Androgens regulate phosphodiesterase type 5 expression and functional activity in corpora cavernosa

By real-time RT-PCR and Western blot analysis, we found that phosphodiesterase type 5 (PDE5) mRNA and protein abundance was several fold higher in human male than in female reproductive tracts. The highest mRNA level (>1 x 10(7) molecules/microg total RNA) was detected in human corpora cavernosa (CC), where PDE5 protein was immunolocalized in both muscular and endothelial compartment. The possible role of androgens in regulating PDE5 expression was studied using a previously established rabbit model of hypogonadotropic hypogonadism. In this model, hypogonadism reduced, and testosterone (T) supplementation restored, CC PDE5 gene and protein expression. In addition, T supplementation completely rescued and even enhanced cyclic GMP conversion to metabolites, without changing IC(50) for sildenafil (IC(50) = 2.16 +/- 0.62 nm). In control CC strips, sildenafil dose-dependently increased relaxation induced by electrical field stimulation, with EC(50) = 3.42 +/- 1.7 nm. Hypogonadism reduced, and T increased, sildenafil effect on electrical field stimulation, again without changing their relative EC(50) values. CC sensitivity to the NO-donor NCX4040 was greater in hypogonadal rabbit strips than in control or T-treated counterparts. Moreover, sildenafil enhanced NCX4040 effect in eugonadal rabbit strips but not in hypogonadal ones. This suggests that androgens up-regulate PDE5 in rabbit penis. We also measured PDE5 gene expression and metabolic activity in human CC from male-to-female transsexual individuals, chronically treated with estrogens and cyproterone acetate. Comparing the observed values vs. eugonadal controls, PDE5 mRNA, protein, and functional activity were significantly reduced. In conclusion, we demonstrated, for the first time, that androgens positively regulate PDE5, thus providing a possible explanation about the highest abundance of this enzyme in male genital tract.

Molecular basis of aromatase deficiency in an adult female with sexual infantilism and polycystic ovaries

We identified two mutations in the CYP19 gene responsible for aromatase deficiency in an 18-year-old 46,XX female with ambiguous external genitalia at birth, primary amenorrhea and sexual infantilism, and polycystic ovaries. The coding exons, namely exons II-X, of the CYP19 gene were amplified by PCR from genomic DNA and sequenced directly. Direct sequencing of the amplified DNA from the patient revealed two single-base changes, at bp 1303 (C-->T) and bp 1310 (G-->A) in exon X, which were newly found missense mutations and resulted in codon changes of R435C and C437Y, respectively. Subcloning followed by sequencing confirmed that the patient is a compound heterozygote. The results of restriction fragment length polymorphism analysis and direct sequencing of the amplified exon X DNA from the patient's mother indicate maternal inheritance of the R435C mutation. Transient expression experiments showed that the R435C mutant protein had approximately 1.1% of the activity of the wild type, whereas C437Y was totally inactive. Cysteine-437 is the conserved cysteine in the heme-binding region believed to serve as the fifth coordinating ligand of the heme iron. To our knowledge, this patient is the first adult to have described the cardinal features of a syndrome of aromatase deficiency. Recognition that such defects exist will lead to a better understanding of the role of this enzyme in human development and disease.

Clinical spectrum of steroid sulfatase deficiency: X-linked recessive ichthyosis, birth complications and cryptorchidism

When boys affected with steroid sulfatase deficiency are delivered, the lack of the enzyme in the placenta may cause birth complications. In postnatal life this gene defect gives rise to X-linked recessive ichthyosis. In a series of 25 patients birth complications were reported in 9 cases. Of these boys, 4 displayed bilateral inguinal cryptorchidism and one was affected unilaterally. In a further boy we observed unilateral inguinal cryptorchidism without a history of birth complications. In one patient who had been delivered by forceps, abdominal bilateral cryptorchidism resulted in severe hypogenitalism. A review of the literature revealed 30 cases with X-linked recessive ichthyosis displaying hypogenitalism or cryptorchidism or both. In conclusion, cryptorchidism should be considered as a further clinical manifestation of steroid sulfatase deficiency.

