Aromatase Deficiency Research Articles

Congenital Hypopituitarism as a Cause of Undetectable Estriol Levels in the Maternal Triple-Marker Screen

We are reporting a child with congenital panhypopituitarism, in whom deficient fetal steroidogenesis was suspected prenatally because of undetectable estriol levels measured in the maternal triple-marker screen. No fetal abnormalities were detected by ultrasonography. Amniocentesis demonstrated a normal 46,XX karyotype. Measurement of maternal urinary steroids failed to show elevation in the excretion of the major precursor for estriol, 16 alpha-hydroxydehydroepiandrosterone, indicating that the fetus did not have steroid sulfatase deficiency (placental sulfatase deficiency), the most common genetic cause of extremely low estriol. The steroid analysis excluded other rare single gene defects, including aromatase deficiency and 17 alpha-hydroxylase deficiency. We therefore suspected that the cause of low estriol in this fetus was adrenal insufficiency. Postnatal evaluation was consistent with panhypopituitarism, characterized by deficiency of all anterior pituitary hormones. Because this screen is now offered to more than half the pregnant women in the United States, reports of low estriol levels have become increasingly common. Therefore, it is essential that physicians be familiar with the various etiologies, perform the appropriate antenatal evaluation to determine the specific cause, and closely monitor both mother and child ante- and postnatally.

RETRACTED: Neurological effects of aromatase deficiency in the mouse

In the brain, the conversion from androgen into estrogen is an important process for the differentiation of the brain function in male rodents. The aromatase is expressed in some nucleus of the brain. To assess the functional significance of the aromatase gene in development and activation of sex-specific behavior, we analyzed behavioral phenotypes of the aromatase knockout (ArKO) male mice. ArKO males obviously decreased their fertility and showed deficits in male sexual behavior including mount, intromission and ejaculation. Noncontact penile erection was not significantly affected by defect of the aromatase gene. A reduction of aggressive behavior against male intruders was also observed in ArKO males, while they tend to exhibit aggression toward estrous females during male copulatory tests. Moreover, the infanticide toward the pups was observed in the ArKO males, whereas characteristic parental behavior, but not infanticide was observed in wild-type males. These results indicate that aromatase gene expression is a critical step not only for motivational and consummatory aspects of male sexual behavior, but also for aggressive and parental behaviors in male mice.

Role of estrogen and androgen in pubertal skeletal physiology.

Since both estrogen and androgen are present in each sex, it has been difficult to discern the exact role that each sex steroid plays in skeletal physiology. However, studying clinical syndromes in which there is either only estrogen or androgen action has allowed us to gain insight into the unique role that each sex steroid plays in the growing skeleton. In complete androgen insensitivity syndrome (AIS) the only functional sex steroid receptor is that for estrogen. Effected XY females have a pubertal growth spurt that is typical of normal females, both in magnitude and timing. Individuals with AIS have a mild reduction in bone density but it is difficult to distinguish whether this is the result of androgen resistance or estrogen deficiency. These observations suggest that estrogen action only is sufficient to induce a normal pubertal growth spurt, epiphyseal maturation, and near normal bone mineral accretion in women. Until recently, the skeletal effects of estrogen were not thought to be of importance in the male. Conventional wisdom dictated that, in the male, testosterone mediated these skeletal changes. The notion that estrogen is of little importance in the male has been challenged by the recent discovery of two human syndromes in which estrogen action is lacking. In males with either estrogen resistance (inability to respond to circulating estrogen) or aromatase deficiency (inability to synthesize estradiol), as a result of the lack of estrogen action, a pubertal growth spurt does not appear to occur. Furthermore, complete epiphyseal maturation does not take place allowing for continued growth in adulthood and resultant tall stature. Finally normal bone mineral accretion does not take place resulting in severe osteoporosis. These findings indicate that estrogen plays a critical role in skeletal physiology of males as well as females.

Progressive development of insulin resistance phenotype in male mice with complete aromatase (CYP19) deficiency.

