Pituitary and placental gonadotrophins and sex steroids in the human and sub-human primate fetus

Placental weight Z-score and pubertal timing: A population-based cohort study

BACKGROUND

The placenta provides nutrients, oxygen, and hormonal support for adequate fetal growth and development of the hormonal axes, which are important for pubertal timing later in life.

OBJECTIVES

We investigated if an indicator of poor placental function, low gestational age-specific Z-score for placental weight at birth, was associated with earlier pubertal timing.

METHODS

The study is based on a population-based cohort of 15 195 singleton boys and girls (68% of 22 439 invited) born 20 to 43 weeks of gestation (2000-2003) nested within the Danish National Birth Cohort. Placental Z-score was estimated from data collected at birth. Between 2012 and 2018, the children returned half-yearly web-based questionnaires from age of 11 years on status of the pubertal milestones: Tanner stages, voice break, first ejaculation, menarche, acne, and axillary hair. We estimated adjusted monthly differences in mean age at attaining the pubertal milestones and pubertal timing overall with placental Z-score continuously and as restricted cubic splines. Further, we explored whether growth by birthweight Z-score and body mass index Z-score around 7 years mediated the associations.

RESULTS

Placental Z-score was positively associated with age at attaining most of the pubertal milestones in girls, particularly for age at menarche, but not in boys. Effect sizes were modest, and when combining all pubertal milestones, one standard deviation increase in placental Z-score was associated with 0.5 months (95% confidence interval [CI] 0.2, 0.9) later pubertal timing overall in girls. The associations in girls were largely mediated through fetal growth.

CONCLUSIONS

Assuming that placental Z-score correlates with placental function, these findings suggest that placental dysfunction (low placental Z-score) advances pubertal timing in girls slightly by reducing fetal growth. Future studies need to evaluate whether placental weight sufficiently captures intrauterine growth of importance for pubertal development and search for other potential candidates reflecting placental function.

Clinical Management of Congenital Hypogonadotropic Hypogonadism

The initiation and maintenance of reproductive capacity in humans is dependent on pulsatile secretion of the hypothalamic hormone GnRH. Congenital hypogonadotropic hypogonadism (CHH) is a rare disorder that results from the failure of the normal episodic GnRH secretion, leading to delayed puberty and infertility. CHH can be associated with an absent sense of smell, also termed Kallmann syndrome, or with other anomalies. CHH is characterized by rich genetic heterogeneity, with mutations in >30 genes identified to date acting either alone or in combination. CHH can be challenging to diagnose, particularly in early adolescence where the clinical picture mirrors that of constitutional delay of growth and puberty. Timely diagnosis and treatment will induce puberty, leading to improved sexual, bone, metabolic, and psychological health. In most cases, patients require lifelong treatment, yet a notable portion of male patients (∼10% to 20%) exhibit a spontaneous recovery of their reproductive function. Finally, fertility can be induced with pulsatile GnRH treatment or gonadotropin regimens in most patients. In summary, this review is a comprehensive synthesis of the current literature available regarding the diagnosis, patient management, and genetic foundations of CHH relative to normal reproductive development.

Luteinizing hormone and human chorionic gonadotropin: distinguishing unique physiologic roles

Luteinizing hormone (LH) and human chorionic gonadotropin (hCG) are integral components of the hypothalamic-pituitary-gonadal axis, which controls sexual maturation and functionality. In the absence of signaling through their shared receptor, fetal sexual differentiation and post-natal development cannot proceed normally. Although they share a high degree of homology, the physiologic roles of these hormones are unique, governed by differences in expression pattern, biopotency and regulation. Whereas LH is a key regulator of gonadal steroidogenesis and ovulation, hCG is predominantly active in pregnancy and fetal development. Emerging evidence has revealed endogenous functions not previously ascribed to hCG, including participation in ovulation and fertilization, implantation, placentation and other activities in support of successful pregnancy. Spontaneous and induced mutations in LH, hCG and their mutual receptor have contributed substantially to our understanding of reproductive development and function. The lack of naturally occurring, functionally significant mutations in the β-subunit of hCG reinforce its putative role in establishment of pregnancy. Rescue of reproductive abnormalities resulting from aberrant gonadotropin signaling is possible in certain clinical contexts, depending on the nature of the underlying defect. By understanding the physiologic roles of LH and hCG in normal and pathologic states, we may better harness their diagnostic, prognostic and therapeutic potential.

