Pituitary and gonadal function in pubertal and adult male rabbits with pseudohermaphroditism secondary to immunization of mothers against testosterone

Pituitary and testicular function was studied in pubertal and adult rabbits with pseudohermaphroditism secondary to immunization of mothers against testosterone. Circulating testosterone, LH and FSH levels showed a developmental pattern during sexual maturation, similar to that observed in controls. Plasma FSH levels were elevated in male pseudohermaphrodites despite normal plasma testosterone concentrations. Fighting, male sexual behaviour and coitus occurred normally as in controls. The testicular response to endogenous elevated LH levels and the pituitary LH and FSH responses to LRH injection and to castration were similar in affected males and in controls. These observations suggest that inhibition of the central effects of androgens during the embryonic and perinatal period has little or no effect on the differentiation and maturation of the hypothalamo-pituitary-testicular axis in rabbit.     

Pituitary gonadal function in adult male rats subjected to crowding

The effect of crowding on the pituitary-gonadal axis was studied in adult male rats. Crowding reduced body weight gain, did not alter relative adrenal weight and increased relative testis weight. Neither basal levels of corticosterone nor its response to acute stress were altered by crowding. Likewise, LH secretion was similar in control and crowded rats. Prolactin levels tended to be lower in crowded than control rats, but they did not reach statistical significance. In contrast, impaired testosterone secretion was observed in crowded rats, at least in part due to reduced Leydig cell responsiveness to gonadotropin release. In addition, some mechanisms other than pituitary-adrenal hyperactivity might be responsible for reduced testosterone secretion during crowding.     

Comparison between beta-cell function and insulin resistance indexes in prepubertal and pubertal obese children

Several methods have been developed to assess insulin resistance (IR), insulin secretion, and sensitivity: some of them, such as the homeostasis model assessment (HOMA) for IR (HOMA IR) and for insulin secretion (HOMA beta cell) and the quantitative insulin sensitivity check index (QUICKI) are based on fasting levels of glucose (fasting G) and insulin (fasting I); others, such as the pancreatic insulin response to glucose (IRG) and the insulin sensitivity index (ISI) are derived from the glycemic and insulinemic responses to the oral glucose tolerance test (OGTT). The aim of the study was to compare these indexes in a large group of prepubertal and pubertal obese subjects and verify whether the data from fasting samples were enough for evaluating IR and insulin secretion or if OGTT was mandatory. A total of 405 obese subjects (221 boys and 184 girls) was studied. Ninty-three were prepubertal (Tanner stage I), 98 early pubertal (stage II to III) and 214 late pubertal (stage IV to V). In each subject, a 120-minute OGTT was performed, and the glycemic (mean blood glucose [MBG]) and insulinemic (mean serum insulin [MSI]) responses, expressed as AUC/120, as well as IRG and ISI were calculated. The fasting I/fasting G ratio (FIGR), HOMA IR, HOMA beta cell, and QUICKI were then measured. FIGR and HOMA IR increased in both sexes during puberty, but in girls, the increase was already evident from stage I to stage II to III, while in boys, it was evident only from stage II to III to stage IV to V. QUICKI decreased in girls at the onset of puberty and was lower than in boys in stage II to III; on the other hand, HOMA beta cell did not show any variation. IRG increased throughout puberty, although it was higher in boys than in girls in stages II to III and IV to V, while ISI decreased at the onset of puberty in boys; HOMA IR correlated with MSI and IRG, and HOMA beta cell with MSI in pubertal subjects only. In conclusion, the indexes deriving from fasting samples, such as FIGR and HOMA IR, proved to be enough for evaluating IR in prepubertal and pubertal obese subjects, as did QUICKI for insulin sensitivity, However, OGTT is still useful for assessing insulin secretion, because IRG is more sensitive in depicting the pubertal variations of IR than HOMA beta cell.     

Pituitary and gonadal function in the infant son of a patient with hypogonadotropic hypogonadism

We have evaluated the pituitary-gonadal function of the infant son of a patient with hypogonadotropic hypogonadism. The father was treated with hCG and FSH to induce fertility. The son had normal external genitalia and his testicular volume increased appropriately during early infancy. Basal and post GnRH gonadotropin levels, as well as testosterone concentrations increased during early infancy. The data suggest that this infant had adequate gonadotropin secretion and testicular function. The patient illustrates the potential usefulness of evaluating the pituitary-gonadal function of male infants suspected of having hypogonadotropic hypogonadism.     

