Suppression of urinary and plasma follicle-stimulating hormone by exogenous estrogens in prepubertal and pubertal children

Luteinizing Hormone Secretion during Gonadotropin-Releasing Hormone Stimulation Tests in Obese Girls with Central Precocious Puberty

OBJECTIVE

Girls with precocious puberty have high luteinizing hormone (LH) levels and advanced bone age. Obese children enter puberty at earlier ages than do non-obese children. We analyzed the effects of obesity on LH secretion during gonadotropin-releasing hormone (GnRH) tests in girls with precocious puberty.

METHODS

A total of 981 subjects with idiopathic precocious puberty who had undergone a GnRH stimulation testing between 2008 and 2014 were included in the study. Subjects were divided into three groups based on body mass index (BMI). Auxological data and gonadotropin levels after the GnRH stimulation test were compared.

RESULTS

In Tanner stage 2 girls, peak stimulated LH levels on GnRH test were 11.9±7.5, 10.4±6.4, and 9.1±6.1 IU/L among normal-weight, overweight, and obese subjects, respectively (p=0.035 for all comparisons). In Tanner stage 3 girls, peak stimulated LH levels were 14.9±10.9, 12.8±7.9, and 9.6±6.0 IU/L, respectively (p=0.022 for all comparisons). However, in Tanner stage 4 girls, peak stimulated LH levels were not significantly different among normal, overweight, and obese children. On multivariate analysis, BMI standard deviation score was significantly and negatively associated with peak LH (β=-1.178, p=0.001).

CONCLUSION

In girls with central precocious puberty, increased BMI was associated with slightly lower peak stimulated LH levels at early pubertal stages (Tanner stages 2 and 3). This association was not valid in Tanner stage 4 girls.

The Role of Blood Spot Dehydroepiandrosterone Sulfate Levels in Adjunct to Hand Wrist Radiographs as Skeletal Maturity Indicator

Objective

The purpose of this study was to find out whether blood spot Dehydroepiandrosterone Sulfate (DHEAs) levels can be used as Skeletal Maturity Indicators (SMI) by correlating them to hand-wrist maturation stages.

Methods

The cross sectional study population consisted of 107 subjects (62 females and 45 males) 5-25 years old. Hand-wrist radiographs were obtained, and the subjects were divided into 5 groups based on the hand-wrist skeletal maturity stages. A blood spot sample was collected and immunoassayed for DHEAs. Analysis of variance was used to compare the mean DHEAs levels corresponding to the hand-wrist maturation stages. Pearson's correlations were performed to determine the DHEAs trends relating to the various hand-wrist maturation stages.

Results

DHEAs levels increased continuously from the prepubertal stage to the acceleration, high growth velocity/peak, deceleration, and postpubertal stages (r=0.17), but the total increase was not found to be statistically significant (p=0.08).

Conclusion

The blood spot DHEAs level cannot be used as an SMI in individuals. Nevertheless, it can be used in conjunction with hand wrist radiographs to predict and validate the skeletal maturation. The role of DHEAs in the termination of growth and residual growth may be a subject for further research.

Impact of body mass index on luteinizing hormone secretion in gonadotropin-releasing hormone stimulation tests of boys experiencing precocious puberty

OBJECTIVE

Excess adiposity may influence various aspects of pubertal development, including the timing of pubertal initiation and hormonal parameters during puberty. The aim of the study was to evaluate the impact of body mass index (BMI) on luteinizing hormone (LH) secretion to gonadotropin-releasing hormone (GnRH) stimulation test in boys with precocious puberty.

METHODS

Boys with precocious puberty, who were normal weight, overweight, and obese underwent GnRH stimulation tests between 2003 and 2010. Subjects were classified as normal weight (BMI ≥5th percentile and BMI <85th percentile), overweight (BMI ≥85th percentile and BMI <95th percentile), and obese (BMI ≥95th percentile).

RESULTS

Of 56 children whose data were included in the final analysis, mean age at diagnosis was 8.7 ± 1.0 years. The majority of boys were of normal weight (n = 28, 50%), while 15 children (26%) were overweight, and 13 (23%) obese. Peak LH levels after GnRH stimulation were 19.8 ± 8.8, 9.0 ± 3.5, and 8.1 ± 4.0 mIU/ml among normal weight, overweight, and obese subjects, respectively (p < 0.001 for all comparisons). By multivariate analysis, there was a significant negative association of BMI with peak-stimulated LH level.

