Fetal testosterone surge: specific modulations induced in male rats by maternal stress and/or alcohol consumption

Uterine injury during diestrus leads to placental and embryonic defects in future pregnancies in mice†

Uterine injury from procedures such as Cesarean sections (C-sections) often have severe consequences on subsequent pregnancy outcomes, leading to disorders such as placenta previa, placenta accreta, and infertility. With rates of C-section at ~30% of deliveries in the USA and projected to continue to climb, a deeper understanding of the mechanisms by which these pregnancy disorders arise and opportunities for intervention are needed. Here we describe a rodent model of uterine injury on subsequent in utero outcomes. We observed three distinct phenotypes: increased rates of resorption and death, embryo spacing defects, and placenta accreta-like features of reduced decidua and expansion of invasive trophoblasts. We show that the appearance of embryo spacing defects depends entirely on the phase of estrous cycle at the time of injury. Using RNA-seq, we identified perturbations in the expression of components of the COX/prostaglandin pathway after recovery from injury, a pathway that has previously been demonstrated to play an important role in embryo spacing. Therefore, we demonstrate that uterine damage in this mouse model causes morphological and molecular changes that ultimately lead to placental and embryonic developmental defects.

Prenatal, perinatal and parental risk factors for autism spectrum disorder in China: a case- control study

BACKGROUND

Autism spectrum disorder (ASD) is heritable neurodevelopmental disorders (NDDs), but environmental risk factors have also been suggested to a play a role in its development. Prenatal, perinatal and parental factors have been associated with an increased risk of ASD in children. The aim of the present study was to explore the prenatal, perinatal, and parenting risk factors in children with autism spectrum disorder (ASD) from Beijing, China by comparing them with typically developing (TD) children.

METHODS

A sample of 151 ASD children's parents who from rehabilitation institutions in Beijing were enrolled in this study, and an additional 151 children from kindergartens in Beijing were recruited as a control group (child age: mean = 4.4 years). TD children were matched according to age, sex and maternal education. We explored the maternal AQ (Autism Spectrum Quotient) scores (mean:19.40-19.71, no significant difference between two groups) to referring the genetic baseline. This study evaluated 17 factors with unadjusted and adjusted analyses.

RESULTS

Birth asphyxia was associated with a more than a thirteen-fold higher risk of ASD (adjusted odds ratio (AOR) = 13.42). Breastfeeding difficulties were associated with a higher risk of ASD(AOR = 3.46). Parenting influenced the risk of ASD, with low responding (LR) and harsh or neglectful parenting associated with a higher risk of ASD in offspring (AOR = 2.37 for LR, AOR = 3.42 for harsh parenting and AOR = 3.01 for neglectful parenting). Maternal fever during pregnancy was associated with a higher risk of ASD in offspring (AOR = 3.81).

CONCLUSIONS

Many factors were associated with ASD in offspring. Further assessment is needed to elucidate the role of modifiable environmental factors to inform prevention strategies.

Sex-biased gene and microRNA expression in the developing mouse brain is associated with neurodevelopmental functions and neurological phenotypes

BACKGROUND

Sex differences pose a challenge and an opportunity in biomedical research. Understanding how sex chromosomes and hormones affect disease-causing mechanisms will shed light on the mechanisms underlying predominantly idiopathic sex-biased neurodevelopmental disorders such as ADHD, schizophrenia, and autism. Gene expression is a crucial conduit for the influence of sex on developmental processes; therefore, this study focused on sex differences in gene expression and the regulation of gene expression. The increasing interest in microRNAs (miRNAs), small, non-coding RNAs, for their contribution to normal and pathological neurodevelopment prompted us to test how miRNA expression differs between the sexes in the developing brain.

METHODS

High-throughput sequencing approaches were used to identify transcripts, including miRNAs, that showed significantly different expression between male and female brains on day 15.5 of development (E15.5).

