Penicillin-induced Epileptiform Research Articles

Electrophysiological evidence on epileptiform activity enhanced by electrical stimulation of teeth in rats

The aim of this study was to evaluate the possible effects of electrical stimulation (ES) of tooth on penicillin-induced epileptiform activity in rats.Experiment was realized on 24 adult male Sprague Dawley rats. Rats were assigned three groups [stimulation group (SG), penicillin group (PG), and penicillin+stimulation group (PSG)]. In SG, ES was only applied. Ten pulses of electrical current were delivered to the teeth for a duration of 2 milliseconds at 1-second intervals from a stimulator. Currents were applied in the range of 40–240 μA with 40 μA steps. Electrocorticography (ECoG) recordings were taken before and after ES. In PG, ECoG recordings were taken before and during the injection of penicillin. In PSG, after epileptiform activity was induced, ES was applied and ECoG recordings were taken as in SG. All the data were analyzed with Student’s t test. Applied currents did not cause any epileptiform activity in SG. When the PSG was compared with the PG it was seen that the spike frequency of epileptiform activity increased in a statistically significant way after application of 240 μA (P < 0·05). On the other hand current application caused an increase in the spike amplitude of the PSG compared with the amplitude of the PG, but it was not statistically significant.We concluded that ES of tooth with high current can trigger epileptiform activity in rats. For this reason, further research is required to evaluate the effects of ES of tooth for pulp testing on epileptic human subjects and antiepileptic drug users.

Electrophysiological evidence for the anticonvulsant effect of alpha-lipoic acid via indirect antioxidant properties in BALB/c mice

Alpha-lipoic acid (alpha-LA) is a strong antioxidant whose effect on epilepsy has not been completely clarified yet. The present study was designed to investigate the effects of alpha-LA on epileptiform activity induced by penicillin in BALB/c mice.In the present study, 56 adult male BALB/c mice were divided into seven groups. Under urethane anesthesia, the mice were injected with intracortical (i.c.) 200 IU penicillin following craniotomy to start epileptiform activity. The effects of alpha-LA on epileptiform activity were examined through the intraperitoneal (i.p.) application of 25, 50, 100, 200, and 400 mg/kg doses. The electrophysiological data have demonstrated that alpha-LA at the 200 mg/kg dose showed an anticonvulsant effect by reducing penicillin-induced epileptiform activity. This effect obtained at the 200 mg/kg dose was determined to emerge 80 minutes after injection (i.p.) and last throughout the experiment. Alpha-LA (400 mg/kg) was appointed as the toxic dose for the BALB/c mice used in this study.The findings of the study indicate that alpha-LA at the 200 mg/kg dose show an anticonvulsant effect by reducing penicillin-induced epileptiform activity. Besides this, the delayed anticonvulsant effect of alpha-LA observed in this study gives the impression that it could result from its indirect antioxidant activity.

The involvement of iNOS activity in the anticonvulsant effect of grape seed extract on the penicillin-induced epileptiform activity in rats

Grape seed extract (GSE) has been known as being neuroprotective due to its antioxidant properties. The aim of the present study was to examine both the effect of GSE on the penicillin-induced epileptiform activity in rat and the role of nitric oxide (NO) pathway in the effect of GSE. GSE, at doses of 50, 100, 200 mg/kg, significantly decreased the mean frequency of epileptiform activity. GSE, at the highest dose (400 mg/kg), did not change either the frequency or amplitude of epileptiform activity. GSE, at a dose of 200 mg/kg, was the most effective in changing the frequency of epileptiform activity. The occurrence of anticonvulsant activity of GSE was significantly delayed in the presence of selective inducible nitric oxide synthase (iNOS) inhibitor, aminoguanidine (60 mg/kg), which was inhibited by the NO precursor, L-arginine (500 mg/kg). The administration of a non-selective NOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) partially reversed the anticonvulsant activity of GSE. Selective neuronal nitric oxide synthase (nNOS) inhibitor, 7-nitroindazole (7-NI) and L-arginine showed a similar anticonvulsant activity in the presence of GSE. The electrophysiological evidence of the present study indicates that GSE decreases the mean frequency of penicillin-induced epileptiform activity, suggesting an anticonvulsant role. iNOS/NO pathway could be involved in mediating anticonvulsant effect of GSE on the epileptiform activity.

