Infidelity in male voles linked to uneven alcohol consumption

Male prairie voles that drink more alcohol than their partner are more likely to be unfaithful, mirroring behaviour found in humans, a recent study has revealed.

Image: UC Davis.

Heavy-drinking and teetotal rodents are not a match made in heaven, according to a study conducted by the Department of Behavioural Neuroscience at the Oregon Health and Science University in Portland.

Researchers conducting tests on the role of alcohol abuse in relationship breakdown have found that the behaviour of prairie voles mirrors that of humans.

Unusually for rodents, prairie voles have a taste for alcohol. Like humans, they form long-term, monogamous relationships which suffer when there is “discordant drinking” in the partnership.

In the experiment, male and female prairie voles were allowed to form a “pair bond” for one week. After this “cohabitation period”, the male voles were given access to 10% continuous ethanol while their female counterparts had access to either alcohol and water, or just water.

The male voles were then given a choice between huddling up beside their female partner, or beside a new female. The scientists then timed how long the male spent with each female and, using the Brown–Forsythe test to determine normality, they determined the ‘bond strength’ between the male and the original female.

When there was “discordant drinking” – in other words a discrepancy in alcohol consumption – the male voles expressed “a decrease in partner preference”. However, when both parties were drinking the same volumes of alcohol, males showed “no inhibition in partner preference”.

The study, which has been published in the journal Frontiers in Psychiatry, has demonstrated that changes found in a region of the brain known as the periaqueductal gray could hold the key to the alcohol-induced infidelity.

Scientists have said that these changes could indicate that alcohol-induced relationship breakdown could have “biological underpinnings”.

Alcohol abuse during a marriage has been associated with decreased marital satisfaction and an increase rate of divorce. According to the study, it has been shown that marital dissatisfaction and divorce rates increase when partners drink different amounts.

The scientists in charge of the study, Dr Andre T. Walcott and Dr Andrey E. Ryabinin, wrote: “We used male prairie voles to investigate the effects of discrepancies in alcohol intake on established pair bonds. We hypothesized that when there was a discrepancy in alcohol access between partners, the prairie voles would show a decrease in partner preference compared with voles that had a partner who was given access to alcohol.”

“Our results demonstrate that discordant, but not concordant, alcohol drinking leads to a decrease in partner preference in male prairie voles. Follow-up experiments testing effects of alcohol on immunoreactivity of oxytocin, arginine vasopressin (AVP), and FosB suggest that the effect of discrepant drinking may involve activation of the periaqueductal gray (PAG). To the best of our knowledge, this is the first demonstration of alcohol’s effects on pair-bond maintenance and the first investigation of neurocircuits that might mediate this effect”.

“We know that in humans, heavy drinking is associated with increased separation rates in couples, in which one of the partners is a heavy drinker and the other is not,” said Dr Andrey Ryabinin.

“We will need to do further work to confirm this for humans. In future studies, we might be able to find strategies to overcome the negative effects of alcohol, to improve relationships that are disrupted by problematic drinking”.