Aromatase (CYP19) is a cytochrome P450 enzyme that catalyzes the formation of aromatic C18 estrogens from C19 androgens. It is expressed in various tissues and contributes to sex-specific differences in cellular metabolism. We have generated aromatase-knockout (ArKO) mice in order to study the role of estrogen in the regulation of glucose metabolism. The mean body weights of male ArKO (-/-) mice (n=7) and wild-type littermates (+/+) (n=7) at 10 and 12 weeks of age were 26.7+/-1.9 g vs 26.1+/-0.8 g and 28.8+/-1.4 g vs 26.9+/-1.0 g respectively. The body weights of the ArKO and wild-type mice diverged between 10 and 12 weeks of age with the ArKO males weighing significantly more than their wild-type littermates (P<0.05). The ArKO males showed significantly higher blood glucose levels during an intraperitoneal glucose tolerance test compared with wild-type littermates beginning at 18 weeks of age. By 24 weeks of age, they had higher fasting blood glucose levels compared with wild-type littermates (133.8+/-22.8 mg/dl vs 87.8+/-20.3 mg/dl respectively; P<0.01). An intraperitoneal injection of insulin (0.75 mU insulin/g) caused a continuous decline in blood glucose levels in wild-type mice whereas ArKO males at 18 weeks and older exhibited a rebound increase in glucose levels 30 min after insulin injection. Thus, ArKO male mice appear to develop glucose intolerance and insulin resistance in an age-dependent manner. There was no difference in fasting serum triglyceride and total cholesterol levels between ArKO male mice and wild-type littermates at 13 and 25 weeks of age. However, serum triglyceride and cholesterol levels were significantly elevated following a meal in ArKO mice at 36 weeks of age. Serum testosterone levels in ArKO male mice were continuously higher compared with wild-type littermates. Treatment of ArKO males with 17beta-estradiol improved the glucose response as measured by intraperitoneal glucose and insulin tolerance tests. Treatment with fibrates and thiazolidinediones also led to an improvement in insulin resistance and reduced androgen levels. As complete aromatase deficiency in man is associated with insulin resistance, obesity and hyperlipidemia, the ArKO mouse may be a useful animal model for examining the role of estrogens in the control of glucose and lipid homeostasis.

Aromatase expression and role of estrogens in male gonad : a review.

The ability of the testis to convert irreversibly androgens into estrogens is related to the presence of a microsomal enzymatic complex named aromatase, which is composed of a specific glycoprotein, the cytochrome P450 aromatase (P450arom) and an ubiquitous reductase. The aromatase gene is unique in humans and contained 18 exons, 9 of them being translated. In the rat testis we have immunolocalized the P450arom not only in Leydig cells but also in germ cells and especially in elongated spermatids. Related to the stage of germ cell maturation, we have shown that the level of P450arom mRNA transcripts decreases, it is much more abundant in pachytene spermatocytes and round spermatids than in mature germ cells whereas the aromatase activity is 2–4 fold greater in spermatozoa when compared to the younger germ cells. Using a highly specific quantitative competitive RT-PCR method we have evidenced that several factors direct the expression of the aromatase gene in Leydig cells, Sertoli cells, pachytene spermatocytes and round spermatids, and it is obvious that promoter PII is the main one but other promoters could be concerned.In the bank-vole testis we have observed a positive correlation between a fully developed spermatogenesis and a strong immunoreactivity for both P450arom and estrogen receptor β not only in Sertoli cells but also in pachytene spermatocytes and round spermatids. Our recent data obtained from ejaculated human spermatozoa demonstrate the presence of aromatase both in terms of mRNA and protein, and in addition, we suggest that aromatase could be involved in the acquisition of sperm motility. Indeed in men the congenital aromatase deficiency is associated with severe bone maturation problems and sterility. Together with the widespread distribution of estrogen receptors in testicular cells these data clearly show that estrogens play a physiological role in the regulation of spermatogenesis in mammals.