Penicillin-induced epileptiform activity elevates focal brain temperature in anesthetized rats

To elucidate a relationship between changes in focal brain temperature and severity of abnormal brain activity, epileptiform discharges and behavioral seizures were induced by Penicillin G in anesthetized rats, and focal brain-temperature was measured. Penicillin G was injected into the right primary sensorimotor cortex (400IU/μl). After the injection, epileptiform discharges induced a temperature increase gradually by 0.65±0.24°C. Moreover, when behavioral seizures were induced by reducing the anesthesia level, the temperature was raised by 0.26±0.22°C. These results suggest that elevation of the focal brain temperature is associated with the severity of epileptic activity.

The Role of CB1‐Receptors in the Proconvulsant Effect of Leptin on Penicillin‐Induced Epileptiform Activity in Rats

Prior studies have demonstrated the involvement of leptin and cannabinoids in food intake and metabolism. However, the interaction between leptin and cannabinoids in epilepsy has not been studied. This study elucidated the relationship between leptin and cannabinoids in penicillin-induced epileptiform activity in rats. The CB1 receptor agonist, arachidonyl-2-chloroethylamide (ACEA), at doses of 2.5 and 7.5 μg, the CB1 receptor antagonist, [N-(piperidine-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3 carboxamide] (AM-251), at doses of 0.125 and 0.25 μg, and leptin, at the dose of 1 μg, were administered intracerebroventricularly (i.c.v.) 30 min after intracortical penicillin (i.c.) application. Leptin caused proconvulsant activity in all groups. The administration of AM-251, at a dose of 0.25 μg, increased the frequency of penicillin-induced epileptiform activity by producing status epilepticus-like activity, whereas AM-251, at a dose of 0.125 μg, was not effective when applied alone. ACEA, at a dose of 7.5 μg, decreased the frequency of epileptiform activity. Leptin reversed the anticonvulsant activity of ACEA and enhanced the proconvulsant activity of AM-251. This study provides electrophysiological evidence that the proconvulsant activity of leptin is mediated, at least in part, by inhibition of cannabinoids in the experimental model of epilepsy.

The effect of combined treatment of alpha-tocopherol, ascorbic acid, and pyridoxine with NMDA blocker memantine on penicillin-induced epileptiform activity in rats

To evaluate the effects of coadministration of vitamins alpha-tocopherol, ascorbic acid, and pyridoxine with memantine on a penicillin-induced experimental epilepsy model in rats so as to clarify the eventual interaction between these vitamins and the N-methyl-D-aspartate (NMDA) system. Materials and methods: The epileptic focus was produced by intracortical penicillin G potassium injection. The effects of intraperitoneal injections of memantine, memantine + alpha-tocopherol, memantine + ascorbic acid, and memantine + pyridoxine combinations on epileptiform activity were evaluated in electrocorticogram recordings. Results: The antiepileptiform effects appeared earlier in all memantine and vitamin coadministrated groups compared to the memantine-alone group, but the difference between the groups was not statistically significant considering the frequency and amplitude of the epileptiform activity. Conclusion: Coadministration of vitamins does not enhance the antiepileptiform activity of memantine in penicillin-induced epilepsy in rats. However, this coadministration causes the earlier appearance of antiseizure effects. Since moderate doses of these vitamins have no side effects, it might be a good idea to use them with NMDA blockers to provide an earlier antiepileptic effect.

