Enteral nutrition and keratinocyte growth factor regulate expression of glutathione-related enzyme messenger RNAs in rat intestine.
BACKGROUND
Malnutrition is associated with increased reactive oxygen species (ROS) formation and depletion of the critical antioxidant glutathione (GSH) in the intestine. The malnutrition-induced decrease in gut GSH levels is prevented by recombinant keratinocyte growth factor (KGF) administration. We investigated whether enzymes that are induced by oxidants and modulate tissue GSH supply are regulated by enteral nutrients or KGF at the messenger RNA (mRNA) level.


METHODS
Adult rats were fasted for 3 days alone or fasted for 3 days then refed ad libitum. In a second model, rats were fasted for 3 days and then refed ad libitum or 25% of ad libitum intake with daily intraperitoneal saline or recombinant KGF (5 mg/kg/d) for 3 subsequent days. mRNA levels for gamma-glutamylcysteine synthetase (gamma-GCS), gamma-glutamyl transpeptidase (gamma-GT), glutathione-S-transferase Ya-subunit, gastrointestinal glutathione peroxidase (GI-GPx), and non-selenium-dependent glutathione peroxidase (ns-GPx) were determined in ileum and colon by ribonuclease protection assay.


RESULTS
Fasting increased ileal gamma-GCS, ns-GPx, and glutathione-S-transferase mRNAs (by 36%, 165%, and 130% of controls) and decreased GI-GPx mRNA (to 55% of controls). In the colon, mRNAs for GSH-related enzymes were unchanged by fasting or refeeding. Prolonged enteral nutrient restriction (25% refeeding after a 3-day fast) increased gamma-GCS and glutathione-S-transferase mRNAs (by >270% of controls), decreased GI-GPx mRNA (to <50% of controls) in ileum and colon and increased ns-GPx mRNA (by 180%) in colon. KGF treatment increased ns-GPx mRNA in the ileum and colon and glutathione-S-transferase mRNA in the colon (by >200% of controls).


CONCLUSIONS
Enteral nutrient intake regulates GSH-related enzyme mRNA levels in the intestine, which may contribute to the decrease in mucosal GSH during malnutrition. Increased ns-GPx and glutathione-S-transferase mRNA levels during malnutrition and with KGF administration may increase detoxifying functions in the gut under these conditions.
Jonas
C R
CR
Department of Medicine, Emory University, Atlanta, Georgia 30322, USA.
Farrell
C L
CL
Scully
S
S
Eli
A
A
Estívariz
C F
CF
Gu
L H
LH
Jones
D P
DP
Ziegler
T R
TR
D000704:Analysis of Variance; D000818:Animals; D004750:Enteral Nutrition; D005215:Fasting / Q000378:metabolism; D051526:Fibroblast Growth Factor 10; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors; D005721:Glutamate-Cysteine Ligase / Q000235:genetics / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism*; D006133:Growth Substances / Q000494:pharmacology*; D017403:In Situ Hybridization; D007422:Intestines / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D008297:Male; D012333:RNA, Messenger / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D005723:gamma-Glutamyltransferase / Q000378:metabolism
C496455:Fgf7 protein, rat; D051526:Fibroblast Growth Factor 10; D006133:Growth Substances; D012333:RNA, Messenger; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors; D005723:gamma-Glutamyltransferase; D005982:Glutathione Transferase; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione