Nocturnal levels of chemerin and progranulin in adolescents: influence of sex, body mass index, glucose metabolism and sleep.

Background: Adipokines have been implicated in obesity, insulin resistance and sleep regulation. However, the role of chemerin and progranulin, two recently described adipokines, in the context of sleep remains unclear. The aim of this study was to compare nocturnal serum chemerin and progranulin levels between overweight/obese and normal-weight adolescents and to assess variations by sex, across different sleep stages and in relation to glucose metabolism. Methods: The study sample included 34 overweight/ obese and 32 normal-weight adolescents from secondary schools and the Leipzig Research Center for Civilization Diseases (LIFE) Child study cohort. We obtained longitudinal serum adipokine levels during in-laboratory poly-somnography followed by an oral glucose tolerance test. Results: Overweight/obese adolescents had significantly higher mean nocturnal serum chemerin area under the curve (AUC) levels (348.2 +/- 133.3 vs. 241.7 +/- 67.7 vs. ng/mL x h, p < 0.001) compared to normal-weight controls. In detail, higher chemerin AUC levels in obese/over-weight subjects were exclusively due to increased levels in females. No overall difference for serum progranulin AUC was found between the groups. However, when assessing sex-specific levels, serum progranulin AUC levels were similar to 30% higher in overweight/obese males compared to overweight/obese females. Of note, nocturnal serum chemerin and progranulin AUC did not exhibit a correlation with markers of glucose metabolism or sleep stages. Conclusions: Collectively, we report a sexual dimorphism in nocturnal progranulin and chemerin levels, which may help explain underlying differences in energy balance and body composition between males and females in the context of obesity.