Lamotrigine does not impair motor performance and spontaneous behavior in developing rats

Effects of neonatal antiepileptic drug exposure on cognitive, emotional, and motor function in adult rats

Despite the potent proapoptotic effect of several antiepileptic drugs (AEDs) in developmental rodent models, little is known about the long-term impact of exposure during brain development. Clinically, this is of growing concern. To determine the behavioral consequences of such exposure, we examined phenobarbital, phenytoin, and lamotrigine for their effects on adult behaviors after administration to neonatal rats throughout the second postnatal week. AED treatment from postnatal days 7 to 13 resulted in adult deficits in spatial learning in the Morris water maze and decreased social exploration for all drugs tested. Phenobarbital exposure led to deficits in cued fear conditioning, risk assessment in the elevated plus maze, and sensorimotor gating as measured by prepulse inhibition, but it did not affect motor coordination on the rotorod task. In contrast, phenytoin and lamotrigine exposure led to impaired rotorod performance, but no deficits in sensorimotor gating. Phenytoin, but not lamotrigine or phenobarbital, increased exploration in the open field. Phenytoin and phenobarbital, but not lamotrigine, disrupted cued fear conditioning. These results indicate that AED administration during a limited sensitive postnatal period is sufficient to cause a range of behavioral deficits later in life, and the specific profile of behavioral deficits varies across drugs. The differences in the long-term outcomes associated with the three AEDs examined are not predicted by either the mechanism of AED action or the proapoptotic effect of the drugs. Our findings suggest that a history of AED therapy during development must be considered as a variable when assessing later-life cognitive and psychiatric outcomes.

Involvement of oxidative stress in seizures induced by diphenyl diselenide in rat pups

In the present study the potential neurotoxicity of diphenyl diselenide, as measured by the manifestation of seizures in rat pups (postnatal days, PND, 12-14) was evaluated. The results suggest that the latency for the appearance of tonic-clonic seizures, characterized by rearing and falling of rat pups body, was dependent of the dose tested. Diphenyl diselenide at high doses induced seizure episodes in rat pups. The highest dose of diphenyl diselenide (500 mg/kg) increased the levels of lipid peroxidation and catalase activity as well as decreased delta-ALA-D (delta-aminolevulinate dehydratase) and Na(+), K(+) ATPase activity in the brain of rat pups. Our results indicate the possible involvement of free radical oxygen injury in diphenyl diselenide-induced seizures. The data obtained with the dose of 150 mg/kg in the brain of rats that exhibited seizures are: an increase in lipid peroxidation levels; the lack of effect on catalase activity; an inhibition of delta-ALA-D activity, supporting that the enzyme activity is more sensitive than other parameters analyzed as an indicator of oxidative stress. The lowest dose of diphenyl diselenide emphasizes the relationship between the appearance of seizures and the latency for the onset of the first episode. Taken together, this paper could add to our understanding of diphenyl diselenide neurotoxic effect demonstrated by the appearance of seizures which are, at least in part, related to the oxidative stress.

Motor performance and behavior of immature rats are not compromised by a high dose of topiramate

The first step in a study of possible cognitive side effects of topiramate in immature rats is to determine if and how topiramate (TPM) influences motor ability and spontaneous behavior. We therefore studied the effects of TPM on motor performance of 12- and 25-day-old rats using age-appropriate tests. Spontaneous behavior in the open field was studied in 25-day-old animals only. TPM was administered intraperitoneally at 80 and/or 160 mg/kg; control rats were injected with solvent (dimethylsulfoxide). A battery of motor tests was conducted before and 1, 3, and 24 hours after administration; behavior in the open field was recorded 2 and 24 hours after TPM administration. The effects of TPM on motor performance were similar to those of solvent. A few differences were found only at the 3-hour interval in 12-day-old rats. Behavior in the open field was not impaired by TPM; on the contrary, an apparent anxiolytic effect was observed. Habituation (a decrease in locomotor activity during the 5-minute observation period), a form of simple nonassociative learning, was also not compromised by TPM. A single high dose of TPM resulted only in transient changes in motor performance. A possible anxiolytic effect observed in 25-day-old rats should be studied.