A syndrome of female pseudohermaphrodism, hypergonadotropic hypogonadism, and multicystic ovaries associated with missense mutations in the gene encoding aromatase (P450arom)

We report the features of a new syndrome of aromatase deficiency due to molecular defects in the CYP19 (P450arom) gene in a 46,XX female. At birth, the patient presented with a nonadrenal form of female pseudohermaphrodism. At 17 months of age, laparotomy revealed normal female internal genital structures; the histological appearance of the ovaries was normal. FSH concentrations were markedly elevated at 9.4 ng/mL LER 869, and estrone and estradiol levels were undetectable (< 37 pmol/L). By 14 yr of age, she had failed to exhibit breast development. The clitoris had enlarged to 4 x 2 cm, and pubic hair was Tanner stage IV. The plasma concentration of testosterone was elevated at 3294 pmol/L, as was androstenedione at 9951 pmol/L. Plasma estradiol levels were below 37 pmol/L. ACTH and dexamethasone tests indicated a nonadrenal source of testosterone and androstenedione. Plasma gonadotropin levels were in the castrate range. Pelvic sonography and magnetic resonance imaging showed multiple 4- to 6-cm ovarian cysts bilaterally. Despite increased circulating androgens and clitoral growth, the bone age was 10 yr at chronologic age 14 2/12 yr. Estrogen replacement therapy resulted in a growth spurt, breast development, menarche, suppression of gonadotropin levels, and resolution of the cysts. The clinical findings suggested the diagnosis of P450arom deficiency. Analyses of genomic DNA from ovarian fibroblasts demonstrated two single base changes in the coding region of the P450arom gene, one at 1303 basepairs (C-T), R435C, and the other at 1310 basepairs (G-A), C437Y, in exon 10. The molecular genetic studies indicate that the patient is a compound heterozygote for these mutations. Expression of these mutations showed that the R435C mutation had 1.1% the activity of the wild-type P450arom enzyme, whereas the C437Y mutation demonstrated no activity. The cardinal features of this syndrome are a consequence of P450arom deficiency: 1) the fetal masculinization in this syndrome can be ascribed to defective placental conversion of C19 steroids to estrogens, leading to exposure of the female fetus to excessive amounts of testosterone; 2) the pubertal failure, mild virilization, multicystic ovaries, and hyperstimulation of the ovaries by FSH and LH are the result of the inability of the ovary to aromatize testosterone and androstenedione to estrogens; and 3) the striking delay in bone age at 14 2/12 yr supports the notion that estrogens, in contrast to androgens, are the major sex steroid driving skeletal maturation during puberty. Familial P450arom deficiency, although rare, may be more common than previously suspected.(ABSTRACT TRUNCATED AT 400 WORDS)

Male hypogonadism with gynecomastia caused by late-onset deficiency of testicular 17-ketosteroid reductase

BACKGROUND

17-Ketosteroid reductase deficiency results in male pseudohermaphroditism because conversion of the weak androgen androstenedione to the more potent androgen testosterone is impaired. If a late-onset form exists, hypogonadism and gynecomastia caused by decreased testosterone production and increased estrogen production, respectively, would be expected as the major clinical manifestations in men.

METHODS

We studied 48 male subjects, ranging from 14 to 26 years of age, who had idiopathic pubertal gynecomastia. Serum concentrations of gonadal and adrenal steroid hormones were measured before and after the administration of corticotropin and after the combined administration of chorionic gonadotropin and dexamethasone for three days.