Impact of Estrogen Replacement Therapy in a Male with Congenital Aromatase Deficiency Caused by a Novel Mutation in the CYP19 Gene

Recent reports of the impact of estrogen receptor alpha and aromatase deficiency have shed new light on the importance of estrogen for bone formation in man. We describe a novel mutation of the CYP19 gene in a 27-yr-old homozygous male of consanguinous parents. A C to A substitution in intron V, at position -3 of the splicing acceptor site before exon VI of the CYP19 gene, is the likely cause of loss of aromatase activity. The mRNA of the patient leads to a frameshift and a premature stop codon 8 nucleotides downstream the end of exon V. Both parents were shown to be heterozygous for the same mutation. Apart from genua valga, kyphoscoliosis, and pectus carniatus, the physical examination was normal including secondary male characteristics with normal testicular size. To substitute for the deficiency, the patient was treated with 50 micro g transdermal estradiol twice weekly for 3 months, followed by 25 micro g twice weekly. After 6 months estrogen levels (<20 at baseline and 45 pg/ml at 6 months; normal range, 10-50) and estrone levels (17 and 34 ng/ml; normal range, 30-85) had normalized. Bone maturation progressed and the initially unfused carpal and phalangeal epiphyses began to close within 3 months and were almost completely closed after 6 months. The bone age, assessed by roentgenographic standards for bone development by Gruelich and Pyle, was 16.5 at baseline and 18-18.5 yr after 6 months of treatment. Bone density of the distal radius (left), assessed by quantitative computed tomography, increased from 52 to 83 mg/cm(3) (normal range, 120-160) and bone mineral density of the lumbar spine, assessed by dual-energy x-ray-absorptiometry, increased from 0.971 to 1.043 g/cm(2) (normal range, >1.150). Osteocalcin as a bone formation parameter increased from 13 to 52 micro g/l (normal range, 24-70) and aminoterminal collagen type I telopeptide as a bone resorption parameter increased from 62.9 to 92.4 nmol/mmol creatinine (normal range, 5-54). Semen analysis revealed oligoazoospermia (17.4 million/ml; normal >20) at baseline. After 3 months of treatment, the sperm count increased (23.1 million/ml) and decreased rapidly (1.1 million/ml) during the following 3 months. The sperm motility was reduced at baseline and decreased further during treatment. Area under the curve of insulin, C-peptide, and blood glucose levels during oral glucose tolerance test decreased after 6 months (insulin: 277 vs. 139 micro U/ml.h; C-peptide 52 vs. 15 ng/m.h; area under the curve glucose: 17316 vs. 12780 mg/d.min). Triglycerides (268 vs. 261 mmol/liter) and total cholesterol levels (176 vs. 198 mmol/liter) did not change significantly, but the low-density lipoprotein/high-density lipoprotein ratio decreased from 5.37 to 3.56 and lipoprotein (a) increased from 19.9 to 60.0 mg/dl (normal range, <30). In this rare incidence of estrogen deficiency, estrogen replacement demonstrated its importance for bone mineralization and maturation and glucose metabolism in a male carrying a novel mutation in the CYP19 gene.

Puberty and bone metabolism

Large part of the peak bone mass is determined during puberty. While bone mineral accrual rate reaches maximum by the age of 11 - 14 years, it is attained by 16 years of age due to the pubertal delay by 2 - 3 years in boys. The bone accrual is largely influenced by estrogen, and the sexual dimorphism in bone become apparent during this period. Recent findings in hypogonadal disorders including Estrogen receptor mutation or aromatase deficiency have revealed the importance of estrogen in bone metabolism in male. However, the roles of androgen in bone remains unveiled.

Pituitary Function in a Man with Congenital Aromatase Deficiency: Effect of Different Doses of Transdermal E2 on Basal and Stimulated Pituitary Hormones

Pituitary Function in a Man with Congenital Aromatase Deficiency: Effect of Different Doses of Transdermal E2 on Basal and Stimulated Pituitary Hormones

Congenital estrogen deficiency in men: a new syndrome with different phenotypes; clinical and therapeutic implications in men

The report focuses on the role of estrogens in human male, dealing with two human models of congenital estrogen deficiency: estrogen resistance and aromatase deficiency. Similarities and differences of clinical phenotypes of these models are described and progresses of estrogen treatment of aromatase-deficient men are reported. Finally, the putative use of estrogen in men and the use of aromatase inhibitors and antiestrogen for male disorders are discussed.

