Sinapic acid attenuates kainic acid-induced hippocampal neuronal damage in mice

Pharmacological Activities and Molecular Mechanisms of Sinapic Acid in Neurological Disorders

Sinapic acid (SA) is a phenylpropanoid derivative found in various natural sources that exhibits remarkable versatile properties, including antioxidant, anti-inflammatory, and metal-chelating capabilities, establishing itself as a promising candidate for the prevention and treatment of conditions affecting the central nervous system, such as Alzheimer's disease (AD), Parkinson's disease (PD), ischemic stroke, and other neurological disorders. These effects also include neuroprotection in epilepsy models, as evidenced by a reduction in seizure-like behavior, cell death in specific hippocampal regions, and lowered neuroinflammatory markers. In AD, SA treatment enhances memory, reverses cognitive deficits, and attenuates astrocyte activation. SA also has positive effects on cognition by improving memory and lowering oxidative stress. This is shown by lower levels of oxidative stress markers, higher levels of antioxidant enzyme activity, and better memory retention. Additionally, in ischemic stroke and PD models, SA provides microglial protection and exerts anti-inflammatory effects. This review emphasizes SA's multifaceted neuroprotective properties and its potential role in the prevention and treatment of various brain disorders. Despite the need for further research to fully understand its mechanisms of action and clinical applicability, SA stands out as a valuable bioactive compound in the ongoing quest to combat neurodegenerative diseases and enhance the quality of life for affected individuals.

Trigonelline as an anticonvulsant agent: mechanistic insights into NMDA receptor expression and oxidative stress balance

Glutamatergic neurotransmission and oxidative stress are involved in the pathophysiology of seizures. Some anticonvulsants exert their effects through modulation of these pathways. Trigonelline (TRG) has been shown to possess various pharmacological effects like neuroprotection. Therefore, this study was performed to determine TRG's anticonvulsant effects, focusing on its potential effects on N-methyl-D-aspartate (NMDA) receptors, a type of glutamate receptor, and oxidative stress state in the prefrontal cortex (PFC) in PTZ-induced seizure in mice. Seventy-two male mice were randomly divided into nine groups. The groups included mice that received normal saline, TRG at doses of 10, 50, and 100 mg/kg, diazepam, NMDA (an agonist), ketamine (an antagonist), the effective dose of TRG with NMDA, as well as sub-effective dose of TRG with ketamine, respectively. All agents were administrated intraperitoneally 60 min before induction of seizures by PTZ. Latency to seizure, total antioxidant capacity (TAC), and malondialdehyde (MDA) levels in serum and PFC were measured. Furthermore, the gene expression of NR2A and NR2B, subunits of NMDA receptors, was measured in the PFC. TRG administration increased the latency to seizure onset and enhanced TAC while reducing MDA levels in both the PFC and serum. TRG also decreased the gene expression of NR2B in the PFC. Unexpectedly, the findings revealed that the concurrent administration of ketamine amplified, whereas NMDA mitigated, the impact of TRG on latency to seizure. Furthermore, NMDA diminished the positive effects of TRG on antioxidant capacity and oxidative stress, while ketamine amplified these beneficial effects, indicating a complex interaction between TRG and NMDA receptor modulation. In the gene expression of NMDA receptors, results showed that ketamine significantly decreased the gene expression of NR2B when co-administrated with a sub-effective dose of TRG. It was found that, at least partially, the anticonvulsant effect of TRG in PTZ-induced seizures in male mice was mediated by the attenuation of glutamatergic neurotransmission as well as the reduction of oxidative stress.

Sinapic Acid Mitigates Pentylenetetrazol-induced Acute Seizures By Modulating the NLRP3 Inflammasome and Regulating Calcium/calcineurin Signaling: In Vivo and In Silico Approaches

Sinapic acid (SA) is a naturally occurring carboxylic acid found in citrus fruits and cereals. Recent studies have shown that SA has potential anti-seizure properties due to its anti-inflammatory, antioxidant, and anti-apoptotic effects. The present study investigated the neuroprotective role of SA at two different dosages in a pentylenetetrazol (PTZ)-induced acute seizure model. Mice were divided into six groups: normal control, PTZ, SA (20 mg/kg), SA (20 mg/kg) + PTZ, SA (40 mg/kg), and SA (40 mg/kg) + PTZ. SA was orally administered for 21 days, followed by a convulsive dose of intraperitoneal PTZ (50 mg/kg). Seizures were estimated via the Racine scale, and animals were behaviorally tested using the Y-maze. Brain tissues were used to assess the levels of GABA, glutamate, oxidative stress markers, calcium, calcineurin, (Nod)-like receptor protein-3 (NLRP3), interleukin (IL)-1β, apoptosis-associated speck-like protein (ASC), Bcl-2-associated death protein (Bad) and Bcl-2. Molecular docking of SA using a multistep in silico protocol was also performed. The results showed that SA alleviated oxidative stress, restored the GABA/glutamate balance and calcium/calcineurin signaling, downregulated NLRP3 and apoptosis, and improved recognition and ambulatory activity in PTZ-treated mice. In silico results also revealed that SA strongly interacts with the target proteins NLRP3 and ASC. Overall, the results suggest that SA is a promising antiseizure agent and that both doses of SA are comparable, with 40 mg/kg SA being superior in normalizing glutathione, calcium and IL-1β, in addition to calcineurin, NLRP3, ASC and Bad.

Maintenance of mitochondrial function by sinapic acid protects against tramadol-induced toxicity in isolated mitochondria obtained from rat brain

It is reported that tramadol can induce neurotoxic effects with the production of DNA damage, mitochondrial dysfunction, and oxidative stress. The current study aimed to evaluate the potential role of mitochondrial impairment in the pathogenesis of tramadol-induced neurotoxicity, and protective effect of sinapic acid (SA) against it in isolated mitochondria from rat brain. Mitochondria were isolated and were incubated with toxic concentrations (100 μM) of tramadol and then cotreated with tramadol + SA (10, 50, and 100 μM). Biomarkers of mitochondrial toxicity including succinate dehydrogenases (SDH) activity, reactive oxygen species (ROS), lipid peroxidation (LPO), mitochondrial membrane potential (MMP), GSH depletion, and mitochondrial swelling were assessed. Our results showed a significant decrease in SDH activity, and a significant increase in ROS, LPO, GSH depletion, MMP collapse, and mitochondrial swelling was detected in tramadol group. We observed that 50 and 100 μM SA cotreatment for 1 h efficiently ameliorated tramadol-caused damage in mitochondrial dysfunction, accumulation of ROS, LPO, GSH depletion, depolarization of mitochondrial membrane potential, and mitochondrial swelling. These data suggest that mitochondrial impairment and oxidative stress are mechanisms involved in the pathogenesis of tramadol-induced neurotoxicity. Also, results indicate that SA antagonizes against tramadol-induced mitochondrial toxicity and suggest SA may be a preventive/therapeutic agent for tramadol-induced neurotoxicity complications.

