Endogenous levels of 5 alpha-reduced progestins and androgens in fetal vs. adult rat brains.

5 Alpha-reduced metabolites of certain steroids have been shown to have important functions in adult brains and may play a role in brain development. To assess which 5 alpha-reduced steroid metabolites may have an impact during development, endogenous levels of 5 alpha-reduced androgens and progestins and their parent hormones were measured in male and female fetal brains over the last 5 days of gestation. These levels were compared to levels measured in adult male and female brains (evaluated at different stages of the estrous cycle). Neither the brain levels of parent hormones nor of their 5 alpha-reduced metabolites varied as a function of fetal sex or of gestational age. Therefore, the data from the two sexes were combined. In fetal brains, the levels of the progesterone reduced metabolites were 20-fold higher than levels of progesterone itself whereas levels of testosterone reduced metabolites were 10-fold lower than testosterone levels. In contrast to fetal brain, conversion of progesterone to reduced metabolites was much lower in adult brain, but the level of 5 alpha-reduced androgens was 3-10-fold higher than the level of testosterone in all adult tissue, indicating more conversion of androgen to 5 alpha-reduced metabolites in adult than in fetal brains. These results imply that the reduction of progesterone to reduced metabolites may play a critical role in brain development.     

Androgen regulation of dendritic growth and retraction in the development of a sexually dimorphic spinal nucleus

The spinal nucleus of the bulbocavernosus (SNB) is a sexually dimorphic group of motoneurons whose development and maintenance are under androgenic control. Exposure to androgens early in development permanently alters SNB motoneuron number and soma size; in adulthood, androgens regulate dendritic and synaptic architecture. The present set of experiments investigates the influence of androgens on the development of SNB dendritic morphology. In normal males, SNB dendritic growth is biphasic, reaching exuberant lengths by the fourth postnatal week and then retracting to adult lengths by 7 weeks of age. This dendritic growth is androgen dependent--males castrated on postnatal day (P) 7 and given daily injections of testosterone propionate (TP) had exuberant dendritic lengths similar to those of normal males; dendritic length in oil-treated males remained at P7 levels. The early exuberant dendritic length was retained in TP-treated males through P49. The retraction of SNB dendrites after P28 is also influenced by androgens. Males castrated at P28 and given testosterone implants retained exuberant dendritic length at P49; blank-implanted males had significantly shorter dendritic lengths by P70. These results suggest that androgens are necessary for the early exuberant growth of SNB dendrites. Furthermore, the subsequent retraction of SNB dendrites may be halted when testosterone titers reach a critical level during puberty, stabilizing their adult length.     

Ontogeny of steroid accumulation in spinal lumbar motoneurons of the rat: implications for androgen's site of action during synapse elimination.

Androgens influence the postnatal development of motoneurons in the spinal nucleus of the bulbocavernosus (SNB) by regulating neuromuscular synapse elimination, the process through which multiple axonal inputs are retracted from each muscle fiber until single innervation is established. In the rat levator ani (LA), one of the target muscles for SNB motoneurons, much of this loss of multiple innervation can be prevented by prepubertal androgen treatment. We used steroid autoradiography to measure the ontogeny of steroid accumulation in the SNB and the retrodorsolateral nucleus (RDLN), two motoneuronal groups thought to differ in their sensitivity to androgens. Spinal cord tissue was analyzed from castrated male rats at 7, 14, 21, and 60 days of age after injection of radiolabelled testosterone. SNB and RDLN motoneurons differ in the ontogeny of androgen accumulation. Over 80% of SNB motoneurons develop the capacity to accumulate androgen during the second week after birth, during the period when androgen regulates synapse elimination in the LA. In contrast, androgen accumulation in RDLN motoneurons develops much later (after 21 days). These data suggest that androgen may act directly on SNB motoneurons to influence synapse elimination.     

