Traditionally, lab models used to measure stress in animals have focused on males and failed to accurately reflect ways females respond to stress. There’s no established lab animal model for studying the effects of sexual violence and behavior on brain function in females, yet sexual aggression and violence is a problem for women in many places, including the United States. Worldwide, 30 percent of women have experienced physical or sexual assault by an intimate partner, according to the World Health Organization.
To observe what occurs in the female brain during and after sexual violence, Shors and her colleagues paired a pubescent rodent female daily for 30 minutes with a sexually experienced adult male. During the experiment, the male tracks the region around the anus and genitals of the female as she escapes from “pins.” A “pin” is when an adult male effectively restrains a female either by sitting on top of her or turning her over on her back and using his paws to hold her down. The researchers developed a research model they called Sexual Conspecific Aggressive Response to capture the females’ response.
The findings revealed concentrations of the stress hormone corticosterone were significantly elevated during and after the experience. Moreover, females who were exposed to the adult male during puberty did not perform well when it came to an associative learning task. Most of those who were exposed to the adult male did not learn to care for offspring over the course of 17 days. They expressed minimal maternal behaviors and had fewer newly-generated cells in their hippocampus, the brain’s center of emotion, memory, and the autonomic nervous system.
“This study is important because we need to understand how sexual aggression affects all species,” said Shors.