Effect of Sinapic Acid on Scopolamine-Induced Learning and Memory Impairment in SD Rats

The seriousness of the diseases caused by aging have recently gained attention. Alzheimer’s disease (AD), a chronic neurodegenerative disease, accounts for 60–80% of senile dementia cases. Continuous research is being conducted on the cause of Alzheimer’s disease, and it is believed to include complex factors, such as genetic factors, the accumulation of amyloid beta plaques, a tangle of tau protein, oxidative stress, cholinergic dysfunction, neuroinflammation, and cell death. Sinapic acid is a hydroxycinnamic acid found in plant families, such as oranges, grapefruit, cranberry, mustard seeds, and rapeseeds. It exhibits various biological activities, including anti-inflammatory, anti-oxidant, anti-cancer, and anti-depressant effects. Sinapic acid is an acetylcholine esterase inhibitor that can be applied to the treatment of dementia caused by Alzheimer’s disease and Parkinson’s disease. However, electrophysiological studies on the effects of sinapic acid on memory and learning must still be conducted. Therefore, it was confirmed that sinapic acid was effective in long-term potentiation (LTP) using organotypic hippocampal segment tissue. In addition, the effect on scopolamine-induced learning and memory impairment was measured by oral administration of sinapic acid 10 mg/kg/day for 14 days, and behavioral experiments related to short-term and long-term spatial memory and avoidance memory were conducted. Sinapic acid increased the activity of the field excitatory postsynaptic potential (fEPSP) in a dose-dependent manner after TBS, and restored fEPSP activity in the CA1 region suppressed by scopolamine. The scopolamine-induced learning and memory impairment group showed lower results than the control group in the Y-maze, Passive avoidance (PA), and Morris water maze (MWM) experiments. Sinapic acid improved avoidance memory, short and long-term spatial recognition learning, and memory. In addition, sinapic acid weakened the inhibition of the brain-derived neurotrophic factor (BDNF), tropomyosin receptor kinase B (TrkB) and the activation of prostaglandin-endoperoxide synthase 2 (COX-2) and interleukin 1 beta (IL-1β) induced by scopolamine in the hippocampus. These results show that sinapic acid is effective in restoring LTP and cognitive impairment induced by the cholinergic receptor blockade. Moreover, it showed the effect of alleviating the reduction in scopolamine-induced BDNF and TrkB, and alleviated neuroinflammatory effects by inhibiting the increase in COX-2 and IL-1β. Therefore, we showed that sinapic acid has potential as a treatment for neurodegenerative cognitive impairment.

Sinapis Semen: A review on phytochemistry, pharmacology, toxicity, analytical methods and pharmacokinetics

Sinapis Semen (SS), the dried mature seed of Sinapis alba L. and Brassica juncea (L.) Czern. et Coss., is one of the traditional Chinese medicinal materials with a wide range of pharmacological effects being used for asthma, cough and many other ailments. SS is also widely used in food agriculture, medicine and other industries in North America and South Asia. More recently, the research on SS has gradually intensified and increased. However, there is no systematic review of SS. In this review, through literature exploration and analysis, the research advance on phytochemistry, pharmacology, toxicity, analytical methods and pharmacokinetics of SS was aggregated initially. Total 144 compounds have been isolated and identified from SS. Among them, glucosinolates and their hydrolysates and volatile oils are the main active ingredients and important chemical classification markers. SS has a wide range of pharmacological effects, especially in cough suppressing, asthma calming, anti-inflammatory, neuroprotective, cardiovascular protective, inhibiting androgenic effects, anti-tumor, and skin permeation promoting effects. Sinapine and sinapic acid are the main active ingredients of SS for its medicinal effects. However, SS has a strong skin irritation, presumably related to the time of application, the method of processing, and original medicinal plants. This review will provide useful data for the follow-up research and safe and reasonable clinical application of SS.

Polyphenolic compounds from rapeseeds (Brassica napus L.): The major types, biofunctional roles, bioavailability, and the influences of rapeseed oil processing technologies on the content

The rapeseed (Brassica napus L.) are the important oil bearing material worldwide, which contain wide variety of bioactive components with polyphenolic compounds considered the most typical. The rapeseed polyphenols encompass different structural variants, and have been considered to have many bioactive functions, which are beneficial for the human health. Whereas, the rapeseed oil processing technologies affect their content and the biofunctional activities. The present review of the literature highlighted the major types of the rapeseed polyphenols, and summarized their biofunctional roles. The influences of rapeseed oil processing technologies on these polyphenols were also elucidated. Furthermore, the directions of the future studies for producing nutritional rapeseed oils preserved higher level of polyphenols were prospected. The rapeseed polyphenols are divided into the phenolic acids and polyphenolic tannins, both of which contained different subtypes. They are reported to have multiple biofunctional roles, thus showing outstanding health improvement effects. The rapeseed oil processing technologies have significant effects on both of the polyphenol content and activity. Some novel processing technologies, such as aqueous enzymatic extraction (AEE), subcritical or supercritical extraction showed advantages for producing rapeseed oil with higher level of polyphenols. The oil refining process involved heat or strong acid and alkali conditions affected their stability and activity, leading to the loss of polyphenols of the final products. Future efforts are encouraged to provide more clinic evidence for the practical applications of the rapeseed polyphenols, as well as optimizing the processing technologies for the green manufacturing of rapeseed oils.

Sinapic Acid Ameliorates REV-ERB α Modulated Mitochondrial Fission against MPTP-Induced Parkinson's Disease Model

Parkinson’s disease (PD) is the second most common neurodegenerative disease worldwide, and accumulating evidence indicates that mitochondrial dysfunction is associated with progressive deterioration in PD patients. Previous studies have shown that sinapic acid has a neuroprotective effect, but its mechanisms of action remain unclear. The neuroprotective effect of sinapic acid was assayed in a PD mouse model generated by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) as well as in SH-SY5Y cells. Target protein expression was detected by western blotting. Sinapic acid treatment attenuated the behavioral defects and loss of dopaminergic neurons in the PD models. Sinapic acid also improved mitochondrial function in the PD models. MPTP treatment increased the abundance of mitochondrial fission proteins such as dynamin-related protein 1 (Drp1) and phospho-Drp1 Ser616. In addition, MPTP decreased the expression of the REV-ERB α protein. These changes were attenuated by sinapic acid treatment. We used the pharmacological REV-ERB α inhibitor SR8278 to confirmation of protective effect of sinapic acid. Treatment of SR8278 with sinapic acid reversed the protein expression of phospho-Drp1 Ser616 and REV-ERB α on MPTP-treated mice. Our findings demonstrated that sinapic acid protects against MPTP-induced PD and these effects might be related to the inhibiting abnormal mitochondrial fission through REV-ERB α.

Neferine, an Alkaloid from Lotus Seed Embryos, Exerts Antiseizure and Neuroprotective Effects in a Kainic Acid-Induced Seizure Model in Rats

Current anti-seizure drugs fail to control approximately 30% of epilepsies. Therefore, there is a need to develop more effective anti-seizure drugs, and medicinal plants provide an attractive source for new compounds. This study aimed to evaluate the possible anti-seizure and neuroprotective effects of neferine, an alkaloid from the lotus seed embryos of Nelumbo nucifera, in a kainic acid (KA)-induced seizure rat model and its underlying mechanisms. Rats were intraperitoneally (i.p.) administrated neferine (10 and 50 mg/kg) 30 min before KA injection (15 mg/kg, i.p.). Neferine pretreatment increased seizure latency and reduced seizure scores, prevented glutamate elevation and neuronal loss, and increased presynaptic protein synaptophysin and postsynaptic density protein 95 expression in the hippocampi of rats with KA. Neferine pretreatment also decreased glial cell activation and proinflammatory cytokine (interleukin-1β, interleukin-6, tumor necrosis factor-α) expression in the hippocampi of rats with KA. In addition, NOD-like receptor 3 (NLRP3) inflammasome, caspase-1, and interleukin-18 expression levels were decreased in the hippocampi of seizure rats pretreated with neferine. These results indicated that neferine reduced seizure severity, exerted neuroprotective effects, and ameliorated neuroinflammation in the hippocampi of KA-treated rats, possibly by inhibiting NLRP3 inflammasome activation and decreasing inflammatory cytokine secretion. Our findings highlight the potential of neferine as a therapeutic option in the treatment of epilepsy.

