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Influence of carbohydrate infusion on lipogenic enzyme and regulatory protein gene expression in growing beef steers
Author(s) -
Baldwin Ransom Leland,
McLeod K R,
Baumann R G,
Connor E E
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.lb84-a
Subject(s) - medicine , endocrinology , lipogenesis , adipose tissue , chemistry , carbohydrate responsive element binding protein , sterol regulatory element binding protein , gene expression , hydrolysate , digestion (alchemy) , rumen , carbohydrate , biology , biochemistry , gene , transcription factor , hydrolysis , chromatography , fermentation
Shifting carbohydrate (CHO) digestion from the rumen to the small intestine of cattle increases in vitro rates of lipogensis and in vivo adiposity, especially in visceral depots. Accordingly, 40 beef steers (243 ± 2 kg BW) were used to determine the effects of site and complexity of CHO infusion on expression of genes encoding lipogenic enzymes and regulatory proteins in subcutaneous (SC), mesenteric (MES) and omental (OM) adipose. Treatments were a forage‐based diet fed at 161 (LI) or 214 Kcal ME·(kg BW.75) −1 ·d −1 , LI plus ruminal (R) or abomasal (A) infusion of starch hydrolysate (SH), and LI plus abomasal infusion of glucose (AG). Isoenergetic infusion of starch and glucose required rates of 12.6 and 14.4 g·(kg BW.75) −1 ·d −1 , respectively. After 35 d, RNA was isolated from harvested adipose and used for quantitative realtime RT‐PCR of selected genes. Although gene expression in SC was unaffected by treatment, expression in visceral adipose was highly responsive to dietary energy intake (DME) and CHO. Greater DME increased (P<.05) expression of FAS , ACC , spot14 , ChREBP , SREBP , SREBP‐1 , SREBP‐2 , and SCAP in MES, but not OM. For MES, AG increased (P<.05) ACC , spot14 , SREBP‐2 and SCAP expression compared to ASH, whereas SH infusion did not alter gene expression. For OM, expression of ACC , SREBP‐1 and ChREBP was greater (P<.05) for ASH vs RSH, while expression of FAS , ACC , spot14 , SREBP , SREBP‐2 , and SCAP was greater (P<.05) for AG vs ASH. Both DME and site of digestion and complexity of CHO affect expression of lipogenic enzyme and regulatory genes of visceral adipose depots while SC adipose appears resilient to dietary manipulations.