| ObjectiveThe epileptiform activity was induced by perfusing bicuculline (Bic), a GABAAreceptor antagonist, in normal hippocampal slices and temporal lobe epilepsy (TLE)model was established by kainic acid (KA) injected into the center site of righthippocampus CA3region with the stereotaxic technology. To investigate the effects ofresveratrol (Res) with different concentrations on evoked epileptiform discharges in rathippocampal CA1region so as to provide a theoretical basis for the clinicaldevelopment of antiepileptic drugs.Methods1. Model establishment.1.1TLE model. Adult male Wistar rats (200~240g and clean stage) were used in theexperiments. Under chloral hydrate (350mg/kg) anesthesia, rats were placed on thestereotaxic apparatus and2.5~3μl KA (0.4μg/μl) was slowly injected (about15min) tothe CA3region of right hippocampus (4.0mm posterior to bregma,4.4mm lateral tothe midline,3.8mm below dura). The microsyringe was removed10min later and therat scalp was sutured. The behavioral progression of KA-induced seizures was scoredaccording to Racine’s standard classification. Only those rats that could reach at leastthe class Ⅳ seizures were used in subsequent studies. Themodel rats should beprepared for field recoring in2-4weeks after surgery.1.2Acute epileptiform activity. The normal hippocampal slices were perfused withGABAAreceptor antagonist, Bic (30μmol/L), to induce epileptiform activity. 2. Slice preparation. Rats were anesthetized with2%pentobarbital sodium anddecapitated. Their brains were rapidly removed and placed in oxygenated (95%O2and5%CO2) artificial cerebrospinal fluid (ACSF) at4°C. Transverse hippocampal slices(400μm thick) were cut and transferred to a storage chamber for1~2h. The ACSF inthe store chamber was gassed continuously with95%O2and5%CO2at30±2°C.3. Field-potential recording. After a recovery period of1~2h, an individual slicewas transferred to a recording chamber, in which the slice was continuously superfusedwith oxygenated ACSF at a rate of2ml/min at32°C. Population spike (PS) wasrecorded in CA1pyramidal cell layer by stimulating the Shaffer collaterals in stratumradiatum.4. Statistical Analysis. All statistical analysis was performed using SPSS13.0software. Values are expressed as mean±SEM. Comparisons between means wereperformed using Student’s t-test. The level of significance was set at P <0.05.Results1. Effects of Res on PS in rat hippocampal CA1region. Single PS was usuallyrecorded in normal pyramidal cell layer of hippocampal CA1region. The amplitude ofPS recorded in normal hippocampal slices was not significantly affected by perfusingACSF with low, middle and high doseof Res (5μmol/L,15μmol/L and50μmol/L),respectively (n=8, P>0.05).2. Effects of Res on evoked epileptiform discharges in rat hippocampal CA1region.The epileptiform discharges in rat hippocampal CA1region can be evoked by perfusingACSF with Bic or TEL-evoked by injecting KA in the center site of hippocampus CA3region. The recorded PS was of a4-6peaks like multiple epileptiform dischargesevoked by perfusing ACSF with Bic (30μmol/L)20min. After perfusing ACSF withlow or middle dose of Res (5μmol/L or15μmol/L) based on perfusing ACSF with Bic,the amplitudes of the first four peaks of PS and the total peak numbers of PS were not significantly affected (n=8and P>0.05, n=8and P>0.05, respectively). However,after perfusing ACSF with high dose of Res (50μmol/L) based on perfusing ACSF withBic, the amplitudes of the first four peaks of PS were all decreased obviously (n=8, P<0.01), and the total peak numbers of PS were decreased significantly by82.02±1.3%（n=8, P﹤0.01）compared with the control. The recorded PS was also of a4-6peakslike multiple epileptiform discharges in rat TEL model. After perfusing ACSF with lowor middle dose of Res (5μmol/L or15μmol/L) in rat TLE model, the amplitudes of thefirst four peaks of PS and the total peak numbers of PS were no significantly affected (n=6and P>0.05, n=6and P>0.05, respectively). However, after perfusing ACSFwith high dose of Res (50μmol/L), the amplitudes of the first four peaks of PS were alldecreased obviously (n=6, P <0.01), and the total peak numbers of PS were decreasedsignificantly by84.58±2.4%（n=6, P﹤0.01）compared with the control.Conclusion1. The amplitude of PS in normal hippocampal slices is not significantly affected by low,middle and high dose (5μmol/L,15μmol/L and50μmol/L) of Res, respectively.2. Low and middle dose (5μmol/L and15μmol/L) of Res are not affected on theamplitude and number of PS. However, high dose of Res (50μmol/L) can partly inhibitevoked epileptiform discharges in rat hippocampal CA1region. |
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