RESULTS

Robust sex differences were identified for some genes and miRNAs, confirming the influence of biological sex on RNA. Many miRNAs that exhibit the greatest differences between males and females have established roles in neurodevelopment, implying that sex-biased expression may drive sex differences in developmental processes. In addition to highlighting sex differences for individual miRNAs, gene ontology analysis suggested several broad categories in which sex-biased RNAs might act to establish sex differences in the embryonic mouse brain. Finally, mining publicly available SNP data indicated that some sex-biased miRNAs reside near the genomic regions associated with neurodevelopmental disorders.

CONCLUSIONS

Together, these findings reinforce the importance of cataloguing sex differences in molecular biology research and highlight genes, miRNAs, and pathways of interest that may be important for sexual differentiation in the mouse and possibly the human brain.

Kiss1-dependent and independent release of luteinizing hormone and testosterone in perinatal male rats

Prenatal and postnatal biphasic increases in plasma testosterone levels derived from perinatal testes are considered critical for defeminizing/masculinizing the brain mechanism that regulates sexual behavior in male rats. Hypothalamic kisspeptin neurons are indispensable for stimulating GnRH and downstream gonadotropin, as well as the consequent testicular testosterone production/release in adult male rats. However, it is unclear whether kisspeptin is responsible for the increase in plasma testosterone levels in perinatal male rats. The present study aimed to investigate the role of Kiss1/kisspeptin in generating perinatal plasma LH and the consequent testosterone increase in male rats by comparing the plasma testosterone and LH profiles of wild-type (Kiss1^+/+) and Kiss1 knockout (Kiss1^-/-) male rats. A biphasic pattern of plasma testosterone levels, with peaks in the prenatal and postnatal periods, was found in both Kiss1^+/+ and Kiss1^-/- male rats. Postnatal plasma testosterone and LH levels were significantly lower in Kiss1^-/- male rats than in Kiss1^+/+ male rats, whereas the levels in the prenatal embryonic period were comparable between the genotypes. Exogenous kisspeptin challenge significantly increased plasma testosterone and LH levels and the number of c-Fos-immunoreactive GnRH neurons in neonatal Kiss1^-/- and Kiss1^+/+ male rats. Kiss1 and Gpr54 (kisspeptin receptor gene) were found in the testes of neonatal rats, but kisspeptin treatment failed to stimulate testosterone release in the cultured testes of both genotypes. These findings suggest that postnatal, but not prenatal, testosterone increase in male rats is mainly induced by central kisspeptin-dependent stimulation of GnRH and consequent LH release.

Fibroblast growth factor 2: Role in prenatal alcohol-induced stimulation of hypothalamic peptide neurons

Prenatal alcohol exposure (PAE) increases alcohol consumption and risk for alcohol use disorder. This phenomenon in rodents is suggested to involve a stimulatory effect of PAE, in female more than male offspring, on neurogenesis and density of neurons expressing neuropeptides in lateral hypothalamus (LH), including melanin-concentrating hormone (MCH), known to promote alcohol intake. With evidence suggesting a role for fibroblast growth factor 2 (FGF2) and its receptor FGFR1 in stimulating neurogenesis and alcohol drinking, we investigated here whether the FGF2-FGFR1 system is involved in the PAE-induced increase in MCH neurons, in postnatal offspring of pregnant rats given ethanol orally (embryonic day 10-15) at a low-moderate (2 g/kg/day) or high (5 g/kg/day) dose. Our results demonstrate that PAE at the low-moderate but not high dose stimulates FGF2 and FGFR1 gene expression and increases the density of MCH neurons co-expressing FGF2, only in females, but FGFR1 in both sexes. PAE induces this effect in the dorsal but not ventral area of the LH. Further analysis of FGF2 and FGFR1 transcripts within individual MCH neurons reveals an intracellular, sex-dependent effect, with PAE increasing FGF2 transcripts positively related to FGFR1 in the nucleus as well as cytoplasm of females but transcripts only in the cytoplasm of males. Peripheral injection of FGF2 itself (80 μg/kg, s.c.) in pregnant rats mimics these effects of PAE. Together, these results support the involvement of the FGF2-FGFR1 system in mediating the PAE-induced, sex dependent increase in density of MCH neurons, possibly contributing to increased alcohol consumption in the offspring.

