The animals displayed "depressive behaviors," Young said. "They become more passive, more likely to give up."
When researchers killed the voles and looked inside their brains, they found elevated levels of CRF, which is known to have a role in depression.
A control group of 10 male voles that had been separated from a male sibling displayed no depressive behaviors or increases in CRF, researchers said, indicating there was something special about monogamous bonds.
Voles that received a drug that blocked CRF behaved normally when separated from their female mates, according to the study, which was funded by the National Institutes of Health, and other research organizations and foundations.
Several pharmaceutical companies are developing drugs that act on CRF as treatments for depression and anxiety-related disorders.
In some cases, researchers said, the pain of separation can serve a useful purpose. Young said uneasy feelings that come with separation may keep males close to their nests, where they can protect offspring from predators, for example.
C. Sue Carter, a professor of psychiatry at the University of Illinois at Chicago who works with voles, cautioned against anthropomorphizing the animals, adding there is more than one way to interpret their behavior.
"What humans call depression might be an adaptive strategy," she said. The passive voles might simply be conserving their energy for more important things, she suggested, such as searching for a new mate.
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denise.gellene@latimes.com
