Anywhere from 8 to 19 percent of women report having frequent postpartum depressive symptoms, according to the Centers for Disease Control and Prevention (CDC). Many of these mothers who seek medical care are treated with conventional antidepressants, but little is known about the diagnosis itself. Now, scientists have developed an animal model to study postpartum depression and how to treat it.

“Lots of women get depressed, lots end up taking these antidepressants, but surprisingly not a lot is known about what actually causes postpartum depression and because of that, we don’t really know the best way to treat it,” Benedetta Leuner, senior study author and assistant professor of psychology and neuroscience at Ohio State University, told FoxNews.com.

Leuner said past biomedical research has largely ignored studying women, but things are turning around now and more work will be done studying the different stages of women’s lives, such as puberty, post-partum and menopause.

For their study, scientists induced depressive-like symptoms in rats by subjecting them to chronic stress during the last two weeks of their pregnancy. A rat’s gestation period is only three weeks. Chronic stress is a major risk factor for the development of postpartum depression.

During the postpartum period, the rats were studied for indicators of depression, including drinking less sugar water and floating rather than swimming in a swim test. They were also studied for anhedonia, the inability to experience pleasure.

In addition to depressive symptoms, the subjects also showed impaired maternal behavior, just as mothers with postpartum depression do.

“Our model recapitulates a lot of what is seen in the human condition,” Leuner said.

Researchers also focused on the brain’s nucleus accumbens, the region that regulates feelings or reward and motivation. They found that the rats that were stressed in pregnancy had far fewer connections in the neurons of nucleus accumbens and prefrontal cortext than unstressed animals. Previous studies have shown that humans show a similar response when depressed.

When subjects were given the antidepressant Citolopram, a selective serotonin reuptake inhibitor (SSRI) commonly prescribed to women with postpartum depression, the connections were restored, as well as their moods. They also no longer exhibited depressive-like behavior.

“We’ve established the model, seen [the] brain changes, and now moving forward this will be the model we use to further understand what’s happening in the brain and how we can change those behaviors that are typical postpartum depression,” Leuner said.

One effect of postpartum depression that is not addressed by antidepressant medication is poor maternal care.

“What’s interesting is that while mood improves, many times other symptoms don’t improve; [patients] exhibit impaired caregiving procedures that don’t improve with antidepressant treatment,” Leuner said.

“It can be pretty devastating for the development of the child, and of course there are variations in severity of the disorder,” she said, noting short-term effects include impaired physical growth and long-term effects include slowed cognitive and social development. Children are more susceptible to depression in adulthood as well.

Moving forward, scientists plan to use the model to study the effects of stress on brain systems and neurochemicals known to be important for regulating maternal behavior.

“It’s important to treat the mother, making her feel better, and also in doing so potentially preventing some of those devastating effects that then can be transferred to the child,” Leuner said.