RESULTS

We identified three unrelated subjects (ages, 16, 17, and 26 years) with results indicative of a partial deficiency of testicular 17-ketosteroid reductase. The three subjects had gynecomastia as well as decreased libido and impotence. Their mean (+/- SD) base-line serum androstenedione and estrone concentrations were elevated as compared with the levels in the 45 subjects without this enzyme deficiency (androstenedione, 380 +/- 70 vs. 110 +/- 70 ng per deciliter [13 +/- 2 vs. 4 +/- 2 nmol per liter]; estrone, 138 +/- 12 vs. 46 +/- 9 pg per milliliter [511 +/- 44 vs. 170 +/- 33 pmol per liter]). After the administration of chorionic gonadotropin, the mean serum androstenedione concentration in these three subjects was 910 +/- 48 ng per deciliter (32 +/- 2 nmol per liter) and the mean serum estrone concentration was 260 +/- 16 pg per milliliter (962 +/- 59 pmol per liter). The mean serum testosterone concentration at base line was 210 +/- 80 ng per deciliter (7.4 +/- 2.8 nmol per liter) in the 3 subjects, as compared with a value of 410 +/- 12 ng per deciliter (14.4 +/- 0.42 nmol per liter) in the 45 other subjects, and it did not increase in response to the administration of chorionic gonadotropin. The concentrations of androstenedione and estrone in spermatic venous serum were 19 times higher and 73 times higher, respectively, than in normal men. The serum concentrations of follicle-stimulating hormone and luteinizing hormone in these three subjects were inappropriately low, suggesting the presence of hypogonadotropic hypogonadism.

CONCLUSIONS

A late-onset form of testicular 17-ketosteroid reductase deficiency can cause gynecomastia and hypogonadism in men.

Testosterone action on erythropoiesis does not require its aromatization to estrogen: Insights from the testosterone and estrogen treatment of two aromatase-deficient men

Androgens act on erythropoiesis, but the relative role of testosterone (T) and estradiol (E(2)) on erythropoietic parameters in men is a poorly investigated issue. In order to evaluate separately the effects on erythropoiesis of high-dose T administration alone and of physiological dose of E(2) administration alone two adult men with aromatase deficiency were assessed before and during each treatment. Blood cell count, hemoglobin (Hb), hematocrit (Hct), erythrocyte mean cell volume (MCV), erythrocyte mean corpuscular hemoglobin (MCH), erythrocyte mean corpuscular hemoglobin concentration (MCHC), serum ferritin, iron and total iron-binding capacity (TIBC), serum erythropoietin, serum total testosterone and estradiol were evaluated. Hb, Hct and red cell count rose during testosterone treatment, consistently with the increase in circulating testosterone, but failed to increase during estradiol treatment. A decrease in Hb, Hct and red cell count was recorded in one of the two subjects during estradiol treatment, with a concomitant decrease in serum testosterone. Circulating T alone is capable of and sufficient to influence erythropoiesis, especially at supraphysiological dosage, while circulating E(2) have not the same effect on erythropoietic parameters, suggesting the hypothesis that the erythropoietic changes induced by androgens are not mediated via its aromatization to estrogens.

Cognitive dysfunction and hypogonadotrophic hypogonadism in a Brazilian patient with mitochondrial neurogastrointestinal encephalomyopathy and a novel ECGF1 mutation

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is caused by mutations in the thymidine phosphorylase gene (ECGF1). We present the first detailed report of a Brazilian MNGIE patient, harboring a novel ECGF1 homozygous mutation (C4202A, leading to a premature stop codon, S471X). Multiple deletions and the T5814C change were found in mitochondrial DNA. Together with gastrointestinal symptoms, endocrine involvement and memory dysfunction, not reported in MNGIE to date, were the most preeminent features.

