EFFECT OF THE NEUROACTIVE STEROID ALPHA-THDOC ON STAIRCASE TEST BEHAVIOR IN MICE

This study examined the effect of the neuroactive steroid 3 alpha, 5 a lpha-tetrahydrodeoxycorticosterone (alpha-THDOC) as compared to the be nzodiazepines diazepam and midazolam and the barbiturate phenobarbital on the number of rearing events and the number of steps ascended in t he mouse staircase test. The benzodiazepines, phenobarbital and alpha- THDOC all reduced rearing activity at doses that did not affect climbi ng. The rearing-suppression effect of the benzodiazepines and alpha-TH DOC, but not of phenobarbital, was blocked by the benzodiazepine antag onist flumazenil. It appears that, although such neuroactive steroids, like barbiturates, bind to distinct sites within the chloride ion cha nnel of the gamma-aminobutyric acid type A (GABA(A)) receptor complex, alpha-THDOC behavioral activity is modulated by the benzodiazepine re cognition site.