Enhanced fear responses in mice treated with anabolic androgenic steroids

Abstract

Corticolimbic neurons express neurosteroid biosynthesis, which is altered during anabolic androgenic steroid (AAS) treatment. The brain circuits and neurons that underlie the behavioral deficits found after AAS treatment remain undefined. We studied the effects of testosterone propionate (testosterone) on fear conditioning responses and in primary output corticolimbic neurons on 5alpha-reductase-type-I and 3alpha-hydroxysteroid-dehydrogenase expression. Testosterone fails to change cued fear responses although it induces excessive contextual fear associated with corticolimbic 5alpha-reductase-type-I mRNA expression downregulation in the prefrontal cortex, hippocampus, and basolateral amygdala glutamatergic neurons. Increased fear responses are abolished by normalizing corticolimbic allopregnanolone levels with allopregnanolone treatment (8 micromol/kg) or selective brain steroidogenic stimulants, including S-norfluoxetine (1.8 micromol/kg). Agents that increase corticolimbic allopregnanolone levels may be beneficial in treating AAS users.