Selective affinity of 1-N-trifluoroethyl benzodiazepines for cerebellar type 1 receptor sites

In binding studies with rat brain membranes, 1,4-benzodiazepines containing a trifluoroethyl moeity at the 1-N position, including halazepam and quazepam, had significantly higher affinities for binding sites in cerebellum than in cortex. This selectivity for cerebellar sites is not a property of benzodiazepines without the trifluoroethyl moiety, but is similar to that seen with the triazolopyridazines. Since halazepam and quazepam, like the triazolopyridazines, have behavioral effects in animals at doses much lower than those that cause ataxia, it is tempting to attribute this separation of pharmacologic activities to differential activity at subpopulations of benzodiazepine receptors. Further work is necessary to clarify this possibility.