we exposed murine blood platelets to garcinol (33 µM, 30 min) without and with activation by collagen-related peptide (CRP) (2-5 µg/mL) or thrombin (0.01 U/mL); flow cytometry was employed to estimate cytosolic Ca²⁺-activity ([Ca²⁺]_i) from Fluo-3 fluorescence, platelet degranulation from P-selectin abundance, integrin activation from αIIbβ3 integrin abundance, caspase activity utilizing an Active Caspase-3 Staining kit, phosphatidylserine abundance from annexin-V-binding, relative platelet volume from forward scatter, and aggregation utilizing staining with CD9-APC and CD9-PE. As a result, in the absence of CRP and thrombin, the exposure of the platelets to garcinol did not significantly modify [Ca²⁺]_i, P-selectin abundance, activated αIIbβ3 integrin, annexin-V-binding, cell volume, caspase activity, and aggregation. Exposure of platelets to CRP or thrombin was followed by a significant increase of [Ca²⁺]_i, P-selectin abundance, αIIbβ3 integrin activity, annexin-V-binding, caspase activity, and aggregation, as well as significant cell shrinkage. All effects of CRP were strong and significant; those of thrombin were only partially and slightly blunted in the presence of garcinol. In conclusion, garcinol blunts CRP-induced platelet activity, apoptosis and aggregation.

Myricetin attenuates the severity of seizures and neuroapoptosis in pentylenetetrazole kindled mice by regulating the of BDNF-TrkB signaling pathway and modulating matrix metalloproteinase-9 and GABAA

Currently available antiepileptic drugs are effective; however, frequently associated with adverse effects that limit their therapeutic value. Compounds that target the molecular events underlying epilepsy, with minor or no adverse effects, would be of clinical value. Matrix metalloproteinase-9 (MMP-9) and the brain-derived neurotrophic factor (BDNF)-tropomyosin receptor kinase B (TrkB) signaling pathway may be involved in epileptogenesis. The current study investigated the effects of the plant-derived hydroxyflavone, myricetin, in a pentylenetetrazole (PTZ)-induced mouse model of epilepsy. Mice received an intraperitoneal injection of 35 mg/kg body weight PTZ on alternate days (13 injections) and were observed for 30 min following each PTZ injection. Myricetin (100 or 200 mg/kg body weight) was administered orally to the treatment groups (n=18/group) for 26 days, 30 min prior to each PTZ injection. Treatment with myricetin reduced seizure and mortality rates. Increased apoptotic cell count and elevated expression levels of apoptotic proteins caused by PTZ kindling were downregulated following treatment with myricetin. The BDNF-TrkB signaling pathway and MMP-9 expression levels were regulated by myricetin. Expression of γ-aminobutyric acid A (GABA) receptor and glutamic acid decarboxylase 65, as well as the glutamate/GABA balance, were restored following treatment with myricetin. The results of the present study indicated that myricetin may exert protective effects by regulating the molecular events associated with epileptogenesis.

M-Calpain Activation Facilitates Seizure Induced KCC2 Down Regulation

Potassium chloride co-transporter 2 (KCC2), a major chloride transporter that maintains GABA_A receptor inhibition in mature mammalian neurons, is down-regulated in the hippocampus during epileptogenesis. Impaired KCC2 function accelerates or facilitates seizure onset. Calpain, with two main subtypes of m- and μ-calpain, is a Ca²⁺-dependent cysteine protease that mediates the nonlysosomal degradation of KCC2. Although recent studies have demonstrated that calpain inhibitors exert antiepileptic and neuroprotective effects in animal models of acute and chronic epilepsy, whether calpain activation affects seizure induction through KCC2 degradation remains unknown. Our results showed that: (1) Blockade of calpain by non-selective calpain inhibitor MDL-28170 prevented convulsant stimulation induced KCC2 downregulation, and reduced the incidence and the severity of pentylenetetrazole (PTZ) induced seizures. (2) m-calpain, but not μ-calpain, inhibitor mimicked MDL-28170 effect on preventing KCC2 downregulation. (3) Phosphorylation of m-calpain has been significantly enhanced during seizure onset, which was partly mediated by the calcium independent MAPK/ERK signaling pathway activation. (4) MAPK/ERK signaling blockade also had similar effect as total calpain blockade on both KCC2 downregulation and animal seizure induction. The results indicate that upregulated m-calpain activation by MAPK/ERK during convulsant stimulation down regulates both cytoplasm- and membrane KCC2, and in turn facilitates seizure induction. This finding may provide a foundation for the development of highly effective antiepileptic drugs targeting of m-calpain.