Chronic application of topiramate and carbamazepine differentially affects the EEG and penicillin-induced epileptiform activity in rats

Carbamazepine (CBZ) and topiramate (TPM) are among commonly used antiepileptic drugs. The acute actions of these drugs are well known but the effects of long-term use on partially induced epileptiform characteristics are yet to be clarified. The rats were received CBZ (154 mg/kg/day), TPM (10 mg/kg/day) or tap water by gavage. We investigated penicillin-induced cortical epileptiform activity and electroencephalogram spectral power of rats by using electrocorticogram recordings. Animals were anesthetized with i.p. urethane (1·25 g/kg). Analysis of electroencephalogram recordings prior to epileptiform activity revealed that 3-week treatment of CBZ significantly increased relative power of delta (P<0·01) while reduced alpha (P<0·017) and beta (P<0·017) relative power compared to both control group and TPM group. TPM had no effect on absolute power and relative power of any frequency band. TPM treatment of 21 days significantly reduced the spike frequency (P<0·01). This preventive effect was missing in CBZ-treated rats. Upon the application of the last dose of drugs during ongoing epileptiform activity, the drugs suppressed the epileptiform activity. However, TPM was more rapid and effective than CBZ. In conclusion, our in vivo electrophysiological data suggest that TPM is more effective in animal model of partial epilepsy at the applied doses in this study.

The Interactions of Nitric Oxide and Acetylcholine on Penicillin-Induced Epilepsy in Rats

The aim of this study was to investigate the interaction between nitric oxide (NO) and acetylcholine (ACh) in penicillin-induced experimental epilepsy. Adult male Wistar rats weighing 220 ± 35 g were used in the experiments. The epileptiform activity was induced by microinjection of penicillin (200 IU/1 μl) into the left sensorymotor cortex. Electrocorticogram was recorded by using Ag/AgCl ball electrodes. Sodium nitroprusside (SNP), a NO donor, given intracortically 30 min after penicillin significantly reduced the spike frequency whereas ACh increased the epileptiform activity for 5 min. Atropine, an antagonist for muscarinic receptors, was given intracortically 30 min after penicillin and did not significantly affect epileptiform activity for 30 min. SNP given after atropine significantly suppressed the epileptiform activity. ACh given 10 min after Nω-nitro-L: -arginine methyl ester (L-NAME), a nonspecific nitric oxide synthase inhibitor, did not have a significant effect on spike frequency. When ACh and SNP were administered together, penicillin induced epileptiform activity and spike frequency were significantly suppressed from the 10th minute onwards. It can be concluded that ACh increases the penicillin-induced epileptiform activity while co-administration of ACh and SNP produces a potent anticonvulsant effect as compared to SNP alone.

Effect of curcumin, the active constituent of turmeric, on penicillin-induced epileptiform activity in rats.

Curcumin is a major constituent of turmeric and has many biological functions such as anticancer and anti-inflammatory effects. The present study was conducted to investigate the effects of curcumin and diazepam in separate and combined treatments on penicillin-induced seizures in rats. In urethane-anesthetized rats, epileptiform activity was induced by intracortical (i.c.) administration of penicillin (200 IU, 1 µl), and frequency and amplitude of spike waves were analyzed using electrocorticographic recordings. Intraperitoneal (i.p.) injections of curcumin at doses of 100 and 200 mg/kg, and intracerebroventricular (i.c.v.) injection of diazepam at a dose of 5 µg significantly (p<0.05) reduced both frequency and amplitude of spike waves. Co-administrations of curcumin (50 mg/kg, i.p.) with diazepam (5 µg, i.c.v) enhanced the antiepileptic effect of diazepam (5 µg, i.c.v). The results suggested that both curcumin and diazepam suppressed penicillin-induced epileptiform activity. A potentiation effect was observed between curcumin and diazepam in reducing penicillin-induced seizures.