Phenolic Acids and Prevention of Cognitive Decline: Polyphenols with a Neuroprotective Role in Cognitive Disorders and Alzheimer's Disease

Cognitive impairment, also known as cognitive decline, can occur gradually or suddenly and can be temporary or more permanent. It represents an increasingly important public health problem and can depend on normal aging or be linked to different neurodegenerative disorders, including Alzheimer's disease (AD). It is now well-established that lifestyle factors including dietary patterns play an important role in healthy aging as well as in the prevention of cognitive decline in later life. Among the natural compounds, dietary polyphenols including phenolic acids have been recently the focus of major attention, with their supplementation being associated with better cognitive status and prevention of cognitive decline. Despite their therapeutic potential, human studies investigating the relation between phenolic acids intake and cognitive outcomes are rather scarce. In this review, we provide preclinical evidence that different dietary polyphenols such as rosmarinic acid, ellagic acid, and cinnamic aldehyde can exert neuroprotective and pro-cognitive activities through different molecular mechanisms including the modulation of pro-oxidant and antioxidant machinery as well as inflammatory status. Future and more numerous in vivo studies are needed to strengthen the promising results obtained at the preclinical level. Despite the excellent pharmacokinetic properties of phenolic acids, which are able to be accumulated in the brain at pharmacologically relevant levels, future studies should also identify which among the different metabolites produced as a consequence of phenolic acids' consumption may be responsible for the potential neuroprotective effects of this subgroup of polyphenols.

Phenolic Acids and Prevention of Cognitive Decline: Polyphenols with a Neuroprotective Role in Cognitive Disorders and Alzheimer's Disease

Cognitive impairment, also known as cognitive decline, can occur gradually or suddenly and can be temporary or more permanent. It represents an increasingly important public health problem and can depend on normal aging or be linked to different neurodegenerative disorders, including Alzheimer's disease (AD). It is now well-established that lifestyle factors including dietary patterns play an important role in healthy aging as well as in the prevention of cognitive decline in later life. Among the natural compounds, dietary polyphenols including phenolic acids have been recently the focus of major attention, with their supplementation being associated with better cognitive status and prevention of cognitive decline. Despite their therapeutic potential, human studies investigating the relation between phenolic acids intake and cognitive outcomes are rather scarce. In this review, we provide preclinical evidence that different dietary polyphenols such as rosmarinic acid, ellagic acid, and cinnamic aldehyde can exert neuroprotective and pro-cognitive activities through different molecular mechanisms including the modulation of pro-oxidant and antioxidant machinery as well as inflammatory status. Future and more numerous in vivo studies are needed to strengthen the promising results obtained at the preclinical level. Despite the excellent pharmacokinetic properties of phenolic acids, which are able to be accumulated in the brain at pharmacologically relevant levels, future studies should also identify which among the different metabolites produced as a consequence of phenolic acids' consumption may be responsible for the potential neuroprotective effects of this subgroup of polyphenols.

Cynanchi atrati and Its Phenolic Constituent Sinapic Acid Target Regulator of Calcineurin 1 (RCAN1) to Control Skin Inflammation

Atopic dermatitis (AD) is a common inflammatory skin disorder, and numerous pharmacological approaches are employed to reduce symptoms. Natural products of plant-derived materials have been accepted as complementary therapy for the treatment of a wide range of inflammatory diseases. Cynanchi atrati (CA) is an oriental medicinal herb used in the treatment of acute urinary infection, febrile diseases, and laryngopharyngitis. However, the role of CA root extract in skin inflammation such as AD has not been explored yet. In this study, we examined the possible effect of CA root extract on skin inflammation and evaluated the underlying signaling mechanism using in vitro and in vivo modeling systems. Raw264.7 macrophages were used for in vitro experiments, and an oxazolone-induced AD mouse model was used to evaluate in vivo effects. CA extract significantly inhibited the expression levels of lipopolysaccharide (LPS)-induced pro-inflammatory cytokines such as interleukin-6 (IL-6) and interleukin-1β (IL-1β) in RAW264.7 macrophages. The CA root extract mediated suppression of pro-inflammatory cytokine expression and was associated with the decreased nuclear factor kappa B (NF-κB) gene transcriptional activation. Moreover, CA root extract attenuated the in vivo expression of IL-6 and tumor necrosis factor-α (TNF-α) and ear swelling in the AD mouse models. We also observed that the inhibitory effect of CA root extract on skin inflammation was accompanied by the upregulation of calcineurin 1 (RCAN1) expression, which functions in the inflammatory pathways by suppressing NF-κB signaling. We consistently observed that the immunosuppressive effect of CA root extract in AD was significantly perturbed in the RCAN1 knockout mice. In addition, we isolated a phenolic acid compound, sinapic acid (SA), from the CA root extract and found that SA consistently exerted an immunosuppressive effect in RAW264.7 macrophages by inducing RCAN1 expression. Our results provide the first evidence that CA root extract and its phenolic acid constituent, SA, modulate NF-κB signaling pathways by inducing RCAN1 expression in the skin inflammation process. Thus, we suggest that CA root extract has a therapeutic value for the treatment of AD by targeting endogenous immune regulators.

Sinapic Acid Controls Inflammation by Suppressing NLRP3 Inflammasome Activation

A natural phenolic acid compound, sinapic acid (SA), is a cinnamic acid derivative that contains 3,5-dimethoxyl and 4-hydroxyl substitutions in the phenyl ring of cinnamic acid. SA is present in various orally edible natural herbs and cereals and is reported to have antioxidant, antitumor, anti-inflammatory, antibacterial, and neuroprotective activities. Although the anti-inflammatory function of SA has been reported, the effect of SA on the NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasome has not been explored. In the present study, to elucidate the anti-inflammatory mechanism of SA, we examined whether SA modulates the NLRP3 inflammasome. We found that SA blocked caspase-1 activation and IL-1β secretion by inhibiting NLRP3 inflammasome activation in bone marrow-derived macrophages (BMDMs). Apoptosis-associated speck-like protein containing CARD (ASC) pyroptosome formation was consistently blocked by SA treatment. SA specifically inhibited NLRP3 activation but not the NLRC4 or AIM2 inflammasomes. In addition, SA had no significant effect on the priming phase of the NLRP3 inflammasome, such as pro-IL-1β and NLRP3 inflammasome expression levels. Moreover, we found that SA attenuated IL-1β secretion in LPS-induced systemic inflammation in mice and reduced lethality from endotoxic shock. Our findings suggest that the natural compound SA has potential therapeutic value for the suppression of NLRP3 inflammasome-associated inflammatory diseases.