The Long-Term Effect Of Specific Type II 5α-Reductase Inhibition With Finasteride on Bone Mineral Density in Men: Results of a 4-Year Placebo Controlled Trial

We determine the effect of long-term suppression of dihydrotestosterone with finasteride, a specific type II 5alpha-reductase inhibitor, on bone mineral density. As part of a large (3,040 cases) 4-year, double-blind, placebo controlled trial designed to assess the long-term effects of finasteride in men with benign prostatic hyperplasia, 157 men 46 to 76 years old who were randomized to receive either 5 mg. finasteride or placebo underwent dual energy x-ray absorptiometry of the lumbar spine at baseline and at years 2, 3 and 4. Of 117 patients who had a baseline measurement and at least 1 additional measurement during the study baseline mean plus or minus standard deviation bone mineral density values were 1.12 +/- 0.17 gm./cm.2 in the finasteride group (63) and 1.10 +/- 0.17 gm./cm.2 in the placebo group (54). After 4 years bone mineral density was not different between treatment groups (finasteride 1.14 +/- 0.17 gm./cm.2 and placebo 1.13 +/- 0.18 gm./cm.2). Similar results were obtained for the 33 finasteride and 25 placebo treated patients who completed the study with year 4 bone mineral density measurements. These data demonstrate that long-term inhibition of type II 5alpha-reductase with finasteride does not adversely affect bone mineral density.

Effect of estrogen replacement on insulin sensitivity, serum lipid and bone resorption marker in hypogonadal males

Recent reports of osteoporosis in congenital estrogen deficiency in humans from estrogen resistance or aromatase deficiency have called attention to the importance of estrogen in males. It is the purpose of the present study to evaluate the effects of low- dose estrogen on glucose, lipid and bone metabolism in males with hypogonadism. Nine Thai males with primary or secondary hypogonadism were included in the study. Testosterone was discontinued at least 8 weeks before the study. The subjects received 0.3 mg of conjugated equine estrogen (CEE) daily for 4 weeks. Serum C-terminal telopeptide of type 1 collagen (CTX), total cholesterol (TC), LDL cholesterol (LDL-C), HDL cholesterol (HDL-C), triglyceride (TG) and parameters related to insulin sensitivity were measured at baseline and 4 weeks after treatment. Insulin sensitivity was assessed by frequent intravenous glucose tolerance test. The mean age of subjects was 35.77 years (22–70 years). Insulin sensitivity index ( S I) did not change significantly after the administration of CEE ( P=0.09). Likewise, no change in acute insulin response (AIR glucose) was detected. However, glucose effectiveness ( S G) significantly decreased after CEE ( P<0.05). No significant change in serum TC, LDL-C, HDL-C or TG was detected. In regard to bone turnover, serum CTX significantly decreased after CEE administration ( P<0.05). We concluded that low-dose estrogen administration in hypogonadal males for 4 weeks causes a decrease in bone turnover and an increase in glucose effectiveness. No effect on serum lipid concentrations or insulin sensitivity and secretion was detected.

The essential role of the aromatase/p450arom.