Thyrotoxicosis in prepubertal children compared with pubertal and postpubertal patients

The course of Graves' thyrotoxicosis in 7 prepubertal children (6.4+/-2.4 yr) was compared with that in 21 pubertal (12.5+/-1.1 yr) and 12 postpubertal (16.2+/-0.84 yr) patients. In the prepubertal group the main complaints were weight loss and frequent bowel movements (86%), whereas typical symptoms (irritability, palpitations, heat intolerance, and neck lump) occurred significantly less often (P < 0.01). The most prominent manifestation at diagnosis was accelerated growth and bone maturation: their height SD score was significantly greater than that of the pubertal and postpubertal patients (2.6+/-0.7 us. 0.15+/-0.65 and 0.15+/-0.9, respectively, P < 0.001), and their bone age to chronological age ratio was 1.39+/-0.35 compared with 0.98+/-0.06 in the pubertal children (P = 0.02). T3 levels were also significantly higher than in the other two groups (9.9+/-2.9 nmol/L vs. 6.32+/-1.9 nmol/L and 6.02+/-2.0 nmol/L, P = 0.01). All patients were initially prescribed antithyroid drugs (ATDs). Overall, adverse reactions to ATDs occurred in 35%, with a higher rate among the prepubertal children (71%) than the pubertal (28%) and postpubertal (25%) patients (P = 0.08). Major adverse reactions were noted in two children, both prepubertal. Remission was achieved in 10 patients (28%). Although the rate of remission did not differ among the three groups, time to remission tended to be longer in the prepubertal children (P = 0.09). In conclusion, thyrotoxicosis has an atypical presentation and more severe course in prepubertal children. Considering their adverse reactions to ATD, overall low remission rate, and long period to remission, definitive treatment should be considered earlier in this age group.     

Characterization of serum SHBG isoforms in prepubertal and pubertal girls

OBJECTIVE: SHBG is a circulating glycoprotein that binds dihydrotestosterone, testosterone and oestradiol with high affinity and low capacity. In girls, serum concentrations of SHBG gradually decrease with age due to a true fall in concentration and not to a change in the binding characteristics. The aim of our study was to determine the pattern of serum SHBG isoforms in normal girls in early childhood (ECh), late childhood (LCh) and puberty (P). SUBJECTS: Fifteen normal girls were studied. They were divided into three groups according to their age: ECh: 3.7 +/- 0.9 years (mean +/- SD, n = 5); LCh: 6.4 +/- 0.5 years (n = 5); and P: 13.4 +/- 1.5 years (n = 5). METHODS AND MEASUREMENTS: Preparative isoelectric focusing was used to isolate SHBG isoforms according to their isoelectric point (pI). Three groups of isoforms were isolated: SI: pI 5.2-5.4; SII: pI 5.4-5.6 and SIII: pI 5.6-5.8. Steroid levels in serum were determined by RIA. RESULTS: The relative distribution of SHBG isoforms (% of the total SHBG recovered, mean +/- SD) in the three groups of girls studied was: ECh: SI: 25.8 +/- 9.9, SII: 53 +/- 10.5 and SIII: 21.2 +/- 1.6; LCh: SI: 8.8 +/- 3.1, SII: 58.8 +/- 12.2 and SIII: 31.8 +/- 8.6; P: SI: non-detectable; SII: 51.6 +/- 12.6 and SIII: 48.4 +/- 12.6. CONCLUSION: These results indicate that serum SHBG is more heterogeneous before puberty. A considerable proportion of acidic isoforms are present early in life; they decrease during the prepubertal period and disappear when sexual development is completed. After puberty the glycoprotein is more homogeneous and an important proportion of more basic isoforms is present. At puberty serum SHBG not only falls in concentration but also has an altered sialic acid content which modulates its circulating half-life.     

Circadian rhythms in gonadotropin excretion in prepubertal and pubertal children.

Timed urinary collections were obtained during sleep and waking hours from 27 prepubertal children ranging in age from 2-12 years and from 13 subjects in various stages of puberty, 12-18 years old. The urine samples were extracted with acetone and introduced into FSH and LH radioimmunoassays. Results of the study indicate a significant nocturnal augmentation of LH secretion in pubertal subjects, confirming existing reports using blood sampling techniques. Increased LH and FSH excretion during sleep was also found in prepubertal children.     

Adrenomedullary response to caffeine in prepubertal and pubertal obese subjects.

