Scientists have managed to breed a permanently happy mouse.
The new breed of rodent has been bred without the gene (TREK-1) that obstructs the pathway of the happy drug serotonin in the brain.
This means that the happy mouse – or 'knock-out' mouse - is effectively depression-resistant, which the researchers are hoping will assist in providing new hope for the treatment of clinical depression.
"Depression is a devastating illness, which affects around ten per cent of people at some point in their life," said the study's principal author Dr Guy Debonnel.
"Current medications for clinical depression are ineffective for a third of patients, which is why the development of alternative treatments is so important."
"The discovery of a link between TREK-1 and depression could ultimately lead to the development of a new generation of anti-depressant drugs," he added.
The study was a collaboration between scientists from the Universities of McGill in Canada and Nice in France. The paper is published in the journal Nature Neuroscience.