Aromatase (P450arom) catalyzes the conversion of testosterone to estradiol, androstenedione to estrone, and 16a-hydroxylated dehydroepiandrosterone to estriol. P450arom is encoded by the human CYP19 gene (15q21.1) spanning about 123 kb with a coding region of 9 exons (about 30 kb, exon II to exon X). Although there are a number of alternative first exons and nine different transcriptional start sides with individual promoters that permit tissue-specific regulation of expression, the protein expressed in these various tissue sites (placenta, adipose tissue, brain, bone, ovary, etc.) always remains the same. As not only androgens but also estrogens are of importance particularly in male pubertal development including bone changes, which were classically considered androgen dependent, the features of the aromatase deficiency syndrome in affected boys and girls as well as adult males and females are discussed. There is growing awareness that androgens and estrogens have general metabolic roles that reach far beyond reproductive processes. For instance, estrogen has a significant impact on carbohydrate and lipid metabolism, vascular function, and arteriosclerosis. In addition, extragonadal estrogen biosynthesis plays an important but often underestimated physiological and pathophysiological role, for example, in breast cancer and endometriosis. Based on that knowledge, progress has been made as far as treatment and follow-up of this disorder are concerned.

Matters of Sex

Despite the popular concept that heart disease preferentially affects the male population, in every year for the past 16 years, cardiovascular disease has killed more women than men.1 Unfortunately, a disparity still exists between men and women in the diagnosis and aggressive treatment of heart disease. The perception that women are relatively protected is reflected by the fact that women are much more fearful of dying from some form of cancer than from cardiovascular disease.1 Understanding any risk factors that predispose or protect the female population from cardiovascular and coronary disease is therefore a compelling goal for the research community. See p 1419 Left ventricular hypertrophy is a compensatory response of the heart to a variety of stresses, and it is a strong predictor of morbidity and mortality in individuals whether or not they have been diagnosed with cardiovascular disease. Sex differences in the development of this disease over time have been suggested by clinical studies dealing with patients who suffer from aortic stenosis or hypertension.2,3 For example, older female patients with aortic stenosis tend to have increased hypertrophy accompanied by greater concentric remodeling and preserved left ventricular function when compared with male patients. Premenopausal women, in fact, exhibit a thinner posterior wall, smaller left ventricular mass, and better load-dependent and load-independent cardiac function than age-matched men under conditions of mild essential hypertension.4 Population studies have shown an age-dependent increase in left ventricular mass in healthy normotensive women that is not seen in men, as determined by echocardiography.5 These and many other studies in both humans and animals suggest that estrogens can affect the remodeling of the heart. Estrogens are potent vasodilators; they act in this capacity by increasing nitric oxide production. However, recent findings indicate that estrogens have direct actions on the myocardium as …

The effects of oestrogens on linear bone growth

Regulation of linear bone growth in children and adolescents comprises a complex interaction of hormones and growth factors. Growth hormone (GH) is considered to be the key hormone regulator of linear growth in childhood. The pubertal increase in growth velocity associated with GH has traditionally been attributed to testicular androgen secretion in boys, and to oestrogens or adrenal androgen secretion in girls. Research data indicating that oestrogen may be the principal hormone stimulating the pubertal growth spurt in boys as well as girls is reviewed. Such an action is mediated by oestrogen receptors (ER‐α and ER‐β) in the human growth plate, and polymorphisms in the ER gene may influence adult height in healthy subjects. Prepubertal oestradiol concentrations are significantly higher in girls than in boys, explaining sex‐related differences in pubertal onset. Men with a disruptive mutation in the ER gene (oestrogen resistance) or in the CYP19 gene (aromatase deficiency) who have no pubertal growth spurt and continue to grow into adulthood due to lack of epiphyseal fusion supports this notion. Furthermore, phenotypic females with complete androgen insensitivity syndrome have a normal female growth spurt despite lack of androgen action. Oestrogens may also influence linear bone growth indirectly via modulation of the GH‐insuIin‐like growth factor‐I (IGF‐I) axis. Thus, ER blockade diminishes endogenous GH secretion, androgen receptor (AR) blockade increases GH secretion in peripubertal boys, and non‐aromatizable androgens [oxandrolone or dihydrotestosterone (DHT)] have no effect on GH secretion. Treatment with aromatase inhibitors reduces circulating IGF‐I concentrations in healthy males, and reduces growth in boys with testotoxicosis. Taken together, these findings suggest that oestrogens may, in addition to their direct effects, stimulate GH secretion and thereby increase circulating IGF‐I, which in turn may stimulate growth. Thus, oestrogens have important biphasic actions on longitudinal growth in boys as well as in girls. Very low levels of oestrogens may stimulate bone growth without affecting sexual maturation directly at the growth plate as well as through stimulation of the GH‐IGF axis, which in turn may stimulate growth. Conversely, higher levels of oestrogens stimulate secondary sexual characteristics and epiphyseal fusion.