Inhibition of microglia overactivation restores neuronal survival in a mouse model of CDKL5 deficiency disorder

Background

CDKL5 deficiency disorder (CDD), a severe neurodevelopmental disorder characterized by early onset epilepsy, intellectual disability, and autistic features, is caused by mutations in the CDKL5 gene. Evidence in animal models of CDD showed that absence of CDKL5 negatively affects neuronal survival, as well as neuronal maturation and dendritic outgrowth; however, knowledge of the substrates underlying these alterations is still limited. Neuroinflammatory processes are known to contribute to neuronal dysfunction and death. Recent evidence shows a subclinical chronic inflammatory status in plasma from CDD patients. However, to date, it is unknown whether a similar inflammatory status is present in the brain of CDD patients and, if so, whether this plays a causative or exacerbating role in the pathophysiology of CDD.

Methods

We evaluated microglia activation using AIF-1 immunofluorescence, proinflammatory cytokine expression, and signaling in the brain of a mouse model of CDD, the Cdkl5 KO mouse, which is characterized by an impaired survival of hippocampal neurons that worsens with age. Hippocampal neuron survival was determined by DCX, NeuN, and cleaved caspase-3 immunostaining in Cdkl5 KO mice treated with luteolin (10 mg/kg), a natural anti-inflammatory flavonoid. Since hippocampal neurons of Cdkl5 KO mice exhibit increased susceptibility to excitotoxic stress, we evaluated neuronal survival in Cdkl5 KO mice injected with NMDA (60 mg/kg) after a 7-day treatment with luteolin.

Results

We found increased microglial activation in the brain of the Cdkl5 KO mouse. We found alterations in microglial cell morphology and number, increased levels of AIF-1 and proinflammatory cytokines, and activation of STAT3 signaling. Remarkably, treatment with luteolin recovers microglia alterations as well as neuronal survival and maturation in Cdkl5 KO mice, and prevents the increase in NMDA-induced cell death in the hippocampus.

Conclusions

Our results suggest that neuroinflammatory processes contribute to the pathogenesis of CDD and imply the potential usefulness of luteolin as a treatment option in CDD patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02204-0.

Pharmacological and therapeutic applications of Sinapic acid-an updated review

Phenolic compounds, present in plants, are considered to be indispensable parts of human dietary sources. Sinapic acid, is a natural herbal compound containing phenolic acid. It is found in oranges, grapefruits, and cranberries and in herbs like canola, mustard seed and rapeseed. Sinapic acid is chemically studied as a cinnamic acid derivative that contains 3, 5-dimethoxyl and 4-hydroxyl substitutions in the phenyl group of cinnamic acid. Sinapic acid has been pharmacologically evaluated for its potent antioxidant, anti-inflammatory, anti-cancer, hepatoprotective, cardioprotective, renoprotective, neuroprotective, anti-diabetic, anxiolytic and anti-bacterial activities. In this review we have summarized the potential pharmacological and therapeutic effects of Sinapic acid in various models.

Effect of thiamazole on kainic acid-induced seizures in mice

Kainic acid (KA) induced epileptic seizures in mice is a commonly used experimental model of epilepsy. Previous studies have suggested the roles of various neurotransmitters and oxidative stress in KA-induced seizures. An important role of hypothyroidism has also been suggested in epilepsy. Thiamazole (TZ) is an anti-hyperthyroid drug with antioxidant property. This study reports the effect of TZ on KA-induced epileptic seizures in mice, produced by intraperitoneal (IP) injection of KA (18 mg/kg). Prior to KA injection, the animals were treated with TZ (12.5, 25 and 50 mg/kg IP). Our results showed that in KA alone group, about half of the animals developed seizures. Pre-treatment of mice with TZ significantly increased the frequency of seizures in dose-dependent manner. Administration of TZ significantly reduced the latency time and aggravated the severity of seizures. TZ also increased the mortality in KA-treated mice. Striatal dopamine and serotonin levels were markedly increased in KA alone treated mice, which were not significantly affected by TZ treatment. Among the indices of oxidative stress, we observed a significant reduction in cerebral vitamin E whereas the levels of cerebral malondialdehyde and conjugated dienes were significantly increased in animals with high severity of seizures. In conclusion, TZ potentiated the frequency and severity of experimental seizure in mice. There is a possibility of altered metabolism of KA in presence of TZ that might have potentiated the toxicity of KA. These findings suggest a caution while administering anti-hyperthyroid drugs in epileptic seizures.

Silymarin Inhibits Glutamate Release and Prevents against Kainic Acid-Induced Excitotoxic Injury in Rats

Silymarin, a polyphenoic flavonoid derived from the seeds of milk thistle (Silybum marianum), exhibits neuroprotective effects. In this study, we used a model of rat cerebrocortical synaptosomes to investigate whether silymarin affects the release of glutamate, an essential neurotransmitter involved in excitotoxicity. Its possible neuroprotective effect on a rat model of kainic acid (KA)-induced excitotoxicity was also investigated. In rat cortical synaptosomes, silymarin reduced glutamate release and calcium elevation evoked by the K⁺ channel blocker 4-aminopyridine but did not affect glutamate release caused by the Na⁺ channel activator veratridine or the synaptosomal membrane potential. Decreased glutamate release by silymarin was prevented by removal of extracellular calcium and blocking of N- and P/Q-type Ca²⁺ channel or extracellular signal-regulated kinase 1/2 (ERK1/2) but not by blocking of intracellular Ca²⁺ release. Immunoblotting assay results revealed that silymarin reduced 4-aminopyridine-induced phosphorylation of ERK1/2. Moreover, systemic treatment of rats with silymarin (50 or 100 mg/kg) 30 min before systemic KA (15 mg/kg) administration attenuated KA-induced seizures, glutamate concentration elevation, neuronal damage, glial activation, and heat shock protein 70 expression as well as upregulated KA-induced decrease in Akt phosphorylation in the rat hippocampus. Taken together, the present study demonstrated that silymarin depressed synaptosomal glutamate release by suppressing voltage-dependent Ca²⁺ entry and ERK1/2 activity and effectively prevented KA-induced in vivo excitotoxicity.

Luteolin Protects Against CIRI, Potentially via Regulation of the SIRT3/AMPK/mTOR Signaling Pathway

Mitochondrial abnormalities accelerate the progression of ischemic brain damage. Sirtuin 3 (SIRT3) is mainly found in mitochondria and affects almost all major aspects of mitochondrial function. Luteolin, a flavonoid with diverse biological properties, including antioxidant activity, inhibition of cell apoptosis and regulation of autophagy. It also modulates the activity of AMP activated kinase and/or sirtuin 1 (SIRT 1) by regulating the expression of sirtuins. We investigated the protective effects of luteolin on cerebral ischemia-reperfusion. It was found through experiments that luteolin reduced the infarcted area of MCAO rat model, and based on the experimental results, it was inferred that luteolin affected the AMPK, mTOR and SIRT3 pathways, thereby protecting brain cells. As expected, we found that luteolin can reduce the neurological function score, the degree of cerebral edema, the cerebral infarction volume, alleviate morphological changes in the cortex and hippocampus, increase neuron survival and decrease the number of apoptotic neurons. At the same time, luteolin significantly reduced the number of GFAP and Iba-1 positive glial cells in the hippocampus while enhanced the scavenging of oxygen free radicals and the activity of SOD in mitochondria. Addtionally, it can also enhance antioxidant capacity via the reversal of mitochondrial swelling and the mitochondrial transmembrane potential. Moreover, luteolin can increase SIRT3-targeted expression in mitochondria, decrease the phosphorylation of AMPK, and increase phosphor-mTOR (p-mTOR) levels, which may have occurred specifically through activation of the SIRT3/AMPK/mTOR pathway. We speculate that luteolin reduces the pathological progression of CIRI by increasing SIRT3 expression and enhancing mitochondrial function. Therefore, the results indicate that luteolin can increase the transduction of SIRT3, providing a potential mechanism for neuroprotective effects in patients with cerebral ischemia.

