sarcopenia, growth hormone and DHEA

Doug Skrecky oberon at vcn.bc.ca
Wed Jan 27 04:35:40 EST 1999


Citations: 1-2
<1>
Authors
  Roubenoff R.  Rall LC.  Veldhuis JD.  Kehayias JJ.  Rosen C.  Nicolson M. 
  Lundgren N.  Reichlin S.
Institution
  Nutrition Exercise Physiology and Sarcopenia Laboratory,
  Jean Mayer U.S. Department of Agriculture, Human Nutrition Research Center on
  Aging, Tufts University, Boston, Massachusetts 02111, USA.
  roubenoff:hnrc.tufts.edu
Title
  The relationship between growth hormone kinetics and
  sarcopenia in postmenopausal women: the role of fat mass and
  leptin.
Source
  Journal of Clinical Endocrinology & Metabolism.  83(5):1502-6, 1998 May.
Abstract
  Sarcopenia, the decline in body cell mass (BCM) and
  especially in muscle mass with age, is an important age-related cause of
  frailty and loss of independence in the elderly. Because the decline in BCM
  with age parallels a decline in GH secretion from young adulthood to old age,
  loss of GH secretion has been considered an important contributory cause of
  sarcopenia in the elderly. To test this hypothesis in a
  group of healthy postmenopausal women (n = 15; mean +/- SD age, 66.9 +/- 7.8
  yr), 24-h GH concentrations and secretory kinetics were correlated with BCM
  (measured by whole body counting of 40K) and percent body fat (measured by
  dual energy x-ray absorptiometry or neutron inelastic scattering). Serum
  leptin levels were determined as a measure of adipocyte mass. Contrary to
  prediction, GH secretion was lower in women with higher BCM (r = 0.50; P <
  0.05), whereas their mean fat mass was higher (r = 0.51, P < 0.05). These
  data indicate that sarcopenia in postmenopausal women is not
  associated with reduced GH secretion and is inversely correlated with fat
  mass. Serum leptin levels were inversely associated with GH secretion (r =
  -0.67; P < 0.006). Although a causal relationship has not been demonstrated,
  these data suggest that leptin could modulate GH secretion through its action
  on the aging hypothalamic-pituitary axis, or that GH regulates leptin
  secretion.

<2>
Authors
  Proctor DN.  Balagopal P.  Nair KS.
Institution
  Endocrine Research Unit, Mayo Clinic and Foundation, Rochester, MN 55905,
  USA.
Title
  Age-related sarcopenia in humans is associated with reduced
  synthetic rates of specific muscle proteins. [Review] [33 refs]
Source
  Journal of Nutrition.  128(2 Suppl):351S-355S, 1998 Feb.
Abstract
  Sarcopenia of aging is not explained entirely on the basis
  of age-associated reduced physical activity. Progressive neuromuscular
  changes and diminishing anabolic hormone levels are thought to contribute to
  the pathogenesis of sarcopenia. Decline in muscle mass
  indicates a decline in muscle protein content. Recent studies demonstrated an
  age-related decline in synthesis rate of mixed muscle proteins, myosin heavy
  chain and mitochondrial protein. Reductions in myosin heavy chain and
  mitochondrial protein synthesis rates have been correlated with
  age-associated decrements in muscle strength and aerobic exercise tolerance,
  respectively. These changes have been reported as early as 50 y of age and
  are related to the decline in insulin-like growth factor (IGF)-I,
  testosterone and dehydroepiandrosterone (DHEA)-sulfate. The declining ability
  to remodel these important muscle proteins may therefore play a role in the
  development of muscle wasting, metabolic abnormalities and impaired physical
  functioning seen in old age. [References: 33]




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