1
|
Jalil M, Coverdell TC, Gutierrez VA, Crook ME, Shi J, Stornetta DS, Schwalbe DC, Abbott SBG, Campbell JN. Molecular Disambiguation of Heart Rate Control by the Nucleus Ambiguus. bioRxiv 2023:2023.12.16.571991. [PMID: 38168262 PMCID: PMC10760142 DOI: 10.1101/2023.12.16.571991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
The nucleus ambiguus (nAmb) provides parasympathetic control of cardiorespiratory functions as well as motor control of the upper airways and striated esophagus. A subset of nAmb neurons innervates the heart through the vagus nerve to control cardiac function at rest and during key autonomic reflexes such as the mammalian diving reflex. These cardiovagal nAmb neurons may be molecularly and anatomically distinct, but how they differ from other nAmb neurons in the adult brain remains unclear. We therefore classified adult mouse nAmb neurons based on their genome-wide expression profiles, innervation of cardiac ganglia, and ability to control HR. Our integrated analysis of single-nucleus RNA-sequencing data predicted multiple molecular subtypes of nAmb neurons. Mapping the axon projections of one nAmb neuron subtype, Npy2r-expressing nAmb neurons, showed that they innervate cardiac ganglia. Optogenetically stimulating all nAmb vagal efferent neurons dramatically slowed HR to a similar extent as selectively stimulating Npy2r+ nAmb neurons, but not other subtypes of nAmb neurons. Finally, we trained mice to perform voluntary underwater diving, which we use to show Npy2r+ nAmb neurons are activated by the diving response, consistent with a cardiovagal function for this nAmb subtype. These results together reveal the molecular organization of nAmb neurons and its control of heart rate.
Collapse
Affiliation(s)
- Maira Jalil
- Department of Biology, University of Virginia, Charlottesville, VA
| | | | | | - Maisie E. Crook
- Department of Biology, University of Virginia, Charlottesville, VA
| | - Jiachen Shi
- Department of Biology, University of Virginia, Charlottesville, VA
| | | | - Dana C. Schwalbe
- Department of Biology, University of Virginia, Charlottesville, VA
| | | | - John N. Campbell
- Department of Biology, University of Virginia, Charlottesville, VA
| |
Collapse
|
2
|
Gupta D, Burstein AW, Schwalbe DC, Shankar K, Varshney S, Singh O, Paul S, Ogden SB, Osborne-Lawrence S, Metzger NP, Richard CP, Campbell JN, Zigman JM. Ghrelin deletion and conditional ghrelin cell ablation increase pancreatic islet size in mice. J Clin Invest 2023; 133:e169349. [PMID: 38099492 PMCID: PMC10721155 DOI: 10.1172/jci169349] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 10/05/2023] [Indexed: 12/18/2023] Open
Abstract
Ghrelin exerts key effects on islet hormone secretion to regulate blood glucose levels. Here, we sought to determine whether ghrelin's effects on islets extend to the alteration of islet size and β cell mass. We demonstrate that reducing ghrelin - by ghrelin gene knockout (GKO), conditional ghrelin cell ablation, or high-fat diet (HFD) feeding - was associated with increased mean islet size (up to 62%), percentage of large islets (up to 854%), and β cell cross-sectional area (up to 51%). In GKO mice, these effects were more apparent in 10- to 12-week-old mice than in 4-week-old mice. Higher β cell numbers from decreased β cell apoptosis drove the increase in β cell cross-sectional area. Conditional ghrelin cell ablation in adult mice increased the β cell number per islet by 40% within 4 weeks. A negative correlation between islet size and plasma ghrelin in HFD-fed plus chow-fed WT mice, together with even larger islet sizes in HFD-fed GKO mice than in HFD-fed WT mice, suggests that reduced ghrelin was not solely responsible for diet-induced obesity-associated islet enlargement. Single-cell transcriptomics revealed changes in gene expression in several GKO islet cell types, including upregulation of Manf, Dnajc3, and Gnas expression in β cells, which supports decreased β cell apoptosis and/or increased β cell proliferation. These effects of ghrelin reduction on islet morphology might prove useful when designing new therapies for diabetes.