Fetal growth from mid‐ to late pregnancy is associated with infant development: the Generation R Study

Aim The aim of this study was to investigate within a population‐based cohort of 4384 infants (2182 males, 2202 females) whether fetal growth from early pregnancy onwards is related to infant development and whether this potential relationship is independent of postnatal growth. Method Ultrasound measurements were performed in early, mid‐, and late pregnancy. Estimated fetal weight was calculated using head and abdominal circumference and femur length. Infant development was measured with the Minnesota Infant Development Inventory at 12 months (SD 1.1mo, range 10–17mo). Information on postnatal head size and body weight at 7 months was obtained from medical records. Results After adjusting for potential confounders and for postnatal growth, faster fetal weight gain from mid‐ to late pregnancy predicted a reduced risk of delayed social development (odds ratio [OR] 0.82; 95% confidence interval [CI] 0.71–0.95, p=0.008), self‐help abilities (OR 0.84; 95% CI 0.73–0.98, p=0.023), and overall infant development (OR 0.65; 95% CI 0.49–0.87, p=0.003). Similar findings were observed for fetal head growth from mid‐ to late pregnancy. Interpretation Faster fetal growth predicts a lower risk of delayed infant development independent of postnatal growth. These results suggest that reduced fetal growth between mid‐ and late pregnancy may determine subsequent developmental outcomes.     

Late gestational maternal serum cortisol is inversely associated with fetal brain growth

To analyze the association between fetal brain growth and late gestational blood serum cortisol in normal pregnancy.Blood total cortisol was quantified at delivery in 432 Chinese mother/child pairs. Key inclusion criteria of the cohort were: no structural anomalies of the newborn, singleton pregnancy, no alcohol abuse, no drug abuse or history of smoking no hypertensive disorders and no impairment of glucose tolerance and no use of steroid medication during pregnancy. Differential ultrasound examination of the fetal body was done in early (gestational day 89.95 ± 7.31), middle (gestational day 160.17 ± 16.12) and late pregnancy (gestational day 268.89 ± 12.42). Newborn's cortisol was not correlated with any of the ultrasound measurements during pregnancy nor with birth weight. Multivariable regression analysis, considering timing of the ultrasound examination, the child's sex, maternal BMI, maternal age, maternal body weight at delivery, the timing of cortisol measurement and maternal uterine contraction states, revealed that maternal serum total cortisol was significantly negative correlated with ultrasound parameters describing the fetal brain: late biparietal diameter (R2=0.512, p=0.009), late head circumference (R2=0.498, p=0.001), middle biparietal diameter (R2=0.819, p=0.013), middle cerebellum transverse diameter R2=0.76, p=0.014) and early biparietal diameter(R2=0.819, p=0.013). The same analysis revealed that birth weight as well as ultrasound parameters such as abdominal circumference and femur length were not correlated to maternal cortisol levels. In conclusion, our study demonstrates that maternal cortisol secretion within physiological ranges may be inversely correlated to fetal brain growth but not to birth weight. It remains to be demonstrated whether maternal cortisol secretion negatively influencing fetal brain growth translates to adverse neurological outcomes in later life.     

Reduced postnatal cerebral glucose metabolism measured by PET after asphyxia in near term fetal lambs.

The effects of fetal asphyxia on cerebral function and development, involve the transition from fetal to neonatal life. Changes in cerebral glucose metabolism may be an early postnatal indicator of fetal asphyxia. The objective is to develop an experimental lamb model involving the transition from fetal to neonatal life and to examine the effect of fetal asphyxia with cerebral hypoxic ischemia on early postnatal cerebral glucose metabolism. Fetal asphyxia was induced by total umbilical cord occlusion in eight near-term fetal lambs (134-138 days) with the ewe under isoflurane-opiate anesthesia. The mean occlusion time until cardiac arrest was 14.5 (4.2) min (SD). Lambs were immediately delivered and standardized resuscitation was instituted after 2 min asystole. At 4 hr postnatal age, [18-F]Fluoro-2-deoxy-glucose (18-FDG) was injected intravenously in eight asphyxiated lambs and in eight controls. Cerebral glucose metabolism was examined by positron emission tomography (PET). As a result the mean arterial blood pressure, acid-base values, blood glucose and serum lactate at 4 hr postnatal age did not differ significantly between lambs subjected to umbilical cord occlusion and controls. EEG was abnormal in all lambs subjected to cord occlusion and normal in the controls at 4 hr postnatal age. Global cerebral metabolic rate (CMRgl) as determined by PET was significantly lower in lambs subjected to cord occlusion mean/median (SD) 22.2/19.6 (8.4) micromol/min/100 g) than in controls mean/median (SD) 37.8/35.9 (6.1); P < 0.01). Global CMRgl is significantly reduced in newborn lambs 4 hr after fetal asphyxia induced by umbilical cord occlusion. A reduction in CMRgl is an early indicator of global hypoxic cerebral ischemia.     

