Possible nitric oxide mechanism in the protective effect of hesperidin against pentylenetetrazole (PTZ)-induced kindling and associated cognitive dysfunction in mice
ABSTRACT Epilepsy is a complex neurological disorder manifested by recurrent episodes of convulsive seizures, loss of consciousness, and sensory disturbances. Pentylenetetrazole (PTZ)-induced kindling primarily represents a model of generalized epilepsy. The present study has been undertaken to evaluate the neuroprotective potential of hesperidin and its interaction with nitric oxide modulators against PTZ-induced kindling and associated cognitive dysfunction in mice. The experimental protocol comprised of eleven groups (n=6), where a subconvulsive dose of PTZ (40mg/kg, i.p.) had been administered every other day for a period of 12days, and seizure episodes were noted after each PTZ injection over a period of 30min. The memory performance tests were carried out on days 13 and 14 followed by the estimation of biochemical and mitochondrial parameters. Chronic administration of a subconvulsive dose of PTZ resulted in an increase in convulsive activity culminating in generalized clonic-tonic seizures, as revealed by a progressive increase in seizure score as well as alteration in antioxidant enzyme levels (lipid peroxidation, nitrite, glutathione, super oxide dismutase, and catalase) and mitochondrial complex (I, II, and IV) activities, whereas chronic treatment with hesperidin (200mg/kg) significantly attenuated these behavioral, biochemical, and mitochondrial alterations. Further, treatment with l-arginine (100mg/kg) or l-NAME (10mg/kg) in combination with hesperidin significantly modulated the protective effect of hesperidin which was significant as compared to their effects per se in PTZ-treated animals. Thus, the present study suggests a possible involvement of the NO-cGMP pathway in the neuroprotective effect of hesperidin in PTZ-kindled mice.
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ABSTRACT: Epilepsy is a serious neurological condition and pharmacotherapy is not effective for all patients and causes serious adverse effects and pharmacokinetic and pharmacodynamic interactions. Natural products and ethnobotanical resources can help develop new therapeutic options for conditions like epilepsy. In Puerto Rico, ethnobotanical resources highlight the anxiolytic properties of a tea like preparation made from the leaves of the Citrus aurantium tree or bitter orange. Studies performed with essential oils from the peel of the fruit have shown to increase seizure latency to pentylenetetrazole (PTZ) and maximal electroshock seizure in mice. We characterized the extract composition, and used a model of PTZ induces seizures in the zebrafish and a receptor-ligand binding assay to determine if this preparation has anticonvulsant properties and its mechanism of action. We determined that the aqueous extract made from the leaves of the C. aurantium tree contains hesperidin, neohesperidin, and neohesperidin dihydrochalcone. Using our zebrafish model, we determined that exposure to the C. aurantium 28 mg/mL extract in aquarium water increases seizure latency by 119% compared to controls. We ruled out a mechanism involving GABAA receptors using the selective antagonist gabazine. We used two approaches to study the role of glutamate in the mechanism of the C. aurantium extract. The ligand binding assay revealed C. aurantium extracts at concentrations of 0.42 to 5.6 mg/mL significantly reduced [(3)H]Glu binding indicating an interaction with glutamate receptors, in particular with NMDA receptors and mGluR II. This interaction was confirmed with our animal model using selective receptor antagonists and we identified an interaction with mGluR I, not observed in the ligand binding experiment. These study provide evidence of the anticonvulsant properties of the aqueous extract made from the leaves of the C. aurantium tree and a mechanism involving NMDA and mGluR's I and II.Frontiers in Pharmacology 01/2014; 5:284. DOI:10.3389/fphar.2014.00284
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ABSTRACT: Oxidative stress, together with mitochondrial dysfunction, has been reported to be involved in the pathogenesis of epileptogenesis and its associated comorbidities. Phytoflavonoids have shown numerous beneficial ameliorative effects on different neurological disorders by virtue of their antioxidant effect. The present study investigated the effect of flavonoid-rich ethyl acetate fraction of the crude fig extract of Ficus religiosa in combination with phenytoin on seizure severity, depressive behavior, and cognitive deficit in pentylenetetrazol (PTZ)-kindled mice. The flavonoid-rich ethyl acetate fraction of the crude fig extract was found to show significant antioxidant potential in various in vitro free radical scavenging assays. Combined treatment of this fraction (2.5, 5, and 10 mg/kg; i.p.) along with a subeffective dose of phenytoin (15 mg/kg; i.p.) in postkindled animals once daily for fifteen days showed a dose-dependent decrease in the seizure severity score, a decreased number of mistakes, increased step-down latency in passive shock avoidance paradigm, and decreased immobility time in the tail suspension test in comparison with the phenytoin only-treated group. Biochemical investigations of the brain tissue showed amelioration of thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) levels, and reduced catalase and acetylcholinesterase (AChE) activities, thereby indicating suppression of oxidative stress. In conclusion, the results of the present study showed the protective effect of the flavonoid-rich fraction of F. religiosa along with a subeffective dose of phenytoin in PTZ-kindling-associated cognitive deficit and depressive behavior with complete suppression of seizures through reduction of oxidative stress, supporting the the need for clinical evaluation of the supplementation of phytoflavonoids along with antiepileptic drugs (AEDs) for management of epilepsy and its psychiatric and cognitive comorbidities.Epilepsy & Behavior 10/2014; 41:171–178. DOI:10.1016/j.yebeh.2014.10.002 · 2.06 Impact Factor
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ABSTRACT: Antioxidant compounds have been extensively investigated as a pharmacological alternatives to prevent epileptogenesis. Rosmarinic acid (RA) and caffeic acid (CA) are compounds with antioxidant properties, and RA has been shown to inhibit GABA transaminase activity (in vitro). Our aim was to evaluate the effect of RA and CA on seizures induced by pentylenotetrazole (PTZ) using the kindling model in mice. Male CF-1 mice were treated once every three days during 16days with RA (1, 2 or 4mg/kg; i.p.), or CA (1, 4 or 8mg/kg; i.p.), or positive controls diazepam (1mg/kg; i.p.) or vigabatrin (600mg/kg; p.o.), 30min before PTZ administration (50mg/kg; s.c.). After the last treatment, animals were sacrificed and the cortex was collected to evaluate free radicals (determined by 2',7'-dichlorofluorescein diacetate probe), superoxide dismutase (SOD) and genotoxic activity (Alkaline Comet Assay). Rosmarinic acid 2mg/kg increased latency and decreased percentage of seizures, only on the 4th day of observation. The other tested doses of RA and CA did not show any effect. Rosmarinic acid 1mg/kg, CA 4mg/kg and CA 8mg/kg decreased free radicals, but no dose altered the levels of enzyme SOD. In the comet assay, RA 4mg/kg and CA 4mg/kg reduced the DNA damage index. Some doses of rosmarinic acid and CA tested showed neuroprotective action against oxidative and DNA damage produced in the kindling epilepsy model, although they did not produce antiepileptogenic effect in vivo. Copyright © 2014. Published by Elsevier Inc.Life Sciences 12/2014; 122. DOI:10.1016/j.lfs.2014.11.009 · 2.30 Impact Factor