Failure of adrenal androgen to induce puberty in familial cytomegalic adrenocortical hypoplasia

nr0b1 (DAX1) loss of function in zebrafish causes hypothalamic defects via abnormal progenitor proliferation and differentiation

The nuclear receptor DAX-1 (encoded by the NR0B1 gene) is presented in the hypothalamic tissues in humans and other vertebrates. Human patients with NR0B1 mutations often have hypothalamic-pituitary defects, but the involvement of NR0B1 in hypothalamic development and function is not well understood. Here, we report the disruption of the nr0b1 gene in zebrafish causes abnormal expression of gonadotropins, a reduction in fertilization rate, and an increase in post-fasting food intake, which is indicative of abnormal hypothalamic functions. We find that loss of nr0b1 increases the number of prodynorphin (pdyn)-expressing neurons but decreases the number of pro-opiomelanocortin (pomcb)-expressing neurons in the zebrafish hypothalamic arcuate region (ARC). Further examination reveals that the proliferation of progenitor cells is reduced in the hypothalamus of nr0b1 mutant embryos accompanying with the decreased expression of genes in the Notch signaling pathway. Additionally, the inhibition of Notch signaling in wild-type embryos increases the number of pdyn neurons, mimicking the nr0b1 mutant phenotype. In contrast, ectopic activation of Notch signaling in nr0b1 mutant embryos decreases the number of pdyn neurons. Taken together, our results suggest that nr0b1 regulates neural progenitor proliferation and maintenance to ensure normal hypothalamic neuron development.

The early dehydroepiandrosterone sulfate rise of adrenarche and the delay of pubarche indicate primary ovarian failure in Turner syndrome

Pubarche without thelarche has been taken as clinical evidence that adrenarche is independent of gonadarche in females. This study examines whether the course of adrenarche [rise of serum dehydroepiandrosterone sulfate (DHEAS)] and pubarche (Tanner stage PH2) is independent from ovarian function. Serum DHEAS levels (n = 867) were longitudinally measured in 111 girls with Turner syndrome between 1990 and 2002. Of these, 22 had spontaneous puberty onset (Tanner stage B2), and 45 had primary ovarian failure (POF). Serum DHEAS levels were assayed by chemiluminescence and compared with those of healthy girls (n = 322; age range, 3-17 yr in both groups). Between the ages of 7 and 17 yr, girls with Turner syndrome had significantly higher age-related DHEAS levels than normal girls (P </= 0.02). Moreover, in the 9- to 15-yr-old girls, DHEAS levels were significantly higher in girls with Turner syndrome and POF than in Turner syndrome girls with spontaneous puberty onset (P </= 0.02). This discrepancy was caused by an earlier adrenarche (DHEAS levels reaching 1.1 micro mol/liter) in Turner syndrome girls with POF, which occurred at a median age of 8.3 yr (80% confidence interval, 6.5-10.4 yr) vs. 10.5 yr (8.6-12.2) and 11.0 yr (8.9-12.6) in Turner syndrome girls with spontaneous puberty onset and normal girls, respectively (P = 0.003). In contrast, pubarche was delayed in Turner syndrome girls with POF [median age, 13.0 yr (80% confidence interval, 10.6-15.0) vs. 11.9 yr (10.5-13.2) in Turner syndrome girls with spontaneous puberty onset (P = 0.02) and 11.6 yr (10.6-12.5) in normal girls]. Primary gonadal failure in Turner syndrome is associated with an earlier onset of adrenarche, but delayed pubarche. These data demonstrate that normal timing of adrenarche is dependent on gonadal function and suggest that normal pubarche is the clinical manifestation of the ovarian conversion of DHEAS to active androgens.

Premature adrenarche--normal variant or forerunner of adult disease?

Adrenarche is the puberty of the adrenal gland. The descriptive term pubarche indicates the appearance of pubic hair, which may be accompanied by axillary hair. This process is considered premature if it occurs before age 8 yr in girls and 9 yr in boys. The chief hormonal product of adrenarche is dehydroepiandrosterone (DHEA) and its sulfated product DHEA-S. The well documented evolution of adrenarche in primates and man is incompatible with either a neutral or harmful role for DHEA and implies most likely a positive role for some aspect of young adult pubertal maturation and developmental maturation. Premature adrenarche has no adverse effects on the onset and progression of gonadarche in final height. Both extra- and intraadrenal factors regulate adrenal androgen secretion. Recent studies have shown that premature adrenarche in childhood may have consequences such as functional ovarian hyperandrogenism, polycystic ovarian syndrome, and insulin resistance in later life, sometimes already recognizable in childhood or adolescence. Premature adrenarche may thus be a forerunner of syndrome X in some children. The association of these endocrine-metabolic abnormalities with reduced fetal growth and their genetic basis remain to be elucidated.

Dehydroepiandrosterone inhibits replication of feline immunodeficiency virus in chronically infected cells

Dehydroepiandrosterone (DHEA) is a steroid hormone produced by the adrenal cortex that serves as an intermediary in sex steroid synthesis. DHEA is produced in abundance by humans and most other warm-blooded animals. Based upon previous reports demonstrating the antiviral and immunostimulatory activities of DHEA and DHEA-sulfate (DHEAS) we sought to determine whether introduction of these compounds would affect replication of feline immunodeficiency virus (FIV) in chronically infected cells. When cell number, cell viability, cellular DNA synthesis, and levels of FIV reverse-transcriptase (RT) were measured in cell cultures treated with various dilutions of DHEA or DHEAS it was found that the production of FIV RT was inhibited by DHEA at levels where cellular viability and DNA synthesis were not affected. At the concentrations tested DHEAS did not inhibit FIV replication or impact on cellular viability or proliferation.