CONCLUSIONS

The higher BMI is associated with lower LH response to the GnRH stimulation test in boys experiencing precocious puberty. In boys with precocious puberty, BMI should be considered when interpreting GnRH stimulation test.

Neuronal plasticity and seasonal reproduction in sheep

Seasonal reproduction represents a naturally occurring example of functional plasticity in the adult brain as it reflects changes in neuroendocrine pathways controlling gonadotropin-releasing hormone (GnRH) secretion and, in particular, the responsiveness of GnRH neurons to estradiol negative feedback. Structural plasticity within this neural circuitry may, in part, be responsible for seasonal switches in the negative feedback control of GnRH secretion that underlie annual reproductive transitions. We review evidence for structural changes in the circuitry responsible for seasonal inhibition of GnRH secretion in sheep. These include changes in synaptic inputs onto GnRH neurons, as well as onto dopamine neurons in the A15 cell group, a nucleus that plays a key role in estradiol negative feedback. We also present preliminary data suggesting a role for neurotrophins and neurotrophin receptors as an early mechanistic step in the plasticity that accompanies seasonal reproductive transitions in sheep. Finally, we review recent evidence suggesting that kisspeptin cells of the arcuate nucleus constitute a critical intermediary in the control of seasonal reproduction. Although a majority of the data for a role of neuronal plasticity in seasonal reproduction has come from the sheep model, the players and principles are likely to have relevance for reproduction in a wide variety of vertebrates, including humans, and in both health and disease.

Timing and completion of puberty in female mice depend on estrogen receptor alpha-signaling in kisspeptin neurons

Puberty onset is initiated by activation of neurons that secrete gonadotropin-releasing hormone (GnRH). The timing and progression of puberty may depend upon temporal coordination of two opposing central mechanisms--a restraint of GnRH secretion before puberty onset, followed by enhanced stimulation of GnRH release to complete reproductive maturation during puberty. Neuronal estrogen receptor α (ERα) has been implicated in both controls; however, the underlying neural circuits are not well understood. Here we test whether these mechanisms are mediated by neurons that express kisspeptin, a neuropeptide that modulates GnRH neurosecretion. Strikingly, conditional ablation of ERα in kisspeptin neurons results in a dramatic advancement of puberty onset in female mice. Furthermore, subsequent pubertal maturation is arrested in these animals, as they fail to acquire normal ovulatory cyclicity. We show that the temporal coordination of juvenile restraint and subsequent pubertal activation is likely mediated by ERα in two separate kisspeptin neuronal populations in the hypothalamus.

Maturation of sleep-wake gonadotrophin-releasing hormone secretion across puberty in girls: potential mechanisms and relevance to the pathogenesis of polycystic ovary syndrome

Neuroendocrine mechanisms underlying the progression of sleep-wake gonadotrophin-releasing hormone (GnRH) pulse secretion across puberty have remained enigmatic. Here, the changes of sleep-wake luteinising hormone (LH) (and, by inference, GnRH) pulse secretion across puberty in normal girls are reviewed, primarily focusing on available human data. It is suggested that the primary control of GnRH pulse frequency changes across puberty, with sex steroid feedback exerting minimal control during childhood, but primary control during adulthood. A working model is proposed regarding how such a transfer of GnRH pulse frequency control may partly account for the prominent day-night differences of GnRH pulse frequency characteristic of puberty. How this model may be relevant to the genesis of abnormal GnRH secretion in peripubertal girls with hyperandrogenaemia is then described.

Modulation of gonadotropin-releasing hormone pulse generator sensitivity to progesterone inhibition in hyperandrogenic adolescent girls--implications for regulation of pubertal maturation

CONTEXT

Adult women with polycystic ovary syndrome (PCOS) have decreased GnRH pulse generator sensitivity to progesterone (P)-mediated slowing. This defect is androgen mediated because it is reversed with androgen receptor blockade. Adolescent hyperandrogenism often precedes PCOS.

OBJECTIVE

The aim of the study was to evaluate GnRH pulse generator sensitivity to P-mediated slowing in normal and hyperandrogenic girls.

DESIGN

We conducted a controlled interventional study.

SETTING

The study was conducted in a general clinical research center.

PARTICIPANTS

A total of 26 normal control (NC) and 26 hyperandrogenic (HA) girls were studied.

