aroCre mice express Cre recombinase under the direction of the Cyp19a1 (cytochrome P450, family 19, subfamily a, polypeptide 1) gene. The presence of cre does not affect the expression of Cyp19a1. CYP19A1 encodes aromatase, an enzyme responsible for the aromatization of androgens into estrogens in the brain. Aromatase is expressed in the posterodorsal medial amygdala of the male brain where it controls neural circuits underlying courtship vocalization, mating, aggression, and territory marking in male mice. Brains of female mice contain lower levels of aromatase. Homozygous mice are viable and fertile. When these mice are bred with mice containing loxP-flanked sequence, Cre-mediated recombination will result in deletion of the floxed sequences in the Cre-expressing cells of the offspring.
Injection of an adeno-associated virus (AAV) encoding Cre-dependent caspase-3 into mice carrying this aroCre and one copy of a aro- allele triggers apoptosis exclusively in aromatase+ cells. Males show no changes in courtship or mating habits, but do show increased aggression towards other males. Females display increased maternal aggression towards intruders.
When injected with cre-dependent DREADD-Gi:mCherry, which inhibits GABAergic neurons, mice show increased latency of attack on other males.