Effects of histone acetyltransferase inhibitors on L-DOPA-induced dyskinesia in a murine model of Parkinson's disease

Histone acetylation is a key regulatory factor for gene expression in cells. Modulation of histone acetylation by targeting of histone acetyltransferases (HATs) effectively alters many gene expression profiles and synaptic plasticity in the brain. However, the role of HATs on L-DOPA-induced dyskinesia of Parkinson's disease (PD) has not been reported. Our aim was to determine whether HAT inhibitors such as anacardic acid, garcinol, and curcumin from natural plants reduce severity of L-DOPA-induced dyskinesia using a unilaterally 6-hydroxydopamine (6-OHDA)-lesioned PD mouse model. Anacardic acid 2 mg/kg, garcinol 5 mg/kg, or curcumin 100 mg/kg co-treatment with L-DOPA significantly reduced the axial, limb, and orofacial (ALO) score indicating less dyskinesia with administration of HAT inhibitors in 6-OHDA-lesioned mice. Additionally, L-DOPA's efficacy was not altered by the compounds in the early stage of treatment. The expression levels of c-Fos, Fra-2, and Arc were effectively decreased by administration of HAT inhibitors in the ipsilateral striatum. Our findings indicate that HAT inhibitor co-treatment with L-DOPA may have therapeutic potential for management of L-DOPA-induced dyskinesia in patients with PD.

Protective Role of L-3-n-Butylphthalide in Cognitive Function and Dysthymic Disorders in Mouse With Chronic Epilepsy

Epilepsy is a common neurological disease with recurrent seizures and neurobehavioral comorbidities, including cognitive impairment and psychiatric disorders. Recent studies suggest that L-3-n-butylphthalide (NBP), an extract from the seeds of Apium graveolens Linn. (Chinese celery), ameliorates cognitive dysfunction in ischemia and/or Alzheimer’s disease animal models. However, little is known about the role of NBP in epilepsy and the associated comorbidities. Here, using a pilocarpine-induced chronic epileptic mouse model, we found that NBP supplement not only alleviated seizure severity and abnormal electroencephalogram, but also rescued cognitive and emotional impairments in these epileptic mice. The possible underlying mechanisms may be associated with the protective role of NBP in reducing neuronal loss and in restoring the expression of neural synaptic proteins such as postsynaptic density protein 95 (PSD95) and glutamic acid decarboxylase 65/67 (GAD65/67). In addition, NBP treatment increased the transcription of neuroprotective factors, brain-derived neurotrophic factor and Klotho. These findings suggest that NBP treatment may be a potential strategy for ameliorating epileptogenesis and the comorbidities of cognitive and psychological impairments.

Safety profile of 40% Garcinol from Garcinia indica in experimental rodents

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Evaluated standardized 40% Garcinol in Wistar rats for its safety.

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Acute, sub-acute sub-chronic and reproductive/developmental toxicity study conducted.

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40% Garcinol safe up to 2000 mg/kg at single dose.

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NOAEL of 40% Garcinol at sub acute, sub-chronic and reproductive/developmental study is 100 mg/kg/day.

The present study was taken up to evaluate the single dose acute toxicity, 28 days and 90 days repeated dose toxicity and reproductive/developmental toxicity of standardized 40% Garcinol in experimental rodents. The studies were conducted in compliance with OECD principles of good laboratory practice, guidelines for testing of chemicals no.420, 407, 408 and 421 respectively. Single dose acute oral toxicity was conducted on female Wistar rats as sighting study step-I (300 mg/kg) & sighting study step-II (2000 mg/kg) and main study (2000 mg/kg). Sub-acute, sub-chronic and reproductive/developmental studies were conducted in Wistar rats divided equally in vehicle control, 20, 50 and 100 mg/kg dose group along with recovery groups for vehicle control and high dose. Reproductive/developmental study was carried out for minimum of 28 days and in females during pregnancy and 4 days post partum. There were no abnormal clinical signs/behavioural changes, reproductive and developmental parameters, gross and histopathological changes as well as no alteration in the body weight, body temperature, haematology and other biochemical parameters in all the four studies. 40% Garcinol has a low toxicity profile in rodents and had no observed effects under experimental conditions used.

Research Progress of Polycyclic Polyprenylated Acylphloroglucinols

Polycyclic polyprenylated acylphloroglucinols (PPAPs) are a class of hybrid natural products sharing the mevalonate/methylerythritol phosphate and polyketide biosynthetic pathways and showing considerable structure and bioactivity diversity. This review discusses the progress of research into the chemistry and biological activity of 421 natural PPAPs in the past 11 years as well as in-depth studies of biological activities and total synthesis of some PPAPs isolated before 2006. We created an online database of all PPAPs known to date at http://www.chem.uky.edu/research/grossman/PPAPs . Two subclasses of biosynthetically related metabolites, spirocyclic PPAPs with octahydrospiro[cyclohexan-1,5'-indene]-2,4,6-trione core and complicated PPAPs produced by intramolecular [4 + 2] cycloadditions of MPAPs, are brought into the PPAP family. Some PPAPs' relative or absolute configurations are reassigned or critically discussed, and the confusing trivial names in PPAPs investigations are clarified. Pharmacologic studies have revealed a new molecular mechanism whereby hyperforin and its derivatives regulate neurotransmitter levels by activating TRPC6 as well as the antitumor mechanism of garcinol and its analogues. The antineoplastic potential of some type B PPAPs such as oblongifolin C and guttiferone K has increased significantly. As a result of the recent appearances of innovative synthetic methods and strategies, the total syntheses of 22 natural PPAPs including hyperforin, garcinol, and plukenetione A have been accomplished.