Central effect of crocin on penicillin-induced epileptiform activity in rats

AbstractIn the present study, the effects of separate and combined intracerebroventricular (icv) injections of crocin and diazepam were investigated on penicillin-induced epileptiform activity. In urethane-anesthetized rats, epileptiform activity was induced by intracortical (ic) administration of penicillin (200IU, 1μl) and was analyzed using electrocorticographic (ECoG) recordings. The icv injections of crocin at doses of 25, 50 and 100μg and diazepam at a dose of 10μg increased the latency time to onset of first spike wave, and decreased the frequency and amplitude of spike waves. Co-administration of an effective dose of crocin (50μg) with an ineffective dose of diazepam (2.5μg), increased the latency time to onset of first spike wave and decreased frequency and amplitude of spike waves as compared with crocin (50μg). These results indicated that crocin and diazepam produced antiepileptic activities at the levels of the brain. Crocin potentiated the antiepileptic effect of diazepam. A GABAA-benzodiazepine receptor-mediated mechanism may be involved in the antiepileptic activity of crocin.

The interactions of nitric oxide and adenosine on penicillin-induced epileptiform activity in rats.

In this study, the influence of nitric oxide (NO) and adenosine systems on penicillin-induced epileptiform activity was examined in rats. NO donor, sodium nitroprusside (SNP, 50 micrograms per rat, i.c.v.) reduced the frequency but not the amplitude of epileptiform discharges. Non-selective NOS inhibitor, N-omega-nitro-L-arginine methyl ester (L-NAME, 100 micrograms per rat, i.c.v.) practically did not exert any effect on the spike frequency and amplitude. Adenosine (100 micrograms per rat, i.c.) reduced spike frequency but not the amplitude, whereas theophylline (100 micrograms per rat, i.c.v.) increased the mean spike frequency and amplitude of penicillin-induced epileptiform discharges. Co-injection of theophylline and L-NAME did not cause a further increase in the epileptiform activity compared with theophylline. When NO production was blocked with L-NAME, the inhibitory effects of adenosine were lost. The obtained results suggest that NO and adenosine may decrease penicillin-induced epileptiform activity in rats and that NO, at least in part, may mediate the anticonvulsant effect of adenosine.

Short-duration swimming exercise decreases penicillin-induced epileptiform ECoG activity in rats.

The aim of the present study is to understand the basic relationship between swimming exercise and natural course of epilepsy in animals by performing an electrophysiological study. For this purpose, male Wistar rats were submitted to daily swimming exercise program of three different durations. Animals were swim-exercised for 90 days with either 15 minutes, 30 minutes or 60 minutes/day. Thereafter, the epileptiform activity was induced by a single microinjection of penicillin (500 units) into the left somatomotor cortex. Short-duration swimming exercise (15 min per day for 90 days) decreased the mean frequency and amplitude of penicillin-induced epileptiform activity in the 70 and 90 minutes after penicillin injection compared to penicillin administered group, respectively. Moderate-duration (30 min per day for 90 days) and long-duration (60 min per day for 90 days) swimming exercise did not alter either the frequency or amplitude of epileptiform activity. The results of the present study provide electrophysiologic evidence that short-duration swimming exercise partially inhibits penicillin-induced epileptiform activity. These data also suggest that moderate and long-duration swimming exercise do not increase either the frequency or severity of seizure in the model of penicillin-induced epilepsy.

The effect of co-administration of the NMDA blocker with agonist and antagonist of CB1-receptor on penicillin-induced epileptiform activity in rats

