Absence of positive feedback effect of oestrogen on LH release in patients with testicular feminization syndrome

The Pathogenesis of Polycystic Ovary Syndrome (PCOS): The Hypothesis of PCOS as Functional Ovarian Hyperandrogenism Revisited

Polycystic ovary syndrome (PCOS) was hypothesized to result from functional ovarian hyperandrogenism (FOH) due to dysregulation of androgen secretion in 1989-1995. Subsequent studies have supported and amplified this hypothesis. When defined as otherwise unexplained hyperandrogenic oligoanovulation, two-thirds of PCOS cases have functionally typical FOH, characterized by 17-hydroxyprogesterone hyperresponsiveness to gonadotropin stimulation. Two-thirds of the remaining PCOS have FOH detectable by testosterone elevation after suppression of adrenal androgen production. About 3% of PCOS have a related isolated functional adrenal hyperandrogenism. The remaining PCOS cases are mild and lack evidence of steroid secretory abnormalities; most of these are obese, which we postulate to account for their atypical PCOS. Approximately half of normal women with polycystic ovarian morphology (PCOM) have subclinical FOH-related steroidogenic defects. Theca cells from polycystic ovaries of classic PCOS patients in long-term culture have an intrinsic steroidogenic dysregulation that can account for the steroidogenic abnormalities typical of FOH. These cells overexpress most steroidogenic enzymes, particularly cytochrome P450c17. Overexpression of a protein identified by genome-wide association screening, differentially expressed in normal and neoplastic development 1A.V2, in normal theca cells has reproduced this PCOS phenotype in vitro. A metabolic syndrome of obesity-related and/or intrinsic insulin resistance occurs in about half of PCOS patients, and the compensatory hyperinsulinism has tissue-selective effects, which include aggravation of hyperandrogenism. PCOS seems to arise as a complex trait that results from the interaction of diverse genetic and environmental factors. Heritable factors include PCOM, hyperandrogenemia, insulin resistance, and insulin secretory defects. Environmental factors include prenatal androgen exposure and poor fetal growth, whereas acquired obesity is a major postnatal factor. The variety of pathways involved and lack of a common thread attests to the multifactorial nature and heterogeneity of the syndrome. Further research into the fundamental basis of the disorder will be necessary to optimally correct androgen levels, ovulation, and metabolic homeostasis.

Clinical review: Adolescent anovulation: maturational mechanisms and implications

CONTEXT

Adolescents are at high risk for menstrual dysfunction. The diagnosis of anovulatory disorders that may have long-term health consequences is too often delayed.

EVIDENCE ACQUISITION

A review of the literature in English was conducted, and data were summarized and integrated from the author's perspective.

MAIN FINDINGS

Normal adolescent anovulation causes only minor menstrual cycle irregularity: most cycles range from 21-45 days, even in the first postmenarcheal year, 90% by the fourth year. Approximately half of symptomatic menstrual irregularity is due to neuroendocrine immaturity, and half is associated with increased androgen levels. The former is manifest as aluteal or short/deficient luteal phase cycles and usually resolves spontaneously. The latter seems related to polycystic ovary syndrome because adolescent androgen levels are associated with adult androgens and ovulatory dysfunction, but data are sparse. Obesity causes hyperandrogenemia and, via unclear mechanisms, seems to suppress LH; it may mimic polycystic ovary syndrome. The role of pubertal insulin resistance in physiological adolescent anovulation is unclear. High-sensitivity gonadotropin and steroid assays, the latter by specialty laboratories, are necessary for accurate diagnosis of pubertal disorders. Polycystic ovaries are a normal ultrasonographic finding in young women and are associated with nearly 2-fold increased anti-Müllerian hormone levels. Oral contraceptives are generally the first-line treatment for ongoing menstrual dysfunction, and the effects of treatment are similar among preparations.

CONCLUSIONS

Menstrual cycle duration persistently outside 21-45 days in adolescents is unusual, and persistence ≥ 1 year suggests that disordered hypothalamic-pituitary-gonadal function be considered. Research is needed on the mechanisms and prognosis of adolescent anovulation.

