ESPE Abstracts (2015) 84 P-2-538

Plasma Humanin Levels During Normal Childhood and Puberty. Study of Possible Correlations with Sex, Age, and Insulin Levels

Valeria De Donaa, Marta Ciaccioa, Junxiang Wanb, Gabriela Guercioa, Elisa Vaiania, Gabriela Krochika, Mercedes Maceirasa, Juan Manuel Lazzatia, Marco Rivarolaa, Pinchas Cohenb & Alicia Belgoroskya

aHospital Nacional de Pediatria “Juan P. Garrahan”, Buenos Aires, Argentina; bLeonard Davis School of Gerontology, University of Southern California, Los Angeles, USA

Background: Humanin is a novel signaling peptide which has been showed, by in vitro and in vivo studies, to improve insulin sensitivity. As plasma humanin levels decrease during adulthood, particularly during aging, it has been proposed that the increment of insulin resistance in aging might be associated with lesser humanin plasma values.

Objective and hypotheses: The physiological insulin resistance observed during puberty in normal children might be related to a physiological decrement of plasma humanin levels. Since there are no data available in normal children and adolescents of both sexes our aim was to evaluate the developmental changes of plasma humanin levels in normal children of both sexes as a function of chronological age (CA), pubertal stage and insulin levels.

Method: Plasma humanin and serum insulin levels were determined in 69 girls (33 pre-pubertal) and 94 boys (69 pre-pubertal).

Results: Plasma humanin levels did not change as a function of CA, sex and Tanner stage of pubertal development (mean ± SD (pg/ml); boys 1852±367, and girls 1856±314). However, in boys, linear correlation analysis between plasma humanin levels and CA showed a tendency to decrease (P=0.05). In the whole group (P<0.02), in all males (P<0.03) as well as in pubertal males (P<0.02), but not in normal pubertal girls, a significant negative correlation between plasma humanin and serum insulin levels was found. In a Multiple Regression Model including BMI, CA, serum insulin and sex steroids (testosterone, androstenedione, and DHEAS) no significant correlation was found.

Conclusion: As non dynamic changes of plasma humanin levels in normal pre-pubertal and pubertal children of both sexes was observed, it seems that humanin might not be involved directly in the mechanism of physiological insulin resistance described in puberty. However, the relevancy of the sexual dimorphism in insulin/humanin negative correlation during puberty should be elucidated.