Parenteral nutrition with lipid or glucose suppresses liver growth and response to GH in adolescent male rats

Our aim was to investigate the effects of modifying the carbohydrate-to-lip id ratio of parenteral nutrition (PN) on body composition and the anabolic actions of insulin-like growth factor I (IGF-I) and growth hormone (GH). Ad olescent male Sprague-Dawley rats were randomized to receive 7 days of GH, IGF-I (3.5 mg.kg(-1).day(-1) for both) or placebo while receiving high-carb ohydrate PN (CHO-PN), high-lipid PN (L-PN), or an oral diet (chow) (the PN protocols were isonitrogenous and isocaloric). PN impaired muscle growth, w hich was reversed by GH in the CHO-PN group only (P<0.03). PN increased car cass lipid (P<0.02), the effect being greater in the L-PN than in the CHO-P N group (P<0.001). Visceral lean tissue growth was significantly impaired b y PN (P<0.001). IGF-I reversed this impairment, but GH had no effect. PN im paired the normal increase in hepatic protein and DNA (P<0.001) and produce d liver steatosis (P<0.001). However, this steatosis was less in L-PN than in CHO-PN (P<0.001). Serum IGF-I and the acid-labile subunit (ALS) were dec reased by PN (P<0.001) and were not affected by GH during PN treatment. How ever, GH significantly increased serum ALS concentrations in the chow-fed r ats (P=0.032). In conclusion, modifying the CHO-to-L ratio of PN had no sig nificant effect on IGF-I action, but CHO-PN increased the peripheral effect of GH. L-PN increased carcass lipid significantly and decreased hepatic st eatosis. Nevertheless, PN caused significant liver steatosis and profound i mpairment of hepatic cell growth, which was associated with relative hepati c GH resistance.