male friendships could provide positive health effects similar to those seen in romantic relationships, especially when dealing with stress, according to a new study of male rats by researchers at the University of California, Berkeley.

Human studies show that social interactions increase the level of the hormone oxytocin in the brain, and that oxytocin helps people bond and socialise more, increasing their resilience in the face of stress and leading to longer, healthier lives. Studies of male-female rat pairs and other rodents, such as monogamous prairie voles, confirm these findings.

The new study extends these studies to male rats housed in the same cage, and demonstrates that mild stress can actually make male rats more social and co-operative than they are in an unstressed environment, much as humans come together after non-life-threatening events, such as a national tragedy.

After a mild stress, the rats showed increased brain levels of oxytocin and its receptor, and huddled and touched more.

“A Bromance can be a good thing,” said lead author Elizabeth Kirby, who started work on the study while a doctoral student at UC Berkeley and continued it after assuming a postdoctoral fellowship at Stanford.

“Males are getting a bad rap when you look at animal models of social interactions, because they are assumed to be instinctively aggressive. But even rats can have a good cuddle – essentially a male-male bromance – to help recover from a bad day….These rats are using their rat friendships to recover from what would otherwise be a negative experience.”

The new study will be published in the journal Neuropsychopharmacology.

The research also has implications for post-traumatic stress disorder, said senior author Daniela Kaufer, a UC Berkeley associate professor of integrative biology. The work supports attempts to treat PTSD with oxytocin nasal sprays as a way to encourage social interactions that could lead to recovery.

“We think oxytocin, which is released after stress, is a way of bringing people closer in times of acute stress, which leads to more sharing, bonding and potentially better fear extinction and an increase in cognitive health,” said first author Sandra Muroy, a UC Berkeley graduate student.