A drug commonly used to treat severe acne can lead to depressive behaviour in mice, according to research published in the journal Neuropsychopharmacology.
Since the drug's introduction in the early 1980s there have been controversial reports of depression and suicidal behaviour that may have occurred in some people taking Roaccutane.
This has led to the drug's manufacturers, Roche, including a warning in the product information that taking the medication may cause depression, psychosis and suicidal behaviour.
However, the chemical mechanism by which this might happen has never been established.
In new independent research, scientists at the universities of Bath and Texas at Austin gave Roaccutane to mice over a period of six weeks, and then monitored the rodents' behaviour.
They found that whilst there was no change in the physical abilities of the mice, the rodents spent significantly more time immobile in a range of laboratory assessments designed to test their stress responsiveness - suggesting that administration of Roaccutane increases depression-related behaviour in mice.
"Without more research it is difficult to say for sure whether the same link applies to people taking the drug," said Dr Sarah Bailey from the Department of Pharmacy and Pharmacology at the University of Bath.
"However, establishing a link between the active molecules within the drug and a change in depression-related behaviour, albeit in mice, is an important step forward in our understanding of the effects of this drug in the wider context of brain function.
"To date the only evidence for any link with patients has come from individual case reports and such patient data is complicated by the psychosocial effects of having severe acne.
"This laboratory evidence provides a useful model for future research into Roaccutane and understanding how this family of compounds affects the brain."