THE EFFECTS OF CONVULSANT AND ANTICONVULSANT TREATMENTS ON THE BEHAVIORAL-EFFECTS OF ULTRASOUND PRESENTATION IN LISTER HOODED RATS

Lister hooded rats exhibit bursts of locomotion when exposed to a 20 k Hz acoustic stimulus; this ultrasound-induced locomotion has been sugg ested as a potential model for panic attacks. The present studies dete rmined the effects of treatment with the convulsant agents strychnine and pentylenetetrazole and the anticonvulsant agents pentobarbital and ethosuximide on locomotor behaviour elicited by experimenter-presente d ultrasounds in Lister hooded rats. Behaviour in a circular arena was viewed live and tracked electronically. In Experiment 1, brief exposu re to an ultrasound stimulus typically resulted in short intensity-rel ated bursts of locomotion in control rats. Pentobarbital or ethosuximi de treatment reduced this short-term ultrasound-induced locomotion in a dose-related manner, whereas pentylenetetrazole or strychnine treatm ent increased these locomotor bursts. In Experiment 2, exposure to the ultrasound stimulus for a longer period resulted in irregular cycles of bursts of locomotion followed by periods of relative inactivity in control rats. In addition, approximately 10% of control rats exhibited convulsions associated with this long-duration ultrasound exposure at 98 dB sound pressure level. Sub-convulsant doses of the convulsant tr eatments increased the frequency of occurrence of convulsions associat ed with the ultrasound stimulus; pentobarbital or ethosuximide pretrea tment significantly reduced this effect. The present findings suggest that a relationship exists between ultrasound-induced locomotor bursts and convulsant activity. (C) 1998 Rapid Science Ltd.