Audiogenic seizures in the developmentally primed Long-Evans rat

The Long-Evans rat is a hybrid rodent strain with little innate susceptibility to audiogenic seizures (AGS). The present study examines parameters of acoustic priming (induced susceptibility) and testing for AGS during postnatal development subsequent to auditory function, and identifies the effects of stimulus intensity, repeated testing, and gender upon AGS activity. Rats were exposed to 125-dB SPL 10-kHz tone bursts at 14-36 days of age and tested with white noise at 14 or 19 days following sound exposure. All priming/testing combinations yielded AGS susceptibility; animals primed at 18 days showed the highest incidence of clonic seizures when tested 14 days later. All subjects displayed clonus at testing intensities of 120 dB, although some seizure behaviors could be elicited at 100 dB. Repeated testing at 120 dB increased latency to clonus and clonus duration, and total wild running activity. Gender differences for AGS expression were minimal. These results demonstrate the viability of the seizure-resistant Long-Evans rat for study of AGS.