Performance-enhancing and thermoregulatory effects of intracerebroventricular dopamine in running rats.
To assess the role of central dopamine on metabolic rate, heat balance and running performance, 2.0 microL of 5 x 10(-3)M dopamine solution (DA) or 0.15M NaCl (SAL) was intracerebroventricularly injected in Wistar rats 1 min before running on a motor-driven treadmill, according to a graded exercise protocol, until fatigue. Oxygen consumption (VO(2)) and body temperature (T(b)) were recorded at rest, during exercise, and after 30 min of recovery. DA induced a marked increase in workload (approximately 45%, p<0.05). At fatigue point, DA-injected rats attained approximately 29% higher maximum oxygen consumption (VO(2max)) and approximately 0.75 degrees C higher T(b) than SAL-injected rats. Despite the higher VO(2max) and T(b) attained during exercise, DA-treated rats reached VO(2) basal values within the same recovery period and dissipated heat approximately 33% faster than SAL-treated rats (p<0.05). The mechanical efficiency loss rate was approximately 40% lower in DA than in SAL-treated rats (p<0.05), however, the heat storage was approximately 35% higher in the DA group (p<0.05). Our results demonstrate that increased DA availability in the brain has a performance-enhancing effect, which is mediated by improvements in the tolerance to heat storage and increases in the metabolic rate induced by graded exercise. These data provide further evidence that central activation of dopaminergic pathways plays an important role in exercise performance.
Balthazar
Cláudio H
CH
Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Pampulha, 31270-901 Belo Horizonte, MG, Brazil.
Leite
Laura H R
LH
Rodrigues
Alex G
AG
Coimbra
Cândido C
CC
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D001833:Body Temperature Regulation / Q000187:drug effects*; D001921:Brain / Q000378:metabolism; D004298:Dopamine / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D004734:Energy Metabolism / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D007276:Injections, Intraventricular; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D011301:Preoptic Area / Q000187:drug effects / Q000378:metabolism; D011597:Psychomotor Performance / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D012420:Running / Q000502:physiology*
D015102:3,4-Dihydroxyphenylacetic Acid; D004298:Dopamine