[A decreased frequency of peeking out from the dark compartment--the only constant index of the effect of anxiogens on the behavior of mice in a "light-darkness" chamber].

Special measurements of the effects of anxiolytics and anxiogens on the commonly used parameters of behavior of mice in a dark-light chamber (the rate of transitions and time spent in a dark and light compartments) demonstrated their low reproducibility in consecutive experiments. Therefore, these indices are not reliable (Lapin, 1992). One more parameter was tested in the present study. A decrease in the rate of leanings out of the dark compartment appeared to be a constant effect of standard anxiety-inducing drugs: caffeine, pentylenetetrazole, yohimbine, and a putative endogenous anxiogen phenylethylamine. Increase in the rate of leanings out, like increase in the rate of transitions and shortening of the time spent in a dark compartment produced by anxiolytics diazepam, chlordiazepoxide, hydroxyzine, phenibut and baclofen were not significant in the majority of experiments. That is why these effects of anxiolytics are not reliable for measuring the activity of anxiolytics in a dark-light chamber.