title: Central nitric oxide inhibition modifies metabolic adjustments induced by exercise in rats.
abstract: The influence of the central nervous system on metabolic function is of interest in situations deviating from basal states, such as during exercise. Our previous study in rats demonstrated that central nitric oxide (NO) blockade increases metabolic rate, reducing mechanical efficiency during exercise. To assess the role of brain nitric oxide in the plasma glucose, lactate and free fatty acids (FFAs) concentrations of rats submitted to an incremental exercise protocol on a treadmill until fatigue, 1.43 micromol (2 microl) of N(omega)-nitro-l-arginine methyl ester (L-NAME, n=6), a NO synthase inhibitor, or 2 microl of 0.15M NaCl (SAL, n=6) was injected into the lateral cerebral ventricle (icv) of male Wistar rats immediately before exercise (starting at 10 m/min, with increments of 1m/min every 3 min until fatigue, 10% inclination). Blood samples were collected through a chronic jugular catheter at rest and during exercise until fatigue. During exercise, the L-NAME-treated animals had the following metabolic response compared to controls: (1) an increased hyperglycemic response during the first 60% of time to fatigue; (2) higher plasma lactate levels; and (3) a significant transitory increase in plasma free fatty acids during the dynamic phase of exercise that returned to basal levels earlier than controls during the steady state phase of exercise. In addition L-NAME-treated rats fatigued earlier than controls. The data indicate that the inhibition of the brain nitrergic system induced by icv L-NAME treatment disrupted the accuracy of the neural mechanism that regulates plasma glucose and free fatty acids mobilization during exercise in rats.
authors.affiliation: Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, 31270-901 Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Ana Cristina R
authors.initials: AC
authors.lastname: Lacerda
authors.forename: Umeko
authors.initials: U
authors.lastname: Marubayashi
authors.forename: Cláudio H
authors.initials: CH
authors.lastname: Balthazar
authors.forename: Laura H R
authors.initials: LH
authors.lastname: Leite
authors.forename: Cândido C
authors.initials: CC
authors.lastname: Coimbra
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D001786:Blood Glucose / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005230:Fatty Acids, Nonesterified / Q000097:blood; D007276:Injections, Intraventricular / Q000379:methods; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008660:Metabolism / Q000187:drug effects / Q000502:physiology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001786:Blood Glucose; D004791:Enzyme Inhibitors; D005230:Fatty Acids, Nonesterified; D009569:Nitric Oxide; D019344:Lactic Acid; D019331:NG-Nitroarginine Methyl Ester