INTERVENTION

Frequent blood sampling was performed for 11 h to assess LH pulse frequency before and after 7 d of oral estradiol and P.

MAIN OUTCOME MEASURE

We measured the slope of the percentage reduction in LH pulse frequency as a function of d 7 P (slope).

RESULTS

Overall, Tanner 3-5 HA subjects were less sensitive to P-mediated slowing than Tanner 3-5 NC (slope, 4.7 +/- 3.4 vs. 10.3 +/- 7.7; P = 0.006). However, there was variability in the responses of HA subjects; 15 had P sensitivities within the range seen in NC, whereas nine were relatively P insensitive. The two groups had similar testosterone levels. Fasting insulin levels were higher in P-insensitive HA girls (39.6 +/- 30.6 vs. 22.2 +/- 13.9 microIU/ml; P = 0.02), and there was an inverse relationship between fasting insulin and P sensitivity in HA girls (P = 0.02). Tanner 1-2 NC had lower testosterone levels and were more P sensitive than Tanner 3-5 NC (slope, 19.3 +/- 5.8; P = 0.04).

CONCLUSIONS

Hyperandrogenism is variably associated with reduced GnRH pulse generator sensitivity to P-mediated slowing during adolescence. In addition to androgen levels, insulin resistance may modulate P sensitivity.

Progesterone acutely increases LH pulse amplitude but does not acutely influence nocturnal LH pulse frequency slowing during the late follicular phase in women

Progesterone (P) is the primary effector of LH (and by inference gonadotropin-releasing hormone) pulse frequency slowing in cycling women, but the time course of this action is unclear. We hypothesized that P administration to estradiol (E2)-pretreated women would slow LH pulse frequency within 12 h. We studied eight normally cycling women in two separate cycles (follicular phase, cycle days 7-11). After 3 days of E2 pretreatment (0.2 mg/day via transdermal patches), a 25-h blood sampling protocol (starting at 0800) was performed to define LH pulsatility. Oral micronized P (100 mg) or placebo (PBO) was administered at 1800 in a randomized, double-blind fashion, with treatment crossover occurring during a subsequent cycle. The 10-h mean P concentration increased from 0.6+/-0.1 ng/ml before P (0800-1800) to 3.9+/-0.3 ng/ml after P administration (2200-0800, P<0.01). Ten-hour mean LH interpulse interval increased significantly after both P and PBO administration, with no significant difference between P and PBO. In contrast, mean LH, LH amplitude, and mean FSH increased significantly within 4 h of P administration, but not after PBO. We conclude that, in E2-pretreated women in the late follicular phase, 1) nocturnal LH pulse frequency is not acutely (within 12 h) influenced by P administration; 2) an acute increase in P causes pronounced augmentation of gonadotropin pulse amplitude within 4 h; and 3) LH pulse frequency slows overnight during the second half of the follicular phase.

The origins and sequelae of abnormal neuroendocrine function in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common clinical disorder characterized by ovulatory dysfunction and hyperandrogenaemia. A neuroendocrine hallmark of PCOS is persistently rapid LH (GnRH) pulsatility, which favours pituitary synthesis of LH over that of FSH and contributes to the increased LH concentrations and LH : FSH ratios typical of PCOS. Inadequate FSH levels contribute to impaired follicular development, whereas elevated LH levels augment ovarian androgen production. Whereas luteal phase elevations in progesterone normally slow GnRH pulse frequency, women with PCOS do not experience normal progesterone-mediated slowing, due in part to impaired hypothalamic progesterone sensitivity. This reduction in hypothalamic progesterone sensitivity appears to be mediated by elevated androgens because sensitivity can be restored with the androgen receptor blocker flutamide. The ovulatory and hormonal abnormalities associated with PCOS generally present during puberty, typically associated with hyperandrogenaemia. Along with elevated LH concentration and pulsatility, some girls with hyperandrogenaemia have impaired hypothalamic progesterone sensitivity similar to that seen in adult women with PCOS. We propose that peripubertal hyperandrogenaemia may lead to persistently rapid GnRH pulse frequency via impaired hypothalamic feedback inhibition. The subsequent abnormalities in gonadotropin secretion, androgen production and ovulatory function may support progression towards the adult PCOS phenotype.