Sinapic acid attenuates cisplatin-induced nephrotoxicity through peroxisome proliferator-activated receptor gamma agonism in rats

AIM

The aim of this study was to investigate the involvement of peroxisome proliferator-activated receptor gamma (PPAR-γ) in renal protection offered by sinapic acid in cisplatin-induced nephrotoxicity in male rats.

MATERIALS AND METHODS

Nephrotoxicity was induced by single dose of cisplatin (5 mg/kg, intraperitoneal [i.p.]) in rats. Cisplatin-induced nephrotoxicity was assessed by measuring serum creatinine, creatinine clearance, urea, uric acid, potassium, magnesium levels, fractional excretion of sodium, and microproteinuria in rats. Superoxide anion generation, thiobarbituric acid reactive substances, myeloperoxidase activity, and reduced glutathione levels were measured to assess oxidative stress in renal tissues. Hematoxylin and eosin stain showed renal histological changes.

RESULTS

The significant changes in serum and urinary parameters, elevated oxidative stress, and renal histological changes established the induction of nephrotoxicity. Sinapic acid treatment (20 and 40 mg/kg, orally [p.o.]) provides dose-dependent and significant (P < 0.05) nephroprotection against cisplatin-mediated nephrotoxicity in rats. Nephroprotective effect of sinapic acid was abolished by PPAR-γ inhibitor, bisphenol A diglycidyl ether (30 mg/kg, i.p.) in rats.

CONCLUSION

It is concluded that PPAR-γ agonism serves as one of the mechanisms in sinapic acid-mediated renoprotection.

Sinapic acid-loaded chitosan nanoparticles in polycaprolactone electrospun fibers for bone regeneration in vitro and in vivo

Sinapic acid (SA) is a plant-derived phenolic compound known for its multiple biological properties, but its role in the promotion of bone formation is not yet well-studied. Moreover, the delivery of SA is hindered by its complex hydrophobic nature, limiting its bioavailability. In this study, we fabricated a drug delivery system using chitosan nanoparticles (nCS) loaded with SA at different concentrations. These were incorporated into polycaprolactone (PCL) fibers via an electrospinning method. nCS loaded with 50 μM SA in PCL fibers promoted osteoblast differentiation. Furthermore, SA treatment activated the osteogenesis signaling pathways in mouse mesenchymal stem cells. A critical-sized rat calvarial bone defect model system identified that the inclusion of SA into PCL/nCS fibers accelerated bone formation. Collectively, these data suggest that SA promoted osteoblast differentiation in vitro and bone formation in vivo, possibly by activating the TGF-β1/BMP/Smads/Runx2 signaling pathways, suggesting SA might have therapeutic benefits in bone regeneration.

Tualang Honey Reduced Neuroinflammation and Caspase-3 Activity in Rat Brain after Kainic Acid-Induced Status Epilepticus

The protective effect of tualang honey (TH) on neuroinflammation and caspase-3 activity in rat cerebral cortex, cerebellum, and brainstem after kainic acid- (KA-) induced status epilepticus was investigated. Male Sprague-Dawley rats were pretreated orally with TH (1.0 g/kg body weight) five times at 12 h intervals. KA (15 mg/kg body weight) was injected subcutaneously 30 min after last oral treatment. Rats were sacrificed at 2 h, 24 h, and 48 h after KA administration. Neuroinflammation markers and caspase-3 activity were analyzed in different brain regions 2 h, 24 h, and 48 h after KA administration. Administration of KA induced epileptic seizures. KA caused significant (p < 0.05) increase in the level of tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), glial fibrillary acidic protein (GFAP), allograft inflammatory factor 1 (AIF-1), and cyclooxygenase-2 (COX-2) and increase in the caspase-3 activity in the rat cerebral cortex, cerebellum, and brainstem at multiple time points. Pretreatment with TH significantly (p < 0.05) reduced the elevation of TNF-α, IL-1β, GFAP, AIF-1, and COX-2 level in those brain regions at multiple time points and attenuated the increased caspase-3 activity in the cerebral cortex. In conclusion, TH reduced neuroinflammation and caspase-3 activity after kainic acid- (KA-) induced status epilepticus.

The Effects of Sinapic Acid on the Development of Metabolic Disorders Induced by Estrogen Deficiency in Rats

Sinapic acid is a natural phenolic acid found in fruits, vegetables, and cereals, exerting numerous pharmacological effects. The aim of the study was to investigate the influence of sinapic acid on biochemical parameters related to glucose and lipid metabolism, as well as markers of antioxidant abilities and parameters of oxidative damage in the blood serum in estrogen-deficient rats. The study was performed on 3-month-old female Wistar rats, divided into 5 groups, including sham-operated control rats, ovariectomized control rats, and ovariectomized rats administered orally with estradiol (0.2 mg/kg) or sinapic acid (5 and 25 mg/kg) for 28 days. The levels of estradiol, progesterone, interleukin 18, insulin, glucose, fructosamine, lipids, and enzymatic and nonenzymatic antioxidants (superoxide dismutase, catalase, and glutathione); total antioxidant capacity; and oxidative damage parameters (thiobarbituric acid-reactive substances, protein carbonyl groups, and advanced oxidation protein products) were determined in the serum. Estradiol counteracted the carbohydrate and cholesterol metabolism disorders induced by estrogen deficiency. Sinapic acid increased the serum estradiol concentration; decreased insulin resistance and the triglyceride and total cholesterol concentrations; and favorably affected the parameters of antioxidant abilities (reduced glutathione, superoxide dismutase) and oxidative damage (advanced oxidation protein products).

Features and outcomes of drugs for combination therapy as multi-targets strategy to combat Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease (AD), a deleterious neurodegenerative disorder that impairs memory, cognitive functions and may lead to dementia in late stage of life. The pathogenic cause of AD remains incompletely understood and FDA approved drugs are partial inhibitors rather than curative. Most of drugs are synthetic or natural products as galanthamine is an alkaloid obtained from Galanthus spp. Huperzine A, an alkaloid found in Huperzia spp., gingkolides a diterpenoids from Gingko biloba and many ethnobotanicals like Withania somnifera (L.) Dunal., Physostigma venenosum Balf., Bacopa monnieri (L.) Wettst., Centella asiatica (L.) Urb. have been used by traditional Indian, Chinese, and European system of medicines in AD. Clinical significance opioid alkaloid in Papaver somniferum has shown another dimension to this study. Over exploitation of medicinal plants with limited bioactive principles has provided templates to design synthetic drugs in AD e.g. rivastigmine, phenserine, eptastigmine based on chemical structure of physostigmine of Physostigma venenosum Balf. Even ZT-1 a prodrug of Hup A and memogain a prodrug of galantamine has achieved new direction in drug development in AD. All these first-line cholinesterase-inhibitors are used as symptomatic treatments in AD. Single modality of "One-molecule-one-target" strategy for treating AD has failed and so future therapies on "Combination-drugs-multi-targets" strategy (CDMT) will need to address multiple aspects to block the progression of pathogenesis of AD. Besides, cholinergic and amyloid drugs, in this article we summarize proteinopathy-based drugs as AD therapeutics from a variety of biological sources. In this review, an attempt has been made to elucidate the molecular mode of action of various plant products, and synthetic drugs investigated in various preclinical and clinical tests in AD. It also discusses current attempts to formulate a comprehensive CDMT strategy to counter complex pathogenesis in AD.

