Abstract Body: Obesity is the greatest impediment to improving cardiovascular health. Despite many methods to lose weight, few people can keep it off in the long-term. The adaptation (suppression) of resting metabolic rate (RMR) appears to mediate weight re-gain after weight loss, yet the neurobiology that controls RMR remains unclear. Previously we published that the angiotensin II type 1 receptor (AT₁R/Agtr1a) within Agouti-related peptide (AgRP/Agrp) neurons of the arcuate nucleus of the hypothalamus (ARC) is critical for integrative control of RMR. In the ARC, AT₁R is only expressed by a subset of AgRP neurons (“Type 1”). In lean animals, AT₁R inhibits this cell via a β-arrestin-1/Gαi-coupled cascade ("Type 1i”). Prolonged diet-induced obesity (DIO) causes RMR adaptation and is associated with a spontaneous G protein cascade switch by AT₁R in the Type 1 neuron, in which AT₁R activation begins stimulating the cell via the Gαq-coupled cascade (“Type 1s”). Our ongoing work aims to clarify the molecular mechanisms that govern AT₁R coupling to Gαi versus Gαq within Type 1 AgRP neurons. First, using a dual-reporter mouse with tdTomato in AT₁R-expressing cells plus green fluorescent protein in somatostatin (SST/Sst)-expressing cells, we confirmed that SST expression is a selective marker of the Type 1 subtype of ARC AgRP neurons. Second, we reanalyzed our previously published single-nucleus RNA sequencing dataset describing the mouse ARC following prolonged DIO (PMC7347451) to explore the effects of DIO upon the transcriptomic profiles of AgRP neuron subtypes. Of 26 cell types initially identified, one cluster strongly expressed both Sst and Agrp (Cluster 5). Sub-clustering of Cluster 5 identified four cell types with strong Agrp expression (subclusters 0, 2, 5, and 6). Subcluster 6 may represent the Type 1i subtype due to high Sst expression, as well as enrichment for signatures of Gαi signaling events. Subcluster 6 also had very few DIO-induced differentially expressed genes (up=3, down=2). Interestingly, Subcluster 2 was comprised almost exclusively of nuclei from the DIO group (95%). Subcluster 2 was more closely related to Subcluster 6 than the other Agrp subclusters in the cluster phylogenetic tree, leading us to hypothesize that this cluster represents the DIO-induced Type 1s subtype. These data identify novel markers of AgRP neuron subtypes within the ARC, and a possible transcriptomic signature of subtype switching induced by prolonged DIO.