Estrogen regulation of placental angiogenesis and fetal ovarian development during primate pregnancy

During human and nonhuman primate pregnancy, an extensive blood vessel network is established within the villous placenta to support fetal growth and follicles develop within the fetal ovary to provide a pool of oocytes for reproductive function in adulthood. These two important developmental events occur in association with a progressive increase in placental estrogen production and levels. This review will describe the developmental processes required for placental vascularization and fetal follicular maturation and recent studies which show that estrogen has an important role in regulating these events.

Pubertal development and menarche

Puberty is the developmental process that culminates in reproductive capability and is the result of a complex series of molecular and physiological events. The release of gonadotropin-releasing hormone from specialized neurons of the hypothalamus begins the hormonal cascade that causes gonadal activation and the physical changes of puberty. Several factors have been proposed to influence the activation of the hypothalamus to trigger puberty, but the involved pathways have not been fully elucidated. The recent observations that the age of pubertal onset may be lowering in American girls calls attention to the lack of knowledge of modulating factors that affect the pubertal process. Genes necessary for puberty have been found by studying persons who do not achieve puberty; such studies have provided insights into the pathways necessary for pubertal development. A multidisciplinary focus is required to elucidate the complex mechanisms involved in the initiation and progression of puberty.

Molecular biology of the 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerase gene family

The 3beta-hydroxysteroid dehydrogenase/Delta(5)-Delta(4) isomerase (3beta-HSD) isoenzymes are responsible for the oxidation and isomerization of Delta(5)-3beta-hydroxysteroid precursors into Delta(4)-ketosteroids, thus catalyzing an essential step in the formation of all classes of active steroid hormones. In humans, expression of the type I isoenzyme accounts for the 3beta-HSD activity found in placenta and peripheral tissues, whereas the type II 3beta-HSD isoenzyme is predominantly expressed in the adrenal gland, ovary, and testis, and its deficiency is responsible for a rare form of congenital adrenal hyperplasia. Phylogeny analyses of the 3beta-HSD gene family strongly suggest that the need for different 3beta-HSD genes occurred very late in mammals, with subsequent evolution in a similar manner in other lineages. Therefore, to a large extent, the 3beta-HSD gene family should have evolved to facilitate differential patterns of tissue- and cell-specific expression and regulation involving multiple signal transduction pathways, which are activated by several growth factors, steroids, and cytokines. Recent studies indicate that HSD3B2 gene regulation involves the orphan nuclear receptors steroidogenic factor-1 and dosage-sensitive sex reversal adrenal hypoplasia congenita critical region on the X chromosome gene 1 (DAX-1). Other findings suggest a potential regulatory role for STAT5 and STAT6 in transcriptional activation of HSD3B2 promoter. It was shown that epidermal growth factor (EGF) requires intact STAT5; on the other hand IL-4 induces HSD3B1 gene expression, along with IL-13, through STAT 6 activation. However, evidence suggests that multiple signal transduction pathways are involved in IL-4 mediated HSD3B1 gene expression. Indeed, a better understanding of the transcriptional factors responsible for the fine control of 3beta-HSD gene expression may provide insight into mechanisms involved in the functional cooperation between STATs and nuclear receptors as well as their potential interaction with other signaling transduction pathways such as GATA proteins. Finally, the elucidation of the molecular basis of 3beta-HSD deficiency has highlighted the fact that mutations in the HSD3B2 gene can result in a wide spectrum of molecular repercussions, which are associated with the different phenotypic manifestations of classical 3beta-HSD deficiency and also provide valuable information concerning the structure-function relationships of the 3beta-HSD superfamily. Furthermore, several recent studies using type I and type II purified enzymes have elegantly further characterized structure-function relationships responsible for kinetic differences and coenzyme specificity.

