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Title: In utero glucocorticoid (GLC) exposure reduces fetal skeletal muscle growth in rats

Author
item GOKULAKRISHNAN, GANGA - Children'S Nutrition Research Center (CNRC)
item ESTRADA, IRMA - Children'S Nutrition Research Center (CNRC)
item SOSA, JR, HORACIO - Children'S Nutrition Research Center (CNRC)
item FIOROTTO, MARTA - Children'S Nutrition Research Center (CNRC)

Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 2/24/2010
Publication Date: 4/24/2010
Citation: Gokulakrishnan, G., Estrada, I.J., Sosa Jr, H.A., Fiorotto, M.L. 2010. In utero glucocorticoid (GLC) exposure reduces fetal skeletal muscle growth in rats [abstract]. Federation of American Societies for Experimental Biology Conference, Session: Protein and amino acid metabolism, April 24-28, 2010, Anaheim, California. 24:740.3.

Interpretive Summary:

Technical Abstract: Maternal undernutrition and stress expose the fetus to above normal levels of GLC and predispose to intrauterine growth restriction. The aim of this study was to determine if fetal GLC exposure impairs skeletal muscle growth independently of maternal undernutrition. Three groups (n=7/group) of timed-pregnant Sprague-Dawley rats were studied: Control (CON): ad libitum food intake. DEX: ad libitum food intake, oral DEX from embryonic day (ED) 13 to 21. Pair-fed (PF): pair-fed to DEX. On ED 22 (term), prior to surgical delivery, in vivo fractional protein synthesis rates (FSR), and total protein content of the fetal quadriceps and diaphragm muscles were measured. Our results showed that DEX treatment (89 +/- 6 ug/ (kg.d)) reduced maternal food intake by 13% (P<0.001) and weight gain by 82% (P<0.001). DEX and PF muscle protein masses were 60% and 80% of CON respectively (P<0.01). Protein FSR was decreased by 35% in DEX fetuses (P<0.001), whereas protein FSR in PF muscles were the same as CON. From the results, we can conclude that a modest reduction in maternal food intake impaired muscle growth. Reduced maternal food intake combined with GLC exposure exacerbated the effects on muscle growth. This can be explained by the effects of GLC on rates of fetal muscle protein synthesis combined with the effects of maternal food restriction on fetal muscle protein degradation.