Semaglutide-induced satiation, nausea, and food reward suppression are mediated by GLP-1 receptors in the area postrema
The GLP-1-based obesity drug semaglutide lowers bodyweight primarily by increasing satiation and satiety, whilst also reducing food reward and commonly causing nausea. The brainstem dorsal vagal complex (DVC) has been identified as a key site of action for these phenotypic components of semaglutides anorectic effect. However, which GLP-1 receptor (GLP-1R) populations within the DVC are recruited to mediate these phenotypic components, and whether they are dissociable, are translationally important but unresolved questions. We addressed these using metabolic and behavioural phenotyping, combined with activity-dependent genetic labelling ( Sema-TRAP) and chemogenetic manipulation of semaglutide-recruited brainstem circuits. Semaglutide potentiated satiation and satiety, caused behavioural proxies of nausea, and suppressed motivation for Western diet, in a largely sex-independent manner. It activated a substantial proportion of GLP-1R-expressing neurons in the brainstem area postrema (AP), but surprisingly most semaglutide-activated neurons in the nucleus tractus solitarius (NTS) did not express GLP-1R. Chemogenetic reactivation of Sema-TRAP neurons in the NTS alone was sufficient to recapitulate the acute effects of semaglutide on satiation, nausea, food reward, and bodyweight. Knockdown of GLP-1R expression in the AP before Sema-TRAPing abolished the recruitment of Sema-TRAPNTS neurons which elicited all these effects, while leaving the effects of semaglutide on satiety and bodyweight intact. These data demonstrate that semaglutide recruits dissociable anorectic circuits to suppress eating via distinct behavioural mechanisms, with non-GLP-1R NTS neurons downstream of GLP-1RAP representing potential therapeutic targets to tune GLP-1-based obesity drugs towards a better-tolerated effect profile.