Chronic inhibition of nitric oxide synthase augments the ACTH response to exercise

Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri Submitted 20 August 2008 ; accepted in final form 6 January 2009 Exercise can activate the hypothalamo-pituitary-adrenocortical (HPA) axis, and regular exercise training can impact how the H...

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Published in:American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2009-03, Vol.296 (3), p.R728-R734
Main Authors: Jankord, Ryan, McAllister, Richard M, Ganjam, Venkataseshu K, Laughlin, M. Harold
Format: Article
Language:English
Subjects:
Adrenocorticotropic Hormone - blood
Animals
Blood pressure
Blood Pressure - physiology
Brain
Enzyme Inhibitors - pharmacology
Exercise
Exercise and Respiratory Physiology
Female
Handling (Psychology)
Hydrocortisone - blood
Hypothalamo-Hypophyseal System - physiology
NG-Nitroarginine Methyl Ester - pharmacology
Nitric oxide
Nitric Oxide - blood
Nitric Oxide - physiology
Nitric Oxide Synthase - antagonists & inhibitors
Physical Conditioning, Animal - physiology
Regional Blood Flow - physiology
Restraint, Physical
Reverse Transcriptase Polymerase Chain Reaction
RNA, Messenger - biosynthesis
RNA, Messenger - genetics
Stress, Psychological - metabolism
Studies
Swine
Swine, Miniature
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Summary:Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri Submitted 20 August 2008 ; accepted in final form 6 January 2009 Exercise can activate the hypothalamo-pituitary-adrenocortical (HPA) axis, and regular exercise training can impact how the HPA axis responds to stress. The mechanism by which acute exercise induces HPA activity is unclear. Therefore, the purpose of this study was to test the hypothesis that nitric oxide modulates the neuroendocrine component of the HPA axis during exercise. Female Yucatan miniature swine were treated with N -nitro- L -arginine methyl ester ( L -NAME) to test the effect of chronic nitric oxide synthase (NOS) inhibition on the ACTH response to exercise. In addition, we tested the effect of NOS inhibition on blood flow to tissues of the HPA axis and report the effects of handling and treadmill exercise on the plasma concentrations of ACTH and cortisol. Chronic NOS inhibition decreased plasma NO x levels by 44%, increased mean arterial blood pressure by 46%, and increased expression of neuronal NOS in carotid arteries. Vascular conductance was decreased in the frontal cortex, the hypothalamus, and the adrenal gland. Chronic NOS inhibition exaggerated the ACTH response to exercise. In contrast, chronic NOS inhibition decreased the ACTH response to restraint, suggesting that the role of NO in modulating HPA activity is stressor dependent. These results demonstrate that NOS activity modulates the response of the neuroendocrine component of the HPA axis during exercise stress. neuroendocrine; restraint; pigs; N -nitro- L -arginine methyl ester; stress Address for reprint requests and other correspondence: R. Jankord, Dept. of Psychiatry, Univ. of Cincinnati, Genome Research Institute, E216, 2170 East Galbraith Rd., Cincinnati, OH 45237 (e-mail: ryan.jankord{at}uc.edu )
ISSN:0363-6119
1522-1490
DOI:10.1152/ajpregu.90709.2008