Role of inhibins in childhood and puberty

Inhibins, produced mainly in the gonads, suppress FSH synthesis. The bioactive dimeric forms of inhibin (A and B) have been proposed as peripheral markers of Sertoli and granulosa cell function. The determination of serum dimeric inhibins from birth through adulthood reflects a distinct pattern of both inhibins in males and females. Concomitantly with the gonadotrophin surge, an important production of inhibin B is observed during the first months of life. In males, inhibin B levels are higher than in females and persist elevated up to childhood, whereas in females they decrease up to prepubertal levels by 6 months of age. In girls, high serum levels of inhibin A are observed during the first two months of life; thereafter, they are undetectable until puberty. An active secretion of inhibin B persists in both males and females in the period of maximal LHRH pulse generator restraint; however, the possible gonadotrophin dependence of this production remains controversial. At puberty, a progressive rise in serum inhibin B occurs concomitantly with the increased production of sex steroids in both males and females. A similar secretion pattern of inhibin A is observed in girls. This increment is mainly exerted by gonadotrophins and modulated by multiple paracrine/autocrine mechanisms within the ovary and the testis that regulate the dimerization of the inhibin subunits throughout pubertal maturation. The differences observed in males and females between circulating dimeric inhibins in relation to gonadotrophins and sex steroid concentrations from birth through puberty has opened a new perspective for research in human reproduction. These new markers may contribute to a better knowledge of the regulation of the hypothalamic-pituitary-gonadal axis function and the physiopathology of the mechanisms involved in sexual differentiation and/or fertility disorders.

Neurobiological mechanisms of the onset of puberty in primates

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

CFTR is functionally active in GnRH-expressing GT1-7 hypothalamic neurons

We have demonstrated the expression of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, mRNA, and protein within the rat and human brains, in areas regulating sexual differentiation and function. We have found that GT1-7, a gonadotropin-releasing hormone (GnRH)-secreting hypothalamic neuronal cell line, expresses the CFTR gene, mRNA, and protein and cAMP-dependent (36)Cl efflux. A linear 7-pS Cl- conductance, which is stimulated by ATP and cAMP analogs and inhibited by glibenclamide, consistent with CFTR activity, has been identified in GT1-7 cells. Antisense oligo(dN) generated against exon 10 of the CFTR gene transcript (mRNA) inhibit GnRH secretion into media [312 +/- 73, 850 +/- 150, 963 +/- 304, and 912 +/- 74 pg GnRH/4 x 10(6) cells for antisense, sense, missense, and no oligo(dN), respectively; P < 0. 029 for antisense oligo(dN)-treated vs. normal cells]. No changes in intracellular synthesis of GnRH were noted [1,400 +/- 371 and 1,395 +/- 384 pg GnRH/4 x 10(6) cells for antisense and sense oligo(dN), respectively]. Antisense oligo(dN), but not sense or missense oligo(dN), inhibited cAMP-dependent 36Cl efflux. The expression of CFTR protein, detected by Western blotting, was also inhibited 68% by preincubation of cells with antisense oligo(dN). GT1-7 hypothalamic neurons express the CFTR gene, mRNA, and protein, which modulate neurosecretion. Abnormal neuropeptide vesicle trafficking by mutant CFTR may help to explain some of the diverse manifestations of cystic fibrosis.

Cryptorchidism. Current concepts

Cryptorchidism is the most common genitourinary disorder of childhood. Even though its incidence has changed only slightly over the years, the number of operations for cryptorchid testes has tripled. Better understanding of the natural history of cryptorchidism, as well as changes that occur in testicular histology both in the cryptorchid and the contralateral descended testis very early in life, are the cause. This experience has led us to advocate early orchiopexy as the optimum means of treatment.

