Other Hormones

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Leptin

  • Peptide hormone produced by adipose tissue
  • Provide signals to the hypothalamus
    • regulate multiple response mechanism
  • An increase in adipose tissue mass
    • results in concentrations of letpin sufficient to induce hypothalamus to:
      • decrease food intake
      • increase energy expenditure
      • modulate other hormones that decrease lipogenesis and increase lipolysis

Leptin is a satiety factor in rodents. Mice unable to produce leptin or with abnormal receptors are obese. The administration of leptin results in weight loss with defective production.

In obese humans, however, leptin levels are elevated, consistent with greater fat tissue. In general, the elevated leptin levels decrease with weight loss. It is possible that this decrease in leptin increases appetite and consequent weight regain. Leptin is limited in its therapeutic effectiveness because obese individuals exibit marked resistance to the appetite-reducing effects of leptin.

Considine RV, Sinha MK, Heiman ML, Kriauciunas A, Stephens TW, Nyce MR, et al (1996). Serum immunoreactive-leptin concentrations in normal-weight and obese humans. N Engl J Med;334:292-5.

Myostatin

  • Myostatin genetic alterations
    • deletions cause reading frame shifts cause extreme muscle hypertrophy
      • AKA: double muscling
    • a member of superfamily of related molecules called transforming growth factors beta


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