A genetic map of the murine dorsal vagal complex and its role in obesity [single-cell RNA-seq and ATAC-seq]
Ontology highlight
ABSTRACT: The brainstem dorsal vagal complex (DVC) is known to regulate energy balance and is the target of appetite suppressing hormones, such as glucagon-like peptide-1 (GLP-1). Here we provide a comprehensive genetic map of the DVC and identify neuronal populations that control feeding. Combining bulk and single-nucleus gene expression and chromatin profiling of DVC cells, we reveal 25 neuronal populations with unique transcriptional and chromatin accessibility landscapes and peptide receptor expression profiles. GLP-1 receptor (GLP-1R) agonist administration induces gene expression alterations specific to two distinct sets of Glp1r neurons – one population in the area postrema (AP) and one in the nucleus of the solitary tract (NTS) that also expresses calcitonin receptor (Calcr). Transcripts and regions of accessible chromatin linked to obesity-associated genetic variants are enriched in AP and NTS neurons that express Glp1r and/or Calcr, and activation of several of these neuronal populations decreases feeding in rodents. Thus, DVC neuronal populations associated with obesity predisposition suppress feeding and may represent targets for therapy of obesity.
Project description:The brainstem dorsal vagal complex (DVC) is known to regulate energy balance and is the target of appetite suppressing hormones, such as glucagon-like peptide-1 (GLP-1). Here we provide a comprehensive genetic map of the DVC and identify neuronal populations that control feeding. Combining bulk and single-nucleus gene expression and chromatin profiling of DVC cells, we reveal 25 neuronal populations with unique transcriptional and chromatin accessibility landscapes and peptide receptor expression profiles. GLP-1 receptor (GLP-1R) agonist administration induces gene expression alterations specific to two distinct sets of Glp1r neurons – one population in the area postrema (AP) and one in the nucleus of the solitary tract (NTS) that also expresses calcitonin receptor (Calcr). Transcripts and regions of accessible chromatin linked to obesity-associated genetic variants are enriched in AP and NTS neurons that express Glp1r and/or Calcr, and activation of several of these neuronal populations decreases feeding in rodents. Thus, DVC neuronal populations associated with obesity predisposition suppress feeding and may represent targets for therapy of obesity.
Project description:Combinatorial therapies are under intense investigation for the development of more efficient anti-obesity drugs, however little is known about how they act in brain to produce enhanced satiety and weight loss. Here we used a multidisciplinary strategy to decipher the central mechanisms engaged downstream from the co-administration of GLP-1R and CCK1R agonists, an efficient combination therapy in obese rodents. The nucleus of the solitary tract (NTS) contained one of the few neuronal populations synergistically activated in response to GLP-1R and CCK1R co-agonism. None of the previously categorized NTS neuronal subpopulations relevant to feeding behaviour were synergistically activated. However, using PhosphoTRAP, we obtained the molecular signature of NTS and ARH neurons synergistically regulated by the GLP-1R and CCK1R co-agonism and identified NTS/AP Calcrl+ neurons and ARH Adcyap1r1+ neurons as targets of this treatment. Collectively these studies advance our understanding of the central mechanisms involved in the synergistic appetite- and weight-suppressive effect of a combinatorial therapy.
Project description:Central glucose-dependent insulinotropic polypeptide (GIP) receptor (GIPR) signalling is critical for GIP-based therapeutics to lower body weight, but pathways leveraged by GIPR agonism pharmacology in the brain remain incompletely understood. We explored the role of Gipr neurons in the hypothalamus and dorsal vagal complex (DVC)—brain regions critical to the control of energy balance. Hypothalamic expression of Gipr expression was not necessary for the synergistic effect of GIPR/ agonism combined with GLP-1R co-agonism on body weight. While chemogenetic stimulation of both hypothalamic and DVC Gipr neurons suppressed food intake, activation of DVC Gipr neurons reduced ambulatory activity and induced conditioned taste avoidance, while there was no effect of a short-acting GIPR agonist (SAGIPRA). Within the DVC, Gipr neurons of the nucleus tractus solitarius (NTS), but not the area postrema (AP), projected to the parabrachial nucleus and paraventricular hypothalamic nucleusdistal brain regions. ScRNAseq and FISH analysis showed that Gipr neurons in the NTS and AP Gipr neurons were transcriptomically distinct. Peripherally-dosed fluorescent GIPR agonists (GIPRAs) revealed that GIPRA access was restricted to circumventricular organs in the CNS. Together tThese data demonstrate that while the hypothalamus, AP and NTS are key sites for Gipr expression, these subpopulations of Gipr neurons in the hypothalamus, AP and NTS differ in their connectivity, transcriptomic profile, peripheral accessibility to peripherally administered GIPRAs, and the appetite controlling pathways they employ. These results highlight the heterogeneity of the central GIPR signalling axis, and suggest that studies aimed at understandinginto the effects of GIP pharmacology on feeding behaviour should consider the interplay of multiple regulatory pathways.