Sex differences in serum hormone levels in umbilical vein blood

OBJECTIVE

To determine the serum levels of FSH, LH, PRL, estradiol, progesterone and testosterone in umbilical vein blood in a group of normal neonates.

METHOD

Umbilical vein blood was obtained for serum analyses from 52 newborns (25 females and 27 males) in the Maternity of the Hospital Regional Virgen de las Nieves, Granada (Spain) and means were compared with Student's t-test.

RESULT

Mean values of prolactin, estradiol and progesterone were similar in both sexes. The levels of gonadotropins in umbilical vein blood found were significantly higher in newborn males than in females (P < 0.001 for LH, P < 0.007 for FSH). Testosterone levels were higher in male neonates than in females (P < 0.004).

CONCLUSION

Our data reflect the dynamic state of male fetal endocrinological status in comparison to female fetuses, and strongly suggest that the mechanisms of hormonal regulation differ in the two sexes.

Ontogeny and subcellular localization of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) in the human and rat adrenal, ovary and testis

Primates are unique in having adrenals that secrete large amounts of the precursor sex steroids (PSS) dehydroepiandrosterone (DHEA) and especially DHEA-sulfate. The adrenal PSS require the action of 3 beta-hydroxysteroid dehydrogenase/5-ene-4 ene isomerase (3 beta-HSD), 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD), 5 alpha-reductase and/or aromatase to form the androgen dihydrotestosterone (DHT) or the estrogens 17 beta-estradiol and androst-5-ene-diol. Knowing the crucial role of 3 beta-HSD and 17 beta-HSD in sex steroid biosynthesis both in classical as well as in peripheral steroidogenic tissues, we have concentrated our efforts on the elucidation of the molecular structure of these enzyme families. We have thus characterized two types of human 3 beta-HSD cDNA clones and their corresponding genes which encode deduced proteins of 371 and 372 amino acids and share 93.5% homology. Human type I 3 beta-HSD is the almost exclusive mRNA species expressed in the placenta and skin, while human type II is the predominant mRNA species in the adrenals, ovaries and testes. We have also recently elucidated the structure of three types of rat 3 beta-HSD cDNAs which all encode a 372 amino acid protein. The predicted rat type I and II 3 beta-HSD proteins expressed adrenals, gonads and adipose tissue share 94% homology while they share 80% similarity with the liver-specific type III 3 beta-HSD. Transient expression of human type I and II as well as rat type I and II 3 beta-HSD cDNAs in HeLa human cervical carcinoma cells reveals that 3 beta-ol dehydrogenase and 5-ene-4-ene isomerase activities reside within a single protein and that these cDNAs encode functional 3 beta-HSD proteins. The expressed rat type III protein possesses a unique property catalyzing selectively the reduction of 3 beta-androstane 5 alpha-steroids such as DHT. Furthermore, we have also demonstrated by site-directed mutagenesis that the lower activity of expressed rat type II compared to rat type I 3 beta-HSD protein is due to a change of four amino acid residues potentially involved in a membrane-spanning domain. In parallel, we have characterized the complete nucleotide sequence of human 17 beta-HSD cDNA clones encoding a 327 amino acid protein as well as two in tandem 17 beta-HSD genes. Two major 17 beta-HSD mRNA species have been detected in several tissues due to a tissue-specific alternative site of initiation of transcription.(ABSTRACT TRUNCATED AT 400 WORDS)

The influence of mercury on the secretion of human chorionic gonadotropin in superfused young placental tissue

