Proopiocortin-related peptide plasma levels throughout prepuberty and puberty

The plasma patterns of ACTH, beta-lipotropin (beta LPH) and beta-endorphin (beta EP), in addition to those of cortisol and dehydroepiandrosterone sulfate (DHAS), were studied in 139 prepubertal children (subdivided into different age groups) and 38 adolescents (subdivided according to Tanner's pubertal stages) aged 10-16 yr. The adult control group was composed of 23 females and 12 males aged 17-40 yr. No sex differences were found in ACTH, beta LPH, beta EP, and cortisol plasma levels. ACTH plasma levels were slightly lower in the 1- to 3-yr-old groups than in males at 4-5 yr and females at 8-9 yr. No further significant differences were observed in any of the age or pubertal groups, the concentrations being constantly in the adult range. beta LPH and beta EP plasma levels were lowest at 1-3 yr in both males (beta LPH: 2.1 +/- 0.25, beta EP: 1.85 +/- 0.59 fmol/ml, mean +/- SE) and females (beta LPH: 2.8 +/- 0.31; beta EP: 2.41 +/- 0.41 fmol/ml); plasma levels of both hormones increased progressively in both sexes until Puberty 1 stage of sexual maturation, at which time levels were 7.3 +/- 0.78 and 8.69 +/- 1.0 fmol/ml in males and 7.1 +/- 0.34 and 6.76 +/- 0.13 fmol/ml in females; these levels are similar to adult values. A highly significant linear correlation was found between both beta LPH and beta EP concentrations and the age of the subjects; this was not true for ACTH plasma levels. Cortisol plasma levels were similar in all groups. DHAS plasma levels increased progressively from 1-3 yr to the end of sexual maturation when adult values were reached. During prepuberty, DHAS levels were significantly correlated with both beta LPH and beta EP, but not ACTH. These data indicate that plasma beta LPH and beta EP concentrations, in contrast to ACTH levels, increase progressively throughout prepuberty and suggest that the processing of the parent proopiocortin molecule or secretion of the processed peptides from the anterior pituitary (or other sources) may change from early infancy to adulthood. Furthermore, the correlation between both beta LPH and beta EP with DHAS plasma levels in prepuberty suggests a role of proopiocortin-related peptides in adrenarche.