Endocrine manipulation in male infertility

Endocrine therapy for male infertility is broadly categorized as specific or nonspecific therapy. Although uncommon, primary endocrine diagnoses in infertile men are amenable to targeted therapy. The efficacy of empiric endocrine therapy for idiopathic male infertility, however, has not been demonstrated conclusively by clinical trials. With better understanding of the underlying pathophysiology of idiopathic male infertility, careful evaluation of endocrine therapy in well-selected treatment groups and well-designed randomized, controlled trials is warranted. Although empiric endocrine therapy for idiopathic male infertility has been largely replaced by assisted reproductive techniques, both treatment modalities could play a role, perhaps as combination therapy.

A clinician looks at androgen resistance

Androgen resistance in genetic males occurs when gonadotropins and testosterone are normal, but the physiological androgen response in androgen target organs is absent or decreased. In androgen-dependent target tissues two main defects may be found: 1) defective testosterone metabolism (5 alpha-reductase type 2 deficiency) and 2) anomalies in androgen receptors (androgen insensitivity syndrome (AIS)). The clinical manifestations of these defects vary from subjects with female external genitalia to subjects with mild forms of impaired masculinization. In particular, in the complete form of AIS (CAIS) the phenotype is feminine, and in the partial form (PAIS) the external genitalia are ambiguous with an extremely variable phenotype. The diagnosis requires clinical, hormonal, genetic, and molecular investigation for appropriate gender assignation and treatment. In AIS, cloning of androgen receptor cDNA using the polymerase chain reaction, denaturing gradient gel electrophoresis, and nucleotide sequencing have enabled a variety of molecular defects in the androgen receptor to be identified. The complexity of phenotypic presentation of AIS probably reflects the heterogeneity of androgen receptor gene mutations, but to date a relationship between genotype/phenotype has been difficult to establish, with the same point mutation reported to be associated with different phenotypic expressions. Other factors must therefore also contribute to the clinical presentation of AIS, although none have yet been identified. Establishing the functional consequences of androgen receptor mutations in vitro systems and correlating them with clinical presentation may ultimately provide an explanation for the variable clinical presentation of AIS and perhaps enable prediction of the response to androgen therapy in infants with PAIS.

Neural sexual mosaicism: sexual differentiation of the human temporo-parietal region for functional asymmetry

Sex differences in human brain organization and behavior are documented by several converging lines of evidence based on patterns of functional asymmetry and cognitive abilities in normal adults and children, in patients with unilateral brain damage, and in clinical groups having atypical levels of sex hormones. Sex differences also exist in the structure of the human brain, and these are reviewed in detail herein. In addition, dichotomous differences, rather than just differences along a continuum, are noted in anatomical-functional correlations between men and women. Many of the anatomical differences cluster in the temporo-parietal regions of the brain, which subserve the asymmetric representation of some linguistic, motoric and spatial functions. The hypothesis is presented that development of the temporo-parietal region of the human brain is an anatomic network dependent on the organizing effects of sex hormones during embryonic or perinatal sexual differentiation, and that in each sex the pattern of functional asymmetries and cognitive attributes is differentially influenced by early sex hormone exposure. It is further suggested that the naturally occurring regressive events of cell death and axon elimination in early brain development contribute to the variation in the structure of the temporo-parietal region, and that this mechanism is differentially influenced by sex hormones in each sex. The specific, directional hypothesis put forward is that in early development of the male brain, lower levels of androgenic hormones or receptors lead to less regressive events in some brain regions, such as the temporo-parietal region, resulting in a larger isthmus of the corpus callosum, less cerebral functional asymmetry, and some cognitive correlates. Some supporting evidence for this hypothesis from neuropsychological studies of clinical groups and homosexual individuals is presented. The neuroanatomical correlate of functional asymmetry in posterior brain regions in women is not evident. The neural regressive events which occur in each sex may be related differently to lateralization. The concept of sexual mosaicism in the human brain is discussed.

