Fatigue is mediated by cholinoceptors within the ventromedial hypothalamus independent of changes in core temperature.
Scand J Med Sci Sports
; 23(1): 46-56, 2013 Feb.
Article
em En
| MEDLINE
| ID: mdl-21672029
ABSTRACT
We investigated brain mechanisms modulating fatigue during prolonged physical exercise in cold environments. In a first set of studies, each rat was subjected to three running trials in different ambient temperatures (T(a)). At 8 °C and 15 °C, core body temperature (T(core)) decreased and increased, respectively, whereas at 12 °C, the T(core) did not change throughout the exercise. In another set of experiments, rats were randomly assigned to receive bilateral 0.2 µL injections of 2.5 × 10(-2) M methylatropine or 0.15 M NaCl solution into the ventromedial hypothalamic nuclei (VMH). Immediately after the injections, treadmill exercise was started. Each animal was subjected to two experimental trials at one of the following T(a) 5 °C, 12 °C or 15 °C. Muscarinic blockade of the VMH reduced the time to fatigue (TF) in cold environments by 35-37%. In all T(a) studied, methylatropine-treated rats did not present alterations in T(core) and tail skin temperature compared with controls. These results indicate that, below the zone of thermoneutrality, muscarinic blockade of the VMH decreases the TF, independent of changes in T(core). In conclusion, our data suggest that VMH muscarinic transmission modulates physical performance, even when the effects of thermoregulatory adjustments on fatigue are minimal.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Regulação da Temperatura Corporal
/
Receptores Muscarínicos
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Temperatura Baixa
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Esforço Físico
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Hipotálamo Médio
Limite:
Animals
Idioma:
En
Revista:
Scand J Med Sci Sports
Assunto da revista:
MEDICINA ESPORTIVA
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Brasil