Effects of estradiol and progesterone on body composition, protein synthesis, and lipoprotein lipase in rats

2001 ◽  
Vol 280 (3) ◽  
pp. E496-E501 ◽  
Author(s):  
Michael J. Toth ◽  
Eric T. Poehlman ◽  
Dwight E. Matthews ◽  
André Tchernof ◽  
Michael J. MacCoss
Keyword(s):  
Skeletal Muscle ◽  
Body Composition ◽  
Protein Synthesis ◽  
Lipoprotein Lipase ◽  
Muscle Protein ◽  
Ovarian Hormones ◽  
Fat Free Mass ◽  
Female Rats ◽  
Synthesis Rate ◽  
Skeletal Muscle Protein

Prior studies suggest that estradiol and progesterone regulate body composition in growing female rats. Because these studies did not consider the confounding effect of changes in food intake, it remains unclear whether ovarian hormones regulate body composition independently of their effects on food intake. We utilized a pair-feeding paradigm to examine the effects of these hormones on body composition. In addition, skeletal muscle protein fractional synthesis rate and adipose tissue lipoprotein lipase activity were measured to examine pathways of substrate deposition into fat and fat-free tissue. Female Sprague-Dawley rats [pubertal: 7–8 wk old; 190 ± 0.5 (SE) g] were separated into four groups: 1) sham-operated (S; n = 8), 2) ovariectomized plus placebo (OVX; n = 8), 3) ovariectomized plus estradiol (OVX+E; n = 8), and 4) ovariectomized plus progesterone (OVX+P; n = 8). All ovariectomized groups were pair-fed to the S group. Body composition was measured using total body electrical conductivity. The relative increase in fat-free mass was greater ( P < 0.01) in the OVX group (31 ± 2%) than in the S (17 ± 2%), OVX+E (18 ± 2%), and OVX+P (22 ± 2%) groups. The fractional synthetic rates of gastrocnemius muscle protein paralleled changes in fat-free mass: OVX had a higher ( P < 0.05) synthesis rate (21 ± 3%/day) than S (12 ± 2%/day), OVX+E (11 ± 2%/day), and OVX+P (8 ± 1%/day) groups. Body fat increased in the S group (31 ± 7%; P < 0.01), whereas the OVX groups lost fat (OVX: −10 ± 7%; OVX+E: −15 ± 7%; OVX+P: −13 ± 7%). No differences in lipoprotein lipase were found. Our results suggest that estradiol and progesterone may regulate the growth of fat and fat-free tissues in female rats. Moreover, ovarian hormones may influence skeletal muscle growth through their effects on skeletal muscle protein synthesis.

Total and net muscle protein breakdown in infection determined by amino acid effluxes

1990 ◽  
Vol 258 (5) ◽  
pp. E856-E863 ◽  
Author(s):  
J. Sjolin ◽  
H. Stjernstrom ◽  
G. Friman ◽  
J. Larsson ◽  
J. Wahren
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Urinary Excretion ◽  
Protein Degradation ◽  
Muscle Protein ◽  
Human Infection ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Skeletal Muscle Protein ◽  
Mild Disease

The present investigation was undertaken to study whether, in human infection of varying severity, peripheral 3-methylhistidine efflux and urinary excretion are associated with net protein degradation and to estimate the protein synthesis rate from the combined effluxes of 3-methylhistidine, tyrosine, and phenylalanine. Quadruplicate femoral arteriovenous differences of 3-methylhistidine, tyrosine, and phenylalanine were multiplied by leg plasma flow in 15 infected patients. Leg effluxes for 3-methylhistidine, tyrosine, and phenylalanine were -0.074 +/- 0.011, -2.57 +/- 0.43, and -3.17 +/- 0.44 mumol/min, respectively. There was a significant linear relationship (P less than 0.01) between the effluxes of tyrosine and phenylalanine and the efflux and urinary excretion of 3-methylhistidine. A significant release of tyrosine and phenylalanine was observed in patients studied at the 3-methylhistidine level seen in normal healthy subjects. It is concluded that in infection 1) there is an increased breakdown of skeletal muscle protein and a reduced rate of protein synthesis, with the latter being relatively more important in patients with mild disease; and 2) urinary 3-methylhistidine excretion is associated with net skeletal muscle protein degradation for the patient group studied.