MATERIALS AND METHODS

Information were collected from classical books on medicinal plants, pharmacopoeias and scientific databases like PubMed, Scopus, GoogleScholar, Web of Science and electronic searches were performed using Cochrane Library, Medline and EMBASE. Also published scientific literatures from Elsevier, Taylor and Francis, Springer, ACS, Wiley publishers and reports by government bodies and documentations were assessed.

RESULTS

60 no. of natural and synthetic drugs have been studied with their significant bioactivities. A decision matrix designed for evaluation of drugs for considering to the hypothetic "CDMT" strategy in AD. We have introduced the scoring pattern of individual drugs and based on scoring pattern, drugs that fall within the scoring range of 18-25 are considered in the proposed CDMT. It also highlights the importance of available natural products and in future those drugs may be considered in CDMT along with the qualified synthetic drugs.

CONCLUSION

A successful validation of the CDMT strategy may open up a debate on health care reform to explore other possibilities of combination therapy. In doing so, it should focus on clinical and molecular relationships between AD and CDMT. A better understanding of these relationships could inform and impact future development of AD-directed treatment strategies. This strategy also involves in reducing costs in treatment phases which will be affordable to a common man suffering from AD.

Histone deacetylase inhibitor SAHA attenuates post-seizure hippocampal microglia TLR4/MYD88 signaling and inhibits TLR4 gene expression via histone acetylation

BACKGROUND

Epilepsy is a common neurological disorder characterized by recurrent unprovoked seizures. Seizure-induced TLR4/MYD88 signaling plays a critical role in activating microglia and triggering neuron apoptosis. SAHA is a histone deacetylase inhibitor that regulates gene expression by increasing chromatin histone acetylation. In this study, we investigated the role of SAHA in TLR4/MYD88 signaling in a rat seizure model.

RESULTS

Sprague-Dawley rats with kainic acid (KA)-induced seizures were treated with SAHA. The expression of TLR4, MYD88, NF-κB P65 and IL-1β in hippocampus was detected at hour 2 and 6 and day 1, 2, and 3 post seizure. SAHA pretreatment increased seizure latency and decreased seizure scores. The expression levels of TLR4, MYD88, NF-κB and IL-1β increased significantly in both activated microglia and apoptotic neurons after KA treatment. The effects were attenuated by SAHA. Chromatin immunoprecipitation assays indicated that the H3 histone acetylation levels significantly decreased while H3K9 levels significantly increased in the KA treatment group. The H3 and H3K9 acetylation levels returned to control levels after SAHA (50 mg/kg) pretreatment. There was a positive correlation between the expression of TLR4 and the acetylation levels of H3K9.

CONCLUSIONS

Histone deacetylase inhibitor SAHA can suppress seizure-induced TLR4/MYD88 signaling and inhibit TLR4 gene expression through histone acetylation regulation. This suggests that SAHA may protect against seizure-induced brain damage.

Kainic Acid-Induced Excitotoxicity Experimental Model: Protective Merits of Natural Products and Plant Extracts

Excitotoxicity is well recognized as a major pathological process of neuronal death in neurodegenerative diseases involving the central nervous system (CNS). In the animal models of neurodegeneration, excitotoxicity is commonly induced experimentally by chemical convulsants, particularly kainic acid (KA). KA-induced excitotoxicity in rodent models has been shown to result in seizures, behavioral changes, oxidative stress, glial activation, inflammatory mediator production, endoplasmic reticulum stress, mitochondrial dysfunction, and selective neurodegeneration in the brain upon KA administration. Recently, there is an emerging trend to search for natural sources to combat against excitotoxicity-associated neurodegenerative diseases. Natural products and plant extracts had attracted a considerable amount of attention because of their reported beneficial effects on the CNS, particularly their neuroprotective effect against excitotoxicity. They provide significant reduction and/or protection against the development and progression of acute and chronic neurodegeneration. This indicates that natural products and plants extracts may be useful in protecting against excitotoxicity-associated neurodegeneration. Thus, targeting of multiple pathways simultaneously may be the strategy to maximize the neuroprotection effect. This review summarizes the mechanisms involved in KA-induced excitotoxicity and attempts to collate the various researches related to the protective effect of natural products and plant extracts in the KA model of neurodegeneration.

Sinapic Acid and Its Derivatives as Medicine in Oxidative Stress-Induced Diseases and Aging

Sinapic acid (3,5-dimethoxy-4-hydroxycinnamic acid) is an orally bioavailable phytochemical, extensively found in spices, citrus and berry fruits, vegetables, cereals, and oilseed crops and is known to exhibit antioxidant, anti-inflammatory, anticancer, antimutagenic, antiglycemic, neuroprotective, and antibacterial activities. The literature reveals that sinapic acid is a bioactive phenolic acid and has the potential to attenuate various chemically induced toxicities. This minireview is an effort to summarize the available literature about pharmacokinetic, therapeutic, and protective potential of this versatile molecule in health related areas.

Anticonvulsant and behavioral effects observed in mice following treatment with an ester derivative of ferulic acid: Isopentyl ferulate

The objective of this study was to evaluate the potential anticonvulsant effect of isopentyl ferulate, a new ester derived from ferulic acid in mice (Mus musculus) subjected to two models of induced seizures. According to the results obtained, the IF at doses of 25, 50 and 75 mg/kg (i.p.) showed protective effect against induced seizures by pilocarpine (400 mg/kg, i.p.) and pentylenetetrazole (70 mg/kg, i.p.). In the two animal models of seizures, the pretreatment of the IF (25, 50 and 75 mg/kg) with flumazenil blocked the anticonvulsant effect, suggesting that the mechanism of action of this ester derived of ferulic acid may be related to activity in the benzodiazepine-binding site of the GABAA receptor (γ-aminobutyric acid, type A). In addition to the anticonvulsant effect, behavioral changes as neurotoxicity indication were assessed by using the rota rod and open field tests. The results obtained showed that the IF (25, 50 and 75 mg/kg) does not induce significant changes in locomotor activity and motor coordination when compared with the control group, unlike the results presented by diazepam. Thus, these results demonstrate a new pharmacological knowledge of IF with potential application against epileptic seizures. However, further studies are needed to elucidate other neurobiological mechanisms underlying epilepsy.

Effect of pioglitazone on excitotoxic neuronal damage in the mouse hippocampus

Pioglitazone (PGZ), a synthetic peroxisome proliferator-activated receptor γ agonist, is known to regulate inflammatory process and to have neuroprotective effects against neurological disorders. In the present study, we examined the effects of 30 mg/kg PGZ on excitotoxic neuronal damage and glial activation in the mouse hippocampus following intracerebroventricular injection of kainic acid (KA). PGZ treatment significantly reduced seizure-like behavior. PGZ had the neuroprotective effect against KA-induced neuronal damage and attenuated the activations of astrocytes and microglia in the hippocampal CA3 region. In addition, MPO and NFκB immunoreactivities in the glial cells were also decreased in the PGZ-treated group. These results indicate that PGZ had anticonvulsant and neuroprotective effects against KA-induced excitotocix injury, and that neuroprotective effect of PGZ might be due to the attenuation of KA-induced activation in astrocytes and microglia as well as KA-induced increases in MPO and NFκB.