No preference for prosocial helping behavior in rats with concurrent social interaction opportunities

Helping behavior tasks are proposed to assess prosocial or "empathic" behavior in rodents. This paradigm characterizes the behavior of subject animals presented with the opportunity to release a conspecific from a distressing situation. Previous studies found a preference in rats for releasing restrained or distressed conspecifics over other controls (e.g., empty restrainers or inanimate objects). An empathy account was offered to explain the observed behaviors, claiming subjects were motivated to reduce the distress of others based on a rodent homologue of empathy. An opposing account attributes all previous results to subjects seeking social contact. To dissociate these two accounts for helping behavior, we presented subject rats with three simultaneous choice alternatives: releasing a restrained conspecific, engaging a nonrestrained conspecific, or not socializing. Subjects showed an initial preference for socializing with the nonrestrained conspecific, and no preference for helping. This result contradicts the empathy account, but is consistent with the social-contact account of helping behavior.

Dose-response analysis of microvasculature changes in the murine fetal brain and the maternal extremities due to prenatal ethanol exposure

SIGNIFICANCE

Prenatal exposure to ethanol causes several morphological and neurobehavioral deficits. While there are some studies on the effects of ethanol exposure on blood flow, research focusing on acute changes in the microvasculature is limited.

AIM

The first aim of this study was to assess the dose-dependent changes in murine fetal brain microvasculature of developing fetuses in response to maternal alcohol consumption. The second aim was to quantify changes in vasculature occurring concurrently in the mother's hindlimb and the fetus's brain after maternal exposure to alcohol.

APPROACH

Correlation mapping optical coherence angiography was used to evaluate the effects of prenatal exposure to different doses of ethanol (3, 1.5, and 0.75  g  /  kg) on murine fetal brain vasculature in utero. Additionally, simultaneous imaging of maternal peripheral vessels and the fetal brain vasculature was performed to assess changes of the vasculature occurring concurrently in response to ethanol consumption.

RESULTS

The fetal brain vessel diameters (VDs) decreased by ∼47  %  , 30%, and 14% in response to ethanol doses of 3, 1.5, and 0.75  g  /  kg, respectively. However, the mother's hindlimb VD increased by 63% in response to ethanol at a dose of 3  g  /  kg.

CONCLUSIONS

Results showed a dose-dependent reduction in vascular blood flow in fetal brain vessels when the mother was exposed to ethanol, whereas vessels in the maternal hindlimb exhibited concurrent vasodilation.

Endocrine Insights into the Pathophysiology of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a class of neurodevelopmental disorders that affects males more frequently than females. Numerous genetic and environmental risk factors have been suggested to contribute to the development of ASD. However, no one factor can adequately explain either the frequency of the disorder or the male bias in its prevalence. Gonadal, thyroid, and glucocorticoid hormones all contribute to normal development of the brain, hence perturbations in either their patterns of secretion or their actions may constitute risk factors for ASD. Environmental factors may contribute to ASD etiology by influencing the development of neuroendocrine and neuroimmune systems during early life. Emerging evidence suggests that the placenta may be particularly important as a mediator of the actions of environmental and endocrine risk factors on the developing brain, with the male being particularly sensitive to these effects. Understanding how various risk factors integrate to influence neural development may facilitate a clearer understanding of the etiology of ASD.

Effect of Maternal Water Restriction on Sexual Behavior, Reproductive Performance, and Reproductive Hormones of Male Rat Offspring

The present study aimed to investigate the effect of maternal water restriction on sexual behavior, reproductive performance, and reproductive hormones of male rat offspring. Forty pregnant female rats were divided into two equal groups: Control (C) and water-restricted (WR). Control dams had ad libitum water access throughout pregnancy, while dams in the WR group were subjected to 50% water-restriction from day 10 of pregnancy onwards. The maternal water restriction provoked a significant reduction (p < 0.05) in body weight of dams before delivery and at birth and litter body weights of offspring at birth. Maternal water restriction did not affect relative weights of reproductive and body organs of male rat offspring. All hormonal concentrations, sperm count, and vitality in male rat offspring were not significantly affected by maternal water restriction. Maternal water restriction exposure induced significant (p < 0.05) reduction in intromission latency, intromission frequency, and post-ejaculation interval in male rat offspring while a significant (p < 0.05) increase in the ejaculation latency was detected in maternal WR group. In conclusion, this study suggests that maternal water restriction had a negative impact on some reproductive characteristics but did not severely affect reproductive performance and reproductive hormones of male rat offspring.