The effect of mercury (Hg), as HgCl2, in levels ranging from 0.75 to 12 micrograms/ml medium, on the secretion of human chorionic gonadotropin (hCG) was examined in first-trimester placental explants, after 6 or 24 hr incubation, employing both static and dynamic systems (the latter by superfusion). Later the unbound Hg was washed for 45 min. with fresh medium devoid of Hg, followed by superfusion with the latter medium for 75 min., during which time samples were collected for hCG assay. For the superfusion experiments the parameters used for evaluating the hCG secretion pattern were: mean peak amplitude, pulse frequency and the area under the hCG secretion curve (AUC). The results observed after 24 hr incubation indicate that in the dynamic system the hCG secretion increased significantly, and this increase was dose-dependent. There was also a dose-related increase in mean total hCG secreted by the explants exposed to Hg. Maximal hCG secretion was observed after 24 hr exposure of explants to 6 micrograms of the metal/ml. Both the mean peak amplitude and AUC parameters showed a statistically-significant increase for this dose level. At 12 micrograms/ml, the pulsatile secretion of hCG decreased, but the value for the mean hCG secretion was still higher than that observed for 0.75 and 3 micrograms/ml. After 6 hr incubation, however, there were no significant changes from the control, as judged by all of the above parameters. The levels of hCG secreted by the explants into the media in the static system were not significantly different from their respective controls, for both incubation periods and Hg levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Secretion of human chorionic gonadotropin in superfused young placental tissue exposed to cadmium

The effect of various concentrations of cadmium (Cd) in levels ranging from 0.75 to 12 micrograms/ml medium, on the secretion of human chorionic gonadotropin (hCG) in first-trimester placental explants, after 6 or 24 h incubation, employing both static and dynamic systems was examined. Later the unbound Cd was washed for 45 min with fresh medium devoid of Cd, followed by superfusion with the latter medium for 75 min, during which time samples were collected for hCG assay. For the superfusion experiments the parameters used for evaluating the hCG secretion pattern were: mean peak amplitude (MPA), pulse frequency (PF) and the area under the hCG secretion curve (AUC). The results indicate that in the dynamic system the hCG secretion increased significantly, and this increase was dose dependent. There was also a dose-related increase in mean total hCG secreted by the explants exposed to Cd. Maximal hCG secretion was observed after 24 h exposure of explants to 6 micrograms of the metal/ml. Both the MPA and AUC parameters showed a statistically significant increase for this dose level. At 12 micrograms/ml, the pulsatile secretion of hCG decreased, the value for the mean hCG secretion being comparable to that observed for 0.75 micrograms/ml. After 6 h incubation, however, there were no significant changes from the control, as judged by all of the above parameters. The levels of hCG secreted by the explants into the media in the static system were not significantly different from their respective controls, for both incubation periods and Cd levels. These results indicate that Cd may affect the normal placental function, as reflected in its hCG secretion pattern.

Pulsatile GnRH-stimulated LH release from the human fetal pituitary in vitro: sex-associated differences

An in-vitro perfusion system was utilized to examine LH release from human fetal (19-24 weeks gestation) anterior pituitaries during repetitive GnRH stimulations. Pituitaries (five male, four female) were dissected into halves, and one hemipituitary of each pair was stimulated with 10-min pulses of 1 nM GnRH administered at 60-min intervals over 24h, whereas the matching hemipituitary received pulses of medium alone. Basal (no GnRH stimulation) LH release from female hemipituitaries was significantly (P less than 0.01) greater than from male hemipituitaries, and the amplitude of LH release associated with GnRH pulses was sixfold greater (P less than 0.001) with female hemipituitaries. Furthermore, the magnitude of LH release associated with individual GnRH pulses was significantly (P less than 0.001) enhanced during the course of female hemipituitary perfusions, but not during perifusion of male hemipituitaries. These studies demonstrate that LH secretion by the female, but not male, mid-gestational human fetal pituitary is increased in response to a physiological pattern and interval of repeated pulsatile GnRH stimulation in vitro.

