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7. Bradford M. M. // Anal. Biochem. 1976. Vol. 72. P. 248254.

ANTICONVULSIVE ACTIVITY OF ETHANOL ON HOMOCYSTEINEINDUCED SEIZURES IN RATS A. Rai-Markovi, D. Hrni, H. Lonar-Stevanovi, O. Stanojlovi, D. Djuric Laboratory of Neurophysiology, Institute of Medical Physiology, School of Medicine, University of Belgrade, Serbia Homocysteine is a sulphur containing amino acid normally present in human plasma and its concentration ranges from 1 to 15mol/L. Deficiencies of either cystathionine -synthase or methylene tetrahydrofolate reductase can result in homocysteinuria and very severe hyperhomocysteinemia with plasma homocysteine concentrations up to 200 mol/L. Patients with severe hyperhomocysteinemia exhibit a wide range of clinical manifestations including neurological abnormalities such as mental retardation, cerebral atrophy, and seizures [1]. Numerous epidemiological studies have shown that hyperhomocysteinemia is related to coronary and cerebrovascular diseases [2]. It is not known whether neurological damage in these patients results from a direct action on neurons or is secondary to vascular changes [3].

Homocysteine is as one of the most potent excitatory agent of the central nervous system. Previous studies suggest that increased homocysteine levels may be related to epileptogenesis and/or suboptimal control of seizures in the patients with epilepsy [4,5].

Systemic administration of homocysteine or homocysteic acid can trigger seizures in animals [6] and patients whith homocystinuria suffer from epileptic seizures [7]. Homocysteine induces activation of both ionotropic [8] and group I metabotropic glutamate receptors (mGLURs) [9]. Homocysteine is as an excitatory amino acid and leads to an increase in glutamatergic neurotransmission and accompanying neurotoxicity and excitotoxicity.

The effects of ethanol on brain electrical activity are complex, and its effects are dependent on dose, tolerance and other factors. [10].

Chronic ethanol consumption has long been considered a major risk factor for epilepsy [11]. Most frequently, seizures occur during the withdrawal period [12]. On the other hand, acute intake of ethanol has an inhibitory effect on central nervous system and increase the threshold for its epileptic activity. [13]. There is growing evidence that chronic alcoholism is associated with derangement of the sulfur amino acid metabolism and increased plasma levels of homocysteine [14]. Ethanol may have either proconvulsive or anticonvulsive effects on epileptic activity in different experimental models of epilepsy [15].

Ethanol exerts its behavioral effects largely by inhibiting N-methyl-D aspartate (NMDA), mGluRs and L-type Ca2+ channels [16,17] while it stimulates -aminobutyric acid type A receptor (GABAA) [18].

The aim of this experiment was to examine the influence of ethanol on behavioral and EEG characteristics of homocysteine induced epilepsy in rats.

Materials and methods. Adult (2-months-old) male Wistar rats, weighing 180-230 g, obtained from the Military Medical Academy Breeding Laboratories, Belgrade, were used in experiments. The animals were kept under controlled environmental conditions during the experiments (ambient temperature 21 1oC, 50% humidity and a h light-dark cycle with lights switched on at 09:00 h). Rats were housed individually in transparent plastic cages (55 x 35 x 15 cm) with free access to standard laboratory animal chow and tap water.

All experimental procedures were in full compliance with The European Council Directive (86/609/EEC) and approved by The Ethical Committee of the University of Belgrade (298/5-2).

For the EEG recordings, rats were anaesthetized with nembuthal (100 mg/kg, i.p.), positioned in a stereotaxic apparatus and three gold plated recording electrodes were implanted over the frontal, parietal, and occipital cortices. Recovery period of 7 days after surgery was allowed.

Animals were divided into following groups: 1. Control (C, 0.9% NaCl, n = 8), 2. Homocysteine (H, D,L homocysteine thiolactone 8 mmol/kg, n = 7), 3 Ethanol (E, 2 g/kg, n = 8) and 4. Ethanol + homocysteine (EH, ethanol 2 g/kg 30 min prior to D, L homocysteine thiolactone 8 mmol/kg, n = 8). All the substances were applied intraperitoneally (i.p.). Each rat was used only once. D,L-homocysteine thiolactone (Sigma-Aldrich Chemical Co., U.S.A.) was dissolved in saline and after adjusting the pH to 7.0 was administred in a volume of 1 ml/100 g body weight.

During 90 min after homocysteine administration, seizure behavior was assesed by incidence of seizures, number of seizure episodes per rat and its intensity determined by a modified descriptive rating scale with grades defined as follow: 1 head nodding, lower jaw twitching;

2 myoclonic body jerks /hot plate reaction/, bilateral forelimb clonus with full rearing /Kangaroo position/;

3 progression to generalized clonic convulsions followed by tonic extension of fore- and hind limbs and tail;

4 prolonged severe tonic-clonic convulsions lasting for more than 10 sec (status epilepticus) or frequent repeated episodes of clonic convulsions for a extended period of time ( 5 min). In addition, latency to seizure, defined as a time from homocysteine injection to the first seizure response, was also recorded. For rats without seizures 90 min latency time was scored. Lethality was recorded after 90 min and 24 h after homocysteine administration.

