Metabolic pathways implicated in the kinetic impairment of muscle glutamine homeostasis in adult and old glucocorticoid-treated rats.
Am J Physiol Endocrinol Metab
; 287(4): E671-6, 2004 Oct.
Article
en En
| MEDLINE
| ID: mdl-15361356
ABSTRACT
An impairment of muscle glutamine metabolism in response to dexamethasone (DEX) occurs with aging. To better characterize this alteration, we have investigated muscle glutamine release with regard to muscle glutamine production (net protein breakdown, de novo glutamine synthesis) in adult and old glucocorticoid-treated rats. Male Sprague-Dawley rats (3 or 24 mo old) were divided into seven groups three groups received 1.5 mg/kg of DEX once a day by intraperitoneal injection for 3, 5, or 7 days; three groups were pair fed to the three treated groups, respectively; and one control group of healthy rats was fed ad libitum. Muscle glutamine synthetase activity increased earlier in old rats (day 3) than in adult rats (day 7), whereas an increase in muscle glutamine release occurred later in old rats (day 5) than in adult DEX-treated rats (day 3). Consequently, muscle glutamine concentration decreased later in old rats (day 5) than in adults (day 3). Finally, net muscle protein breakdown increased only in old DEX-treated rats (day 7). In conclusion, the impairment of muscle glutamine metabolism is due to a combination of an increase in glutamine production and a delayed increase in glutamine release.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Envejecimiento
/
Músculo Esquelético
/
Glucocorticoides
/
Glutamina
/
Homeostasis
Límite:
Animals
Idioma:
En
Revista:
Am J Physiol Endocrinol Metab
Asunto de la revista:
ENDOCRINOLOGIA
/
FISIOLOGIA
/
METABOLISMO
Año:
2004
Tipo del documento:
Article
País de afiliación:
Francia