Although the activation of CB1-receptor by cannabinoids and block of NMDA receptors are known to decrease seizure severity in epilepsy models, the interaction between these systems remain elusive. Therefore, the present study was initiated to evaluate the possible interactions between cannabinoid compounds and NMDA receptor antagonist in the penicillin-induced epileptiform activity in rat. In the first set of experiments, 30 min after intracortical injection of penicillin, five different doses of memantine (3,5-dimethyl-1-adamantanamine hydrochloride, 1, 2.5, 5, 10 or 20mg/kg) were administered intraperitoneally (i.p.). In the second set of experiments, intracerebroventricular (i.c.v.) AM-251 [N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide], (0.25 μg) a CB1-receptor antagonist and ACEA (arachidonyl-2-chloroethylamide), (7.5 μg) a CB1-receptor agonist, were administered 15 min after memantine (i.p.) application. Memantine, NMDA receptor antagonist, at doses of 2.5 and 5mg/kg (i.p.) decreased the mean frequency of penicillin-induced epileptiform activity with a maximal effect at 5mg/kg. Memantine, at the lowest dose (1mg/kg, i.p.) and highest doses (10 and 20mg/kg, i.p.) did not change the frequency of epileptiform activity. ACEA, at a dose of 7.5 μg, also decreased the frequency of epileptiform activity, whereas AM-251, at a dose of 0.25 μg increased the frequency by causing status epilepticus-like activity. The best and earlier anti-epileptiform effects appeared in both the presence of memantine (5mg/kg, i.p.) and ACEA (7.5 μg, i.c.v.), which was blocked by CB1-receptor antagonist, AM-251. The results of the present study provide electrophysiologic evidence for an interaction between cannabinoid system and NMDA receptors, probably via NMDA-mediated Ca(2+) influx in the penicillin-induced epilepsy.

Interaction of leptin and nitric oxide pathway on penicillin-induced epileptiform activity in rats

The aim of the present study was to investigate the role of NO as a mediator of leptin action at the penicillin-induced epileptiform activity in rat. Thirty minutes after penicillin injection, leptin, at a dose of 1 µg, significantly increased the mean frequency of epileptiform activity without changing the amplitude. The effects of systemic administration of nitric oxide synthase (NOS) inhibitors, non-selective NG-nitro- l-arginine methyl ester (L-NAME), selective neuronal NOS inhibitor, 7-nitroindazole (7-NI) and NO precursor, l-arginine on the effects of leptin were investigated. The occurrence of anticonvulsant activity of 7-NI (40 mg/kg, i.p.) was significantly delayed in the presence of leptin (1 µg). The administration of L-NAME (60 mg/kg, i.p.), 30 min before leptin (1 µg) application, did not influence proconvulsant activity of leptin. The administration of l-arginine (1000 mg/kg, i.p.) 30 min before the effective dose of leptin (1 µg, i.c.v.) reversed the proconvulsant effects of leptin whereas the same dose of its inactive enantiomer, d-arginine (1000 mg/kg, i.p.) failed to influence the proconvulsant effect of leptin. The electrophysiological evidence of the present study suggests that neuronal NOS/NO pathway is involved in mediating leptin effects on penicillin-induced epileptiform activity.

Endothelial nitric oxide synthase activity involves in the protective effect of ascorbic acid against penicillin-induced epileptiform activity

Ascorbic acid and nitric oxide are known to play important roles in epilepsy. The aim of present study was to identify the involvement of nitric oxide (NO) in the anticonvulsant effects of ascorbic acid on penicillin-induced epileptiform activity in rats. Intracortical injection of penicillin (500, International Units (IU)) into the left sensorimotor cortex induced epileptiform activity within 2–5 min. Thirty minutes after penicillin injection, nitric oxide synthase (NOS) inhibitor, N G-nitro- l-arginine methyl ester ( l-NAME, 100 mg/kg), neuronal nitric oxide synthase (nNOS) inhibitor 7-nitroindazole (7-NI, 40 mg/kg), NO substrate, l-arginine (500 mg/kg) were administered with the most effective dose of ascorbic acid (100 mg/kg) intraperitoneally (i.p.). The administration of l-arginine significantly decreased the frequency of epileptiform activity while administration of l-NAME did not influence the mean frequency of epileptiform activity. Injection of 7-NI decreased the mean frequency of epileptiform activity but did not influence amplitude. Ascorbic acid decreased both the mean frequency and amplitude of penicillin-induced epileptiform activity in rats. The application of l-NAME partially and temporarily reversed the anticonvulsant effects of ascorbic acid. The results support the hypothesis of neuro-protective role for NO and ascorbic acid. The protective effect of ascorbic acid against epileptiform activity was partially and temporarily reversed by nonspecific nitric oxide synthase inhibitor l-NAME, but not selective neuronal nitric oxide synthase inhibitor 7-NI, indicating that ascorbic acid needs endothelial-NOS/NO route to decrease penicillin-induced epileptiform activity.