Plasma and urinary 19-nor-deoxycorticosterone in 17 alpha-hydroxylase deficiency syndrome

17 alpha-hydroxylase deficiency syndrome (17-OHDS) is associated with hypogonadism, hypertension, and hypokalemia. Aldosterone production, however, is not elevated, and therefore, other known or unknown mineralocorticoids must account for the excess in mineralocorticoid activity. This study sought to determine whether 19-nor-deoxycorticosterone (19-nor-DOC), a potent hypertensinogenic mineralocorticoid, was elevated in this syndrome. Plasma and urine from a young woman with 17-OHDS were examined from various corticosteroids before and after ACTH, dexamethasone, and cortisol administration. In the basal state, urinary and plasma 17-hydroxycorticosteroids were decreased, but 17-deoxycorticosteroids were extremely elevated, including corticosterone (B), 18-hydroxy-B (18-OH-B), tetrahydro-B (TH-B), TH-DOC, and 18-OH-TH-DOC. Basal urinary (UF) 19-nor-DOC measured by both high pressure liquid chromatography (4255 ng/day) and RIA [3800 ng/day; normal, 102 +/- 27 (+/- SD), was markedly elevated. UF 19-nor-DOC did not increase further after ACTH administration (4255 ng/day), but it decreased after both dexamethasone (less than 100 ng/day) and cortisol therapy (612 and 218 ng/day). Basal plasma 19-nor-DOC was elevated and increased after ACTH stimulation (366 pg/ml) and decreased during dexamethasone suppression (6 pg/ml). A plasma 19-nor-DOC precursor that converted to nor-DOC upon acidification (perhaps 19-oic-DOC) also was detectable (172 pg/ml). This study, therefore, demonstrates a marked elevation in UF 19-nor-DOC in 17-OHDS, which could account for some of the excess mineralocorticoid activity in this syndrome.

Testosterone Increases the Expression and Phosphorylation of AMP Kinase α in Men With Hypogonadism and Type 2 Diabetes

CONTEXT

Adenosine 5'-monophosphate-activated protein kinase-α (AMPKα) is a mediator of exercise-induced glucose uptake in skeletal muscle.

OBJECTIVE

We evaluated whether AMPKα expression and phosphorylation are reduced in skeletal muscle and adipose tissue of patients with hypogonadotropic hypogonadism (HH), and whether testosterone replacement therapy results in restoration of the expression and phosphorylation of AMPKα.

DESIGN

This is a secondary analysis of a previously completed trial that showed an insulin-sensitizing effect of testosterone therapy in men with type 2 diabetes and HH.

SETTING

Clinical research center at university.

PATIENTS

Thirty-two men with HH and 32 eugonadal men were compared at baseline.

INTERVENTIONS

Men with HH were treated with intramuscular injections of testosterone or placebo every 2 weeks for 22 weeks. Quadriceps muscle biopsies and subcutaneous abdominal fat biopsies were obtained before and after 4-hour euglycemic hyperinsulinemic clamp, prior to and after testosterone or placebo therapy.

OUTCOME MEASURES AND RESULTS

mRNA expression of AMPKα in hypogonadal men was lower by 37% in adipose tissue and 29% in skeletal muscle, respectively, compared with levels in eugonadal men, while phosphorylated AMPKα was lower by 22% and 28%, respectively. Following testosterone replacement, the expression of AMPKα did not alter in the fasting state but increased markedly by 41% and 46% in adipose tissue and muscle, respectively, after the clamp. In contrast, phosphorylated AMPKα increased by 69% in muscle after testosterone therapy but did not change following the clamp.

CONCLUSIONS

Testosterone modulates the expression of AMPKα and phosphorylated AMPKα. These effects may contribute to the improved insulin sensitivity following testosterone therapy.

Development of cytochrome P450 aromatase mRNA levels and enzyme activity in ovaries of normal and hypogonadal (hpg) mice