Androgen and estrogen receptors in perinatal ferret brain

Using DNA-cellulose affinity chromatography and either 3H-labeled dihydrotestosterone, testosterone, or estradiol, we qualitatively and quantitatively analyzed the androgen- and estrogen-binding activities present in four regions of male and female ferret brain at prenatal, early and late neonatal, and adult ages. The cytosolic androgen- and estrogen-binding activities in ferret brain at all ages studied were qualitatively similar in both sexes and in all brain regions and exhibited characteristics which resemble those of androgen and estrogen receptors from other species, including rodents and nonhuman primates. A developmental analysis indicated that high levels of both androgen and estrogen receptors were present in the hypothalamus-preoptic area as early as 5 days before birth. A significant, transient decline in concentrations of estrogen receptors (approximately 5-fold) occurred in anterior hypothalamus-preoptic area and mediobasal hypothalamus at 12 days of age in both males and females; this phenomenon has not been observed in any other species studied to date. The observed ontogeny of androgen receptors correlates with the known ability of testosterone, acting over postnatal days 5 to 20, to cause coital masculinization in ferrets, whereas the observed postnatal dip in estradiol receptor concentrations correlates with the inability of estradiol to cause coital masculinization or defeminization of receptive behavior in this species.     

Metabolism and binding of androgens in the spinal cord of the rat

The binding of [3H]androgens and estrogens, and the metabolism of [3H]androgens, were studied in the spinal cord of the adult rat. High-affinity, specific binding sites for [3H]testosterone and [3H]estradiol were detected in cytosol fractions from the spinal cords of castrate animals. Equilibrium dissociation constants for reaction of these sites with their respective ligands were similar to those of androgen and estrogen receptors from other regions of the central nervous system. Nuclear binding of [3H]estradiol was observed in the spinal cord 1 h after intravenous administration of the isotope. Likewise, exchange assay demonstrated the presence of high-affinity androgen binding sites in spinal cord nuclei from orchidectomized, testosterone propionate treated animals. 5 alpha-Reductase activity in homogenates of the spinal cord was relatively high, approximately 3 times that in the pooled hypothalamus, preoptic area, septum and amygdala. However, in contrast to the latter brain regions, estrogen formation was not detectable in spinal cord tissue. No sex differences were observed in the metabolism of [3H]testosterone by spinal cord homogenates. These results confirm the presence of androgen and estrogen receptors in the rat spinal cord. The lack of detectable aromatase activity in the spinal cord is consistent with the hypothesis that the effects of circulating testosterone on spinal reflex function are mediated primarily through the androgen receptor system.     

Head growth in Rett syndrome

The longitudinal development of head growth was investigated in girls with Rett syndrome (RS). Growth retardation was expressed in standard deviation (SD) scores. In classic types, the mean head circumference fell successively to 2 SD scores below the norm at the age of 4 years. After the age of 8 it stabilized close to −3 SD scores. In forme fruste variants, the mean head circumference was within normal limits; however, it was significantly below the norm, −0.8 SD scores. In girls with classic RS, head growth had decelerated by less than 1 SD score in 20% of the girls at the age of 6 years and in 10% at the age of 12 years. In forme fruste variants only a small decline in head growth occurred. Head growth decline may thus be very small in classic RS and is usually not present at all in forme fruste variants. In the future, it should, therefore, neither be regarded as a necessary diagnostic criterion for classic RS, nor as a valid one for forme fruste variants.     