The undescended testis. Hormonal and surgical management

Cryptorchidism is the most common disorder of sexual differentiation in males, with an incidence of 3.4 per cent in the term newborn, decreasing to 0.8 per cent at 1 year of age. The mechanisms of normal testicular descent are multifactorial and include an intact hypothalamic-pituitary-testicular axis, as well as a normal gubernaculum and epididymis. In boys with cryptorchidism, the testes demonstrate degenerative changes histologically as early as 1 to 2 years of age. Both testes may be affected, even with a unilateral undescended testis. The most important long-term complications of cryptorchidism include infertility and testicular cancer. The risk of malignancy is 10 to 40 times higher in men with cryptorchidism than in normal men and is highest in men who have had an intra-abdominal testis and in certain intersex conditions. Orchiopexy does not appear to lessen this risk. In clinical trials in the United States, hormonal therapy with hCG or GnRH has not been effective in causing testicular descent; therefore, orchiopexy remains standard treatment. However, hCG is recommended if the clinician suspects that a testis is retractile. Orchiopexy should be performed between 12 and 18 months of age to prevent the degenerative changes that are demonstrable by 2 years.

Cryptorchidism: isolated and associated with other genitourinary defects

Cryptorchidism is the most common disorder of sexual differentiation in male children, with an incidence of 3.4 per cent in the term newborn, decreasing to 0.8 per cent at 1 year of age. The mechanisms of normal testicular descent are multifactorial and include an intact hypothalamic-pituitary-testicular axis, as well as a normal gubernaculum and epididymis. In boys with cryptorchidism, the testes demonstrate degenerative changes histologically as early as 1 to 2 years of age. Both testes may be affected, even with a unilateral undescended testis. The most important long-term complications of cryptorchidism include infertility and testicular cancer. The risk of malignancy is approximately 40 times higher in male subjects with cryptorchidism than in normal men, and is highest in male subjects who have had an intra-abdominal testis and in certain intersex conditions. Orchiopexy does not appear to lessen this risk. Hormonal therapy with HCG or LH-RH has remained unproven in clinical trials in the United States; therefore, orchiopexy remains standard treatment. HCG is recommended if the clinician suspects that a testis is retractile, however. Orchiopexy should be performed between 12 and 18 months of age to prevent the degenerative changes that are demonstrable by 2 years.

Sexual dimorphism in human and canine spinal cord: role of early androgen

Onuf's nucleus, located in the sacral spinal cord of dogs, cats, and primates, innervates perineal muscles involved in copulatory behavior. A sexual dimorphism in Onuf's nucleus was found in humans and dogs: males have significantly more motoneurons in this nucleus than do females. Prenatal androgen treatment of female dogs eliminated the dimorphism. In the homologous nucleus in rats, a similar effect of androgen has been shown to involve sparing of motoneurons from cell death. These results establish a morphological sex difference in a human central nervous system region of known function; well-studied animal models suggest explanations of the development of this dimorphism.

Sexual maturation of the hypothalamus: pathophysiological aspects and clinical implications

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

Serum triiodothyronine and hyperthyroidism in a population sample of women

The serum T3 assay has been regarded as the most sensitive single test for hyperthyroidism although impaired conversion of T4 to T3 in non-thyroidal illness (NTI) might decrease its diagnostic sensitivity. The present report gives experience from the T3 assay in middle-aged females under conditions similar to those in a general health survey. The assays were performed during two periods with an interval of six years. In 1974-75 we studied a representative sample (n = 1283) of women of ages 44, 52, 56, 60 and 66 years in Göteborg, Sweden. Individuals with serum T3 concentration greater than mean + 2.5 SD were selected for a follow-up study (n = 21). Of 16 individuals with no previous thyroid disease and no present treatment with thyroid hormones or oestrogens, 14 were subjected to a TRH-stimulation test giving a normal TSH response in 10 cases having T3 concentrations up to mean + 3.5 SD. Four women with serum T3 concentration greater than or equal to mean + 3.5 SD had previously unrecognized autonomous function thyroid function, of whom two developed hyperthyroidism after two years. The original population sample was reinvestigated after six years in 1980-81 (n = 1138) together with an additional sample of women giving a total sample of 1422 women of ages 26, 38, 50, 58, 62, 66 and 72 years. Of the females studied in 1974-75 eight had developed hyperthyroidism between the two studies; three of these had raised serum T3 at the investigation in 1974-75. No case of hyperthyroidism had been missed by the T3 assay in the 1974-75 study. Of individuals with serum T3 greater than or equal to mean + 2.5 SD selected for a follow-up (n = 29) at least five were found to have previously unrecognized thyroid autonomy. We found a raised serum T3 to be associated with hyperthyroid (n = 2) and euthyroid Graves' disease, autonomously functioning thyroid adenoma(s), possible painless subacute thyroiditis, possible thyrotoxicosis factitia, diminished thyroid reserve and thyroid substitution therapy.