The effects of intracerebroventricular AM‐251, a CB1‐receptor antagonist, and ACEA, a CB1‐receptor agonist, on penicillin‐induced epileptiform activity in rats

Several results support the conclusion that the cannabinoid system has a role in generation and cessation of epileptic seizures. The aim of this study was to evaluate the effects of intracerebroventricular AM-251 [N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide], a CB1-receptor antagonist, and ACEA (arachidonyl-2-chloroethylamide), a CB1-receptor agonist, on penicillin-induced epileptiform activity in rats. In the first set of experiments, 30 min after penicillin injection, AM-251, at doses of 0.125, 0.25, 0.5, and 1 μg, was administered intracerebroventricularly (i.c.v.). In the second set of experiments, 30 min after penicillin injection, ACEA, at doses of 2.5, 5, 7.5, and 15 μg (i.c.v.), was administered. In the third set of experiments, AM-251, at doses of 0.125 and 0.25 μg (i.c.v.), was administered 10 min before ACEA (7.5 μg, i.c.v.) injection. ACEA, at a dose of 7.5 μg, significantly decreased the frequency of penicillin-induced epileptiform activity without changing the amplitude. ACEA, at doses of 2.5, 5, and 15 μg, had no impact on either frequency or amplitude of epileptiform activity. AM-251, at doses of 0.25 and 0.50 μg, significantly increased the frequency of epileptiform activity. AM-251, at a dose of 0.25 μg (i.c.v.), was the most effective in changing the frequency of penicillin-induced epileptiform activity, and it also caused status epilepticus-like activity. AM-251, at doses of 0.125 and 0.25 μg, 10 min before ACEA (7.5 μg), reversed the anticonvulsant action of ACEA. The results of the present study provide electrophysiologic evidence for the role of CB1 receptors in regulating the frequency of epileptiform activity in the model of penicillin-induced epilepsy. To elucidate the precise mechanism of cannabinoid action in the brain during seizure, more advanced electrophysiologic and neurochemical studies are required.

The effect of alpha-tocopherol in the acute ethanol intake and its withdrawal on penicillin-induced epilepsy.

The present study was designed to investigate the influence of acute ethanol intake and its withdrawal on the anticonvulsant effect of alpha-tocopherol in penicillin-induced epileptiform activity. Ethanol-treated rats received a daily dose of 3 g/kg or 9.0 g/kg of 30% ethanol solution for 3 days. Thirty minutes after penicillin injection (500 units, i.c.) the most effective dose of alpha-tocopherol (500 mg/kg) was administered intramuscularly (i.m.). Acute administration of ethanol, in a dose of 3 g/kg, did not change either frequency or amplitude of penicillin-induced epileptiform activity, while dose of 9 g/kg ethanol significantly decreased the mean frequency of penicillin-induced epileptiform ECoG activity in the ethanol-treated group. Ethanol (9 g/kg) withdrawal also caused an increase in the amplitude of epileptiform ECoG activity in the withdrawal group. The results suggest that acute administration of high dose ethanol (9 g/kg) and alpha-tocopherol have some limited anticonvulsive effects in penicillin-induced epileptiform activity in rats.