Association of testosterone and dihydrotestosterone with externalizing behavior in adolescent boys and girls

BACKGROUND: While an association between androgens and different types of aggression has been well documented in male offenders, the influence of androgens on externalizing behavior in adolescents at risk for antisocial behavior has not been investigated so far. METHODS: Plasma levels of the main androgen metabolites testosterone (T) and 5alpha-dihydrotestosterone (DHT) were measured in N = 87 fourteen-year-old (36 boys, 51 girls) from a prospective longitudinal study of children at risk. Externalizing behavior at age 8, 11 and 14 was assessed using the Achenbach Child Behavior Checklist (CBCL) and Teacher Report Form (TRF). RESULTS: Significant higher androgen levels (T, DHT) were found in male, but not in female adolescents with elevated scores of externalizing behavior. Moreover, boys with persistent externalizing behavior exhibited the highest levels of plasma androgens. CONCLUSIONS: There is a link between T, DHT and externalizing behavior in male adolescents at risk for psychopathology. Due to the findings of highest androgen levels in boys with persistent externalizing behavior, a role of androgens in the development of disruptive or later antisocial disorders can be hypothesized.     

Serum androgens return to normal after temporal lobe epilepsy surgery in men

BACKGROUND: Epileptic discharges from the temporal lobe may influence the release of hormones from the hypothalamic-pituitary axis. If epilepsy surgery influences the underlying epileptic disorder one might expect serum hormone concentrations to return to normal following surgery.Patients: Twenty-two men with epilepsy aged 25 to 48 years (mean, 34.9 years) were investigated before surgery and at 3, 6, and 12 months after surgery. Medication (all patients received carbamazepine) was maintained following surgery. METHODS: Hormone measurements included luteinizing hormone, follicle stimulating hormone, estradiol, testosterone, free testosterone, androstenedione, prolactin, dehydroepiandrosterone sulfate, cortisol, growth hormone, and sex hormone-binding globulin. These hormone levels were compared with those of 105 healthy men (mean age, 33.9 years). RESULTS: Fourteen of the 22 patients (63.6%) achieved total seizure control following epilepsy surgery. The 14 patients with successful seizure control entered further analysis. Before surgery these patients' free testosterone and androstenedione concentrations were significantly lower compared with healthy men. In seven of the 14 patients a significant increase of hormone serum concentrations could be demonstrated for testosterone, free testosterone, and androstenedione. Laterality of epileptic focus, enzyme-inducing medication, stress, and the decreasing number of patients during the follow-up did not correlate with the finding of a normalization of serum androgens. Patients without complete seizure control did not show an increase in serum androgen concentrations. CONCLUSION: Successful temporal lobe epilepsy surgery may lead to a normalization of serum androgen concentrations in men with epilepsy.     

Neonatal androgen‐dependent sex differences in lumbar spinal cord dopamine concentrations and the number of A11 diencephalospinal dopamine neurons

A₁₁ diencephalospinal dopamine (DA) neurons provide the major source of DA innervation to the spinal cord. DA in the dorsal and ventral horns modulates sensory, motor, nociceptive, and sexual functions. Previous studies from our laboratory revealed a sex difference in the density of DA innervation in the lumbar spinal cord. The purpose of this study was to determine whether sex differences in spinal cord DA are androgen dependent, influenced by adult or perinatal androgens, and whether a sex difference in the number of lumbar‐projecting A₁₁ neurons exists. Adult male mice have significantly higher DA concentrations in the lumbar spinal cord than either females or males carrying the testicular feminization mutation (tfm) in the androgen receptor (AR) gene, suggesting an AR‐dependent origin. Spinal cord DA concentrations are not changed following orchidectomy in adult male mice or testosterone administration to ovariectomized adult female mice. Administration of exogenous testosterone to postnatal day 2 female mice results in DA concentrations in the adult lumbar spinal cord comparable to those of males. Male mice display significantly more lumbar‐projecting A₁₁ DA neurons than females, particularly in the caudal portion of the A₁₁ cell body region, as determined by retrograde tract tracing and immunohistochemistry directed toward tyrosine hydroxylase. These results reveal an AR‐dependent sex difference in both the number of lumbar‐projecting A₁₁ DA neurons and the lumbar spinal cord DA concentrations, organized by the presence of androgens early in life. The AR‐dependent sex difference suggests thyat this system serves a sexually dimorphic function in the lumbar spinal cord. J. Comp. Neurol. 518:2423–2436, 2010. © 2010 Wiley‐Liss, Inc.     

