Role of amygdaloid nuclei in the anxiolytic effects of benzodiazepines in rats

Previous work has implicated the amygdala, especially the central and basolateral nuclei, in the anxiolytic effects of benzodiazepines in animal models of anxiety. However there are contradictory findings on the relative importance of each nucleus. The experiments reported here show that midazolam (1.0µg) injected bilaterally into the basolateral nucleus significantly increased open arm activity on the elevated plus-maze. In contrast midazolam (1.0µg) had no effect when injected into the central nucleus. These results suggest that the basolateral nucleus is one substrate mediating anxiolytic effects. However, a brief review of the literature supports the suggestion that both nuclei can be involved, but findings will depend upon the particular paradigm used.