The cytochrome P450 aromatase (P450arom) enzyme is required for bioconversion of androgen to oestrogen. In this study ovarian P450arom mRNA and enzyme activity have been measured during development in normal mice and hypogondal (hpg) mice which lack circulating gonadotrophins. A semi-quantitative reverse transcription-PCR (RT-PCR) technique was used to measure cytochrome P450arom mRNA levels and aromatase enzyme activity was measured directly. Using RT-PCR, P450arom mRNA was detectable in the adult mouse ovary and also in the uterus, kidney, brain and skeletal muscle but not in cardiac smooth muscle. In the normal mouse, P450arom mRNA was detectable in the ovary on the day of birth (day 1) and levels increased significantly up to day 15 with the most marked changes seen between days 1 and 5. Aromatase activity was also detectable at all ages in the ovary and increased significantly between days 1 and 7. In ovaries from hpg mice, normal levels of P450arom mRNA were present on day 1 but there was no significant change in P450arom mRNA at later ages up to day 15. These results show that in the newborn mouse ovary, which contains only primordial follicles, there is a basal expression of P450arom mRNA which is not gonadotrophin-dependent. After 1 day, however, gonadotrophins are required for normal expression of ovarian P450arom and this coincides with development of primary and secondary follicles.

ITPase deficiency causes a Martsolf-like syndrome with a lethal infantile dilated cardiomyopathy

Typical Martsolf syndrome is characterized by congenital cataracts, postnatal microcephaly, developmental delay, hypotonia, short stature and biallelic hypomorphic mutations in either RAB3GAP1 or RAB3GAP2. Genetic analysis of 85 unrelated "mutation negative" probands with Martsolf or Martsolf-like syndromes identified two individuals with different homozygous null mutations in ITPA, the gene encoding inosine triphosphate pyrophosphatase (ITPase). Both probands were from multiplex families with a consistent, lethal and highly distinctive disorder; a Martsolf-like syndrome with infantile-onset dilated cardiomyopathy. Severe ITPase-deficiency has been previously reported with infantile epileptic encephalopathy (MIM 616647). ITPase acts to prevent incorporation of inosine bases (rI/dI) into RNA and DNA. In Itpa-null cells dI was undetectable in genomic DNA. dI could be identified at a low level in mtDNA without detectable mitochondrial genome instability, mtDNA depletion or biochemical dysfunction of the mitochondria. rI accumulation was detectable in proband-derived lymphoblastoid RNA. In Itpa-null mouse embryos rI was detectable in the brain and kidney with the highest level seen in the embryonic heart (rI at 1 in 385 bases). Transcriptome and proteome analysis in mutant cells revealed no major differences with controls. The rate of transcription and the total amount of cellular RNA also appeared normal. rI accumulation in RNA-and by implication rI production-correlates with the severity of organ dysfunction in ITPase deficiency but the basis of the cellulopathy remains cryptic. While we cannot exclude cumulative minor effects, there are no major anomalies in the production, processing, stability and/or translation of mRNA.

Partial 17alpha-hydroxylase/17,20-lyase deficiency-clinical report of five Chinese 46,XX cases

OBJECTIVES

To summarize the clinical characteristics of partial 17alpha-hydroxylase/17,20-lyase deficiency (17OHD) in 46,XX Chinese patients.

METHODS

Five cases of 46,XX partial 17OHD from Peking Union Medical College Hospital were studied retrospectively by summarizing and analyzing their clinical data. The molecular pathogenic mechanisms involved are discussed after reviewing the literature.

RESULTS

Both complete and partial 17OHD patients have hypergonadotropic hypogonadism and elevated serum levels of adrenocorticotropic hormone and mineralocorticoids. The clinical characteristics of partial 17OHD are different from those of complete 17OHD; patients with the former having various degrees of estrogenic and androgenic impacts such as the development of breasts and pubic hair, and oligomenorrhea or secondary amenorrhea. Elevated serum progesterone with or without elevated serum 17alpha-hydroxyprogesterone and recurrent ovarian cysts are typical manifestations of partial 17OHD. Furthermore, hypokalemic hypertension may be absent in partial 17OHD. The 46,XX partial 17OHD should be differentiated from pure gonadal dysgenesis, premature ovarian failure and polycystic ovarian syndrome. It has been reported that specific mutations of the CYP17 gene can cause partial loss of 17alpha-hydroxylase/17,20-lyase activities or dissociation between the 17alpha-hydroxylase and the 17,20-lyase functions. Oral contraceptive pills are effective for artificial menstruation, but not for the correction of hormone deficiency. A low dose of cortisol should be prescribed in the presence of hypokalemic hypertension.

