Ghrelin and peptide YY in youth: are there race-related differences?

J Clin Endocrinol Metab. 2006 Aug;91(8):3117-22. doi: 10.1210/jc.2005-2448. Epub 2006 May 23.

Abstract

Objective: Obesity prevalence is higher in African-American (AA) vs. American white (AW) youth. Ghrelin is a "hunger" peptide that is high preprandially and decreases postprandially, and peptide YY (PYY) is a "satiety" hormone increasing after meals. Impaired regulation of ghrelin/PYY may be conducive to obesity. We hypothesized that racial differences in childhood obesity could partly be explained by differences in ghrelin/PYY dynamics.

Research design and methods: We investigated: 1) ghrelin suppression/PYY elevation in response to an oral glucose tolerance test (OGTT) in AA vs. AW, and 2) the relationship of ghrelin and PYY dynamics to insulin sensitivity. Thirty-three AA and 54 AW prepubertal children underwent an OGTT measuring ghrelin, PYY, glucose, and insulin. Fasting glucose to insulin ratio (G(F)/I(F)) was used to assess the relationship of insulin sensitivity to fasting and post-OGTT ghrelin and PYY levels.

Results: OGTT-induced suppression in ghrelin (Delta ghrelin) was lower in AA youth. Delta ghrelin correlated with G(F)/I(F) (r = 0.47, P < 0.001) and Delta insulin at 30 min (r = -0.47, P < 0.001). In multiple regression analysis, race (P = 0.013) and G(F)/I(F) (P = 0.004) contributed independently to the variance in Delta ghrelin (R(2) = 0.28, P < 0.001). Fasting and post-OGTT PYY levels were lower in AAs and were not related to insulin sensitivity.

Conclusion: The lower suppression of ghrelin in AA, but not the lower PYY levels, correlates with insulinemia and insulin resistance. Less ghrelin suppression and PYY elevation after a meal in black youth could be a potential mechanism of race-related differences in hunger/satiety predisposing to risk of obesity.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • African Americans
  • Blood Glucose / analysis
  • Body Composition
  • Body Mass Index
  • Child
  • Continental Population Groups*
  • European Continental Ancestry Group
  • Fasting
  • Female
  • Ghrelin
  • Glucose Tolerance Test
  • Humans
  • Insulin / blood
  • Insulin Resistance
  • Male
  • Obesity / epidemiology
  • Peptide Hormones / blood*
  • Peptide YY / blood*
  • Regression Analysis

Substances

  • Blood Glucose
  • Ghrelin
  • Insulin
  • Peptide Hormones
  • Peptide YY