Collapse
Affiliation(s)
- Deepali Gupta
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Avi W. Burstein
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Dana C. Schwalbe
- Department of Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Kripa Shankar
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Salil Varshney
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Omprakash Singh
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Subhojit Paul
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Sean B. Ogden
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Sherri Osborne-Lawrence
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Nathan P. Metzger
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Corine P. Richard
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - John N. Campbell
- Department of Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Jeffrey M. Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
- Division of Endocrinology and Metabolism, Department of Internal Medicine and
- Department of Psychiatry, UT Southwestern Medical Center, Dallas, Texas, USA
| |
Collapse
|
3
|
Webster AN, Becker JJ, Li C, Schwalbe DC, Kerspern D, Karolczak EO, Godschall EN, Belmont-Rausch DM, Pers TH, Lutas A, Habib N, Güler AD, Krashes MJ, Campbell JN. Molecular Connectomics Reveals a Glucagon-Like Peptide 1 Sensitive Neural Circuit for Satiety. bioRxiv 2023:2023.10.31.564990. [PMID: 37961449 PMCID: PMC10635031 DOI: 10.1101/2023.10.31.564990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
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. GLP-1RAs inhibit hunger-promoting Agouti-related peptide (AgRP) neurons of the arcuate hypothalamus (Arc) but only indirectly, implicating synaptic afferents to AgRP neurons. To investigate, we developed a method combining rabies-based connectomics with single-nuclei transcriptomics. Applying this method to AgRP neurons in mice predicts 21 afferent subtypes in the mediobasal and paraventricular hypothalamus. Among these are Trh+ Arc neurons (TrhArc), which express the Glp1r gene and are activated by the GLP-1RA liraglutide. Activating TrhArc neurons inhibits AgRP neurons and decreases feeding in an AgRP neuron-dependent manner. Silencing TrhArc neurons increases feeding and body weight and reduces liraglutide's satiating effects. Our results thus demonstrate a widely applicable method for molecular connectomics, reveal the molecular organization of AgRP neuron afferents, and shed light on a neurocircuit through which GLP-1RAs suppress appetite.
Collapse
Affiliation(s)
- Addison N. Webster
- Neuroscience Graduate Program, University of Virginia, Charlottesville, VA, U.S.A
| | - Jordan J. Becker
- Section on Motivational Processes Underlying Appetite, Diabetes, Endocrinology, & Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, U.S.A
| | - Chia Li
- Section on Motivational Processes Underlying Appetite, Diabetes, Endocrinology, & Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, U.S.A
| | - Dana C. Schwalbe
- Department of Biology, University of Virginia, Charlottesville, VA, U.S.A
| | - Damien Kerspern
- Section on Motivational Processes Underlying Appetite, Diabetes, Endocrinology, & Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, U.S.A
| | - Eva O. Karolczak
- Section on Motivational Processes Underlying Appetite, Diabetes, Endocrinology, & Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, U.S.A
| | | | | | - Tune H. Pers
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Andrew Lutas
- Section on Motivational Processes Underlying Appetite, Diabetes, Endocrinology, & Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, U.S.A
| | - Naomi Habib
- Center for Brain Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ali D. Güler
- Department of Biology, University of Virginia, Charlottesville, VA, U.S.A
| | - Michael J. Krashes
- Section on Motivational Processes Underlying Appetite, Diabetes, Endocrinology, & Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, U.S.A
| | - John N. Campbell
- Neuroscience Graduate Program, University of Virginia, Charlottesville, VA, U.S.A
- Department of Biology, University of Virginia, Charlottesville, VA, U.S.A
| |
Collapse
|
4
|
Liu Y, Savier EL, DePiero VJ, Chen C, Schwalbe DC, Abraham-Fan RJ, Chen H, Campbell JN, Cang J. Mapping visual functions onto molecular cell types in the mouse superior colliculus. Neuron 2023; 111:1876-1886.e5. [PMID: 37086721 PMCID: PMC10330256 DOI: 10.1016/j.neuron.2023.03.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 03/17/2023] [Accepted: 03/28/2023] [Indexed: 04/24/2023]
Abstract
The superficial superior colliculus (sSC) carries out diverse roles in visual processing and behaviors, but how these functions are delegated among collicular neurons remains unclear. Here, using single-cell transcriptomics, we identified 28 neuron subtypes and subtype-enriched marker genes from tens of thousands of adult mouse sSC neurons. We then asked whether the sSC's molecular subtypes are tuned to different visual stimuli. Specifically, we imaged calcium dynamics in single sSC neurons in vivo during visual stimulation and then mapped marker gene transcripts onto the same neurons ex vivo. Our results identify a molecular subtype of inhibitory neuron accounting for ∼50% of the sSC's direction-selective cells, suggesting a genetic logic for the functional organization of the sSC. In addition, our studies provide a comprehensive molecular atlas of sSC neuron subtypes and a multimodal mapping method that will facilitate investigation of their respective functions, connectivity, and development.
Collapse
Affiliation(s)
- Yuanming Liu
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Elise L Savier
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Victor J DePiero
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Chen Chen
- Department of Psychology, University of Virginia, Charlottesville, VA 22904, USA
| | - Dana C Schwalbe
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | | | - Hui Chen
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - John N Campbell
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA.
| | - Jianhua Cang
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA; Department of Psychology, University of Virginia, Charlottesville, VA 22904, USA.
| |
Collapse
|