With approximately 1 in 10 American adults reporting some form of depression, finding new ways to treat the disorder has been a major focus for researchers. Now, investigators from the University of Texas Southwestern Medical Center say they have made important breakthroughs in this field.
The researchers, including Dr. Jeffrey Zigman, associate professor of internal medicine and psychiatry at UT Southwestern, say they have uncovered an important mechanism by which ghrelin - a natural antidepressant hormone - works inside the brain.
In addition, the team has uncovered a neuroprotective drug that they say has the potential to be a powerful treatment for depression.
To reach their findings, recently published in the journal Molecular Psychiatry, the researchers began by analyzing ghrelin in mice models. Ghrelin is referred to as the "hunger hormone," as it is known for its ability to arouse appetite.
In a 2008 study led by Dr. Zigman, the research team found that ghrelin had natural antidepressant properties that are prominent when its levels increase due to prolonged psychological stress or caloric restriction.
In this latest study, the researchers found that the hormone can trigger the formation of new neurons, known as neurogenesis, in the hippocampus - the brain region that regulates mood, memory and complex eating behaviors.
Furthermore, they found that this process is imperative to reduce the severity of depression after prolonged stress exposure.
P7C3 compounds boost neurogenesis
The team then wanted to determine whether this antidepressant effect could be enhanced with P7C3 compounds, which were discovered by another team of UT Southwestern researchers in 2010.
Previous studies have shown that P7C3 compounds have neuroprotective abilities in patients with Parkinson's disease, amyotrophic lateral sclerosis (ALS) and traumatic brain injury. And now, it seems the compounds could also help treat depression.
The team found that the P7C3 compounds enhanced the neurogenesis properties of ghrelin, leading to a strong antidepressant effect. Additionally, the team found that a "highly active analog" of the compounds - P7C3-A20 - boosted new neuron formation much more than antidepressant drugs that are currently available.
Dr. Zigman adds:
"By investigating the way the so-called 'hunger hormone' ghrelin works to limit the extent of depression following long-term exposure to stress, we discovered what could become a brand new class of antidepressant drugs."
The investigators say their findings suggest that the P7C3 compounds could prompt a good treatment response in people with depression linked to chronic stress, or those with altered ghrelin levels or ghrelin resistance - conditions that have been described in people with obesity or anorexia nervosa.
The team says that in future studies, they want to apply their findings to other forms of depression, as well as create clinical trials to determine whether P7C3 compounds have antidepressant effects for individuals with major depressive disorder.
Medical News Today recently reported on a study from the Icahn School of Medicine at Mount Sinai in New York, NY, which revealed how activating neurons that trigger depression could help treat the disorder.