The effect of N-methyl-D-aspartate receptor antagonists on D,L-homocysteine thiolactone induced seizures in adult rats

The aim of our study was to investigate the effects of ifenprodil and MK-801 on D, L-homocysteine thiolactone induced seizures in adult rats. Male Wistar rats were divided into following groups: 1. Saline-treated (C, n=10); 2. D, L-homocysteine thiolactone 8 mmol/kg, i.p. (H, n=7); 3. Ifenprodil 20 mg/kg i.p. (IF, n=8); 4. MK-801 0.5 mg/kg, i.p. (MK, n=8) and 5. Groups that received IF or MK 30 minutes prior to H (IFH, n=8 and MKH, n=8). Seizure behavior was assessed by incidence, latency, number and intensity of seizure episodes. Seizure severity was described by a descriptive scale with grades 0-4. Lethality in experimental group was recorded 90 min and 24 h upon D, L-homocysteine thiolactone administration. There were no behavioral signs of seizure activity in groups C, IF and MK. Pre-treatment with MK-801 (MKH) showed tendency to reduced incidence of convulsions, latency to the first seizure onset and the severity of seizure episodes, but statistical significance was not attained comparing to the H group. However, median number of seizure episodes was significantly decreased in MKH (p < 0.05), comparing to the H group. On the other hand, ifenprodil (IFH) decreased the latency to the first seizure onset and increased the median number of seizure episodes (p < 0.05). The majority of seizure episodes in IFH (72.1%, p < 0.05) and MKH (73.1%, p < 0.05) groups was grade 2 and significantly different comparing to the H (36.0%). Our findings suggest that MK-801 has a mild anticonvulsive effect on D, L-homocysteine thiolactone induced seizures in adult rats.