Growth hormone increases muscle mass and strength but does not rejuvenate myofibrillar protein synthesis in healthy subjects over 60 years old.

Abstract

The rate of synthesis of myofibrillar proteins is slower in muscle of healthy subjects over 60 yr old than it is in young adults. Previous research suggests that reduced activity of the GH/insulin-like growth factor-I system could be a determinant of this slowing of protein synthesis. To test the hypothesis that GH could rejuvenate the rate of myofibrillar protein synthesis, we studied healthy subjects over 60 yr old, after a single injection (0.03 mg/kg.sc) of recombinant human GH (n = 6 males/2 females) or placebo (n = 6 males/2 females), or after 3 months of either GH (0.03 mg/kg, sc, 3 x /week, n = 5 males) or placebo (n = 5 males) treatment. Myofibrillar protein synthesis and whole-body protein metabolism were evaluated with the tracer L-[1-13C]leucine. GH reduced whole-body leucine oxidation by 36% (P < 0.01) in the single injection study. There was no effect of GH on whole-body protein breakdown or synthesis, or on myofibrillar protein synthesis in the quadriceps, either acutely or after 3 months of treatment. GH treatment for 3 months increased lean body mass (3.3 +/- 0.7 kg, P < 0.01, as evaluated by 40K counting), muscle mass (3.3 +/- 1.1 kg, P < 0.02, as evaluated by urinary creatinine excretion), and thigh strength (14 +/- 5%, P < 0.05, as evaluated by isokinetic dynamometry). We conclude that GH can increase muscle mass and strength in healthy men over 60 yr old, but does not restore a youthful rate of myofibrillar protein synthesis.

Endocrinology and Dialysis Series Editor: Jean L. Holley: A Review of the Effects of Growth Hormone Changes on Symptoms of Frailty in the Elderly with Chronic Kidney Disease

“…This association is mainly derived from studies in which GH replacement therapy of GH‐deficient adults resulted in increased muscle mass and muscle strength (20,21). Similar results were noted in healthy elderly subjects (42–46). These improvements in body composition in the elderly were noted using a smaller dose of GH than in younger subjects with GH deficiency (47).…”

Energy expenditure and aging

“…Testosterone levels are correlated with myosin heavy chain synthesis rates and when levels are replaced in hypogonadal men, mixed muscle protein synthesis is increased (Urban et al, 1995; Brodsky et al, 1996). On the other hand, long-duration growth hormone replacement in older adults do not change muscle protein synthesis rates (Welle et al, 1996). Nutrient uptake into the muscle is also related to the decline in protein synthesis with increased age.…”

Validated treatments and therapeutics prospectives regarding pharmacological products for sarcopenia

“…In contrast, other groups reported significant improvements in muscle strength in older adults after GH supplementation. For instance, Welle et al showed an increase of muscle mass and thigh strength in healthy older persons after three months of GH treatment (83). Other two small studies reported improved muscle strength after GH supplementation in healthy elderly and in osteoporotic old women (84,85).…”