EEG activity was recorded during experiments. An EEG apparatus (RIZ, Zagreb, Croatia) with a modified output enabling transfer of out put signals to the input circuit of an 8-channel, 12-byte analogue to digi tal card (PCL-711B;

Advantech Co.Ltd., Taiwan, ROC) installed into a computer and the corresponding software (Neurophysiology LaBG EEG) were used. Frequency range was defined by the time constant (0. sec, lower and upper limit frequencies of 0.5 and 100 Hz, respectively) and digitized at a sample rate of 512 Hz.

Significance of the differences between groups in the incidence of seizures and lethality was evaluated using Fishers exact probability test. Since the normal distribution of the data on seizure latency, number and intensity of seizure episodes has not been estimated by Kolmogo rov-Smirnov test, therefore the non-parametric analyses (Kruskal-Wallis ANOVA and Mann Whitney U-test) were used to determine the statistical significance of the differences between the groups (* p 0.05, ** p 0.01). These data were expressed as medians with 25th and 75th percentiles.

Results and discussion.

Seizure behavior. No behavioral signs of seizure activity were ob served in C and E groups. Seizure incidence in H group was 100% (7/7) and in EH 62.5% (5/8) (p 0.05, Fig 1).

Median latency to the first seizure episode in EH group [69 (48-90) min] was significantly longer comparing to H group [28 (2139) min] (p 0.01, Fig 2). Median number of seizure episodes per rat in EH group was 4 (1-5) and 2 (0-4) in H group (p 0.05, Fig 3).

In EH group the majority of seizure episodes (60 %) were scored with grade 1, while in H group 36% of the seizure episodes were scored with grade 2 and 20% with grade 4 (Figs 4 and 5).

Fig 1. Seizure incidence in homocysteine (H, D,L homocysteine thiolactone 8 mmol/ kg, n = 7) and ethanol + homocysteine (EH, ethanol 2 g/kg 30 min prior to D, L homocysteine thiolactone 8 mmol/kg, n = 8) group. Significance of the differences between the groups was analyzed by Fishers exact probability test Fig 2. Seizure latency (time from homocysteine administration to the first seizure episode) in experimental groups. Significance of the differences between the groups was estimated by Kruskal-Wallis ANOVA and Mann Whitney U test (** p 0.01). For details, see caption to Fig Fig 3. Number of seizure episodes per a rat in experimental groups. Significance of the differences between the groups was analyzed by Kruskal-Wallis ANOVA and Mann Whitney U test (** p 0.01) Fig 4. Intensity of seizure episodes in Fig 5. Seizure episode intensity grade experimental groups. Seizure episode distribution in experimental groups.

intensity was assessed by descriptive For details see caption to Fig 1 and rating scale with defined grades 1-4.

Significance of the differences between the groups was estimated by Kruskal Wallis ANOVA and Mann Whitney U test (**p0.01). For details, see caption to Fig Lethality after 90 min in EH group was 0% and it was different, but not statistically comparing to H group (42.85%, p 0.05). Lethality after 24h in EH group was 87.5% and 85.7% in H group (p 0.05, Fig 6).

Fig 6. Lethality in experimental groups recorded 90 min and 24h after homocysteine administration. Lethality number of exited rats out of a total number of rats expressed in percentage. For details, see caption to Fig 1. Significance of the differences between the groups was analyzed by Fishers exact probability test EEG analysis. There were no signs of epileptiform activity in EEG recorded in rats from C and E groups. Ethanol administration led to wave synchronization, decreased frequency and increased wave amplitude in EEG.

In EEG of rats from H and EH groups, isolated spikes and spike wave complexes were registered. Generalized bursts of synchronous high voltage spikes in EEG (Fig 7) were accompanied with behavioral seizures of maximal intensity (grades 3 and 4). However, EEG signs of epileptiform activity were not always accompanied with expected behavioral manifestations. Applied dose of ethanol did not suppress ictal activity induced by homocysteine.

In the present study, we investigated the effects of ethanol on behavioral and EEG characteristics of homocysteine-induced epilepsy in rats. Our results presented here demonstrated that ethanol decreased the incidence and the number of convulsive episodes in homocysteine induced epilepsy, but not significantly. Ethanol administration significantly increases latency to the first convulsive episode and decreases the intensity of convulsive episodes in EH group, in comparison with H group.

Fig 7. EEG tracings recorded in rat from EH group. LF RP left frontal right parietal LFO left frontal occipital cortex Time calibration 1s. Amplitude calibration 100 V Ethanol administration 30 min prior to homocysteine decreases lethality after 90 min, but not significantly, and does not affect lethality after 24 h. These results implicate the inhibitory effect of ethanol, which decreases hyperexcitability induced by homocysteine.

