Identification of peripheral neural circuits that regulate heart rate using optogenetic and viral vector strategies

Study Purpose: Heart rate is under the precise control of the autonomic nervous system. However, the wiring of peripheral neural circuits that regulate heart rate is poorly understood. The purpose of this study was to record and evaluate the activities of individual mouse brainstem neurons and nerves (phrenic, hypoglossal, vagus, RLN, and vagus) with regard to breathing, the cardiac cycle, swallowing, electrical stimulation of the superior laryngeal/vagus nerve, and induced asthma-like conditions

Data Collection: Here, we developed a clearing-imaging-analysis pipeline to visualize the innervation of intact hearts in 3D and employed a multi-technique approach to map parasympathetic and sympathetic neural circuits that control heart rate in mice. This data set is part of a larger data set that will also include functional analyses.

Primary Conclusion: We anatomically and functionally identify cholinergic neurons and noradrenergic neurons in an intrinsic cardiac ganglion and the stellate ganglia, respectively, that project to the sinoatrial node. We also report that the heart rate response to optogenetic versus electrical stimulation of the vagus nerve displays different temporal characteristics and that vagal afferents enhance parasympathetic and reduce sympathetic tone to the heart via central mechanisms.

Curator's Notes

Experimental Design: The mouse was transcardially perfused with PBS followed by heparin, prior to the heart tissue being fixed with PFA. The fixed heart was then dehydrated and prepared for iDISCO immunolabeling. Following immunolabeling, the heart was mounted and imaged using confocal or light-sheet microscopy.

Completeness: This data set is part of a larger data set that will also include functional analyses: Identification of peripheral neural circuits that regulate heart rate using optogenetic and viral vector strategies.

Subjects & Samples: This dataset contains data from a single 12 weeks old male C57BL/6J mouse. Samples were derived from the subject's heart.

Primary vs derivative data: Primary data consists of confocal microscopy to image large tissue volumes and light-sheet microscopy to image entire hearts of one subject: H-4. Image data (JPEG2000 and OME-TIFF) in the derivative folder was derived from primary images (.czi). The primary images were converted with 20:1 compression to JPEG2000 (.jp2) with MicroFile+ by MBF Bioscience for web streaming and visualization on the SPARC Data Portal. The primary images were also converted with lossless compression to OME-TIFF (.tif) by MBF Bioscience. Microscopy image metadata is included in the file header of all .jp2 and .tif in the derivative folder, as indicated on the manifest. The derivative folder also contains integrated scaffold files (JSON) for H-4 experimental data that can be viewed and interacted with through the portal viewer.

Important Notes: A web-based interactive visualization of the 3D dataset is available at https://www.ics.uci.edu/~fowlkes/SPARC/volume/. A detailed description of procedures and findings is published in Nature Communications doi: 10.1038/s41467-019-09770-1

Code Availability: All image processing was performed using Zeiss Zen 2.1 v11, Adobe Photoshop and Illustrator, NIH ImageJ, Bitplane Imaris 8.3, and custom Matlab scripts.