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.
- SourceAvailable from: Coral Rosa-Falero[Show abstract] [Hide abstract]
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
- [Show abstract] [Hide abstract]
ABSTRACT: Epileptogenesis is a progressive process which culminates with spontaneous, recurrent and unpredictable epileptic seizures due to enhanced neuronal excitability. Well-characterized animal models of this process are needed to clarify its underlying molecular mechanisms, in which the role of nitric oxide has been a controversial component. We have used kindling with a sub-convulsive dose of pentylenetetrazole to objectively characterize early electroencephalographic changes during epileptogenesis. We used electroencephalographic recordings both during pentylenetetrazole (20 mg/kg) kindling for 20 days and then, 24 days later to quantify the number, duration and spectral power of epileptic discharges. The levels of nitric oxide were modulated locally in the cerebral cortex by pharmacological agents. The number of epileptiform discharges increased during the kindling protocol as well as 24 days later, revealing the induction of a self-sustaining epileptogenic process. Epileptic discharges were characterized by theta frequencies (4-10 Hz) that were associated with absence-like seizures. However, during kindling, the spectral power of the theta band progressively decreased, while the power of higher frequencies, in the beta band, increased. Nitric oxide in the cerebral cortex inhibited the number and amplitude of epileptic discharges. The electroencephalographic characterization of this kindling protocol provides a valuable tool to detect consequences of therapeutic interventions undertaken at initial phases of epileptogenesis, especially those targeted towards stopping this process. Increases of nitric oxide in the cerebral cortex could be a useful intervention to negatively modulate neuronal excitability, epileptic discharges and the progression of epileptogenesis.Neurochemical Research 01/2014; DOI:10.1007/s11064-014-1237-y · 2.55 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The present study was aimed to investigate the potential beneficial effect of curcumin, a polyphenol with pleiotropic properties, on mitochondrial dysfunctions, oxidative stress and cognitive deficits in kindled model of epilepsy. Kindled epilepsy was induced in rats by administering sub-convulsive dose of pentylenetetrazole (PTZ, 40mg/kg body weight) every alternate day for 30days. PTZ administered rats exhibited marked cognitive deficits assessed using active and passive avoidance task. This was accompanied by significant decrease in NADH: cytochrome c reductase (complex I) and cytochrome-c oxidase (complex IV) activity along with increase in ROS, lipid peroxidation and protein carbonyls. The levels of glutathione were also decreased in cortex and hippocampus. Electron micrographs revealed disruption of mitochondrial membrane integrity with distorted cristae in PTZ treated animals. Histopathological examination showed pyknotic nuclei and cell loss in hippocampus as well as cortex of PTZ treated animals. Curcumin administration at a dose of 100mg/kg, p.o. throughout the treatment paradigm was able to ameliorate memory deficits with no significant effect on seizure scores. Curcumin was able to restore the activity of mitochondrial complexes. In addition, significant reduction in ROS generation, lipid peroxidation and protein carbonyls were observed in PTZ animals supplemented with curcumin. Moreover, glutathione levels were also restored in PTZ treated rats supplemented with curcumin. Curcumin protected mitochondria from seizure induced structural alterations. Further, the curcumin supplemented PTZ rats had normal cell morphology and reduced cell loss. These results suggest that curcumin supplementation has potential to prevent mitochondrial dysfunctions and oxidative stress with improved cognitive functions in chronic model of epilepsy.Pharmacology Biochemistry and Behavior 08/2014; 125. DOI:10.1016/j.pbb.2014.08.001 · 2.82 Impact Factor