A pilot study on the effect of early provision of dietary docosahexaenoic acid on testis development, functions, and sperm quality in rats exposed to prenatal ethanol

BACKGROUND

Prenatal ethanol (EtOH) exposure is associated with adverse effect on the male reproductive function. Dietary docosahexaenoic acid (DHA) is known to improve testis function and sperm parameters, thereby male fertility. This study piloted whether dietary DHA influences testis development and function in rats exposed to prenatal EtOH.

METHODS

Pregnant female Sprague-Dawley rats (n = 30) received either EtOH (3 g/kg, twice a day, n = 14) or dextrose (n = 16) throughout pregnancy. Moreover, they were fed either diet supplemented with (Cont + DHA, n = 8, EtOH + DHA, n = 6) or without DHA (1.4% w/w of total fatty acids) (Cont, EtOH, n = 8 each), with pups being continued on their mothers' diet after weaning. Tissues were collected at gestational day (GD) 20, postnatal day (PD) 4, 21, 49 and 90 for analyzing testicular developmental markers and sperm parameters, and plasma for testosterone.

RESULTS

Dietary DHA increased serum testosterone at GD20 (p < .05) and sperm normal morphology at PD90 (p < .0001) compared to the group without DHA supplementation. Dietary DHA also increased the height of germinal epithelium at peripuberty, PD49 (p < .03). The EtOH exposure induced a marked decline in the testicular gene expression of StAR at PD49 (p < .02) than those of non-EtOH treated group.

CONCLUSIONS

These findings indicate that dietary DHA may positively contribute to male fertility by impacting sperm normal morphology likely by increasing fetal testosterone level. Prenatal EtOH exposure did not adversely affect the overall testis developmental markers during development and sperm parameters in adulthood.

Fetal androgen signaling defects affect pancreatic β-cell mass and function, leading to glucose intolerance in high-fat diet-fed male rats

We previously demonstrated that androgen signaling expands pancreatic β-cell mass in the sexual maturation period (Am J Physiol Endocrinol Metab 314: E274-E286, 2018). The aim of this study was to elucidate whether fetal androgen signaling plays important roles in β-cell mass development and β-cell function in adulthood, defects of which are associated with type 2 diabetes mellitus. In the pancreas of male fetuses, androgen receptor (AR) was strongly expressed in the cytoplasm and at the cell membrane of Nkx6.1-positive β-cell precursor cells but was markedly reduced in insulin-positive β-cells. Administration of the anti-androgen flutamide to pregnant dams during late gestation reduced β-cell mass and Ki67-positive proliferating β-cells at birth in a male-specific manner without affecting body weight. The decrease of β-cell mass in flutamide-exposed male rats was not recovered when rats were fed a standard diet, whereas it was fully recovered when rats were fed a high-fat diet (HFD), at 6 and 12 wk of age. Flutamide exposure in utero led to the development of glucose intolerance in male rats due to a decrease in insulin secretion when fed HFD but not standard diet. Insulin sensitivity did not differ between the two groups irrespective of diet. These results indicated that the action of fetal androgen contributed to β-cell mass expansion in a sex-specific manner at birth and to the development of glucose intolerance by decreasing the secretion of insulin in HFD-fed male rats. Our data demonstrated the involvement of fetal androgen signaling in hypothesized sex differences in the developmental origins of health and disease by affecting pancreatic β-cell function.