The role of nitric oxide in the inhibitory effect of ghrelin against penicillin-induced epileptiform activity in rat

Ghrelin, a gastric peptide with key action on food intake, has been recently recognized as a potential antiepileptic agent. In the present study, we investigated the involvement of nitric oxide in the effect of ghrelin on penicillin-induced epileptiform activity in rat. Thirty minutes after penicillin injection, ghrelin, at doses of 0.5, 1, 2 microg, was administered intracerebroventricularly (i.c.v.). Ghrelin, at a dose of 1 microg, significantly decreased the mean frequency of epileptiform activity without changing the amplitude whereas other doses of ghrelin (0.5 and 2 microg) did not alter either the mean of frequency or amplitude of epileptiform activity. The effects of systemic administration of nitric oxide synthase (NOS) inhibitors, non-selective N(G)-nitro-l-arginine methyl ester (l-NAME), selective neuronal NOS inhibitor, 7-nitroindazole (7-NI) and NO substrate, l-arginine on the anticonvulsive effects of ghrelin were investigated. The administration of l-NAME (60 mg/kg, i.p.), 15 min before ghrelin (1microg) application, reversed the anti-epileptiform effects of ghrelin whereas 7-NI (40 mg/kg, i.p.) did not influence it. The present study provides electrophysiological evidence that the intracerebroventricular injection of ghrelin has an inhibitory effect against epileptiform activity in the penicillin model of epilepsy. The anti-epileptiform activity of ghrelin was reversed by nonspecific nitric oxide synthase inhibitor l-NAME, but not selective neuronal nitric oxide synthase inhibitor 7-NI, indicating that ghrelin requires activation of endothelial-NOS/NO route in the brain.

Anticonvulsant effect of carnosine on penicillin-induced epileptiform activity in rats

Carnosine is a compound of naturally-occurring dipeptide that synthesized by the carnosine synthetase from β-alanine and l-histidine. Recent reports claim that carnosine plays an important role in the control of epilepsy but its involvement in anticonvulsant functions remains unknown. In this study, we investigated the effects of carnosine in a rat model of epilepsy using the intracortical penicillin injection method. Thirty minutes after penicillin injection, the doses of 125, 250, 500, 1000 mg/kg carnosine and 90 min before penicillin injection the dose of 500 mg/kg carnosine were administered intraperitoneally. The epileptiform activity was verified by electrocorticographic (ECoG) recordings. The mean spike frequency of penicillin-induced epileptiform activity was significantly decreased in all carnosine-treated rats when compared with those of penicillin-injected. The dose of 500 mg/kg for carnosine treated and pretreated rats was found to be the most effective dose in reducing the frequency of penicillin-induced epileptiform activity. There was no significant difference in the mean onset of epileptiform activity between penicillin and 500 mg/kg carnosine pretreated groups. These findings indicate that carnosine has an anticonvulsant effect on penicillin-induced epilepsy in rats. Thus, our data support the hypothesis that carnosine may be a potential anticonvulsant drug for clinical therapy of epilepsy in the future.

Detailed spectral profile analysis of penicillin-induced epileptiform activity in anesthetized rats

Penicillin model is a widely used experimental model for epilepsy research. In the present study we aimed to portray a detailed spectral analysis of penicillin-induced epileptiform activity in comparison with basal brain activity in anesthetized Wistar rats. Male Wistar rats were anesthetized with i.p. urethane and connected to an electrocorticogram setup. After a short period of basal activity recording, epileptic focus was induced by injecting 400IU/2 microl penicillin-G potassium into the left lateral ventricle while the cortical activity was continuously recorded. Basal activity, latent period and the penicillin-induced epileptiform activity periods were then analyzed using both conventional methods and spectral analysis. Spectral analyses were conducted by dividing the whole spectrum into different frequency bands including delta, theta (slow and fast), alpha-sigma, beta (1 and 2) and gamma (1 and 2) bands. Our results show that the most affected frequency bands were delta, theta, beta-2 and gamma-2 bands during the epileptiform activity and there were marked differences in terms of spectral densities between three investigated episodes (basal activity, latent period and epileptiform activity). Our results may help to analyze novel data obtained using similar experimental models and the simple analysis method described here can be used in similar studies to investigate the basic neuronal mechanism of this or other types of experimental epilepsies.