Effects of maturation and priming on audiogenic seizure thresholds in mice

The rise and fall of audiogenic seizure vulnerability were followed in three lines of mice selected for brain/body weight ratio and in the heterogeneous stock from which they were derived. Over a period of 12 to 24 days, susceptibility increased and then declined. Subjects retested after a 2-day interval were more susceptible, but this priming effect declined steadily. Differences in seizure threshold varied unsystematically among the lines. No sex differences in susceptibility were found. Mice who seized were heavier on the average than nonseizers of the same age and line. It is proposed that mice with a slower development rate are less susceptible to the stimulus used to evoke seizures. If so, rapid development may tend to lower the threshold of audiogenic seizures in mice.