Skeletal muscle protein synthesis and degradation exhibit sexual dimorphism after chronic alcohol consumption but not acute intoxication

2007 ◽  
Vol 292 (6) ◽  
pp. E1497-E1506 ◽  
Author(s):  
Charles H. Lang ◽  
Robert A. Frost ◽  
Thomas C. Vary
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Translation Initiation ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Alcohol Intoxication ◽  
Female Rats ◽  
Chronic Alcohol ◽  
Skeletal Muscle Protein ◽  
Male And Female Rats

Epidemiological evidence suggests alcoholic myopathy is more severe in females than males, but comparable animal studies are lacking that make elucidating the biochemical locus for this defect problematic. The present study determined whether skeletal muscle protein synthesis and markers of degradation exhibit a sexual dimorphic response to either chronic alcohol consumption or acute intoxication. Male and female rats were fed an alcohol-containing diet, pair-fed for 26 wk (chronic), or received an intraperitoneal injection of alcohol (acute). In males, chronic alcohol decreased gastrocnemius protein synthesis by 20%. This reduction was associated with a twofold increase in the inactive eukaryotic initiation factor (eIF) 4E·4E-binding protein 1 (4E-BP1) complex and a 60% reduction in the active eIF4E·eIF4G complex. This redistribution of eIF4E was associated with decreased phosphorylation of both 4E-BP1 and eIF4G (50–55%). The phosphorylation of ribosomal protein S6 was also reduced 60% in alcohol-consuming male rats. In contrast, neither rates of protein synthesis nor indexes of translation initiation in muscle were altered in alcohol-fed female rats despite blood alcohol levels comparable to males. Chronic alcohol ingestion did not alter atrogin-1 or muscle RING finger-1 mRNA content (biomarkers of muscle proteolysis) in males but increased their expression in females 50–100%. Acute alcohol intoxication produced a comparable decrease in muscle protein synthesis and translation initiation in both male and female rats. Our data demonstrate a sexual dimorphism for muscle protein synthesis, translation initiation, and proteolysis in response to chronic, but not acute, alcohol intoxication; however, they do not support evidence indicating females are more sensitive toward the development of alcoholic skeletal muscle myopathy.

Leucine incorporation into mixed skeletal muscle protein in humans

1988 ◽  
Vol 254 (2) ◽  
pp. E208-E213 ◽  
Author(s):  
K. S. Nair ◽  
D. Halliday ◽  
R. C. Griggs
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Fiber Type ◽  
Whole Body ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Skeletal Muscle Protein ◽  
Body Protein

Fractional mixed skeletal muscle protein synthesis (FMPS) was estimated in 10 postabsorptive healthy men by determining the increment in the abundance of [13C]-leucine in quadriceps muscle protein during an intravenous infusion of L-[1-13C]leucine. FMPS in our subjects was 0.046 +/- 0.003%/h. Whole-body muscle protein synthesis (MPS) was calculated based on the estimation of muscle mass from creatinine excretion and compared with whole-body protein synthesis (WBPS) calculated from the nonoxidative portion of leucine flux. A significant correlation (r2 = 0.73, P less than 0.05) was found between MPS (44.7 +/- 3.4 mg.kg-1.h-1) and WBPS (167.8 +/- 8.5 mg.kg-1.h-1). The contribution of MPS to WBPS was 27 +/- 1%, which is comparable to the reports in other species. Morphometric analyses of adjacent muscle samples in eight subjects demonstrated that the biopsy specimens consisted of 86.5 +/- 2% muscular as opposed to other tissues. Because fiber type composition varies between biopsies, we examined the relationship between proportions of each fiber type and FMPS. Variation in the composition of biopsies and in fiber-type proportion did not affect the estimation of muscle protein synthesis rate. We conclude that stable isotope techniques using serial needle biopsies permit the direct measurement of FMPS in humans and that this estimation is correlated with an indirect estimation of WBPS.