Project description:Objective: The area postrema (AP) and the nucleus tractus solitaris (NTS), located in the hindbrain, are key nuclei that sense and integrate peripheral nutritional signals and, consequently, regulate feeding behaviour. While single cell transcriptomics have been used in mice to reveal the gene expression profile and heterogeneity of key hypothalamic populations, similar in-depth studies have not yet been performed in the hindbrain. Methods: Using single-nucleus RNA sequencing, we provide a detailed survey of 16,034 cells within the AP and NTS of the mouse, in the fed and fasted state. Results: Of these, 8910 are neurons that group into 30 clusters, with 4289 coming from mice fed ad libitum and 4621 from overnight fasted mice. 7124 nuclei are from non-neuronal cells, including oligodendrocytes, astrocytes and microglia. Interestingly, we identified that the oligodendrocyte population was particularly transcriptionally sensitive to an overnight fast. The receptors GLP1R, GIPR, GFRAL and CALCR, which bind GLP1, GIP, GDF15 and amylin respectively, are all expressed in the hindbrain and are major targets for anti-obesity therapeutics. We characterise the transcriptomes of these four populations and show that their gene expression profiles are not dramatically altered by an overnight fast. Notably, we find that roughly half of cells that express GIPR are oligodendrocytes. Additionally, we profile POMC expressing neurons within the hindbrain and demonstrate that 84% of POMC neurons express either PCSK1, PSCK2 or both, implying that melanocortin peptides are likely produced by these neurons. Conclusion: We provide a detailed single-cell level characterisation of AP and NTS cells expressing receptors for key anti-obesity drugs that are either already approved for human use or are in clinical trials. This resource will help delineate the mechanisms underlying the effectiveness of these compounds, and also prove useful in the continued search for other novel therapeutic targets.
Project description:In this study, we compared the treatment with one of 2 GLP-1 receptor agonists, Liraglutide and Semaglutide on the gene expression in 6 different DIO rat brain areas known to express the GLP-1 receptor. DIO rats were treated with vehicle, liraglutide, semaglutide or weight-matched for 23 days and tissue from the brain areas LS, PVH, ARH, DMH, AP and NTS was obtained with LCM.
Project description:Arterial pressure (AP) is lower in pre-menopausal women than in men of similar age. Pre-menopausal women exhibit a lower sympathetic outflow and a greater baroreceptor reflex, however molecular mechanisms for the gender differences of AP regulation are still not well understood. Since the nucleus tractus solitarius (NTS), a pivotal region of the medulla oblongata for regulating the set-point of AP is strongly associated with the AP level, we hypothesized that a different neuronal functions at the level of the NTS between men and women could contribute to the gender difference in cardiovascular homeostasis. Females Spontaneous Hypertensive Rats (SHRs) clearly exhibit lower AP levels than their male counterparts at similar age and their NTS is characterized by a specific gene expression profile. This gender dependence of AP level is less marked in the normotensive strain, Wistar Kyoto rats (WKY). In this study, we investigated the gender-dependent gene expression profile of the NTS of WKY by using microarray technique.
Project description:Arterial pressure (AP) is lower in pre-menopausal women than in men of similar age. Pre-menopausal women exhibit a lower sympathetic outflow and a greater baroreceptor reflex, however molecular mechanisms for the gender differences of AP regulation are still not well understood. Since the nucleus tractus solitarius (NTS), a pivotal region of the medulla oblongata for regulating the set-point of AP, is strongly associated with the AP level, we hypothesized that a different neuronal functions at the level of NTS between men and women could contribute to the gender difference in cardiovascular homeostasis. Since females Spontaneous Hypertensive Rats (SHRs) clearly exhibit lower AP levels than their male counterparts at similar age, we investigated whether the NTS of SHRs exhibit gender differences in gene expression by using microarray technique.
Project description:Chronic inflammation has been proposed to contribute to the pathogenesis of diet-induced obesity. However, scarce therapeutic options are available to treat obesity and the associated immunometabolic complications. Glucocorticoids are routinely employed for the management of inflammatory diseases, but their pleiotropic nature leads to detrimental metabolic side effects. We developed a glucagon-like peptide-1 (GLP-1)-Dexamethasone co-agonist in which GLP-1 selectively delivers Dexamethasone to GLP-1 receptor-expressing cells. GLP-1-Dexamethasone lowers body weight up to 25% in obese mice by targeting the hypothalamic control of feeding and by increasing energy expenditure. This strategy reverses hypothalamic and systemic inflammation while improving glucose tolerance and insulin sensitivity. The selective preference for GLP-1 receptors bypasses deleterious effects of Dexamethasone on glucose handling, bone integrity, and hypothalamus-pituitary-adrenal axis activity. Thus, GLP-1-directed glucocorticoid pharmacology represents an efficacious therapy option for diet-induced immunometabolic derangements and the resulting obesity.
Project description:Liraglutide and other agonists of the glucagon-like peptide 1 receptor (GLP-1RAs) are effective weight-loss drugs, but how they suppress appetite remains unclear. One potential mechanism is by activating neurons which inhibit hunger-promoting Agouti-related peptide (AgRP) neurons of the arcuate hypothalamus (Arc). To identify these afferents, we developed a method combining rabies-based connectomics with single-nuclei transcriptomics. Applying this method to AgRP neurons predicted at least 21 afferent subtypes in the mouse mediobasal and paraventricular hypothalamus. Among these are Trh+ Arc neurons (TrhArc), inhibitory neurons which express the Glp1r gene and are activated by the GLP-1RA liraglutide. Activating TrhArc neurons inhibits AgRP neurons and feeding, likely in an AgRP neuron-dependent manner. Silencing TrhArc neurons causes over-eating and weight gain and attenuates liraglutide’s effect on body weight. Our results demonstrate a widely applicable method for molecular connectomics, comprehensively identify local inputs to AgRP neurons, and reveal a circuit through which GLP-1RAs suppress appetite.