Summary: Blockbuster weight-loss medications such as semaglutide (Wegovy/Ozempic) and liraglutide (Saxenda) have revolutionized treatment for obesity and diabetes. Yet until now we lacked a clear, high-resolution map of where the glucagon-like peptide 1 (GLP-1) system is located in the brain and whether its distribution differs by sex. A new peer-reviewed study constructed the first sex-specific, single-transcript atlas of GLP-1 expression across 25 distinct brain regions in mice. The atlas reveals striking geographic and sex-dependent differences that help explain clinical observations about drug effectiveness and point to broader therapeutic opportunities for psychiatric and neurodegenerative disorders.
The findings clarify how GLP-1 analogs may produce stronger appetite suppression and greater weight loss in females and suggest sex-specific roles for GLP-1 signaling in reward, motivated behavior, and neuroprotection. This resource offers a roadmap for tailored preclinical work and more precise therapeutic development.
Key Facts
- First comprehensive atlas: High-sensitivity RNAscope was used to map GLP-1 (Glp1) mRNA at single-transcript resolution across 25 brain nuclei and subnuclei in male and female mice.
- Female-predominant sites: Several hindbrain regions showed significantly higher GLP-1 density in females, aligning with clinical data that women often lose more weight on GLP-1 medications than men.
- Male-specific olfactory pattern: Males showed greater GLP-1 density in the olfactory bulb, a finding that may relate to odor-driven insulin responses observed in male mice.
- Behavioral and psychiatric implications: GLP-1 was found in reward-related and motivated-behavior regions (for example, the ventral tegmental area in females and the lateral hypothalamus in males), indicating potential sex-specific psychiatric effects.
- Relevance to neurodegeneration: GLP-1 transcripts appear in brain areas vulnerable to neurodegeneration, supporting further investigation of GLP-1 analogs for cognitive decline and neuroinflammation.
Source: Genomic Press
The drugs have names that sound planetary—semaglutide, liraglutide, lixisenatide—yet despite their clinical success, the precise brain locations of GLP-1 and possible sex differences remained unclear.
A team at the Icahn School of Medicine at Mount Sinai led by Vitaly Ryu, Anisa Gumerova, Georgii Pevnev, Tony Yuen, and senior author Mone Zaidi published a study in Brain Medicine establishing a sex-specific GLP-1 expression atlas in the mouse brain. Using RNAscope, the group identified Glp1 transcripts across medulla, olfactory bulb, midbrain, pons, hippocampus, hypothalamus, thalamus and the ependymal layer of the third ventricle, and mapped differences between females and males in fine anatomical detail.
The authors emphasize that sex-specific distribution matters because metabolic diseases and some psychiatric disorders display distinct clinical patterns between women and men. For example, GLP-1 analogs appear to suppress appetite and regulate glucose more strongly in females than males, and the atlas provides an anatomical framework to probe why that occurs.
Methods refined for low-abundance targets
GLP-1 is produced at low levels in the brain and degrades quickly, making detection difficult with older approaches. RNAscope overcomes this by detecting individual mRNA transcripts with probe sets that hybridize across thin whole-brain sections. The study analyzed three female and three male mice. Two independent, blinded observers manually counted transcripts across systematic sections, and probe specificity was validated using positive and negative tissue controls. The result is a quantitative, single-transcript–level compendium that did not previously exist.
Hindbrain differences highlight sex-biased expression
Both sexes had the highest overall Glp1 counts in the medulla and olfactory bulb, but the subnuclear distribution diverged. Females showed the highest hindbrain Glp1 densities in the raphe obscurus nucleus (ROb), the ventral portion of the nucleus of the solitary tract (SolV), and the medial solitary tract (SolM). Males had higher densities in central (SolCe), intermediate (SolIM) and medial subnuclei of the solitary tract. Notably, Glp1-expressing neuron counts were significantly higher in the SolV of females (P = 0.034), with a trend in the ventrolateral solitary tract (SolVL).
Some hindbrain nuclei displayed sex-biased presence of Glp1 transcripts—observed only in one sex—although the authors caution that low-frequency events and the modest sample size mean these sex-specific absences should be treated as hypotheses to test in larger studies.
Olfactory bulb and metabolic signaling
The olfactory bulb produced an unexpected, metabolically relevant signal: males had significantly greater Glp1 density overall in the olfactory bulb, driven by higher density in the granular cell layer (GrO). Prior work has located GLP-1–releasing interneurons in the olfactory bulb that may modulate mitral cell activity and post-prandial anorexigenic responses. The new data suggests a possible sex-specific interaction linking olfactory-driven signaling, insulin responses, and diet-induced metabolic changes in males, while estrogenic modulation in females may compensate for lower olfactory GLP-1 density.