Neuroendocrine responses to exogenous estrogen: no differences between heterosexual and homosexual men

Plasma LH concentrations were determined in 55 men before and for four days following injection of 10 mg, 20 mg, or 30 mg Premarin or a placebo injection of vehicle. Testosterone (T) and dihydrotestosterone (DHT) concentrations were also determined in plasma samples taken just prior to Premarin or placebo injection and in samples taken three days later. All subjects provided self-descriptions of their sexual orientation and, based upon these descriptions, were classified as heterosexual (N = 39) or homosexual (N = 16). Premarin injection resulted in a reliable reduction in plasma LH 24 hr later. In subsequent samples, LH values rose and in many cases exceeded baseline levels, most reliably in those subjects receiving the 10 mg dose. Contrary to some previous reports, we observed no significant differences between heterosexual and homosexual subjects in the likelihood of their exhibiting elevated LH concentrations following exogenous estrogens. T, but not DHT, concentrations were suppressed after Premarin injection in both groups of subjects. Other than Premarin dosage, we could not identify any variable which predicted the likelihood of elevated LH values.

Effect of exogenously administered estrogens on luteinizing hormone release in a complete testicular feminization syndrome patient with very low testosterone levels, before and after gonadectomy

The response of LH to exogenously administered estrogens was evaluated in a 63-year-old patient affected by complete testicular feminization syndrome (CTFS) with very low testosterone (T) levels, before and after gonadectomy. Prior to gonadectomy a durative fall in gonadotropin levels was observed after estrogen administration, without observing of an estrogenic positive feed-back (EPF) from LH. After gonadectomy, following an initial decrement in both gonadotropins, the characteristic. LH peak was seen, 48 h after E2B (Estradiol Benzoate) administration. This observation, together with the very low T levels that we found in this patient, prompted us to construe that absence of EPF in males is not due, as previously believed, to a direct inhibitory action of T or E2, deriving from T aromatization, on the hypothalamus, but by a still unknown gonadal factor. The hypothesis that this factor has a tubular origin is formulated and discussed.

Hormones and psychosexual differentiation: implications for the management of intersexuality, homosexuality and transsexuality

During fetal development of subprimate mammals, sexual differentiation of the genitals and of specific sex-dimorphic brain systems depends on androgens; corresponding sex differences are displayed in prepubertal behaviours as well as in behaviours that depend on activation by pubertal hormones. In human beings, fetal hormones play the same role in genital differentiation. Hormone-dependent structural brain changes are also very likely but have not yet been demonstrated. The corresponding effects of fetal hormones on childhood behaviour have been found both in subhuman primates and in man, while the evidence concerning later behaviour, including sexual orientation, is not yet clear. The development of gender identity in humans is a cognitive process that has no counterpart in animal behaviour and is unlikely to be based on a specific hormone-sensitive brain system. It appears that the hormone-dependent variations of sex-dimorphic behaviour in childhood can be accommodated within either gender identity, provided that the child's physical appearance is gender adequate and the parental (or other caregivers') rearing style does not interfere with typical gender role development. In intersex individuals, changes in gender identity seem to occur primarily when genital and/or general physical appearance are in conflict with the assigned gender and/or when rearing has been ambiguous. The available descriptions of such changes do not seem compatible with a primarily neuroendocrine explanation. Thus, decisions on sex assignment and reassignment of intersex patients need to be based on expected social and sexual functioning, and the clinical management of such patients must minimize the risk of ambiguous rearing and of the development of a gender-incongruent physical appearance. The development of a sexual orientation in humans as hetero- or homosexual does not seem to depend on pubertal hormones. The evidence for a role of fetal hormones is suggestive, but the issue is not yet settled. Attempts to implicate the H-Y antigen in the aetiology of transsexuality seem to have failed; psychoendocrine research here parallels that on sexual orientation. Some recent developments in the management of transsexual patients are discussed.

Effects of prenatal sex hormones on gender-related behavior

Gender identity depends largely on postnatal environmental influences, while sex-dimorphic behavior and temperamental sex differences appear to be modified by prenatal sex hormones. A role of the prenatal endocrine milieu in the development of erotic partner preference, as in hetero-, homo-, or bisexual orientation, or of cognitive sex differences has not been conclusively demonstrated.