Carbamazepine attenuates inducible nitric oxide synthase expression through Akt inhibition in activated microglial cells

Abstract Background: Carbamazepine, which was developed primarily for the treatment of epilepsy, is now also useful for the treatment of non-epileptic disorders and inflammatory hyperalgesia. However, the mechanism of its anti-neuroinflammatory action remains poorly understood.

OBJECTIVE

This study elucidates the anti-neuroinflammatory capacity of carbamazepine on microglial activation and the relative mechanisms involved.

MATERIALS AND METHODS

The microglial BV-2 cells were pretreated with carbamazepine for 15 min before activation by lipopolysaccharide (LPS). After LPS stimulation, the expression of inducible nitric oxide synthase (iNOS) was analyzed by Western blotting (WB) and reverse transcription-polymerase chain reaction. Signaling proteins and cyclooxygenase (COX)-2 were also evaluated by WB. The levels of nitrate and tumor necrosis factor (TNF)-α were analyzed by the Griess method and enzyme-linked immunosorbant assay, respectively. The formation of intracellular reactive oxygen species (ROS) was examined by fluorescent analysis.

RESULTS

Carbamazepine strongly attenuated LPS-induced production of NO and iNOS protein at concentrations of 5, 10, and 20 μM. Consistently, it could markedly suppress iNOS mRNA expression stimulated by LPS. Among the signaling pathways, LPS-mediated IκBα degradation or JNK MAPK phosphorylation was not affected by carbamazepine. Interestingly, it was found that carbamazepine could concentration-dependently inhibit LPS-activated phospho-Akt expression. Nevertheless, LPS-induced ROS production was not affected by carbamazepine. Carbamazepine (20 μM) affected either COX-2 expression or TNF-α production induced by LPS with approximately 70% and 51% inhibition, respectively.

DISCUSSION AND CONCLUSION

Our findings showed that carbamazepine exerted selective inhibition on LPS-induced microglial iNOS expression through the down-regulation of Akt activation, and thus may play a pivotal role of anti-neuroinflammation in its therapeutic efficacy.

The effects of atomoxetine and methylphenidate on the prepulse inhibition of the acoustic startle response in mice

Atomoxetine (ATM) and methylphenidate (MPD) have been used for the treatment of attention deficit hyperactivity disorder (ADHD). ATM is a selective norepinephrine reuptake inhibitor, whereas MPD is a psychostimulant and acts as a norepinephrine and dopamine reuptake inhibitor. In the present study, we investigated the effects of ATM (1, 3 or 10mg/kg) and MPD (5, 10 or 20mg/kg) on pharmacological mouse models of sensorimotor gating measured by prepulse inhibition (PPI) using the acoustic startle response test. MK-801, a non-competitive N-methyl-d-aspartate receptor antagonist, or apomorphine, a non-competitive dopamine receptor agonist, was used to induce PPI deficits. ATM (3 or 10mg/kg, s.c.) significantly attenuated the MK-801-, but not apomorphine-, induced PPI deficits. In contrast to ATM, MPD did not reverse the PPI deficits induced by either MK-801 or apomorphine. Immunostaining revealed that the number of c-Fos-immunopositive cells was increased in the nucleus accumbens following MK-801 treatment, and this was reversed by the administration of ATM (3mg/kg), but not MPD (10mg/kg). However, neither ATM nor MPD reversed the increased number of c-Fos-immunopositive cells in the nucleus accumbens following apomorphine treatment. These results suggest that the attenuating effect of ATM on the increased c-Fos immunoreactivity in the nucleus accumbens induced by MK-801 may be attributed to the PPI deficit-ameliorating effects of ATM and that ATM would be useful to treat sensorimotor gating-related disorders by improving the patient's attention span or cognitive function.

Involvement of mGlu5 receptor in 3-nitropropionic acid-induced oxidative stress in rat striatum

OBJECTIVES

The excitotoxin 3-nitropropionic acid (3-NP) induces a suitable experimental model of Huntington's disease (HD). This compound induces neurodegeneration via glutamatergic activation and oxidative stress, suggesting that the metabotropic glutamate receptor blockage and free radical scavenging are potential therapeutic targets in HD. In this study, we evaluated the role of 3-[(2-methyl-1,3-thiazol-4-yl) ethynyl]-pyridine (MTEP), a selective mGlu5 receptor antagonist, in a 3-NP model of HD.

METHODS

We administered 3-NP (20 mg/kg, intraperitoneal) to rats for 4 days. MTEP at doses of 2·5 and 5 mg/kg was administered 30 min before 3-NP. Behavioral tests and biochemical experiments were performed to assess the effects of 3-NP and the ability of MTEP to ameliorate these changes.

RESULTS

3-NP administration induced body weight loss, decreased locomotor activity, and inhibition of succinate dehydrogenase and Na(+)-K(+) adenosine triphosphate (ATP)ase activities in rat striatum. We also observed increases in reactive species (RS) levels and glutathione reductase activity, decreased non-protein thiol levels, and an inhibition of glutathione peroxidase activity in the striatum of rats treated with 3-NP. Notably, all of these effects were attenuated by MTEP treatment.

DISCUSSION

Our results demonstrate the neuroprotective effect of MTEP and reinforce the involvement of mGluR5 in 3-NP-induced oxidative stress in rat striatum.

Chemopreventive effect of sinapic acid on 1,2-dimethylhydrazine-induced experimental rat colon carcinogenesis

Sinapic acid (SA) is a naturally occurring phenolic acid found in various herbal plants which is attributed with numerous pharmacological properties. This study was aimed to investigate the chemopreventive effect of SA on 1,2-dimethylhydrazine (DMH)-induced rat colon carcinogenesis. Rats were treated with DMH injections (20 mg kg(-1) bodyweight (b.w.) subcutaneously once a week for the first 4 consecutive weeks and SA (20, 40 and 80 mg kg(-1) b.w.) post orally for 16 weeks. At the end of the 16-week experimental period, all the rats were killed, and the tissues were evaluated biochemically. Our results reveal that DMH alone treatment decreased the levels/activities of lipid peroxidation by-products such as thiobarbituric acid reactive substances, conjugated dienes and antioxidants such as superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase and reduced glutathione in the intestine and colonic tissues which were reversed on supplementation with SA. Moreover, the activities of drug-metabolizing enzymes of phase I (cytochrome P450 and P4502E1) were enhanced and those of phase II (glutathione-S-transferase, DT-diaphorase and uridine diphosphate glucuronosyl transferase) were diminished in the liver and colonic mucosa of DMH alone-treated rats and were reversed on supplementation with SA. All the above changes were supported by the histopathological observations of the rat liver and colon. These findings suggest that SA at the dose of 40 mg kg(-1) b.w. was the most effective dose against DMH-induced colon carcinogenesis, and thus, SA could be used as a potential chemopreventive agent.

