Résumé
To compare the anxiolytic effects of reduced metabolite of progesterone and benzodiazepine.Methods The effects of allopregnanolone and diazepam on spontaneous locomotor activity and on exploration in the elevated plus-maze were studied in C57 mice 20 min after vehicle or drug intraperitoneal administration.Results Allopregnanolone (0.1 mg.kg-1,ip) elicited marked anxiolytic effects in terms of significantly reducing the latency to enter the open arm from (31.30±8.39)s to (8.80±6.00)s,(P<0.001),and significantly increasing both the number of open arm entries from 1.20 ± 0.42 to 4.80 ±1.75,(P<0.001) and the proportion of total time spent on the open arm from 7.13％ to 32.50％,(P<0.001).Meanwhile,the diazepam (0.25 mg·kg-1) produced a lower anxiolytic effect comparing to that of the allopregnanolone.Analysis of spontaneous locomotor activity showed while 0.5 mg·kg-1 of diazepam decreased the locomotor activity (P<0.01),neither 0.1 mg·kg-1 of allopregnanolone nor 0.25 mg·kg-1 of diazepam affect the locomotor activity score.Conclusion Together,these results provide evidence for differential behavioral actions of the neurosteroids and benzodiazepines.Since the allopregnanolone produce a selective anxiolytic effect without affecting the spontaneous locomotor activity,the allopregnanolone may be a better alternative for diazepam in treating anxiety.