CONCLUSION

The congenital partial 17OHD should be included in the differential diagnosis of menstrual disorders. In these cases, elevated progesterone offers a valuable clue for further investigation.

Hypergonadotrophic hypogonadism in an XX female subject due to 17,20 steroid desmolase deficiency

A 22 year old XX female patient with primary amenorrhoea and sexual infantilism was studied. Persistently elevated serum LH and FSH concentrations and exaggerated LRH pituitary responsiveness indicated deficient ovarian hormonal production. Serum levels of C21 and C19 steroids measured by specific radioimmunoassays before and after appropriate stimulations demonstrated an impairment of adrenal and ovarian steroid biosynthesis. Baseline levels of androstenedione (delta 4-A), testosterone (T), and oestradiol-17 beta (E2) were persistently below the normal range for healthy women at early follicular phase, whereas progesterone (P) and 17 alpha-OH-progesterone (17-OH-P) serum levels were significantly higher than those observed for normal women. Adrenal and gonadal stimulation with ATCH and hCG, respectively, resulted in a considerable rise in serum P and 17-OH-P without any significant change in circulating levels of delta 4-A, T, and E2. These findings were consistent with the diagnosis of 17,20 steroid desmolase deficiency at both adrenal and ovarian levels. This is the first report of a 17,20 desmolase deficiency in an XX individual, and is in line with previous suggestions that familial occurrence of the disorder would fit an autosomal recessive pattern of inheritance.

Steroidogenic enzyme activity in the hypogonadal (hpg) mouse testis and effect of treatment with luteinizing hormone

The hypogonadal (hpg) mouse, which lacks circulating gonadotrophins during development, has been used (a) to determine whether initial expression of steroidogenic enzyme activity is dependent upon gonadotrophins and (b) to examine the responsiveness of these enzymes to luteinizing hormone (LH) stimulation. Activities of 17 alpha-hydroxylase, 17-ketosteroid reductase and 5 alpha-reductase were very low but detectable in the hpg testis while cholesterol side-chain cleavage (CSCC) activity was undetectable. In contrast, 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) activity was high (11% of normal testis). Treatment with LH increased CSCC and 17 alpha-hydroxylase activity more than 11-fold within 24 h. 5 alpha-Reductase activity was increased 3-fold after 3 days treatment while 17-ketosteroid reductase and 3 beta HSD activities did not respond until after 10 days of treatment. The overall increases in 5 alpha-reductase (4-fold) and 3 beta HSD (6-fold) activities were low while changes in 17-ketosteroid reductase (20-fold) and, particularly, CSCC (greater than 130-fold) and 17 alpha-hydroxylase (153-fold) were more marked. Results show (1) that expression of 3 beta HSD activity may be independent of gonadotrophins, (2) that activity of 17 alpha-hydroxylase, 17-ketosteroid reductase and 5 alpha-reductase is expressed, though at low levels, in the absence of gonadotrophins and (3) that prior exposure to gonadotrophins is not required for a rapid response to LH stimulation, particularly with respect to the cytochrome P-450 enzymes.

A recessive PRDM13 mutation results in congenital hypogonadotropic hypogonadism and cerebellar hypoplasia

