The anxiolytic effects of intra-hippocampal midazolam are antagonized by intra-septal L-glutamate.

According to Gray [The Neuropsychology of Anxiety: An Enquiry into the Functions of the Septo-hippocampal System, Oxford University Press, New York, 1982], the hippocampus and the septum act in concert to control anxiety. We found that micro-infusion of midazolam into the dorsal hippocampus increased rats' open-arm exploration in the elevated plus-maze. Co-infusion of L-glutamate into the septum suppressed this anxiolytic effect. However, intra-hippocampal midazolam failed to alter rats' burying behavior in the shock-probe test. These findings suggest that the hippocampus and septum work together to regulate rats' behaviors in some (plus-maze) but not all (burying) animal tests of anxiety.