Summary: Researchers have pinpointed a distinct population of brainstem neurons that drive the appetite-suppressing and weight-loss actions of semaglutide while appearing not to mediate its nausea-related side effects. In mice, direct activation of these neurons reproduced the drug’s effects on reduced food intake and fat loss, and selective loss of these cells blunted semaglutide’s benefits on weight without eliminating adverse symptoms. This insight opens the door to more targeted obesity therapies that preserve metabolic benefits while reducing discomfort.
Semaglutide, a member of the GLP-1R agonist class, is already widely used to treat obesity and type 2 diabetes. Despite its effectiveness at lowering appetite and body weight, treatment can be accompanied by gastrointestinal side effects and, in some cases, loss of lean mass. The new findings from the Sahlgrenska Academy at the University of Gothenburg clarify how specific brain circuits underlie these outcomes, offering a path toward safer, more selective treatments.
Key Facts:
- Targeted Neurons: A defined group of neurons in the dorsal vagal complex (DVC) — many of which express Adcyap1 — mediate semaglutide’s appetite- and weight-reducing effects.
- Side Effect Separation: These DVC neurons appear to control beneficial metabolic responses while not driving side effects such as nausea or significant muscle loss.
- Therapeutic Potential: Selective targeting of semaglutide-responsive Adcyap1+ neurons could enable future obesity treatments that maintain efficacy but reduce unwanted symptoms.
Research context
To understand how semaglutide alters energy balance, investigators used mouse models to map which brainstem neurons are activated by the drug. They focused on two neighboring regions within the dorsal vagal complex: the area postrema (AP) and the nucleus of the solitary tract (NTS). Many semaglutide-responsive neurons in these areas express Adcyap1, a molecular marker the team used to identify and manipulate the relevant cells.
Key experiments and findings
Instead of administering semaglutide, the team selectively reactivated the neurons that the drug normally stimulates. This reactivation alone produced the same principal outcomes as semaglutide treatment: reduced food intake, progressive weight loss, and preferential loss of fat mass. In contrast, when the researchers ablated the Adcyap1+ neurons in AP/NTS, semaglutide’s ability to reduce eating and body weight was largely reversed in both lean and subchronically treated obese mice. Importantly, eliminating these neurons attenuated the drug’s metabolic effects while leaving nausea-like responses and loss of lean mass relatively intact.
These results indicate that semaglutide’s beneficial actions on appetite and body composition are mediated specifically through Adcyap1-expressing neurons in the dorsal vagal complex, and that other neural circuits account for certain adverse effects. The study further shows that NTS Adcyap1+ neurons act downstream of GLP-1R-expressing AP neurons and are required for activating several satiety-related brain regions.
Implications
The ability to dissociate therapeutic effects from side effects at the level of defined neurons is significant. If future therapies can selectively engage Adcyap1+ neurons in the dorsal vagal complex — or mimic their downstream signaling — it may be possible to retain semaglutide’s appetite-suppressing and fat-reducing benefits while minimizing nausea and other intolerances that limit patient adherence.
Beyond obesity, GLP-1R agonists are being explored for a range of conditions, including substance use disorders and neurodegenerative diseases. A clearer mechanistic map of how these drugs act in the brain will support development of improved compounds and more precise clinical strategies.
“We have identified a specific group of nerve cells necessary for the effects semaglutide has on weight and appetite, but which does not appear to contribute substantially to side effects such as nausea,” says Júlia Teixidor-Deulofeu, first author and PhD student at the Sahlgrenska Academy. Linda Engström Ruud, supervisor on the project, emphasizes that deeper knowledge of drug action increases the opportunity to refine therapies for better outcomes and tolerability.
About this semaglutide and neuroscience research news
Author: Júlia Teixidor-Deulofeu
Source: University of Gothenburg
Contact: Júlia Teixidor-Deulofeu – University of Gothenburg
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Semaglutide effects on energy balance are mediated byAdcyap1+neurons in the dorsal vagal complex” by Júlia Teixidor-Deulofeu et al. Cell Metabolism
Abstract
Semaglutide effects on energy balance are mediated by Adcyap1+ neurons in the dorsal vagal complex
The GLP-1R agonist semaglutide is transforming obesity treatment, yet the precise neural mechanisms that control energy balance are not fully understood. This study demonstrates that reactivating semaglutide-responsive neurons in the dorsal vagal complex reproduces the drug’s effects of reduced food intake, body weight loss, increased fat utilization, and conditioned taste aversion. Many semaglutide-activated neurons in the area postrema and nucleus of the solitary tract express Adcyap1, and selective ablation of these AP/NTS Adcyap1+ neurons largely reverses semaglutide’s acute effects on energy balance in lean mice and in subchronically treated obese mice.
Semaglutide-activated AP/NTS Adcyap1+ neurons drive preferential loss of fat rather than lean mass, with only modest contributions to conditioned taste aversion. Additionally, NTS Adcyap1+ neurons are engaged by GLP-1R-expressing AP neurons and are required for activation of multiple downstream satiety-related structures. Selective targeting of semaglutide-responsive Adcyap1+ neurons therefore offers a promising strategy for developing improved anti-obesity treatments.