OBJECTIVE: To investigate whether blunted adrenomedullary responsiveness to stimuli is a primary feature of human obesity in childhood and adolescence DESIGN: Comparison of plasma catecholamine response to caffeine in obese and lean subjects before and after puberty onset. SUBJECTS: Twelve lean prepubertal subjects (six males and six females), 15 prepubertal obese subjects (seven males and eight females), 12 pubertal lean subjects (six males and six females) and 24 pubertal obese subjects (12 males and 12 females) MEASUREMENTS: Plasma levels of Luteinizing hormone (LH), follicle-stimulating hormone (FSH), 17beta-estradiol and testosterone were used to validate Tanner score. Systolic and diastolic blood pressure, pulse rate and plasma catecholamines before and after caffeine administration (4 mg/kg of ideal body weight). RESULTS: Caffeine administration significantly stimulated adrenaline release in all subjects studied. The incremental area of adrenaline response to caffeine, analysed by multiple comparison test, was lower in pubertal obese subjects with respect to other groups. CONCLUSIONS: At variance with what is observed in adulthood obesity, prepubertal obese subjects show an intact adrenomedullary response to caffeine.     

Role of endogenous opiates in pubertal maturation: opposing actions of naltrexone in prepubertal and late pubertal boys

Despite the acute enhancement of gonadotropin output that occurs in the presence of opiate blockade in sexually immature rats and adult men, studies thus far have not demonstrated a role for endogenous opioid peptides during pubertal development in the human. We studied 15 normal boys, 5 sexually developed (Tanner stages IV-V) and 10 sexually infantile, before and after chronic (1-month) administration of a selective micromicron-opiate-receptor antagonist (naltrexone). Gonadotropin secretion was assessed by repetitive venous sampling for 24 h to appraise the pulsatile features of LH release as well as by graded serum LH responses to GnRH. Using an objective pulse detection method, we found that 1) in response to naltrexone, pubertal boys had significantly higher LH pulse frequency (P = 0.044), mean LH concentration (P = 0.0325), and area under the LH vs. time curve (P = 0.0325) compared to those in the basal state; and 2) in sexually immature individuals, naltrexone significantly decreased LH pulse frequency (P = 0.014), mean LH concentration (P = 0.049), and absolute LH peak concentration (P = 0.039) compared to those in the basal state. We suggest that the paradoxical inhibitory response to naltrexone in prepubertal boys represents an agonist-like effect of chronic naltrexone administration. This consideration implies that opiate neural pathways are responsive if not highly sensitive to the agonist effect of opiate substances in the prepubertal male. Accordingly, physiological pubertal progression may be accompanied by decreased sensitivity of the hypothalamic gonadostat to the inhibitory effects of opioid peptides.     

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.     

Plasma adrenal and gonadal sex steroids in human pubertal development.

Plasma free dehydroepiandrosterone (DHA), androstenedione (delta), testosterone (T), dihydrotestosterone (DHT), estrone (E1), and estradiol (E2) were measured by radioimmunoassay in 55 boys and 54 girls 3.5 to 16.3 years of age. Plasma DHA increased significantly between 6 and 8 years of age in girls and between 8 and 10 years of age in boys. A further significant increase was noted between 10 and 12 years of age in both sexes. Delta rose significantly between 8 and 10 years of age in girls and between 10 and 12 years in boys. In contrast, no significant increase in T, DHT, or E1, was noted prior to 12 years of age in both sexes. However, E2 showed a significant increase between 10 and 12 years of age in girls. This early rise in the course of pubertal development of the two sex steroids predominantly of adrenal origin, DHA and delta, and its occurence 1 to 2 years earlier in girls than in boys, as does puberty itself, suggest a possible role for these steroids in the mechanisms involved in triggering the hypothalamic-pituitary-gonadal axis at puberty.     

Effect of short dexamethasone suppression on plasma steroids in prepubertal and pubertal girls

In 40 girls aged from 2 to 14 years, subdivided into groups according to age and pubertal development, and in 6 adult female volunteers, plasma cortisol (F), pregnenolone (delta 5), dehydroepiandrosterone (DHA) progesterone (P), 17-hydroxyprogesterone (17P), androstenedione (A), testosterone (T) and estradiol (E2) were measured before and after short dexamethasone (DXM) suppression. The results confirmed the capacity of DXM to inhibit plasma steroids in all age groups, except T in 2-9 year old and P1 Tanner's stage girls. The percentage suppression of each given steroid was constant over the age groups from 6-9 years to P4-5 Tanner's stage, while lower suppression was found in 17P, P and DHA in 2-5 year old girls and in 17P, DHA and E2 in adult women. These results emphasize the fundamental role of ACTH as the overall stimulating factor of adrenal steroidogenesis but do not negate the possibility of another factor responsible for the development of the adrenal androgen secreting cells throughout prepuberty and puberty.     

Urinary excretion of immunoreactive gonadotropin-releasing hormone-like material in prepubertal and pubertal children.

