A type of love hormone called Oxytocin, which is important in the regulation of social and maternal behavior, is also found helpful in treatment for many mental health disorders including postpartum depression. 

The oxytocin receptor cells are present in the brain area and are thought to be involved in the regulation of maternal behavior. Moreover, the expression of oxytocin receptors in these cells are only present when estrogen is also present. This implies that these cells are involved in inducing maternal behavior. In addition, it confirms what many recent human studies have shown: there is a connection between altered expression of oxytocin receptors and postpartum depression. 

"Many researchers have attempted to investigate the difference between the oxytocin system in females versus males, but no one has successfully found conclusive evidence until now. Our discovery was a big surprise," said Ryoichi Teruyama, LSU Department of Biological Sciences associate professor and lead researcher of the study published in the journal 'PLOS ONE'. 

Postpartum depression contributes to poor maternal health and has negative effects on a child's development. A number of studies have found that children of depressed mothers are at risk for a wide range of cognitive, emotional, behavioral and medical problems. Therefore, postpartum depression is a major public health concern that has significant adverse effects on both mother and child. About 10 to 20 percent of women experience postpartum depression after childbirth. 

This new discovery opens doors to potential new treatments and drugs for postpartum depression targeting oxytocin receptor cells. "I think our discovery could be universal to all mammals that exhibit maternal behavior, including humans," Teruyama said.