Role of estrogen on bone in the human male: insights from the natural models of congenital estrogen deficiency

The reports of congenital estrogen deficiency — notably, estrogen resistance and aromatase deficiency — have completely changed our knowledge on the role of estrogen on bone in males. Particularly, the bone changes at puberty, which were classically considered androgen-dependent, are now considered to be induced at least in part by estrogen action. Clinical cases of congenital estrogen deficiency have clearly demonstrated that the role of estrogens in epiphyseal closure, skeletal proportions and bone mineralization is crucial not only in women but also in men. In addition progress have been made in the treatment of such a rare disease even though further studies are needed to a definitive understanding of this issue.

Congenital estrogen deficiency: in search of the estrogen role in human male reproduction

Recently, a remarkable progress has been made in our understanding about the role of sex steroids in male physiology. In this paper, we consider the clinical aspects of congenital estrogen deficiency — notably, estrogen resistance and aromatase deficiency — in men and we discuss both well-established and supposed estrogen roles in the human male reproductive function. These topics include the role of estrogens in the control of gonadotropin secretion, in male fertility determination and psychosexual behavior. Briefly, estrogens play a pivotal role in the control of serum gonadotropin concentrations in the human male. Furthermore, a possible role of estrogens on both human male fertility and sexuality has also been suggested by recent studies, even though the available data are far from being conclusive. Conversely, for what concern fertility and sexual behavior, a well-established effect of estrogens has been provided by recent studies on male rodents, which show impaired sexual behavior and fertility as a consequence of estrogen defect.

Brain aromatase is neuroprotective.

The expression of aromatase, the enzyme that catalyzes the biosynthesis of estrogens from precursor androgens, is increased in the brain after injury, suggesting that aromatase may be involved in neuroprotection. In the present study, the effect of inactivating aromatase has been assessed in a model of neurodegeneration induced by the systemic administration of neurotoxins. Domoic acid, at a dose that is not neurotoxic in intact male mice, induced significant neuronal loss in the hilus of the hippocampal formation of mice with reduced levels of aromatase substrates as a result of gonadectomy. Furthermore, the aromatase substrate testosterone, as well as its metabolite estradiol, the product of aromatase, were able to protect hilar neurons from domoic acid. In contrast, dihydrotestosterone, the 5 alpha-reduced metabolite of testosterone and a nonaromatizable androgen, was not. These findings suggest that aromatization of testosterone to estradiol may be involved in the neuroprotective action of testosterone in this experimental model. In addition, aromatase knock-out mice showed significant neuronal loss after injection of a low dose of domoic acid, while control littermates did not, indicating that aromatase deficiency increases the vulnerability of hilar neurons to neurotoxic degeneration. The effect of aromatase on neuroprotection was also tested in male rats treated systemically with the specific aromatase inhibitor fadrozole and injected with kainic acid, a well characterized neurotoxin for hilar neurons in the rat. Fadrozole enhanced the neurodegenerative effect of kainic acid in intact male rats and this effect was counterbalanced by the administration of estradiol. Furthermore, the neuroprotective effect of testosterone against kainic acid in castrated male rats was blocked by fadrozole. These findings suggest that neuroprotection by aromatase is due to the formation of estradiol from its precursor testosterone. Finally, a role for local cerebral aromatase in neuroprotection is indicated by the fact that intracerebral administration of fadrozole enhanced kainic acid induced neurodegeneration in the hippocampus of intact male rats. These findings indicate that aromatase deficiency decreases the threshold for neurodegeneration and that local cerebral aromatase is neuroprotective. Brain aromatase may therefore represent a new target for therapeutic approaches to neurodegenerative diseases.

