Effects of pentylenetetrazol on conflict behavior and interaction with anxiolytics in rats

Abstract

Effects of pentylenetetrazol (PTZ) on conflict behavior were studied using a punished water-lick (conflict) paradigm in rats. PTZ (5-20 mg/kg i.p.) produced a dose-related enhancement of conflict behavior as demonstrated by a suppression of lick responding in low shock intensity (1.3-2 itiA). Furthermore, PTZ (2-20 mg/kg i.p.) markedly antagonized the release of punished responding induced by diazepam (5 mg/kg i.p.), chlordiazepoxide (10 mg/kg i.p.) or meprobamate (75 mg/kg i.p.) when a high intensity of shock (2.5-3 mA) was used. Bemegride also showed a similar suppressive effect on the anticonflict action of diazepam in low doses. 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 i.p.) did not alter unpunished drinking or flinch-μMp thresholds, 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 activation of the conflict generating mechanisms. A mechanism underlying an induction of convulsion or a GABAergic mechanism may not be involved in the conflict enhancing action of PTZ.