Differential cardiovascular responses to cutaneous afferent subtypes in a nociceptive intersegmental spinal reflex

• Type of Material: Article
• Authors: Hyun Joon Lee, Emory University; Jason M. White, Emory University; Jumi Chung, Emory University; Patrick Malone, Emory University; Stephen DeWeerth, Emory University; Keith Tansey, Emory University
• Language: English
• Date: 2019-12-13
• Publisher: Nature Research (part of Springer Nature): Fully open access journals
• Publication Version: Final Published Version
• Copyright Statement: © 2019, The Author(s). CC BY 4.0
• Final Published Version (URL): http://dx.doi.org/10.1038/s41598-019-54072-7
• Title of Journal or Parent Work: Scientific Reports
• ISSN: 2045-2322
• Volume: 9
• Issue: 1
• Start Page: 19049
• End Page: 19049
• Grant/Funding Information: This research project was supported in part by the Wilson Research Foundation (Jackson, MS).
• Keywords: CORD-INJURY; FIBERS; ORGANIZATION; PHYSIOLOGICAL CONDITION; MUSCLE-REFLEX; SKIN; HEART-RATE; Multidisciplinary Sciences; Science & Technology; RAT; SEGMENTAL LEVELS; Science & Technology - Other Topics; THERMAL STIMULATION
• Research Categories: Biology, Neuroscience; Engineering, Biomedical

Abstract

Electrical stimulation to segmental dorsal cutaneous nerves (DCNs) activates a nociceptive sensorimotor reflex and the same afferent stimulation also evokes blood pressure (BP) and heart rate (HR) responses in rats. To investigate the relationship between those cardiovascular responses and the activation of nociceptive afferents, we analyzed BP and HR responses to electrical stimulations at each DCN from T6 to L1 at 0.5 mA to activate A-fiber alone or 5 mA to activate both A- and C-fibers at different frequencies. Evoked cardiovascular responses showed a decrease and then an increase in BP and an increase and then a plateau in HR. Segmentally, both cardiovascular responses tended to be larger when evoked from the more rostral DCNs. Stimulation frequency had a larger effect on cardiovascular responses than the rostrocaudal level of the DCN input. Stimulation strength showed a large effect on BP changes dependent on C-fibers whereas HR changes were dependent on A-fibers. Additional A-fiber activation by stimulating up to 4 adjacent DCNs concurrently, but only at 0.5 mA, affected HR but not BP. These data support that cutaneous nociceptive afferent subtypes preferentially contribute to different cardiovascular responses, A-fibers to HR and C-fibers to BP, with temporal (stimulation frequency) and spatial (rostrocaudal level) dynamics.