Hypothalamic-pituitary gonadal axis and immune response imbalance during chronic filarial infections

Bi-directional relationships operate between the hypothalamic-pituitary-gonadal axis and the immune system. Cytokines, peptide hormones and their shared receptors/ligands are used as a common biological language for communication within and between the immune and neuroendocrine systems. Such communication suggests an immunoregulatory role for the brain and a sensory function for the immune system. We used a radioimmunoassay to measure the concentrations of steroid hormones (cortisol, testosterone, estradiol and progesterone) and pituitary hormones [follicle stimulating hormone (FSH), luteinizing hormone (LH) human chorionic gonadotropin (HCG) and prolactin] in peripheral blood plasma from 78 young Gabonese women with chronic filarial infections. We used an enzyme-linked immunosorbent assay to determine the concentrations of four proinflammatory cytokines [tumor necrosis factor-alpha (TNF-alpha), gamma interferon (IFN-gamma), interleukin-1 (IL-1) and IL-6] in the same plasma samples. Progesterone was unchanged and all other steroid hormone plasma concentrations were lower in microfilaremic women than in amicrofilaremic women. The concentration of LH was higher in amicrofilaremic women, whereas the prolactin concentration was higher in microfilaremics. The plasma concentrations of TNF-alpha, IFN-gamma, IL-1 and IL-6 were higher in microfilaremic women. A strong negative correlation was found between the steroid and pituitary hormones and the pro-inflammatory cytokines. Conversely, a strong positive correlation was found between prolactin and the same cytokines. These data provide first evidence of immune system and hormonal system disturbance during chronic filarial infections and suggest that the observed imbalance should be taken into account in the diagnosis and treatment of filarial infections.

Neuroendocrine facets of human puberty

The unfolding of pubertal growth and maturation entails multisystem collaboration. Most notably, the outflow of gonadotropins and growth hormone (GH) proceeds both independently and jointly. The current update highlights this unique dependency in the human.

Neurobiological mechanisms of the onset of puberty in primates

An increase in pulsatile release of LHRH is essential for the onset of puberty. However, the mechanism controlling the pubertal increase in LHRH release is still unclear. In primates the LHRH neurosecretory system is already active during the neonatal period but subsequently enters a dormant state in the juvenile/prepubertal period. Neither gonadal steroid hormones nor the absence of facilitatory neuronal inputs to LHRH neurons is responsible for the low levels of LHRH release before the onset of puberty in primates. Recent studies suggest that during the prepubertal period an inhibitory neuronal system suppresses LHRH release and that during the subsequent maturation of the hypothalamus this prepubertal inhibition is removed, allowing the adult pattern of pulsatile LHRH release. In fact, y-aminobutyric acid (GABA) appears to be an inhibitory neurotransmitter responsible for restricting LHRH release before the onset of puberty in female rhesus monkeys. In addition, it appears that the reduction in tonic GABA inhibition allows an increase in the release of glutamate as well as other neurotransmitters, which contributes to the increase in pubertal LHRH release. In this review, developmental changes in several neurotransmitter systems controlling pulsatile LHRH release are extensively reviewed.

Inverse relationship between serum inhibin B and FSH levels in prepubertal boys with cryptorchidism

To investigate the gonadal control of FSH secretion in prepuberty, we studied the relationship between circulating inhibin B and FSH levels in 16 prepubertal boys with cryptorchidism (age range, 1-8 y). The effect of Leydig cell stimulation on the secretion of inhibin B, sex steroids, and FSH was investigated in nine boys who were given human chorionic gonadotropin (hCG) treatment. In these boys, serum inhibin B, testosterone, estradiol, and gonadotropin levels were measured before and on the fourth day of the last (third) hCG injection, given at 1-wk intervals. Except for one boy with both high inhibin B and FSH concentrations, basal serum levels of these hormones correlated negatively (r(s) = -0.79, n = 15, p < 0.005). This inverse relationship remained significant in the subgroup of boys younger than 2 y of age (r(s) = -0.84, n = 11, p = 0.008) who also had greater variance of serum FSH concentrations than 14 control boys of similar age with normally located testes (p < 0.01). hCG stimulation increased serum testosterone and suppressed serum FSH concentrations in each boy (n = 9, p < 0.005). In the four oldest subjects, the serum inhibin B level increased from the mean of 91 to 135 pg/mL (p < 0.05). These findings suggest that inhibin B regulates FSH secretion in early childhood. Moreover, the hCG-induced suppression of FSH secretion was probably mediated by sex steroids rather than by inhibin B. Finally, the increase in serum inhibin B concentration during the hCG treatment was likely to be indirect via Leydig cell-Sertoli cell or Sertoli cell-germ cell interaction(s).

