The aim of our study was to test the hypothesis, that nicotine treatment (in dose of 1 mg/kg or 0.75 mg/kg respectively) can influence brain susceptibility to seizures in young immature rats. Experiments were performed on freely moving 12- and 25-day-old male Wistar rats. 15 minutes after nicotine i.p. administration, cortical afterdischarges (ADs) were elicited by six-time repeated stimulation of the right sensorimotor cortex. The duration of evoked ADs and the shape of evoked graphoelements were monitored. Administration of nicotine (both doses) resulted in significantly longer ADs duration in 12-day-old rats after the first stimulations compared to control group. There was a significant shortening after the 3^rd stimulation (higher nicotine dose), after the 4^th stimulation (lower nicotine dose), after the 5^th stimulation (both doses) and after the 6^th stimulation (lower dose of nicotine). Analysis of ADs duration in 25-day-old animals revealed the prolongation of ADs duration after the 2^nd stimulation (lower dose) and after the 3^rd stimulation (higher dose of nicotine). The results revealed that nicotine modulates brain excitability in age and dose dependent manner.

The work has been supported by grants: MSM 00216 208 16, GACR 305/09/P136 and GACR 309/09/0406.