Title
Diabetes induces neural degeneration in nucleus ambiguus (NA) and attenuates heart rate control in OVE26 mice
Abbreviated Journal Title
Exp. Neurol.
Keywords
Baroreflex; Nucleus ambiguus; Vagal efferent; Cardiac ganglia; Type 1; diabetes; OVE26 mice; CHRONIC INTERMITTENT HYPOXIA; LATERAL TEGMENTAL FIELD; VAGAL; PREGANGLIONIC NEURONS; VENTRAL RESPIRATORY GROUP; CARDIAC GANGLIA; SUBNUCLEAR ORGANIZATION; FUNCTIONAL-SIGNIFICANCE; SPECTRAL-ANALYSIS; TRANSGENIC MICE; MOTOR-NEURONS; Neurosciences
Abstract
Baroreflex sensitivity is impaired by diabetes mellitus. Previously, we found that diabetes induces a deficit of central mediation of baroreflex-mediated bradycardia. In this study, we assessed whether diabetes induces degeneration of the nucleus ambiguus (NA) and reduces heart rate (HR) responses to L-Glutamate (L-Glu) microinjection into the NA. FVB control and OVE26 diabetic mice (5-6 months) were anesthetized. Different doses of L-Glu (0.1-5 mM/1, 20 nl) were delivered into the left NA using a multi-channel injector. In other animals, the left vagus was electrically stimulated at 1-40 Hz (1 ms, 0.5 mA, 20 s). HR and mean arterial blood pressure (MAP) responses to L-Glu microinjections into the NA and to the electrical stimulation of the vagus were measured. The NA region was defined by tracer TMR-D injection into the ipsilateral nodose ganglion to retrogradely label vagal motoneurons in the NA. Brainstem slices at -600, -300, 0, +300, and +600 mu m relative to the obex were processed using Nissl staining and the number of NA motoneurons was counted. Compared with FVB control, we found in OVE26 mice that: I) HR responses to L-Glu injection into the NA at doses of 0.2-0.4 (mM/1, 20 nl) were attenuated (p < 0.05), but MAP responses were unchanged (p > 0.05). 2) HR responses to vagal stimulation were increased (p < 0.05). 3) The total number of NA (left and right) motoneurons was reduced (p < 0.05). Taken together, we concluded that diabetes reduces NA control of HR and induces degeneration of NA motoneurons. Degeneration of NA cardiac motoneurons may contribute to impairment of reflex-bradycardia in OVE26 diabetic mice. (C) 2009 Elsevier Inc. All rights reserved.
Journal Title
Experimental Neurology
Volume
220
Issue/Number
1
Publication Date
1-1-2009
Document Type
Article
Language
English
First Page
34
Last Page
43
WOS Identifier
ISSN
0014-4886
Recommended Citation
"Diabetes induces neural degeneration in nucleus ambiguus (NA) and attenuates heart rate control in OVE26 mice" (2009). Faculty Bibliography 2000s. 2348.
https://stars.library.ucf.edu/facultybib2000/2348