Neuroendocrine control processes. Pubertal onset and progression

This discussion has outlined current concepts in neuroendocrinologic control of pubertal onset and progression. Central nervous system regulation of the arcuate nucleus (ventromedial hypothalamus) pulse generator that subsequently controls pituitary gonadotropin synthesis and secretion has been highlighted. Significant investigative issues that deserve assessment in the next several years include the following: 1. Systematic neuropharmacologic, electrophysiologic, and anatomic assessment of the hypothalamic arcuate nucleus. These assessments would include the use of recombinant DNA technology to probe cellular regulation of GnRH production. 2. Physiologically oriented examination of hypothalamic GnRH synthesis and secretion, along with function in the remaining reproductive endocrine system, during situations of nutritional impairment and excessive energy utilization and psychologic stress. 3. Further assessment of the neurophysiologic inhibition of GnRH production during childhood and the late prepubertal reactivation of the arcuate nucleus pulse generator. Roles of opioids, dopamine, other neurotransmitters, and metabolic signals remain to be clarified. 4. Exploration of regulators of hypothalamic, pituitary, and gonadal function when pulsatile GnRH administration has replaced the usual hypothalamic mechanisms. Pituitary-gonadal interactions may be independently assessed. 5. Assessment of pubertal growth, endocrine function, and neuropharmacologic control mechanisms in circumstances of chemical removal of pituitary gonadotrope function by GnRH agonists or antagonists. 6. Concordance and discordance of potency estimates of gonadotropins made by bioassay and immunoassay. The biologic basis for qualitative changes in bioassayable levels of LH and FSH, often related to carbohydrate content of the glycoprotein, may help to explain changes of gonadal function during the pubertal process. The potential for significant molecular heterogeneity of the gonadotropins is recognized and suggests substantial posttranslational changes of LH and FSH. 7. A cogent delineation of the hormonal, nutritional, and energy regulators of the pubertal growth spurt, though not discussed in this manuscript, remains to be accomplished. The relationship between pituitary gonadotropins and growth hormone, sex steroids, and the various peptide growth factors, especially the relationship between the growth factors and intragonadal steroidogenesis and germ-cell production, remain to be resolved. The importance of local production and action of peptide-growth factors in diverse tissues, skeletal and other, is being increasingly recognized.(ABSTRACT TRUNCATED AT 400 WORDS)

Plasma dehydroepiandrosterone, its sulfate, testosterone and FSH during puberty of African children in Gabon

Plasma levels of dehydroepiandrosterone (DHEA), its sulfate (DHEAS), testosterone (T) and follicle stimulating hormone (FSH) were measured by radioimmunoassay in 111 schoolboys and 95 schoolgirls from 7 to 18 years. 68 male and 55 female adults aged from 19 to 25 were also investigated. Results are expressed as the mean +/- SD, DHEA was the first hormone to vary showing a significant mean increase between the 10 and 11 year age groups of both boys and girls. Higher levels were observed in the age 12 group (boys 164.70 +/- 60.74; girls 256.60 +/- 145.40 ng/dl) but were followed by a significant decrease in both 13 year old groups. Similar increases followed by decreases were also noted for DHEAS, although the increase started between 11 and 12 years and reached a maximum at 13. An abrupt increase in FSH levels between 11 and 12 years followed by a plateau through 15-18 years, was observed for boys and girls. As expected, T levels increasing significantly in boys with the initial rise between 11 and 12 and a climb through to the 15-18 age group. Our results suggest a late plasma DHEAS secretion with adult levels attained after age 19. Menarche was also found to be late.