The positive regulatory (PR) domain containing 13 (PRDM13) putative chromatin modifier and transcriptional regulator functions downstream of the transcription factor PTF1A, which controls GABAergic fate in the spinal cord and neurogenesis in the hypothalamus. Here, we report a recessive syndrome associated with PRDM13 mutation. Patients exhibited intellectual disability, ataxia with cerebellar hypoplasia, scoliosis, and delayed puberty with congenital hypogonadotropic hypogonadism (CHH). Expression studies revealed Prdm13/PRDM13 transcripts in the developing hypothalamus and cerebellum in mouse and human. An analysis of hypothalamus and cerebellum development in mice homozygous for a Prdm13 mutant allele revealed a significant reduction in the number of Kisspeptin (Kiss1) neurons in the hypothalamus and PAX2+ progenitors emerging from the cerebellar ventricular zone. The latter was accompanied by ectopic expression of the glutamatergic lineage marker TLX3. Prdm13-deficient mice displayed cerebellar hypoplasia and normal gonadal structure, but delayed pubertal onset. Together, these findings identify PRDM13 as a critical regulator of GABAergic cell fate in the cerebellum and of hypothalamic kisspeptin neuron development, providing a mechanistic explanation for the cooccurrence of CHH and cerebellar hypoplasia in this syndrome. To our knowledge, this is the first evidence linking disrupted PRDM13-mediated regulation of Kiss1 neurons to CHH in humans.

Development of cytochrome P-450 side chain cleavage mRNA levels in neonatal ovaries of normal and hypogonadal (hpg) mice

Cytochrome P-450 side chain cleavage (P-450scc) is vital for biosynthesis of gonadal steroids. In this study changes in P-450scc mRNA levels and cholesterol side-chain cleavage (CSCC) enzyme activity have been measured during development in the ovary of the normal mouse and the hypogonadal (hpg) mouse which lacks circulating gonadotrophins. Levels of P-450scc mRNA were measured using a semi-quantitative reverse transcription-polymerase chain reaction technique for which part of the 5' sequence of a mouse P-450scc cDNA was sequenced. On the day of birth P-450scc mRNA was present at low levels in the mouse ovary. Thereafter there was no change in P-450scc mRNA levels for 5 days after which time levels increased significantly to reach a peak around day 10. Activity of CSCC showed a similar pattern of development although activity was not detectable on days 1 and 3. In the hpg mouse P-450scc mRNA levels were normal on day 1 but did not increase thereafter up to 15 days. These results show that there is gonadotrophin-independent expression of P-450scc mRNA in the mouse ovary at birth when only primordial follicles and stromal tissue are present. As the ovary develops after 5 days changes in P-450scc mRNA levels become gonadotrophin-dependent and coincide with maturation of secondary follicles.

Sporadic heteroplasmic single 5.5 kb mitochondrial DNA deletion associated with cerebellar ataxia, hypogonadotropic hypogonadism, choroidal dystrophy, and mitochondrial respiratory chain complex I deficiency

This report describes a patient with cerebellar ataxia, hypogonadotropic hypogonadism, and chorioretinal dystrophy, associated with mitochondrial respiratory chain complex I deficiency and a 5.5 kb mtDNA single deletion in skeletal muscle.

Increase in hepatic lipase activity after testosterone substitution in men with hypogonadism of pituitary origin

Ten men with hypogonadism of pituitary origin were studied before and during testosterone substitution therapy with regard to effects on the activities of hepatic lipase (HL) and lipoprotein lipase (LPL) in postheparin plasma, and on plasma lipoprotein concentrations. The mean (+/- SEM) testosterone level increased from 1.8 +/- 0.5 to 16.3 +/- 2.4 nmol/l. The mean activity of HL rose from 327.1 +/- 35.2 to 432.8 +/- 57.2 mU/ml (p less than 0.02), while the activity of LPL did not change significantly, 71.0 +/- 9.1 mU/ml before and 62.2 +/- 3.8 mU/ml after treatment. No significant alterations in lipoprotein concentrations were recorded. These results indicate that a normal testosterone level is of importance for maintaining the activity of HL in men, thereby contributing to the sex difference previously recorded for HL activity.

