Radically different
Interest in glucagon-like peptide 1 receptor agonists (GLP-1s) continues to surge due to their effectiveness in reducing body weight and improving metabolic outcomes. This includes interest in small molecule oral GLP-1s which are more bioavailable and more easily manufactured than their injectable counterparts.
Now data from a new study in mice performed by scientists at the University of Virginia shows that this emerging class of weight-loss drugs suppress hedonic eating by modulating a reward circuit deep in the brain that is separate from previously described mechanisms that broadly affect appetite. The scientists believe that this pathway could be an avenue by which GLP-1s treat other dysfunctions in reward processing such as substance use disorders.
Details of the National Institutes of Health-funded study were published this week in a Nature paper titled “A brain reward circuit inhibited by next-generation weight-loss drugs in mice.” In it, the team reported that they investigated the small-molecule GLP-1s including Eli Lilly’s recently approved drug orforglipron, also known by the brand name Foundayo, as well as danuglipron, an oral GLP-1 that was being developed by Pfizer until the company decided to discontinue its development in 2025.
Previous studies that explored the effects of larger peptide GLP-1s such as semaglutide in the brain have found that they suppress hunger-driven eating by engaging networks in the hypothalamus and hindbrain. What has been less clear is the mechanism by which small-molecule GLP-1s work. “As the accessibility of these medications continues to rise and patient uptake increases, it’s crucial that we understand the neural mechanisms underlying the effects we’re seeing,” said Lorenzo Leggio, MD, PhD, clinical director of NIH’s National Institute on Drug Abuse.
The current study gets scientists one step closer to that goal. According to the paper, the scientists first used gene editing to modify the GLP-1 receptors of mice to make them more humanlike. They then administered orforglipron or danuglipron to the mice, and identified brain regions where the drugs induced activity. The results showed that in addition to inducing activity in familiar pathways, the drugs also triggered the central amygdala, a region associated with desire that is deeper in the brain than scientists previously thought GLP-1s could directly reach. Further testing showed that once activated, the central amygdala reduced the release of dopamine into key hubs of the brain’s reward circuitry during hedonic feeding.
“We’ve known that GLP-1 drugs suppress feeding behavior driven by energy demand,” said co-corresponding author Ali Guler, PhD, a professor of biology at the University of Virginia. “Now it seems oral small-molecule GLP-1s also dial back eating for pleasure by engaging a brain reward circuit.”
Given the effect of these drugs on eating for pleasure, future studies could explore whether small-molecule GLP-1s can also suppress cravings for other addictive substances. It is a question that the team hopes to explore in follow up studies focused specifically on substance use disorder.
The post Oral Small-Molecule GLP-1s Linked to Deep Brain Activity and Reduced Cravings in Mice appeared first on GEN – Genetic Engineering and Biotechnology News.
Research led by New York University suggests a marker of epigenetic aging could be linked to depression.
The team found that accelerated aging of a type of white blood cell called a monocyte was significantly associated with the psychological and cognitive expressions of depression in a group of women with and without HIV.
“Depression is not a one-size-fits-all disorder—it can look really different from person to person, which is why it’s so important to consider varied presentations and not just a clinical label,” said lead researcher Nicole Beaulieu Perez, PhD, assistant professor at NYU Rory Meyers College of Nursing, in a press statement.
“Our study reveals unique biological underpinnings of mental health that are often obscured by broad diagnostic categories.”
As reported in The Journals of Gerontology Series A, the researchers analyzed blood samples and depression scores from 440 women, 261 living with HIV and 179 without, from the Women’s Interagency HIV Study. They tested women with HIV as people with this disease and others affecting the immune system are at greater risk of depression than the general public.
The team looked at biological aging using two epigenetic clocks: a broad multi-tissue clock and a monocyte-specific clock that measures chemical modifications to DNA in these cells.
Depression was measured using the CES-D questionnaire, which separates physical, bodily expressions of depression such as fatigue, appetite loss, and agitation from psychological and cognitive expressions of the disorder such as hopelessness, anhedonia, and feelings of failure.
Accelerated monocyte aging was significantly associated with the psychological and cognitive expressions of depression and with anhedonia specifically, even after adjusting for HIV status, race, and ethnicity. The broader multi-tissue Horvath clock showed no association with any depression domain, suggesting it is the monocyte-specific aging signal, not generalized biological aging, that tracks with mood and cognitive symptoms.
Diagnosis of depression relies largely on self-reported symptoms and not a specific physiological test. The finding that monocyte aging maps onto cognitive and mood symptoms rather than physical ones is counterintuitive, since monocytes are inflammatory cells that one might expect to track physical, inflammation-driven complaints like fatigue.
The study is small and cross-sectional, so causality cannot yet be established, but if the claims of the study were validated it could help to personalize treatment for depression in the future.
“The dynamics of monocyte aging and depression warrant further study to clarify mechanistic links,” conclude the authors.
“Our findings bring us a step closer to this goal of precision mental health care, especially for high-risk populations, by providing a biological framework that could guide future diagnosis and treatment,” adds Beaulieu Perez.
The post Biomarker of Epigenetic Aging Could Signal Depression appeared first on Inside Precision Medicine.
A strategic imperative in mood disorders is to identify innovative mechanisms that translate into improved therapeutics when compared to the extant options. More specifically, there is a need for treatments with greater efficacy, shorter time-to-peak efficacy, greater durability of effect as well as improved tolerability profiles. Moreover, priority has also shifted towards identifying mood disorder therapeutics capable of targeting domains of psychopathology that are most pervasive, debilitating and inadequately treated by conventional pharmacology (e.g., anhedonia, cognitive impairment).