Prenatal androgen excess alters the uterine peroxisome proliferator-activated receptor (PPAR) system

It is known that androgen excess induces changes in fetal programming that affect several physiological pathways. Peroxisome proliferator-activated receptors (PPARs) α, δ and γ are key mediators of female reproductive functions, in particular in uterine tissues. Thus, we aimed to study the effect of prenatal hyperandrogenisation on the uterine PPAR system. Rats were treated with 2mg testosterone from Day 16 to 19 of pregnancy. Female offspring (PH group) were followed until 90 days of life, when they were killed. The PH group exhibited an anovulatory phenotype. We quantified uterine mRNA levels of PPARα (Ppara ), PPARδ (Ppard ), PPARγ (Pparg ), their regulators peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Ppargc1a ) and nuclear receptor co-repressor 1 (Ncor1 ) and cyclo-oxygenase (COX)-2 (Ptgs2 ), and assessed the lipid peroxidation (LP) index and levels of glutathione (GSH) and prostaglandin (PG) E2 . The PH group showed decreased levels of all uterine PPAR isoforms compared with the control group. In addition, PGE2 and Ptgs2 levels were increased in the PH group, which led to a uterine proinflammatory environment, as was LP, which led to a pro-oxidant status that GSH was not able to compensate for. These results suggest that prenatal exposure to androgen excess has a fetal programming effect that affects the gene expression of PPAR isoforms, and creates a misbalanced oxidant-antioxidant state and a proinflammatory status.

Adverse reproductive outcomes associated with fetal alcohol exposure: a systematic review

Fetal alcohol exposure results in well-characterised neurobehavioural deficits in offspring, which form the basis for diagnosing fetal alcohol spectrum disorder. However, there is increasing interest in the full range of health complications that can arise in children and adults with this disorder. We used a systematic review approach to locate all clinical and preclinical studies across a broad range of health outcomes in offspring exposed to prenatal alcohol. Our search encompassed four databases (PubMed, CINAHL, EMBASE and Web of Science) and titles/abstracts from retrieved studies were screened against strict inclusion/exclusion criteria. This review specifically evaluated studies reporting on reproductive outcomes in both males and females. A total of 23 studies were included, 5 clinical and 18 preclinical. Although there was a wide range in the quality of reporting across both clinical and preclinical studies, and variable results, trends emerged amongst the reproductive measures that were investigated. In females, most studies focussed on age at first menarche/puberty onset, with evidence for a significant delay in alcohol-exposed offspring. In males, offspring exposed to prenatal alcohol had altered testosterone levels, reduced testes and accessory gland weights and reduced sperm concentration and semen volume. However, further studies are required due to the paucity of clinical studies, the narrow scope of female reproductive outcomes examined and inconsistencies in outcomes across preclinical studies. We recommend that adolescents and individuals of reproductive age diagnosed with f-etal alcohol spectrum disorder be assessed for reproductive dysfunction to allow appropriate management of their reproductive health and fertility.

Prenatal stress decreases sperm quality, mature follicles and fertility in rats

Prenatal stress disrupts reproductive function in females and males. These alterations have primarily been related to maternal corticosteroid fetal programming due to the stress response, affecting the fetus and causing long-lasting effects. The aim of this study was to investigate the influence of prenatal stress on male and female fertility. Dams were exposed to stress by immersion in cold water twice a day for the last week of gestation (days 15-21). In the adulthood, sperm quality, mature follicles, sexual hormones and fertility were assessed in female and male progeny. The results in prenatally stressed females showed lower body weight, longer estrous cycles, lower estradiol and progesterone, and lower number of pups. In prenatally stressed males, lower body weight, increased testicular cell death, as well as decreased testosterone levels, sperm quality, and fertility were observed. Aside from these effects, corticosterone levels in prenatally stressed males and females increased. These results show that prenatal stress can markedly influence infertility in adult female and male progeny. Abbreviations: 3β-HSD: 3β hydroxysteroid dehydrogenase; CRH: corticotropin releasing hormone; DEX: dexamethasone; ERα: estrogen receptor alpha; H-E: hematoxylin-eosine; HPA: hypothalamus-pituitary-adrenal; KISS: Kisspeptin; ORW: ovarian relative weight; PBS: phosphates; PS: prenatally stressed; PRW: prostatic relative weight; ROS: reactive oxygen species; SRW: seminal relative weight; TdT: terminal deoxynucleotidyl transferase; TUNEL: terminal deoxynucleotidyl transferase dUTP Nick-end labelling; TRW: testicular relative weight; URW: uterine relative weight.