Mutations in the DAX-1 gene give rise to both X-linked adrenal hypoplasia congenita and hypogonadotropic hypogonadism

Adrenal hypoplasia congenita (AHC) is an X-linked disorder characterized by primary adrenal insufficiency. Hypogonadotropic hypogonadism (HHG) is frequently associated with this disorder but is thought not to be caused by the low adrenal androgen levels due to adrenal hypoplasia. It is uncertain whether there are two distinct yet physically linked genes responsible for AHC and HHG or a single gene responsible for both diseases. AHC can occur as a part of a contiguous deletion syndrome together with Duchenne muscular dystrophy (DMD) and/or glycerol kinase deficiency (GKD). From the analysis of deletions, the following gene order has been deduced: Xpter-AHC-GKD-DMD-cen. An AHC critical region of 200-500 kilobases has been defined by physical mapping and partially overlaps with a 160-kilobase dosage-sensitive sex (DSS) reversal critical region. The DAX-1 (DSS-AHC critical region on the X, gene 1) gene was isolated and found to encode a new member of the nuclear hormone receptor family. Here we report that DAX-1 is deleted in 14 patients and point mutations were found in the coding region in DNA from 12 unrelated individuals. All AHC patients over 14 years old and with only point mutations in DAX-1 were also diagnosed with HHG, confirming that the DAX-1 gene is responsible for both X-linked AHC and HHG. But in four sporadic cases and a single familial case, no point mutations were found, suggesting genetic heterogeneity or differential expression of DAX-1.

Contrasting effects of subcutaneous pulsatile GnRH therapy in congenital adrenal hypoplasia and Kallmann's syndrome

A patient with congenital adrenal hypoplasia (AH) and hypogonadotrophic hypogonadism was treated with pulsatile subcutaneous GnRH therapy for 16 weeks in an attempt to induce puberty. No rise in serum LH or FSH concentrations occurred despite increasing doses of GnRH (2.8 micrograms/pulse-22.4 micrograms/pulse). In contrast a similar programme of therapy successfully initiated the biochemical changes of puberty in a patient with Kallmann's syndrome. Both patients before therapy had low basal serum LH and FSH concentrations with blunted LH and FSH responses to GnRH stimulation. After 1 week, serum LH and FSH rose into the normal adult range in the patient with Kallmann's syndrome. This study fails to confirm a previous report which suggested that intermittent low dose GnRH therapy may be of value in inducing puberty in AH. The reasons for the difference of pituitary responsiveness to GnRH in AH and Kallmann's syndrome are unclear at present.

Dissociation of adrenarche and gonadarche in diabetes mellitus

Serum concentrations of testosterone and dehydroepiandrosterone sulphate (DHAS) have been measured in 10 stable insulin-dependent diabetic (IDD) males (chronological age (CA) range 13.0-17.5 years). Their results have been compared with those of a control population of 69 non-diabetic males who presented with mild constitutional growth delay and whose skeletal maturity and pubertal development were similar to the diabetic subjects. Within bone ages (BA) 11.0-14.5 years no significant difference was observed between the serum testosterone concentrations of the diabetic patients and controls: diabetic males, 8.2 (0.3-25) nmol/l (median and range); controls, 7.0 (less than 0.3-23) nmol/l. In contrast, within BA 11.0-14.5 years, the diabetic males had significantly lower serum DHAS concentrations: diabetic males, 1.1 (0.7-4.2) mumol/l; controls, 3.7 (0.7-5.6) mumol/l (P less than 0.001). The serum DHAS concentrations of the diabetic males were also significantly lower than the controls when matched separately for pubic hair and genital development, testicular volume and serum testosterone, (in each comparison P less than 0.02). Serum DHAS concentrations of the diabetic males did not correlate significantly with CA, BA, BA delay (CA-BA), age of onset of diabetes, duration of diabetes, or glycosylated haemoglobin (GHb), but significant correlation was observed between BA delay and duration of diabetes, r = 0.65, P less than 0.05. We conclude that gonadarche appears to proceed despite delayed adrenarche in IDD males. This study presents further evidence in favour of adrenarche and gonadarche being independent physiological events. The causes and clinical significance of low serum DHAS concentrations in adolescent diabetic males remain to be established.

The hypothalamic-pituitary-adrenal axis

Anterior pituitary corticotrophin cells secrete ACTH as part of a larger precursor molecule, pro-opiomelanocortin. Post-translational cleavage of this precursor yields three major peptides: ACTH, beta-LPH and N-POMC. Experiments both in vivo and in vitro suggest that N-POMC may act as a prohormone amplifier for ACTH-induced adrenal steroidogenesis and as regulator of adrenocortical cell growth. The secretion of POMC is under the control of CRF. These findings are discussed in relation to the pathophysiology of corticotrophinoma. The primary defect in this condition appears to reside at the level of the anterior pituitary cell and is readily amenable to treatment by trans-sphenoidal microsurgery. The estimation of plasma ACTH concentrations is proving useful in the monitoring of various clinical conditions including Addison's disease and congenital adrenal hyperplasia.