Regulation of Anxiety-like Behavior by Angiotensinogen-Expressing Astrocytes in Brainstem

Background: Astrocytes are essential glial cells that provide structural and metabolic support to neurons and maintain brain homeostasis. Emerging evidence has demonstrated that astrocytes play critical roles in regulating anxiety- and depressive-like behaviors, as well as cognitive functions such as learning and memory (Williamson et al, 2024; Huang et al, 2024; Martin-Fernandez et al, 2017). Angiotensinogen (Agt), abundantly expressed in the diencephalon of the brain, is notably enriched in astrocytes. However, while Agt is often utilized as an astrocyte marker, its specific functional roles within astrocytes remain poorly understood. The current study aimed to gain a deeper understanding of the function of Agt in the astrocyte, particularly its involvement in regulating anxiety. Methods: The expression of Agt mRNA in astrocytes was analyzed using the multiplex RNAscope™ assay. Region-specific Agt deletion was achieved by injecting Cre-expressing adeno-associated virus (AAV) into the periventricular region of the 4 th ventricle in Agt -flox mice. Elevated plus maze (EPM) was conducted to assess the role of Agt in regulating anxiety-like behavior. Results: Agt was abundantly expressed in the peri-fourth ventricular region, including parabrachial nucleus, locus coeruleus, and tegmental nucleus. The expression of Agt mRNA co-localized with the astrocyte marker GFAP but not with the neuronal marker NeuN in both male and female mice. EPM analysis revealed a significant increase in baseline anxiety levels in male mice following Agt deletion (open arm time: AAV-GFP, 146.9 ± 5.475 s vs. AAV-Cre, 82.78 ± 15.39 s; p < 0.01, n = 5–6/group), while no significant changes were observed in female mice (open arm time: AAV-GFP, 95.25 ± 15.97 s vs. AAV-Cre, 92.88 ± 15.88 s; p > 0.05, n = 6/group). Additionally, there was a trend toward enhanced stress-induced anxiety following 30 minutes of restraint stress in both male (open arm time: AAV-GFP, 47.35 ± 5.279 s vs. AAV-Cre, 27.88 ± 9.073 s; p = 0.08, n = 5–6/group) and female mice (open arm time: AAV-GFP, 43.13 ± 8.814 s vs. AAV-Cre, 22.94 ± 4.702 s; p = 0.09, n = 6/group). Conclusion: These findings demonstrate that Agt-expressing astrocytes may play a contributory role in regulating anxiety-related behaviors, highlighting the functional significance of Agt in astrocytes beyond its use as a cellular marker. Future research will focus on elucidating the underlying mechanisms by which Agt modulates astrocyte activity, such as its role in astrocyte activation, neuroinflammation, and stress-induced neural responses. Understanding these pathways could provide novel insights into the contributions of Agt to emotional regulation and potentially reveal new therapeutic targets for anxiety-related disorders. CDMRP PR10574 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.