Temporal and spatial distribution of alkaline phosphatase activity in male hypogonadic rat (hgn/hgn) testis during postnatal development

In male hypogonadic mutant rat (hgn/hgn), gonocytes degenerate and peritubular cells form multiple layers around seminiferous tubules during early postnatal testicular development. Alkaline phosphatase (AP) activity has been used as not only a tracer for the primordial germ cells (PGCs) but also a histochemical marker for the peritubular myoid cells. In the present study, we examined the localization of AP activity during the postnatal testicular development in the hgn/hgn and phenotypically normal (+/+ or +/hgn) rat. In the normal testis, high AP activity was located in the surface of the PGCs on 3 days of age. As the PGCs differentiated into spermatogonia, the AP activity drastically decreased in intensity on 7 days and was completely lost by 12 days. In the hgn/hgn, the PGCs showing high AP activity occupied the inside of dilated seminiferous tubules on 3 and 7 days of age. The luminal AP activity declined gradually by 18 days and disappeared on 21 days, when the germ cells completely degenerated in the hgn/hgn testis. In the normal, high AP activity emerged in a layer of the peritubular cells surrounding the tubules on 7 days and afterwards, indicating that the peritubular cells were differentiating into myoid cells. In the hgn/hgn, the peritubular cells formed multiple layers around the tubules and showed weak AP activity on 3 to 18 days of age. On 21 days of age, high AP activity emerged in a single layer of the peritubular cells directly attached to the basement membrane in the hgn/hgn. These results indicate that the PGCs showing AP activity kept remained at later stage in the hgn/ hgn and that the single layer of mature myoid cells showing high AP activity appeared much later in the hgn/hgn testis than in normal.

Substitution mutation C268Y causes 17 beta-hydroxysteroid dehydrogenase 3 deficiency

The 17 beta-hydroxysteroid dehydrogenase (HSD) type 3 isozyme catalyzes the conversion of androstenedione to testosterone in the testis. Deleterious mutations in the HSD17B3 gene cause undermasculinization in genetic males attributable to impaired testosterone biosynthesis. Hence, a hallmark of this autosomal recessive disorder is a decreased plasma testosterone-to-androstenedione ratio. Here, a novel C268Y substitution mutation in exon 10 of the HSD17B3 gene, in a subject with 17 beta-HSD 3 deficiency, is reported. Reconstitution experiments with recombinant protein reveal that substitution of tyrosine for cysteine at position 268 of 17 beta-HSD type 3 abrogates the enzymatic activity. This finding brings to 20 the number of mutations in the HSD17B3 gene that cause male undermasculinization.

A family with X-linked ichthyosis and hypogonadism

We describe the clinical, biochemical and ophthalmic findings in four closely related males with X-linked ichthyosis and hypogonadism. Recognition of this association is important for both paediatricians and paediatric dermatologists.

Development of cytochrome P450 17 alpha-hydroxylase (P450c17) mRNA and enzyme activity in neonatal ovaries of normal and hypogonadal (hpg) mice

The cytochrome P450 enzyme 17 alpha-hydroxylase (P450c17) is required for androgen synthesis and therefore regulates substrate supply for aromatization. In this study, changes in P450c17 activity and mRNA levels were measured during ovarian development in the normal mouse and in the hypogonadal (hpg) mouse which lacks circulating gonadotrophins. At birth, low levels of P450c17 activity and mRNA were detectable in normal ovaries. This basal level of expression did not change until after day 10 at which time both enzyme activity and mRNA levels increased by six- to eightfold. In the hpg mouse, levels of P450c17 mRNA were normal at birth but did not change significantly during subsequent development and were significantly less than normal by day 15. Results show that there is a low level of gonadotrophin-independent expression of P450c17 in the ovary at birth and that gonadotrophins are required for the subsequent increase in expression between days 10 and 15. In the ovary, P450c17 is expressed solely in the thecal/interstitial compartment and interstitial cells arise in the mouse ovary around day 11. Changes in P450c17 are likely, therefore, to be related to gonadotrophin-dependent development of the interstitial tissue in the mouse. Treatment of adult hpg mice with LH and FSH showed that both gonadotrophins can act to increase P450c17 activity. Since FSH acts only on the granulosa cell compartment of the ovary it is likely that FSH acts through a paracrine mechanism to regulate thecal/interstitial cell activity.