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Structural changes of adrenarche include increased size and mass of the adrenal cortex, and completion of differentiation into the three zones: zona glomerulosa , zona fasciculata , and zona reticularis .
One of the primary functional changes is further differentiation of sex steroid synthesis among the three zones, so that as in adults, the zona glomerlulosa primarily produces mineralocorticoids such as aldosterone, the zona fasciculata primarily produces glucocorticoids such as cortisol, and the zona reticularis primarily produces androgens such as dehydroepiandrosterone, dehydroepiandrosterone sulfate , and androstenedione.
The second important functional change is a steady increase over several years in the daily production of adrenal androgens. A characteristic aspect of early adrenarche is an inhibition of 3β-hydroxysteroid dehydrogenase, the enzyme which mediates the hydroxylation of 17-hydroxypregnenolone to 17-hydroxyprogesterone , and DHEA to androstenedione. Blood levels of DHEA, androstenedione, and especially DHEAS can be measured by physicians as markers of adrenal maturation.
An initiator of adrenarche has not yet been identified. Researchers have unsuccessfully tried to identify a new pituitary peptide, to be called "adrenal androgen stimulating hormone". Others have proposed that adrenarchal maturation is a gradual process intrinsic to the adrenal glands that has no distinct trigger. A third avenue of research is pursuing a possible relationship with either fetal or childhood body mass and related signals such as insulin and leptinLeptin is a protein hormone produced by adipose tissue. Its concentration in the body provides the brain with a rough indication of adipose mass for the purposes of regulating appetite and metabolism. Leptin works by inhibiting the actions of neuropeptide. Many children born small for gestational age (SGA) because of intrauterine growth retardationIntrauterine growth retardation or Intrauterine growth restriction IUGR refers to the condition during pregnancy where a fetus is considered to be too small for its gestational age (generally in the 10th percentile). The condition is generally diagnosed b (IUGR) have an earlier onset of adrenarche, which raises the possibility that timing of adrenarche may be affected by physiological programming in infancy. Adrenarche also occurs prematurely in many children who are overweightObesity is a condition in which the natural energy reserve of a mammal (such as a human), which is stored in fat, is expanded far beyond usual levels to the point where it causes health stress. Obesity in wild animals is relatively rare, but it is common, suggesting a possible relationship with body mass or adiposity signals.
The principal physical consequences of adrenarche are androgen effects, especially pubic hairPubic hair is hair in the frontal genital area and in the crotch, and sometimes at the top of the inside of the legs; these areas form the pubic region. A slang term is bush . Although fine vellus hair is present in the area in childhood, the term pubic h and the change of sweat composition that produces adult body odorBody odor is the smell of sweat and whatever bacteria growing on the body. It is specific to the individual (except for identical twins in the same environment) and can be used to identify people, though this is more often done by dogs than by humans.. Increased oiliness of the skin and hair and mild acne may occur. In most boys, these changes are indistinguishable from early testicular testosterone effects occurring at the beginning of gonadal puberty. In girls, the adrenal androgens of adrenarche produce most of the early androgenic changes of puberty: pubic hair, body odor, skin oiliness, and acne. In most girls the early androgen effects coincide with, or are a few months behind, the earliest estrogenic effects of gonadal puberty (breast development and growth acceleration). As female puberty progresses, the ovaries and peripheral tissues become more important sources of androgens.
Parents and many physicians often infer (incorrectly) the onset of puberty from the first appearance of pubic hair (termed pubarche). However, the independence of adrenarche and gonadal puberty is apparent in children with atypical or abnormal development, when one process may occur without the other. For instance, adrenarche does not occur in many girls with Addison's disease, who will continue to have minimal pubic hair as puberty progresses. Conversely, girls with Turner syndrome will have normal normal adrenarche and normal pubic hair development, but true gonadal puberty never occurs because their ovaries are defective.