Mystery Gene Glo1 Reveals Novel Anxiety Mechanism via Methylglyoxal and GABA-A Receptors
Key Insights
Researchers at the University of Chicago demonstrated that the Glo1 (search) gene causally influences anxiety-like behavior through copy number variants, with more copies producing greater anxiety in mice.
The study uncovered that methylglyoxal (MG), a metabolic byproduct lowered by Glo1 (search), rapidly reduces anxiety by directly activating GABA-A receptors on neurons — a previously unknown inhibitory mechanism.
A small molecule Glo1 (search) inhibitor developed at the Beckman Research Institute successfully reduced anxiety-like symptoms in mice, suggesting a new therapeutic strategy distinct from traditional benzodiazepines.
A long-debated gene has now been causally linked to anxiety, and the mechanism behind it reveals an entirely new inhibitory pathway in the brain — one that could reshape how anxiety disorders, epilepsy, and sleep disorders are treated.
Researchers at the University of Chicago Medicine (search) have demonstrated that the gene Glo1 (search), encoding the metabolic enzyme glyoxylase 1, directly influences anxiety-like behavior through copy number variants. Animals with more copies of the gene exhibited greater anxiety, and the team traced the effect to a metabolic byproduct called methylglyoxal (MG), which acts as a previously unknown activator of GABA-A receptors on neurons.
The findings, published in the Journal of Clinical Investigation, resolve years of controversy surrounding Glo1 (search) while uncovering what senior author Abraham Palmer, PhD, assistant professor of human genetics, describes as "fundamental new physiology that nobody had appreciated or put together before."
From Genetic Correlation to Causation
The story began in 2005, when a comparison of different mouse strains identified a link between anxiety-like behaviors and Glo1 (search). However, the absence of an obvious connection between glyoxylase 1 and brain function led many scientists to question the association.
"When people discover a gene, they're always most comfortable when they discover something they already knew," Palmer said. "The alarming thing here was there was a discovery of something that nobody knew, and therefore it seemed less likely to actually be correct."
A 2009 study from Palmer's laboratory suggested that differences in Glo1 (search) expression between mouse strains stemmed from copy number variants — segments of the genome containing the gene repeated multiple times. To test this hypothesis directly, lead author Margaret Distler, an MD/PhD student in the Pritzker School of Medicine's Medical Scientist Training Program, inserted two, eight, or ten copies of the Glo1 gene into mouse lines and assessed anxiety behavior using the open field test.
The results confirmed causation: mice with more copies of Glo1 (search) displayed higher anxiety-like behavior.
"It's the first study to show that it's the copy number variant that has the potential to change Glo1 (search) expression and behavior," Distler said. "Our study was a physiological representation of what it means to increase Glo1 expression for anxiety."
Methylglyoxal: A Rapid-Acting Inhibitory Signal
The primary function of glyoxylase 1 is to metabolize and lower cellular levels of methylglyoxal, a waste product of glycolysis. To test whether MG itself could influence behavior, Distler injected MG directly to raise its levels in the brain. The effect was strikingly fast.
"Methylglyoxal changed behavior within 10 minutes of administration, which means it's a rapid onset. It's not changing gene expression, and it's not having long-term downstream effects," Distler said. "That was our first breakthrough."
The short time course suggested a direct effect on neuronal activity. MG also produced sedative effects at high doses — a hallmark of drugs that activate inhibitory GABA receptors. In collaboration with Leigh Plant, now at Brandeis University, the team demonstrated that MG activates GABA-A receptors on neurons, establishing a previously unknown inhibitory mechanism.
"It's a completely different system that is tying neuronal inhibitory tone into metabolic activity," Palmer said. "It turns out now that methylglyoxal, which has been around ever since glycolysis evolved, was also acting at these receptors, and nobody knew that."
A New Therapeutic Angle
Conventional anxiety treatments, such as benzodiazepines and barbiturates, activate GABA-A receptors but carry significant risks including sedation, hypothermia, and high abuse liability. The researchers theorized that targeting the Glo1 (search)/MG interaction could offer a more selective approach by subtly modulating inhibitory tone through an endogenous system.
"The GABA-A receptor (search) agents already out there have a lot of side effects, such as sedation and hypothermia, as well as a high abuse liability," Distler said. "It's possible that taking a Glo1 (search) inhibitor will increase only MG levels to a certain maximum. You could have the potential for more specificity, given that you're activating a system that's already in place, not just dumping methylglyoxal or some other GABA-A receptor agent throughout the brain."
Preliminary experiments supported this theory. Injections of a small molecule Glo1 (search) inhibitor, developed by John Termini at the Beckman Research Institute of the City of Hope, reduced anxiety-like symptoms in mice.
"It's a different way of hitting these GABA-A receptors," Palmer said. "We have yet to determine if that's a better way of doing it, but it's certainly different, and it gives us a unique angle of attack on this system and potential advantages that we have yet to evaluate."
Beyond anxiety, such a drug may prove useful in treating epilepsy and sleep disorders, conditions where GABA-A-targeting drugs have already demonstrated efficacy. While the therapeutic potential remains to be fully evaluated, the research clears the fog around Glo1 (search)'s role in anxiety by providing both behavioral and cellular evidence.
"What's neat is that we started with exploratory, open-ended genetic studies in mice, and we've now gotten into some fundamental new physiology that nobody had appreciated or put together before," Palmer said. "Now we're starting to reap some of the fruit from those types of genetic studies to enrich our understanding of more classical aspects of biology."
The research was supported by grants from the National Institute of Mental Health, the National Institute on Drug Abuse, the National Institute of General Medical Sciences, and the University of Chicago Diabetes Research and Training Center.