Arginine metabolism in developing porcine enterocytes /

The small intestine plays an important role in mammalian

Bibliographic Details
Main Author:	Flynn, Nick Edward
Format:	Thesis Book
Language:	English
Published:	[Place of publication not identified] : [publisher not identified] ; 1997.
Subjects:	major nutrition.
Online Access:	http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739891051&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD

Description
Summary:	The small intestine plays an important role in mammalian arginine synthesis by converting glutamine into citrulline via pyrroline-5-carboxylate synthase (P5CS) and in arginine degradation primarily via the arginase pathway. The objectives of this research are to determine the contribution of intestinal arginine synthesis to arginine homeostasis in neonatal pigs and the role of glucocorticoids in mediating arginine metabolism and expression of intestinal arginase and argininosuccinate synthase (ASS) mRNAs in enterocytes of postweaning pigs. First, 4-d-old pigs were administered gabaculine, an inhibitor of ornithine aminotransferase, (0.83 mg/kg body weight) every 4 h for a 12-h period. Gabaculine administration decreased synthesis of citrulline and arginine from glutamine in enterocytes, decreased plasma concentrations of ornithine, citrulline and arginine, and increased plasma concentrations of glutamine and proline compared with control pigs. Second, 21-d-old suckling pigs were administered hydrocortisone-21-acetate (HYD) (25 mg/kg body weight), RU486 (a glucocorticoid receptor antagonist) (10 mg/kg body weight), HYD plus RU486, or sesame oil (vehicle). At 29 d of age, enterocytes were prepared from the jejunum. Cortisol treatment increased arginine and glutamine metabolism and the activities of arginase, P5CS, and argininosuccinate lyase (ASL). RU486 treatment prevented cortisol-induced increases in arginine and glutamine metabolism and the increase in arginase, P5CS and ASL activity. Third, 21-d-old pigs were weaned to a corn and soybean meal-based diet, or allowed to suckle freely until 29 d of age. Weaned pigs were treated with RU486 (10 mg/kg body weight) or vehicle (sesame oil). Weaning increased the activities of enterocyte arginase ASS, ASL and P5CS, compared with suckling pigs. RU486 treatment prevented the induction of ASL and P5CS, and reduced arginase activity by 73%. mRNA levels of ASS did not differ between suckling and weaned pigs. Untreated weaned pigs exhibited the highest level of intestinal arginase mRNA compared with suckling pigs and RU486-treated weaned pigs. Findings from these suggest that intestinal synthesis of citrulline and arginine plays an important role in maintaining arginine homeostasis in neonatal pigs and that cortisol mediates the enhanced arginine and glutamine metabolism in enterocytes of weaned pigs.
Item Description:	Vita. "Major Subject: Nutrition".
Physical Description:	xiii, 127 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc.
Bibliography:	Includes bibliographical references: pages 104-119.