9207 Anoctamin 4 in the Area Postrema Regulates Glucose and Energy Homeostasis

Abstract

Abstract Disclosure: L. Tu: None. Y. Xu: None. Located on the floor of the 4th ventricle within the dorsal surface of the medulla oblongata, the area postrema (AP) is a circumventricular organ where a proper blood-brain barrier is missing. Numerous studies reveal that neurons in the AP are implicated into suppression of food intake (e.g., glucagon-like peptide 1 (GLP-1)-mediated anorexia), but the role of AP neurons in whole-body glucose homeostasis is less investigated. Here we identified and fully characterized the physiological functions of anoctamin-4 (Ano4, a calcium activated chloride channel)1 in the AP. CRISPR-mediated deletion of Ano4 in the AP caused a lower body weight and reduced blood glucose, concurrent with an improved glucose tolerance and increased insulin sensitivity. Chemogenetic activation of Ano4-expressing neurons in the AP (APAno4) increased food intake and blood glucose, and did not induce conditioned flavor avoidance. Both Ano4 neurons and non-Ano4 neurons (i.e., neurons do not express Ano4) sent projections to the lateral parabrachial nucleus (LPBN). Optogenetic stimulation of APAno4 ◊ LPBN circuit promoted feeding behavior and increased blood glucose, whereas stimulation of APnon-Ano4 ◊ LPBN circuit inhibited food intake and did not influence glucose homeostasis. Finally, RNAscope studies reveal that 45.7% of APAno4 neurons are glutamatergic neurons, and 41.8% of them are GABAergic neurons. Furthermore, APAno4 neurons showed only a 2.6% overlap with Glp-1r-expressing neurons in the AP, but had a 60.8% co-localization with protein tyrosine phosphatase receptor δ2, which serves as orexigenic asprosin receptor. Together, our results indicate that Ano4 neurons in the AP are the first reported orexigenic neurons, and represent potential therapeutic targets for human diseases with glucose imbalance and abnormal feeding behavior. Reference: (1) Tu, L. et al. Anoctamin 4 channel currents activate glucose-inhibited neurons in the mouse ventromedial hypothalamus during hypoglycemia. J Clin Invest 133,14. (2023). (2) Mishra, I. et al. Protein tyrosine phosphatase receptor δ serves as the orexigenic asprosin receptor. Cell Metab 34, 549-563. (2022). Presentation: 6/2/2024