Sexual maturation of the hypothalamus: pathophysiological aspects and clinical implications

Sexual maturation in humans begins early in fetal life and culminates in adulthood when the gonads have acquired a full capacity for reproduction. It is remarkable that during this long process, the pituitary gonadal function, hence its hypothalamic control presents an alternative of activation and inhibition periods, during which the interrelations of the 3 components of the hypothalamic-pituitary-gonadal axis change gradually and inversely. The ontogeny of the hypothalamic-pituitary system, the varying activity of the reproductive endocrine system throughout sexual maturation and the developmental changes in the interrelations of the hypothalamic-pituitary-gonadal axis are reviewed: the most striking feature of human sexual development is the long inhibition of hypothalamo-pituitary function during childhood. Much indirect evidence points to the determining role of the CNS in the maturation of hypothalamic function: the occurrence of rhythms of secretion, the amplitude of secretions and peripubertal specific sleep-related nycthemeral rhythm of secretion at the onset of puberty. Despite the reality of a negative feedback control, these changes do occur independently of gonadal secretions since they are observed (qualitatively if not strictly quantitatively) in agonadal children. It is likely that neurotransmitters (dopamine, serotonine) and opiates have an inhibitory effect on Gn-RH release. But we still don't know their evolution during sexual maturation. It does not appear that melatonine plays any determinant role in the onset of human puberty. The clinical implications of our present understanding of the physiological events occurring during sexual maturation are several. Considering the major problems related to abnormal sexual maturation we will discuss successively: (1) diagnosis of hypogonadotrophic hypogonadism in early infancy; (2) differential diagnosis between premature thelarche and true sexual precocity; (3) the usefulness of endocrine investigations in the evaluation of hypothalamic-pituitary function; and (4) the new developments in the treatment of precocious puberty, delayed puberty or hypogonadism.

Oestrone sulphate, adipose tissue, and breast cancer

Oestrone sulphate, the oestrogen in highest concentration in the plasma, may play a role in the induction and growth of breast cancers. By enzymolysis and radioimmunoassay, oestrone sulphate concentrations were measured in 3 biological fluids. High concentrations of the conjugate (up to 775 nmol/l) were detected in breast cyst fluids from some premenopausal women, the concentrations in blood plasma (0.91-4.45 nmol/l) being much lower. Concentrations in the plasmas from postmenopausal women with (0.23-4.63 nmol/l) or without (0.18-1.27 nmol/l) breast cancer were still lower. Oestrone sulphate concentration in cow's milk or cream (0.49-0.67 nmol/l) was also low: dietary intake in these fluids is probably of little consequence. The capacity of breast tissues for hydrolysis of oestrone sulphate was examined in two ways: In tissue slices incubated with 85 pM (3H) oestrone sulphate solution at 37 degrees C, cancers (131-412 fmol/g tissue/hr) and adipose tissues (23-132 fmol/g tissue/hr) hydrolysed significantly more sulphate than did benign tissues (1-36 fmol/g tissue/hr). In tissue homogenates incubated with 5-25 microM [3H] oestrone sulphate at 37 degrees much higher capacities for hydrolysis (nmol/g tissue/hr) were demonstrated with a Km of 2-16.5 microM: cancers (34-394) and benign tissues (9-485) had significantly higher sulphatase activities than adipose tissues (9-39). On a protein basis, however, the sulphatase activities in the 3 tissues were comparable. It is concluded that oestrone sulphate is present in breast cysts and blood plasma and that in vitro, the conjugated hormone can be hydrolysed by breast tissues. The biological significance of these findings in vivo remains to be established.

The assessment of hypothalamic pituitary maturation during puberty with a combined clomiphene citrate/GnRH test in boys

The diagnosis of idiopathic delayed pubertal development in boys is difficult. A single GnRH test does not give information concerning hypothalamic maturity. After one week clomiphene citrate administration the LH reaction pattern is enhanced in subjects with maturing and depressed in subjects with immature hypothalamic-pituitary function.

Gonadal and adrenal secretion of dehydroepiandrosterone sulfate in prepubertal and pubertal subjects

The Authors have evaluated the relationship between the secretion of dehydroepiandrosterone sulfate (DHA-S) by the adrenal glands and by the gonads in a group of prepubertal and pubertal subjects ("short normal"), both males and females. In the male subjects of a hCG test and an ACTH test were performed; in the female subjects only the latter test was carried out. The behavior of DHA-S under basal conditions was also assessed in both sexes and related to bone age and chronological age in the prepubertal period and during the early stages of puberty. Plasma levels of DHA-S in both sexes increase progressively with chronological age and bone age. A negative correlation was found between DHA-S and bone delay (expressed in percent relative to chronological age) in prepubertal subjects, both males and females. A significant increase in DHA-S after hCG stimulation was found both in prepubertal and pubertal boys. After ACTH stimulation DHA-S increased significantly in prepubertal and pubertal males and females; throughout the test no difference was found between prepubertal and pubertal subjects nor between male and female subjects. Our data confirm that DHA-S is produced both by the adrenals and by the testes.