GLP-1 within a network of peptides
GLP-1 functions within a broader, sexually dimorphic peptide network that controls food intake. Females tend to have fewer orexigenic NPY neurons and more active anorexigenic POMC neurons, with estrogen receptor alpha contributing to reduced food intake in females. Leptin signaling and ghrelin interactions further modulate GLP-1 pathways, including vagal gating mechanisms and close apposition of GLP-1 axons to serotonergic neurons in brainstem regions regulating autonomic appetite suppression. The atlas situates GLP-1 inside this coordinated, sex-influenced peptidergic conversation.
Beyond appetite: psychiatric and neurodegenerative relevance
Glp1 expression was also present—though at lower densities—in midbrain and pons nuclei (including the ventral tegmental area), hippocampal dentate gyrus, posterior and lateral hypothalamus, and thalamic nuclei. The ventral tegmental area showed Glp1 expression only in females, while the lateral hypothalamus showed it only in males. Given emerging evidence that GLP-1 analogs may affect addiction, depression, and cognitive decline, the atlas provides anatomical targets to investigate mechanisms of neuroinflammation, neuronal survival, and memory.
Limitations and next steps
The authors note limitations: sample size was small (n = 3 per sex), females were not staged by estrous cycle, and RNAscope detects mRNA but does not directly measure peptide synthesis, release, or functional engagement. The atlas is best suited for identifying moderate-to-high Glp1 expression and for guiding follow-up functional experiments, rather than definitively ruling out sparse expression in any region.
A foundation for future research
This atlas is intended as a starting point rather than an endpoint. By mapping Glp1 at single-transcript resolution and revealing sex-specific anatomy, the work supports targeted studies of GLP-1 circuits in metabolic regulation, behavior, and neuroprotection. The authors also note that preproglucagon neuron distribution is conserved between rodents and nonhuman primates, increasing translational relevance.
Between the raphe obscurus nucleus in a female mouse and the granular cell layer in a male, this atlas helps explain clinical impressions and opens paths for precision neuropharmacology that accounts for sex-specific biology.
Key Questions Answered:
A: The atlas shows higher GLP-1 density in several hindbrain regions of females, including the nucleus of the solitary tract subregions associated with appetite control. More GLP-1–expressing neurons in these centers may make GLP-1–based drugs more effective at reducing appetite and body weight in females.
A: In male mice, higher GLP-1 density in the olfactory bulb could amplify odor-driven insulin responses, potentially promoting metabolic effects linked to diet. The study suggests a sex-specific olfactory-metabolic interaction, though causal links require further testing.
A: Yes. GLP-1 expression in reward and memory-related brain regions supports exploration of GLP-1 analogs for addiction, depression, and cognitive decline. The atlas helps identify sex-specific targets for those investigations.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full by staff.
- Additional context was added by the editorial team.
About this neuropharmacology research news
Author: Ma-Li Wong
Source: Genomic Press
Contact: Ma-Li Wong – Genomic Press
Image: Image credited to Neuroscience News
Original Research: Open access. “Atlas of GLP-1 expression in the mouse brain: Neuroanatomical basis for metabolic and psychiatric effects” by Ryu V, Gumerova A, Pevnev G, Yuen T, Zaidi M. Brain Medicine. DOI: 10.61373/bm026a.0006
Abstract
Atlas of GLP-1 expression in the mouse brain: Neuroanatomical basis for metabolic and psychiatric effects
Glucagon-like peptide 1 (GLP-1) and its analogs have emerged as potent therapies for obesity and diabetes, and they are being explored for addiction, depression, and other psychiatric conditions. Metabolic and psychiatric disorders often show sex-specific features, and GLP-1’s effects on appetite, glycemic regulation, and weight loss appear stronger in females. Using RNAscope, the authors created a sex-specific atlas (n = 3 per sex) of Glp1 mRNA in the mouse brain. In the hindbrain, Glp1 densities and numbers of Glp1-expressing neurons in the raphe obscurus nucleus and ventral and ventrolateral parts of the solitary nucleus were higher in females. In contrast, Glp1 density in the olfactory bulb granular layer was greater in males. This atlas provides a resource to advance understanding of GLP-1’s central roles in metabolic regulation and psychiatric contexts.