[Effects of pentylenetetrazol on conflict behavior and interactions with anxiolytics in rats]

Effects of pentylenetetrazol (PTZ) on conflict behavior were studied using a punished water-lick (conflict) paradigm in rats. PTZ (5-20 mg/kg, ip) produced a dose-related enhancement of conflict behavior as demonstrated by a suppression of lick responding in low shock intensity (1.3-2.0 mA). Furthermore, PTZ (2-20 mg/kg, ip) clearly antagonized the release of punished responding induced by diazepam (5 mg/kg, ip), chlordiazepoxide (10 mg/kg i.p.) or meprobamate (75 mg/kg, ip) when a high intensity of shock (2.5 or 3 mA) was used. Bemegride also showed a similar suppressive effect on the anticonflict action of diazepam. However, bicuculline, picrotoxin or strychnine neither enhanced conflict behavior nor inhibited the anticonflict action of diazepam, even in high doses. In addition, PTZ (10 or 20 mg/kg, ip) did not show any significant effect on unpunished drinking or flinch-jump threshold, suggesting that the conflict enhancing action of PTZ may not be due to the secondary action including decrease in drive for drinking or increase in sensitivity to shock. These results suggest that PTZ may exert facilitation of conflict behavior or suppression of the anticonflict action of anxiolytics via an activation of the conflict generating mechanisms.