A urinary product with immunological similarity to Gn-RH has been quantified by radioimmunoassay. The i-Gn-RH-like material apparently has a (partial) structure consistent with the 5 leads to 9 amino acid sequence of hypothalamic Gn-RH. It inhibits the binding of 125I-Gn-RH to anti Gn-RH serum in a manner parallel to synthetic standard, is absorbed by incubation with anti Gn-RH serum, and comigrates with synthetic Gn-RH on Sephadex column chromatography. The concentration of i-Gn-RH-like material is maximal in pubertal males. The total urinary excretion of this substance is two-fold greater in pubertal subjects of both sexes than in prepubertal children. There is no diurnal variation in the excretion of this material. There are significant positive correlations between the urinary content of iGN-RH-like material and LH and FSH. The site of origin, structure and physiological significance of this immunological product remain to be elucidated.     

Plasma androgen responce to hCG stimulation in prepubertal boys with hypospadias and cryptorchidism.

Serum levels of testosterone, androstenedione and dehydroepiandrosterone were measured before and after 5 days of treatment with hCG (2000 IU/d) in 36 prepubertal boys with cryptorchidism and 11 with hypospadias in order to determine whether a defect in androgen synthesis could be a common cause for these disorders. Baseline and stimulated levels of testosterone, androstenedione and dehydroepiandrosterone were similar in patients with unilateral cryptorchidism, monorchism and hypospadias; baseline and stimulated levels of testosterone were lower in boys with bilateral cryptorchidism. Testosterone levels did not correlate with either the anatomical location of the testis in patients with unilateral cryptorchidism or with the site of the urethra in boys with hypospadias. Seven of 36 patients with cryptorchidism had a positive family history of a similar disorder; testosterone levels were similar in patients with and without a family history. It is concluded: 1) in all patients studied, the gonadotropin dependent phase of testosterone production is present; 2) hCG stimulation cannot detect unilateral Leydig cell dysfunction; and 3) in familial cases of cryptorchidism, some factor other than an abnormality in androgen synthesis may be responsible for the hereditary tendency.     

Serum androgens in normal prepubertal and pubertal children and in children with precocious adrenarche.

Serum androgens testosterone (T), testosterone-like-substances (TLS), delta4-androstenedione (delta4), dihydrotestosterone (DHT), dehydroepiandrosterone (DHEA) were measured in 85 normal girls and 101 normal boys grouped according to pubic hair development in Tanner stages I to IV/V. The pattern of change with puberty differed for each androgen. In boys T and TLS rose with the onset of puberty but showed a more abrupt rise later in puberty. DHT also was higher in boys in late puberty but did not demonstrate a steep rise. The other androgens did not show a sex difference at any stage of puberty. While delta4 steroids did not show an increase in the years before onset of puberty, DHEA was significantly higher in prepubertal children over 7 years than in those under 7 years (mean +/- SD 166 +/- 110 vs. 31 +/- 25, P less than 0.005). The most rapid increase of DHEA concentrations was observed with the appearance of pubic hair (Stage II) in boys and girls. This contrasted with the more gradual rise of delta4 in both sexes. The oldest boys and girls (Tanner stages IV/V) had mean concentrations of all androgens in the adult range except for DHT. Twenty-two girls with precocious adrenarche (PA) aged 3-8 years had mean concentrations of T, DHT, delta4 and DHEA that were significantly higher (P less than 0.05) than in prepubertal children, but similar to those of girls in stage II and significantly lower (P less than 0.02) than in late pubertal girls (stage IV/V). Longitudinal studies in 12 of the girls indicated fluctuation of androgen concentrations, especially DHEA, but in general no increase during the years of followup. Precocious adrenarche appears to be a non-progressive disorder associated with an advanced maturation of adrenal androgen to an early pubertal stage. A rise in all androgens measured was correlated with the development of sexual hair.     

Adrenal and gonadal function in obesity

Obesity is associated with multiple alterations of the endocrine systems, including abnormal circulating blood hormone concentrations, due to changes in their pattern of secretion and/or metabolism, altered hormone transport, and/or action at the level of target tissues. There is evidence that alterations of endocrine systems regulating sex hormones and corticosteroids may play a crucial role in the development of obesity, particularly the abdominal phenotype. Obese women are characterized by a condition of sc"functional hyperandrogenism", whereas in males, obesity is associated with reduced T levels and decreased LH secretory pattern from the pituitary. In addition, in both sexes a dysregulation of the hypothalamic-pituitary-adrenal axis has been reported, including both neuroendocrine and peripheral alterations, finally leading to inappropriately higher than normal exposure to F of peripheral tissues, particularly the visceral adipose tissue. By these mechanisms, it can be hypothesized that both visceral fat enlargement and alterations of insulin action and associated metabolic disturbances may develop, therefore predisposing abdominally obese individuals to Type 2 diabetes and cardiovascular disease.