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Induction of a Catabolic State in Rats by Dexamethasone: Dose or Time Dependency?
Author(s) -
MinetQuinard Régine,
Moinard Christophe,
Walrand Stéphane,
Villié Françoise,
Normand Bernadette,
Vasson MariePaule,
Chopineau Jean,
Cynober Luc
Publication year - 2000
Publication title -
journal of parenteral and enteral nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.935
H-Index - 98
eISSN - 1941-2444
pISSN - 0148-6071
DOI - 10.1177/014860710002400130
Subject(s) - dexamethasone , medicine , endocrinology , catabolism , metabolism , chemistry
Background: Daily injections of dexamethasone (DEX) given to adult rats are a recognized but nonstandardized model of stress. The aim of this work was to establish a reproducible and accurate model of stress in adult rats by chronic injection of DEX in order to standardize it. For this purpose, the effect of the duration of treatment and the effect of DEX dose were tested. To help understand the mechanisms of the catabolic effect of DEX, the study was extended to the metabolism of glutamine (GLN). In experiment 1, 60 male Sprague‐Dawley rats (3 months old) were divided into 8 groups of 6 rats: groups G 3 , G 5 , G 7 , and G 9 received 1.50 mg/kg/d of DEX by intraperitoneal (IP) injection for 3, 5, 7, or 9 days, respectively. Groups G 3PF , G 5PF , G 7PF , or G 9PF were pair‐fed to groups G 3 , G 5 , G7, or Gg, respectively. Group AL (n = 12) was healthy rats fed ad libitum. Results: In treated rats, nitrogen balance reached its lowest value at day 5. After 9 days treatment by DEX, the catabolic state was reduced. An increase in GLN‐synthetase activity and a decrease in muscle GLN content were related to DEX per se not to DEX‐induced anorexia. In experiment 2, 25 rats were divided into 5 groups of 5 animals. Groups G 0.75 , G 1.50 , and G 2.50 received 0.75, 1.50, and 2.50 mg/kg/d, respectively, of DEX by IP injection for 5 days. Group PF was pair‐fed to group G 2.50 and group AL was control rats. Results: DEX induced a decrease in nitrogen balance that was dose‐independent. GLN‐synthetase activity was increased maximally in gastrocnemius by 0.75 mg/kg. Conclusions: Five days of treatment by DEX and a dose of 0.75 mg/kg/d induced a marked catabolic state. (Journal of Parenteral and Enteral Nutrition 24: 30–36, 2000)