Testosterone concentrations in spermatic venous blood plasma of prepubertal boys

Testosterone concentration has been measured in spermatic and peripheral venous plasma obtained during surgery from a total of 25 prepubertal boys affected either by inguinal hernia (Group I; N = 6; age range 2-8 years) or unilateral undescended testis (Group II; N = 19; age range 5-11 years). Median spermatic venous testosterone level was 58.7 ng/dl) (range 14.0--120.8 ng/dl) in Group I and 43.2 ng/dl (range 12..2-267.5 ng/dl) in Group II; median peripheral testosterone level was 4.9 ng/dl (range 2.3-15.4 ng/dl) and 5.6 ng/dl (range 1.1-89.3 ng/dl) in Group I and II, respectively. The difference between the spermatic and peripheral level was statistically significant in both groups (P less than 0.01 in Group I and P less than 0.001 in Group II). These results indicate that the prepubertal human testis secretes testosterone, even if in a very low amount. It is also suggested that this secretion can be responsible for LH inhibition in prepubertal boys.

Hypothalamic-pituitary responses to high concentrations of gonadal steroids in a three-month-old infant with a feminizing gonadal stromal tumor

A 3-month-old female infant feminized by an ovarian stromal tumor is presented. Clinicopathologic aspects of such tumors occurring in infancy are discussed. In addition, the evaluation of hypothalamic-pituitary function preoperatively and postoperatively are presented. In the preoperative, high-steroid environment, both basal and stimulated secretion of follicle-stimulating hormone (FSH) was suppressed. Secretion of luteinizing hormone (LH) was normal. Following surgical castration, stimulated secretion of both gonadotropins clearly increased. These findings suggest an active but less sensitive negative feedback mechanism for FSH than for LH during infancy, i.e., high concentrations of gonadal steroids are necessary to maximally suppress FSH secretion while normal steroid concentrations appear to maximally suppress LH secretion. Developmental changes in hypothalamic-pituitary sensitivity to negative feedback controls are discussed in light of these findings.

Adrenal and gonadal steroids and pituitary response to LHRH in girls. II. Precocious puberty

Three baby girls between 22 and 30 months of age, presenting with isosexual idiopathic precocious puberty apparently not due to any organic cause, were studied. Basal levels of plasma steroids of adrenal and gonadal origin, circadian rhythm of plasma cortisol, and pituitary response to 25 microgram of LHRH were evaluated. All cases were characterized by high levels of plasma gonadotropins and by a marked response to exogenous LHRH. Normal cortisol circadia rhythm was found in all cases, one of which characterized by slightly raised plasma values. The other adrenal steroids were all higher than those expected for the chronological age, corresponding to those of 5-6 years old girls. On the other hand, steroids of both adrenal and ovarian (A, T) or mainly ovarian origin (E2) and DHT were all found to be higher than those normally reported in girls at stage 2 of sexual development. These data indicate a hypersecretion of gonadotropins in idiopathic isosexual precocious puberty, with a marked gonadal steroidogenetic response. The secretion of adrenal androgens does not appear to have an important role in the etiology of this condition.

Adrenal and gonadal steroids and pituitary response to LHRH in girls. I. Delayed puberty

Plasma levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), dehydroepiandrosterone (DHA), dehydroepiandrosterone-sulphate (DHA-S), 17-hydroxyprogesterone (17P), androstenedione (A), testosterone (T), dihydrotestosterone (DHT) and estradiol (E2) were measured in basal conditions in eleven young women from 16 to 25 years of age characterized by delayed puberty. The gonadotropin response to LHRH (50 microgram iv) was also tested in these cases. The results, as far as gonadotropins and E2 are concerned, indicate that delayed pubertyin girls is a heterogeneous disorder: an impairment in the negative feedback between E2 and FSH coexists with a reduced ovarian response to endogenous gonadotropins. All cases showed evidence of a more or less pronounced delayed adrenarche, which was demonstrated by the markedly reduced levels of DHA-S and DHA (with the exception of this latter steroid in two cases with idiopathic hirsutism). Furthermore, the very low plasma progesterone (P) levels in all cases suggest the existence of impaired delta 5 - delta 4 isomerase activity in the adrenal cells. Despite the low levels of A and T, DHT is within the upper limits of the normal range in all cases.

