An immune response in the brain of stressed mothers may help explain cases of postnatal depression, a study suggests.
New findings from animal studies have linked postnatal depression to inflammation in mood-regulating areas of the brain.
The scientists believe that the results could help them to solve the mystery of the stressful condition, which is poorly understood.
An estimated 15% of new mothers suffer from postnatal depression postnatal depression – also known as postpartum depression.
Postnatal depression can prevent a mother from bonding with her baby, causing feelings of overwhelming fatigue and helplessness.
Dr. Benedetta Leuner of Ohio State University, USA, who led the new study, said: "Understanding the factors that contribute to this serious and widespread disease will be the key to finding ways to treat women like that to fight better. "
The research focused on the medial prefrontal cortex, an mood-regulating brain region previously associated with postnatal depression.
Rats were first stressed during pregnancy to mimic a known risk factor for the disease.
After birth, the animals showed clear signs of depression similar to those of humans, including reduced attention to their puppies.
The scientists found that the stressed rats had more inflammatory biomarkers in their brains than their non-stressed companions.
There was also evidence that stress is related to changes in the function of brain immune cells called microglia.
Co-author dr. Kathryn Lenz, also from Ohio State, said, "It was particularly interesting that we did not find any signs of increased inflammation in the blood, but we found it in this part of the brain that is important for mood regulation.
"We are really excited because this suggests that inflammation in the brain can potentially contribute to postpartum depression."
The findings were presented at the annual meeting of the Society for Neuroscience in San Diego.– Press Association