The effects of oestrogens on linear bone growth.

Regulation of linear bone growth in children and adolescents comprises a complex interaction of hormones and growth factors. Growth hormone (GH) is considered to be the key hormone regulator of linear growth in childhood. The pubertal increase in growth velocity associated with GH has traditionally been attributed to testicular androgen secretion in boys, and to oestrogens or adrenal androgen secretion in girls. Research data indicating that oestrogen may be the principal hormone stimulating the pubertal growth spurt in boys as well as girls is reviewed. Such an action is mediated by oestrogen receptors (ER-alpha and ER-beta) in the human growth plate, and polymorphisms in the ER gene may influence adult height in healthy subjects. Prepubertal oestradiol concentrations are significantly higher in girls than in boys, explaining sex-related differences in pubertal onset. Men with a disruptive mutation in the ER gene (oestrogen resistance) or in the CYP19 gene (aromatase deficiency) who have no pubertal growth spurt and continue to grow into adulthood due to lack of epiphyseal fusion supports this notion. Furthermore, phenotypic females with complete androgen insensitivity syndrome have a normal female growth spurt despite lack of androgen action. Oestrogens may also influence linear bone growth indirectly via modulation of the GH-insulin-like growth factor-I (IGF-I) axis. Thus, ER blockade diminishes endogenous GH secretion, androgen receptor (AR) blockade increases GH secretion in peripubertal boys, and non-aromatizable androgens [oxandrolone or dihydrotestosterone (DHT)] have no effect on GH secretion. Treatment with aromatase inhibitors reduces circulating IGF-I concentrations in healthy males, and reduces growth in boys with testotoxicosis. Taken together, these findings suggest that oestrogens may, in addition to their direct effects, stimulate GH secretion and thereby increase circulating IGF-I, which in turn may stimulate growth. Thus, oestrogens have important biphasic actions on longitudinal growth in boys as well as in girls. Very low levels of oestrogens may stimulate bone growth without affecting sexual maturation directly at the growth plate as well as through stimulation of the GH-IGF axis, which in turn may stimulate growth. Conversely, higher levels of oestrogens stimulate secondary sexual characteristics and epiphyseal fusion.

Sex- and Age-Related Response to Aromatase Deficiency in Bone

Deficiency of sex steroids causes osteoporosis, but the relationship between estrogen and androgen is not clear because androgen is converted into estrogen by aromatase. In this study, we characterized bone metabolism in the aromatase-deficient (ArKO) mouse. At 9 weeks old, a marked loss of cancellous bone due to increased bone resorption was observed not only in female ArKO mice but also in males. The degree of bone loss in ArKO males was similar to that in females, and treatment with 17β-estradiol completely restored the bone mass in both sexes. At 32 weeks old, female ArKO mice showed severe loss of cancellous and cortical bone. Male ArKO mice of this age also showed reduced bone mass, but the degree of bone loss in females was more marked than that in males. Here, we report sex- and age-related responses to aromatase deficiency in bone.

PADAM from the urologic viewpoint

PADAM stands for partial androgen deficiency in the aging male, and it is currently diagnosed with a testosterone level below 3 ng/ml (300 ng/dl or 12 nmol/l), and with symptoms varying according to the individual. The symptoms are a reduction or even loss of libido, a decline in muscle mass and strength, enhancement of visceral fatty tissue-padding, dryness of the skin, apathy, tiredness and distortion of mood right up to depression, and ostalgia due to osteoporosis. Before starting any form of hormonal substitution, which is only indicated if clinical symptoms and testosterone deficiency correlate, it is absolutely essential to exclude prostate cancer by using clinical evaluation and PSA values. Close PSA monitoring is necessary during testosterone substitution. In more than 95% of all patients with erectile dysfunction, the cause is not testosterone deficiency. Even a decreased level of dehydroepiandrosterone (DHEA) in an elderly male needs no replacement. There is also no indication for estradiol therapy in men--except in the rare case of aromatase deficiency.