Growth hormone excess and sexual precocity in polyostotic fibrous dysplasia (McCune-Albright syndrome): evidence for abnormal hypothalamic function

A 5-5/12-year-old boy with gigantism and precocious puberty associated with the McCune-Albright syndrome is presented. Serum concentrations of growth hormone were extremely elevated (128-163 ng/ml) and were not suppressed by hyperglycemia or chlorpromazine. Serum LH (7.4 +/- 1.0 SD mIU/ml) and FSH (5.3 +/- 0.3 SD mIU/ml) concentrations were in the range observed in midpuberty. The secretion pattern of LH was episodic. The administration of estradiol suppressed the secretion of FSH and had an apparent positive feedback effect on release of LH. These findings are compatible with abnormal hypothalamic function as the mechanism for the endocrinopathies associated with the McCune-Albright syndrome.

Hormonal changes of adolescence

Pubescence is characterized by many physical, emotional, and hormonal changes. The hypothalamic-pituitary-gonadal system is maintained in a dormant state (with a low level of activity) during prepubertal years by higher central nervous system inhibition. With the onset of adolescence, the reproductive endocrine system becomes increasingly active. The attainment of sexual maturity in terms of secondary sexual characteristics, the production of spermatozoa in the male, and the cyclical female pattern with release of ova are end-points of the developmental process.

Hormonal mechanisms in the onset of puberty

Sexual maturation is associated with increasing levels of sex steroids. These steroidal events are the result of complex changes that occur at several functional levels including the hypothalamus, pituitary, gonad and adrenal gland. These changes, as outlined in Table 3, are often interrelated.

While considerable progress has been made in our understanding of the hormonal events associated with sexual maturation, many important questions remain unanswered. Further intensive investigation will be required before we have a lucid understanding of the physiological basis of the sequence of hormonal events which occur during the pubertal process.

Sexual precocity associated with a hypothalamic tumour. Effects of sex hormone therapy

A case of sexual precocity of unusually early onset and associated with a hypothalamic tumour is described. The effects of ethinyl oestradiol and medroxyprogesterone acetate treatment have been monitored by plasma testosterone, FSH, and LH estimations. The results suggested a partial suppression of the tumour's influence, the mechanism of which is discussed.

Secretion of unconjugated androgens and estrogens by the normal and abnormal human testis before and after human chorionic gonadotropin

The secretion of androgens and estrogens by normal and abnormal testes was compared by determining the concentrations of dehydroepiandrosterone (DHEA), androstenedione (Delta(4)A), testosterone (T), estrone (E(1)), and 17beta-estradiol (E(2)) in peripheral and spermatic venous plasma samples from 14 normal men and 5 men with unilateral testicular atrophy. Four normal men and one patient with unilateral atrophy of the testis were given human chorionic gonadotropin (HCG) before surgery. Plasma estrogens were determined by radioimmunoassay; plasma androgens were measured by the double-isotope dilution derivative technique. Peripheral concentrations of these steroids before and after HCG were similar in both the normal men and the patients with unilateral testicular atrophy. In normal men, the mean +/-SE spermatic venous concentrations were DHEA, 73.1+/-11.7 ng/ml; Delta(4)A, 30.7+/-7.9 ng/ml; T, 751+/-114 ng/ml; E(1), 306+/-55 pg/ml; and E(2), 1298+/-216 pg/ml. Three of four subjects with unilateral testicular atrophy had greatly diminished spermatic venous levels of androgens and estrogens. HCG treatment increased the testicular secretion of DHEA and T fivefold, Delta(4)A threefold, E(1) sixfold, and E(2) eightfold in normal men. In the single subject with an atrophic testis who received HCG, the spermatic venous concentrations of androgens and estrogens were much less than in normal men similarly treated. We conclude that: (a) E(1) is secreted by the human testis, but testicular secretion of E(1) accounts for less than 5% of E(1) production in normal men; (b) HCG stimulation produces increases in spermatic venous estrogens equal to or greater than the changes in androgens, including testosterone; and (c) strikingly decreased secretion of androgen and estrogen by unilateral atrophic human tests cannot be appreciated by analyses of peripheral steroid concentrations.