Sexual dimorphism and hormone responsiveness in the spinal cord of the socially monogamous prairie vole (Microtus ochrogaster)

Prairie voles (Microtus ochrogaster) are exceptional among rodents in that many aspects of their brain and behavior are not masculinized by exogenous aromatizable androgens. However, the sexually differentiated endpoints studied to date rely on estrogenic mechanisms in other mammals. We examined whether sexual differentiation of an androgen receptor‐dependent sex difference would be similarly distinct in prairie voles. Male mammals have more and larger motoneurons projecting to perineal muscles than do females. This sex difference normally arises from males' perinatal androgen exposure and can be eliminated by treating developing females with androgens. Gross dissection revealed bulbospongiosus muscles in adult male, but not female, prairie voles. Retrograde tracing from males' bulbocavernosus muscles and the external anal sphincter from both sexes revealed sexually dimorphic populations of labeled motoneurons in the ventral horn of the lumbar spinal cord. Similar to other rodents, males had twice as many motoneurons as females, although no sex difference in motoneuron size was detected. Unexpectedly, prenatal or early postnatal exposure to testosterone propionate had no effect on adult females' motoneuron number or size. In adulthood, gonadectomy alone or followed by chronic testosterone treatment also had no effect on females' motoneuron size or number, although castration reduced motoneuron size in males. Comparing gonadally intact weanlings confirmed that the sex difference in motoneuron number exists before adulthood. As with some other sexually dimorphic traits, and perhaps related to their unique social organization, sexual differentiation of the prairie vole spinal cord differs from that found in most other laboratory rodents. J. Comp. Neurol. 516:117–124, 2009. © 2009 Wiley‐Liss, Inc.     

Stressful life events in pregnancy and head circumference at birth

A strong association between stress in pregnancy and small head circumference in infants at birth was reported in 1994. This important finding has never been replicated. In a follow-up study of 4211 participants with singleton pregnancies, information on life events was collected twice during pregnancy and head circumference measured shortly after birth following standard procedures. No association was found between experienced or perceived stress as a result of life events during pregnancy and head circumference in the infants. In conclusion, stress in pregnancy may influence foetal brain development in many ways, but we found no support for an effect on the size of the brain as measured by head circumference at birth.     

Fetal growth in the offspring of epileptic women: results of an Italian multicentric cohort study

An historical cohort study of the association between maternal epilepsy, anticonvulsant drugs and fetal growth was carried out among 47 hospitals collaborating in the Italian Multicentric Registry on Birth Defects (IPIMC). Birth weight, head circumference and body length were studied in 164 babies of epileptic women and compared to 185 controls. Seventy-nine epileptic women were treated by monotherapy, 59 by polytherapy and 26 took no anticonvulsant during pregnancy. An intrauterine growth retardation and a smaller head circumference was observed among babies of epileptic women. No effect was evident for body length. When specific anticonvulsant therapies were taken into account, only phenobarbital showed an effect on birth weight and head circumference; a reduction in head circumference was observed also in the babies of untreated epileptic women. The other antiepileptics (carbamazepine and valproic acid) showed no influence on the outcome considered. The observed effects on fetal growth can be interpreted as a result of an interaction between the effect of the maternal disease and that of the anticonvulsants.     

