Keywords
Nts, cih
Abstract
Chronic Intermittent Hypoxia (CIH) is a model used to study obstructive sleep apnea (OSA). Previously, we showed that baroreflex control of heart rate (HR) (baroreflex sensitivity) is reduced in CIH rats. While afferent function and HR in response to vagal efferent stimulation are enhanced, the effect of CIH on the central components, in particular NTS, is still not completely understood. F344 rats (3-4 mo) were exposed either to CIH or room air (RA) for 35-50 days. Following CIH exposure, rats were anaesthetized with Ket/Ace. Using single-unit extracellular recording technique, we recorded NTS barosensitive neurons in response to arterial pressure (AP) changes induced by descending aorta occlusion. Our data indicated that 1) the mean arterial pressure and HR were similar in RA control and CIH groups. 2) The majority of neurons from RA and CIH NTS neurons increased firing rate, whereas other neurons decreased firing upon AP elevation. 3) In 27 RA and 31 CIH NTS neurons with increased firing rate, 15 RA and 15 CIH neurons were activated at a low ?MAP at the early phase of AP increase (early neurons); whereas 12 RA neurons and 16 CIH neurons were activated at a late phase of AP increase (late neurons). The early neurons rapidly increased their firing during the rising phase of MAP, whereas late neurons did not increase their firing until the ?MAP reached its peak. 4) Early neuron activity-?MAP relationship was further characterized by the logistic sigmoid function curve. CIH significantly increased the maximal gain of the neuron activity-?MAP curve and the range of the response. In addition, CIH early neurons had a significantly higher firing rate than RA early neurons, whereas CIH did not change the firing rate in late neurons. 5) For late neurons, HR reduction correlated with neuronal activity. HR reduction-neuronal activity increase curve was shifted to the right in CIH neurons, indicating that CIH decreased HR control in response to NTS firing increase. Collectively, our data suggest that NTS barosensitive neurons have both early and late neurons, CIH selectively enhances neuron activity in response to AP changes in NTS early neurons and attenuate the baroreflex bradycardia. Along our previous work that CIH-induced the cell loss in the nucleus ambiguus (NA), we conclude that CIH attenuates the functions of NA, whereas enhances the NTS functions to compensate for the loss of function in NA
Notes
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Graduation Date
2015
Semester
Fall
Advisor
Cheng, Zixi (Jack)
Degree
Master of Science (M.S.)
College
College of Medicine
Department
Molecular Biology and Microbiology
Degree Program
Biotechnology
Format
application/pdf
Identifier
CFE0005967
URL
http://purl.fcla.edu/fcla/etd/CFE0005967
Language
English
Release Date
December 2015
Length of Campus-only Access
None
Access Status
Masters Thesis (Open Access)
Subjects
Dissertations, Academic -- Medicine; Medicine -- Dissertations, Academic
STARS Citation
Kolpakova, Jenya, "Functional Identification of Nucleus Tractus Solitarius (NTS) Barosensitive Neurons: Effect of Chronic Intermittent Hypoxia (CIH)" (2015). Electronic Theses and Dissertations. 1381.
https://stars.library.ucf.edu/etd/1381