scholarly journals Resistance exercise maintains skeletal muscle protein synthesis during bed rest

1997 ◽  
Vol 82 (3) ◽  
pp. 807-810 ◽  
Author(s):  
Arny A. Ferrando ◽  
Kevin D. Tipton ◽  
Marcas M. Bamman ◽  
Robert R. Wolfe
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Resistance Training ◽  
Resistance Exercise ◽  
Lean Body Mass ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Bed Rest ◽  
Skeletal Muscle Protein ◽  
Skeletal Muscle Protein Synthesis

Ferrando, Arny A., Kevin D. Tipton, Marcas M. Bamman, and Robert R. Wolfe. Resistance exercise maintains skeletal muscle protein synthesis during bed rest. J. Appl. Physiol. 82(3): 807–810, 1997.—Spaceflight results in a loss of lean body mass and muscular strength. A ground-based model for microgravity, bed rest, results in a loss of lean body mass due to a decrease in muscle protein synthesis (MPS). Resistance training is suggested as a proposed countermeasure for spaceflight-induced atrophy because it is known to increase both MPS and skeletal muscle strength. We therefore hypothesized that scheduled resistance training throughout bed rest would ameliorate the decrease in MPS. Two groups of healthy volunteers were studied during 14 days of simulated microgravity. One group adhered to strict bed rest (BR; n = 5), whereas a second group engaged in leg resistance exercise every other day throughout bed rest (BREx; n = 6). MPS was determined directly by the incorporation of infusedl-[ ring-13C6]phenylalanine into vastus lateralis protein. After 14 days of bed rest, MPS in the BREx group did not change and was significantly greater than in the BR group. Thus moderate-resistance exercise can counteract the decrease in MPS during bed rest.

Growth hormone acutely stimulates forearm muscle protein synthesis in normal humans

1991 ◽  
Vol 260 (3) ◽  
pp. E499-E504 ◽  
Author(s):  
D. A. Fryburg ◽  
R. A. Gelfand ◽  
E. J. Barrett
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Growth Hormone ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Skeletal Muscle Protein ◽  
Skeletal Muscle Protein Synthesis ◽  
Igf I ◽  
Normal Humans

The short-term effects of growth hormone (GH) on skeletal muscle protein synthesis and degradation in normal humans are unknown. We studied seven postabsorptive healthy men (age 18-23 yr) who received GH (0.014 micrograms.kg-1.min-1) via intrabrachial artery infusion for 6 h. The effects of GH on forearm amino acid and glucose balances and on forearm amino acid kinetics [( 3H]Phe and [14C]Leu) were determined after 3 and 6 h of the GH infusion. Forearm deep vein GH rose to 35 +/- 6 ng/ml in response to GH, whereas systemic levels of GH, insulin, and insulin-like growth factor I (IGF-I) were unchanged. Forearm glucose uptake did not change during the study. After 6 h, GH suppressed forearm net release (3 vs. 6 h) of Phe (P less than 0.05), Leu (P less than 0.01), total branched-chain amino acids (P less than 0.025), and essential neutral amino acids (0.05 less than P less than 0.1). The effect on the net balance of Phe and Leu was due to an increase in the tissue uptake for Phe (71%, P less than 0.05) and Leu (37%, P less than 0.005) in the absence of any significant change in release of Phe or Leu from tissue. In the absence of any change in systemic GH, IGF-I, or insulin, these findings suggest that locally infused GH stimulates skeletal muscle protein synthesis. These findings have important physiological implications for both the role of daily GH pulses and the mechanisms through which GH can promote protein anabolism.

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