New trigger for several mood disorders discovered, opening the door to faster-acting meds

Researchers have identified a new trigger for several mood disorders, potentially paving the way for new, faster-acting treatments.

Glycine, a common amino acid and major neurotransmitter, has the ability to transport a “slow down” signal to the brain that likely plays a role in several mood disorders including major depressive order, according to a study published March 30 in Science. Years of research at the Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology led to understanding the process behind this, Kirill Martemyanov, Ph.D., corresponding author of the study and chair of the neuroscience department at the institute, said in a March 30 release.

Martemyanov’s team set out to discover how sensors on brain cells send and receive signals to cells, a process vital to understanding vision, pain, memory and behavior. Amid this work, the team unearthed a new glycine receptor that was involved in stress-induced depression. Mice without the gene for the receptor—which the team initially dubbed GPR158—were more resilient to chronic stress than mice with it.

As the team investigated further, they found the GPR158 receptor looked like a small clamp with a compartment inside, a structure more often seen in bacteria instead of human cells. “We were barking up the completely wrong tree before we saw the structure," Martemyanov said in a release.

“We said, 'Wow, that’s an amino acid receptor.' There are only 20, so we screened them right away and only one fit perfectly. That was it. It was glycine.”

The team figured out when the molecule binds to glycine, it actually acts as an inhibitor. Because of this, they renamed it “mGlyR,” short for “metabotropic glycine receptor.”

The scientists found that glycine, but not a related modulator called taurine, acts through mGlyR to regulate neuronal excitability in the cortex. This means the team identified a major system involved in mediating metabotropic effects of glycine, which contributes to cognition and emotions.

The new research adds to prior understanding of the biological causes of mood disorders and could have significant implications for patients, especially as major depression cases have surged over the last few years. Most depression medications take at least several weeks to kick in, and the possibility of a faster-acting medication could be life-changing for some.