Acacetin inhibits glutamate release and prevents kainic acid-induced neurotoxicity in rats

An excessive release of glutamate is considered to be a molecular mechanism associated with several neurological diseases that causes neuronal damage. Therefore, searching for compounds that reduce glutamate neurotoxicity is necessary. In this study, the possibility that the natural flavone acacetin derived from the traditional Chinese medicine Clerodendrum inerme (L.) Gaertn is a neuroprotective agent was investigated. The effect of acacetin on endogenous glutamate release in rat hippocampal nerve terminals (synaptosomes) was also investigated. The results indicated that acacetin inhibited depolarization-evoked glutamate release and cytosolic free Ca²⁺ concentration ([Ca²⁺]C) in the hippocampal nerve terminals. However, acacetin did not alter synaptosomal membrane potential. Furthermore, the inhibitory effect of acacetin on evoked glutamate release was prevented by the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channel blocker known as ω-conotoxin MVIIC. In a kainic acid (KA) rat model, an animal model used for excitotoxic neurodegeneration experiments, acacetin (10 or 50 mg/kg) was administrated intraperitoneally to the rats 30 min before the KA (15 mg/kg) intraperitoneal injection, and subsequently induced the attenuation of KA-induced neuronal cell death and microglia activation in the CA3 region of the hippocampus. The present study demonstrates that the natural compound, acacetin, inhibits glutamate release from hippocampal synaptosomes by attenuating voltage-dependent Ca²⁺ entry and effectively prevents KA-induced in vivo excitotoxicity. Collectively, these data suggest that acacetin has the therapeutic potential for treating neurological diseases associated with excitotoxicity.

Bupropion attenuates kainic acid-induced seizures and neuronal cell death in rat hippocampus

Excessive release of glutamate is believed to be a major component of cell damage following excitotoxicity associated with epilepsy. Bupropion, an atypical antidepressant, has been shown to inhibit glutamate release from rat cerebrocortical nerve terminals. The present study was undertaken to investigate whether bupropion has anti-seizure and anti-excitotoxic effects by using a kainic acid (KA) rat seizure model, an animal model for temporal lobe epilepsy and excitotoxic neurodegeneration. Our results show that bupropion (10 or 50mg/kg), administrated intraperitoneally to the rats 30 min before the KA (15 mg/kg) intraperitoneal injection, increased the seizure latency and decreased the seizure score. Bupropion pretreatment attenuated KA-induced neuronal cell death and microglia activation in the CA3 region of the hippocampus. Furthermore, KA-induced c-Fos expression and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation in the hippocampus were also reduced by bupropion pretreatment. These results suggest that bupropion has therapeutic potential in the treatment of seizure and other neurological diseases associated with excitotoxicity.

A single pentylenetetrazole-induced clonic-tonic seizure episode is accompanied by a slowly developing cognitive decline in rats

According to different studies, between 5% and 10% of people suffer a single isolated seizure episode at some time in their life. However, little is known about the effects of a single seizure episode on cognitive function, and clinical investigations of this issue are not easy to perform. In this situation, animal models may be a reasonable choice. The aim of our study was to follow the time course of delayed effects of generalized clonic-tonic convulsions on learning and memory functions in rats. A clonic-tonic seizure episode was induced by a single i.p. injection of pentylenetetrazole (70 mg/kg). Different behavioral tests were performed between days 10 and 100 after the convulsant administration. A single seizure episode resulted in a gradual decline in short-term memory function as assessed by novel object recognition and social recognition tests. The seizure episode induced a quick increase in hippocampal cell proliferation; however, the excessive newly generated cells seemed to be eliminated by the time of obvious cognitive impairment. These observations are indicative of a slowly developing and long-lasting influence of a single seizure episode on cognitive function. A rather long time period between the seizure episode and the manifestations of cognitive decline provides a window for a possible therapeutic intervention, and an elaboration of such "post-conditioning" treatments may be a promising opportunity to prevent subsequent mental impairments in patients.

Neuroprotective effect of sinapic acid in a mouse model of amyloid β(1-42) protein-induced Alzheimer's disease

Sinapic acid (SA) is a phenylpropanoid compound with anti-inflammatory and neuroprotective activities. The neuroprotective effects of SA in a mouse model of amyloid β (Aβ)(1-42) protein-induced Alzheimer's disease (AD) were investigated. Mice received a bilateral injection of Aβ(1-42) protein into the hippocampus to verify the efficacy of SA. Mice were treated with SA (10mg/kg/day, p.o.) for 7days beginning immediately after Aβ(1-42) protein injection, and an acquisition trial of the passive avoidance task was conducted 1h after the last administration of SA. Retention trial was conducted 24h after the acquisition trial, and mice were sacrificed for immunohistochemistry immediately after the retention trial. SA rescued neuronal cell death in the hippocampal CA1 region and also attenuated the increase of iNOS expression, glial cell activations and nitrotyrosine expressions induced by Aβ(1-42) protein. SA significantly attenuated memory impairment in the passive avoidance task. These results suggest that SA ameliorated Aβ(1-42) protein-related pathology including neuronal cell death and cognitive dysfunction via its anti-oxidative and anti-inflammatory activities, and may be an efficacious treatment for AD.

Mechanism and kinetics studies on the antioxidant activity of sinapinic acid

The OOH radical scavenging activity of sinapinic acid (HSA) has been studied in aqueous and lipid solutions, using the Density Functional Theory. HSA is predicted to react about 32.6 times faster in aqueous solution than in lipid media. The overall rate coefficients are predicted to be 5.39 × 10(5) and 1.66 × 10(4) M(-1) s(-1), respectively. Branching ratios for the different channels of reaction are also reported for the first time, as well as the UV-Vis spectra of the main products of reaction. It was found that the reactivity of sinapinic acid towards OOH radicals takes place almost exclusively by H atom transfer from its phenolic moiety. However it was found to react via SET, at diffusion-limit controlled rate constants, with ˙OH, ˙OCCl(3) and ˙OOCCl(3) radicals. It was found that the polarity of the environment and the deprotonation of HSA in aqueous solution, both increase the reactivity of this compound towards peroxyl radicals.

Post-treatment with voltage-gated Na(+) channel blocker attenuates kainic acid-induced apoptosis in rat primary hippocampal neurons

Injection of rats with kainic acid (KA), a non-N-methyl-D-aspartate (NMDA) type glutamate receptor agonist, induces recurrent (delayed) convulsive seizures and subsequently hippocampal neurodegeneration, which is reminiscent of human epilepsy. The protective effect of anti-epileptic drugs on seizure-induced neuronal injury is well known; however, molecular basis of this protective effect has not yet been elucidated. In this study, we investigated the effect and signaling mediators of voltage-gated Na(+) channel blockers (Lamotrigine, Rufinamide, Oxcarbazepine, Valproic Acid, and Zonisamide) on KA-induced apoptosis in rat primary hippocampal neurons. Exposure of hippocampal neurons to 10 μM KA for 24 h caused significant increases in morphological and biochemical features of apoptosis, as determined by Wright staining and ApopTag assay, respectively. Analyses showed increases in expression and activity of cysteine proteases, production of reactive oxygen species (ROS), intracellular free [Ca(2+)], and Bax:Bcl-2 ratio during apoptosis. Cells exposed to KA for 15 min were then treated with Lamotrigine, Rufinamide, Oxcarbazepine, Valproic Acid, or Zonisamide. Post-treatment with one of these anti-epileptic drugs (500 nM) attenuated production of ROS and prevented apoptosis in hippocampal neurons. Lamotrigine, Rufinamide, and Oxcarbazepine appeared to be less protective when compared with Valproic Acid or Zonisamide. This difference may be due to blockade of T-type Ca(2+) channels also by Valproic Acid and Zonisamide. Our findings thus suggest that the anti-epileptic drugs that block both Na(+) channels and Ca(2+) channels are significantly more effective than agents that block only Na(+) channels for attenuating seizure-induced hippocampal neurodegeneration.