Abstract

Women are twice as likely to be diagnosed with an anxiety disorder compared to men. Noradrenaline (NE) is a major brain stress signal that is made by the locus coeruleus (LC). LC neurons innervate many structures, including the medial prefrontal cortex (mPFC) which is involved in stress and arousal. The female LC is larger and contains more NE-containing neurons. However, it is not known if these additional neurons result in a larger LC to mPFC circuit in females, or whether these sex differences in LC structure lead to differences in brain-wide NE function. Here we increased brain NE levels in male and female mice using the drug atipamezole to indirectly assess how NE may alter anxiety-like behavior function differently across sexes. We also assessed the size of the LC to mPFC circuit in mice of both sexes using retrograde injections of a fluorescent tracer.