Researchers have pinpointed a mechanism in the brains of mice that could explain why some human mothers become depressed following childbirth. The discovery could lead to improved treatment for postpartum depression.
Supported in part by the National Institute of Mental Health (NIMH), part of the National Institutes of Health, the study used genetically engineered mice lacking a protein critical for adapting to the sex hormone fluctuations of pregnancy and the postpartum period.
"For the first time, we may have a highly useful model of postpartum depression," said NIMH Director Thomas R. Insel, M.D. "The new research also points to a specific potential new target in the brain for medications to treat this disorder that affects 15 percent of women after they give birth."
"After giving birth, female mice deficient in the suspect protein showed depression-like behaviors and neglected their newborn pups," explained Istvan Mody, Ph.D., of the University of California at Los Angeles (UCLA), who led the research. "Giving a drug that restored the protein's function improved maternal behavior and reduced pup mortality."
Mody and Jamie Maguire, Ph.D., UCLA, report on their findings in the July 31, 2008 issue of Neuron.
Researchers had suspected that postpartum depression stemmed from the marked fluctuations in the reproductive hormones estrogen and progesterone that accompany pregnancy and childbirth. Yet manipulating the hormones experimentally triggers depression only in women with a history of the disorder. The roots of their vulnerability remain a mystery.
Evidence suggested that the hormones exert their effects on mood through the brain's major inhibitory chemical messenger system, called GABA, which dampens neural activity, helping to regulate when a neuron fires.