The brain may be particularly vulnerable to high blood levels of homocysteine because it lacks two major metabolic pathways for its elimination: betaine remethylation and transsulfuration [7]. The exact mechanism underlying neurotoxic effect of homocysteine is still far from being completely understood. There are several possible mechanisms whereby homocysteine damages and kills neurons. The various deleterious manifestations of hyperhomocysteinemia are due to overstimulation of NMDA and group I mGLURs receptors, oxidative stress, DNA damage and triggering of apoptosis. Clinical investigations and animal experiments have shown that there is a marked correlation between the occurrence of hyperhomocysteinaemia and alcoholism.

Plasma homocysteine concentration is dependent on the type of alcoholic beverage, the amount of alcohol consumed and the blood ethanol concentration [19]. Anticonvulsant effect of acute ethanol administration may be attributed to its ability to inhibit NMDA, non-NMDA-mediated excitatory responses and voltage-gated Ca2+ channels [20].

We have previously verified in our laboratory that 30 min after i.p.

injection of 2 g/kg of ethanol, the plasma ethanol concentration was 28.99 4.91 mmol/L (20). Our results corroborate with data from other studies showing that ethanol in concentrations between 5-50 mmol have an inhibitory action on NMDA responses [21]. On the other hand, Lovinger et al. [21] found that responses to kainite and quisqualte were affected only slightly by these concentrations. Little at al [22] have reported that doses of ethanol as low as 0.125-0.250 g/kg can induce both behavioral and electrophysiological changes. Doses of ethanol that caused depression of activity, increased synchronisation of the EEG, decreased frequency and increased mean voltage. In humans, 1g/kg ethanol increased EEG power in the theta and beta bands [23], but in rats, 0.75 g/kg ethanol decreased EEG power over all frequencies [24].

Our results show that ethanol in dose 2 g/kg act as an anticonvulsive but not as an antiepileptic agent on homocysteine induced seizures in rats.

Acknowledgement. -This work was supported by the Ministry of Science, Technology and Environment Protection of Serbia (Grants #145029B and #145014B).

References 1. Van den Berg M., van der Knaap M. S., Boers G. H. et al. // Neuroradiology. 1995. Vol. 37. P. 403411.

2. Djuric D., Jakovljevic V., Rasic-Markovic A. et al. // Indian J. Chest Dis. Allied Sci. 2008. Vol. 50. P. 3948.

3. Kruman I. I., Culmsee C., Chan S.L. et al. // J. Neurosci. 2000. Vol. 20. P. 69206926.

4. Mudd S. H., Skovby F., Levy H.L. et al. //. Am. J. Hum. Genet. 1985. 37. P. 131.

5. Schwarz S., Zhou G. Z. // Lancet. 1991. Vol. 337. P. 12261227.

6. Folbergov J., Haugvicov R., Mare P. // Exp. Neurol. 2000. Vol. 161. P. 336345.

7. Sachdev P. S. // Biol. Psychiatry. 2005. Vol. 29. P. 11521161.

8. Lipton S. A., Kim W. K., Choi Y. B. et al. // Proc. Natl. Acad. Sci. USA. 1997. Vol. 94. P. 59235928.

9. Lazarewicz J. W., Ziembowicz A., Matyja E. et al. // Neurochem. Res. 2003. Vol. 28. P. 259269.

10. Gordon E., Devinsky O. // Epilepsia. 2001. Vol. 42. P. 12661272.

11. Chan A. W. // Epilepsia. 1985. Vol. 26. P. 323333.

12. Hillbom M., Pieninkeroinen I., Leone M. //CNS Drugs. 2003. Vol. 17. P. 10131030.

13. Cohen S. M., Martin D., Morrisett R. A. // Brain Res. 1993. Vol. 601. P. 8087.

14. Bleich S., Degner D., Sperling W. et al. // Prog. Neuropsychopharmacol. Biol.

Psychiatry. 2004. Vol. 28. P. 453464.

15. Kozan R., Ayyildiz M., Yildirim M., Agar E. // Brain Res. Bull. 2006. Vol. 71. P. 111115.

16. Hoffman P. L., Rabe C. S., Moses F., Tabakoff B. // J. Neurochem. 1989. Vol. 52. P. 19371940.

17. Tabakoff B., Hoffman P. L. // Behav. Genet. 1993. Vol. 23. P. 231236.

18. Mihic S.J. // Neurochem. Int. 1999. Vol. 35. P. 115-123.

19. Bleich S., Degner D., Javaheripour K. et al. // J. Neural. Transm. 2000. Suppl. 60. P. 187-196.

20. Mladenovi D., Hrnci D., Radosavljevi T. et al. // Can. J. Physiol. Pharma col. 2008. Vol. 86. P. 148152.

21. Lovinger D. M., White G., Weight F. F. // Science. 1989. Vol. 243. P. 17211724.

22. Little H. J. // Pharmacol. Ther. 1999. Vol. 84. P. 333353.

23. Stenberg G., Sano M., Rosen I., Ingvar D. H. // J. Stud. Alcohol. 1994. Vol. 55. P. 645656.

24. Ehlers C. L., Chaplin R. I., Lumeng L., Li T. K. // Alcohol Clin. Exp. Res. 1992. Vol. 15. P. 739744.

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