Maturation of the hypothalamic--pituitary--gonadal axis in the male lamb: a review

We have studied the activity of the hypothalamic--pituitary--gonadal (HPG) axis in the male ovine fetus and newborn lamb. Circulating levels of gonadotropins, prolactin, cortisol (F), testosterone (T), dehydroepiandrosterone sulfate and delta 4androstenedione (delta 4A) were measured in fetal plasma in the third trimester of gestation and the testicular response to hCG was studied in ovine fetuses at 95 - 141 days. Ultradian variations of LH, FSH and testosterone and the testicular response to hCG also were assessed from 1 to 28 days postnatally. The data indicate that (1) fetal plasma LH, FSH, delta 4A and T levels are low from 95 days of gestation to term, while F levels increase in the last 10 days. Postnatally, F decreases rapidly. Spontaneous T peaks may occur as early as 36 hr of life. (2) Spontaneous LH and concomitant or subsequent T secretory peaks are observed by 3 days of age. (3) hCG can induce an increase in T production by interstitial cells in vitro and can increase the T testicular content and its release in the plasma from 95 days of intrauterine life. Desensitization to hCG also can be observed throughout the last trimester of gestation. We conclude that the HPG axis of the male lamb is active ty 36 - 72 hr of postnatal life and that the steroidogenic capacity of the ovine testis is developed several weeks prenatally. Consequently, the relative quiescence of the axis prenatally and in the first 24 hr of life seems to result from relatively low LH secretion and release, related to an undefined endogenous control, together with decreased Leydig cell sensitivity and relatively low enzyme activity limiting T release.

Sexuality and pregnancy: a review

Marital success and failure may be related to sexual satisfaction, including orgasmic capability. Pregnancy represents a life crisis to the pregnant woman and her husband. Complex psychosocial and physiological demands may produce insecurities, anxieties, and somatic complaints. The expectant mother may seek to fulfill increasing nurturant needs through increased physical contact such as cuddling or being held. A pregnant woman's interest in sexual activity may be affected by her changing physical appearance and the hormonal milieu of pregnancy. Although there are marked individual variations and methodological biases and differences among empirical studies, pregnancy appears to be usually accompanied by a decrease in sexual desire, coital frequency, and orgasm. Sexual behavior in pregnancy has been traditionally restricted and is currently poorly defined. Sexual proscriptions may precipitate sexual frustration and marital estrangement. Abortion is only rarely caused by coitus. The relationship of coitus and orgasm to prematurity and distress of the fetus and newborn has not been clearly established. Coitus can indirectly result in maternal, fetal, and neonatal morbidity and mortality through the spread of sexually transmitted diseases. Deaths from air embolism in pregnancy associated with cunnilingus and vaginal insufflation have been reported.

T3 hyperthyroidism and thyroid cancer

The authors present an unusual case of T3 hyperthyroidism caused by a well-differentiated thyroid follicular carcinoma and its large skull metastasis. They suggest iodine deficiency as being the single major factor in the aetiology of both disorders.