No association between the 2D:4D fetal testosterone marker and multidimensional attentional abilities in children with ADHD

Aim It has been suggested that high levels of prenatal testosterone exposure are implied in the aetiology of attention‐deficit–hyperactivity disorder (ADHD). This study examined the association between the ratio of the length of the second and fourth digits (2D:4D ratio), a marker of fetal testosterone exposure, and the presence of ADHD‐related cognitive and behavioural problems in children with ADHD and in typically developing comparison individuals. Method A clinically referred group of 64 children who fulfilled DSM‐IV‐TR criteria for ADHD (47 males, 17 females; mean age 8y 8mo, SD 1y 8mo, range 7–12y) and 46 comparison children (25 males, 21 females; mean age 9y 2mo; SD 1y 10mo, range 7–12y) were included in the study. The length of the second and fourth digits was measured by two independent raters. The Child Behaviour Checklist (CBCL) and the Test of Everyday Attention for Children (TEA‐Ch) were used to assess behavioural problems and different aspects of attention. Results No group differences in 2D:4D ratio were observed between children with (combined, inattentive, or hyperactive‐impulsive subtype of) ADHD and comparison children. The ratio did not show the postulated relation with cognitive and behavioural aspects of ADHD. Interpretation These findings challenge the hypothesis that fetal testosterone exposure plays a prominent role in the aetiology of ADHD.     

Brief Report: A Preliminary Study of Fetal Head Circumference Growth in Autism Spectrum Disorder

Fetal head circumference (HC) growth was examined prospectively in children with autism spectrum disorder (ASD). ASD participants (N = 14) were each matched with four control participants (N = 56) on a range of parameters known to influence fetal growth. HC was measured using ultrasonography at approximately 18 weeks gestation and again at birth using a paper tape-measure. Overall body size was indexed by fetal femur-length and birth length. There was no between-groups difference in head circumference at either time-point. While a small number of children with ASD had disproportionately large head circumference relative to body size at both time-points, the between-groups difference did not reach statistical significance in this small sample. These preliminary findings suggest that further investigation of fetal growth in ASD is warranted.     

The growth and myelination of central and peripheral segments of ventral motoneurone axons. A quantitative ultrastructural study.

This study compares the growth and myelination of those parts of cervical ventral motoneurone axons in the spinal cord (the intramedullary segments) and in the ventral roots of fetal and young rats (up to 21 days postnatal). The same fibre bundles are examined centrally and peripherally. Myelination begins centrally and peripherally at about birth. However, the peripheral segments of some fibres may begin to become myelinated before the central. Over the first 3 weeks after birth the minimum circumference of peripheral segments of myelinated axons remains relatively constant at 3 mum but that of central segments falls from 2.5 mum to just over 1 mum. Axons within the same fibre bundles tend to be thinner and less heavily myelinated centrally than peripherally. With ageing, axon circumference becomes more strongly correlated with sheath thickness. The thickness of the sheath surrounding an axon of a given circumference does not differ statistically from one age to another or between central and peripheral segments. Studies of myelin sheath growth rate show that in the early stages glial and Schwann cells vary independently of one another in the rates at which they add new turns to sheaths around central and peripheral segments of axons in the same bundles.     

Congenital cytomegalovirus effects on postnatal neurological development of squirrel monkey (Saimiri sciureus) offspring

Prenatal cytomegalovirus (CMV) infection has been reported to cause sensory deficits, neurological damage, mental deficiency, low birth weight, microcephaly, impairment of neuromuscular coordination, and retardation of postnatal growth in human offspring. The close taxonomic relationship of diurnal primates to man is reflected in great similarities of sensory, cognitive, motor capacity, timing of the “brain growth spurt” in relation to birth, and other aspects of embryonic, fetal, and postnatal stages of development. Susceptibility of squirrel monkey fetuses to SqCMV was shown by the isolation of the virus from the tissues of one of two stillborn offspring and by the presence of SqCMV-specific IgM antibodies in two of three liveborn, nursery-reared offspring all exposed to the virus during gestation. Reflexes and neuromuscular responses of SqCMV offspring were less accurate, poorly coordinated, and required more time for completion than those of controls. Visual acuity of SqCMV offspring was less at birth and also improved at a slower rate during the first month after birth. SqCMV offspring were significantly inferior in percentage correct responses in tests of visual orientation and discrimination and reversal learning. Prenatal SqCMV effects on postnatal somatometric growth rates included significant reductions of head circumference and crown-rump length, and to a lesser degree, offspring body weight from birth to 90 days. We conclude that diurnal primates provide appropriate models to study congenital CMV effects on the brain as the target organ in terms of sensory impairment, learning capacity, neurological damage, and neuromuscular performance of offspring.