Passing experiences on to future generations: endocrine disruptors and transgenerational inheritance of epimutations in brain and sperm

All animals have body burdens of polychlorinated biphenyls (PCBs) despite their ban decades ago. These and modern endocrine-disrupting chemicals (EDCs) such as the fungicide vinclozolin (VIN) perturb hormone signaling and lead to dysfunctions following prenatal exposures. Beyond direct exposures, transgenerational disease phenotypes can persist for multiple generations without subsequent exposure. The mechanisms of action of these EDCs differ: VIN is anti-androgenic while the PCB mixture Aroclor 1221 (A1221) is weakly estrogenic. Based on limited evidence for the inheritance of epimutations in germline, we measured DNA methylation in brain and sperm of rats. Pregnant dams were exposed from day 8-18 of gestation to low dosages of VIN, A1221, or the vehicle. To produce paternal lineages, exposed F1 males were bred with untreated females, creating the F2 and subsequently F3 generations. In adult F1 and F3 males, mature sperm was collected, and brain nuclei involved in anxiety and social behaviors (CA3 of the hippocampus; central amygdala) were selected for assays of epimutations in CpG islands using reduced representation bisulfite sequencing. In F1 sperm, VIN and PCBs induced differential methylation in 215 and 284 CpG islands, respectively, compared to vehicle. The majority of effects were associated with hypermethylation. Fewer epimutations were detected in the brain. A subset of differentially methylated regions were retained from the F1 to the F3 generation, suggesting a common mechanism of EDC and germline epigenome interaction. Thus, EDCs can cause heritable epimutations in the sperm that may embody the future phenotype of brain-behavior disorders caused by direct or transgenerational exposures.

Neurobiological characteristics underlying metabolic differences between males and females

The hypothalamus is the main integrating center for metabolic control. Our understanding of how hypothalamic circuits function to control appetite and energy expenditure has increased dramatically in recent years, due to the rapid rise in the incidence of obesity and the search for effective treatments. Increasing evidence indicates that these treatments will most likely differ between males and females. Indeed, sex differences in metabolism have been demonstrated at various levels, including in two of the most studied neuronal populations involved in metabolic control: the anorexigenic proopiomelanocortin neurons and the orexigenic neuropeptide Y/Agouti-related protein neurons. Here we review what is known to date regarding the sex differences in these two neuronal populations, as well as other neuronal populations involved in metabolic control and glial cells.

Effects of prenatal stress on anxiety- and depressive-like behaviours are sex-specific in prepubertal rats

The foetal brain is highly susceptible to stress in late pregnancy, with lifelong effects of stress on physiology and behaviour. The present study aimed to determine the physiological and behavioural effects of prenatal stress during the prepubertal period of female and male rats. We subjected pregnant Sprague-Dawley rats to a restraint stress protocol from gestational day 14 to 21, a critical period for foetal brain susceptibility to stress effects. Male and female offspring were subsequently assessed at postnatal day 24 for anxiety- and depressive-like behaviours, as well as spontaneous social interaction. We also assessed maternal behaviours and 2 stress markers: basal vs acute-evoked stress levels of serum corticosterone and body weight gain. Prenatal stress did not affect the maternal behaviour, whereas both female and male offspring had higher body weight gain. On the other hand, lower levels of corticosterone after acute stress stimulation, as well as anxiety- and depressive-like behaviours, were only evident in stressed males compared to control males. These results suggest that prenatal stress induced sex-specific effects on hypothalamic-pituitary-adrenal (HPA) axis activity and on behaviour during prepuberty. The HPA axis of prenatally stressed male rats was less active compared to control males, and they were also more anxious and experienced depressive-like behaviours. These results are useful with respect to studying the neurobiological basis of childhood depression at a preclinical level.

Role of androgens in energy metabolism affecting on body composition, metabolic syndrome, type 2 diabetes, cardiovascular disease, and longevity: lessons from a meta-analysis and rodent studies

Testosterone is a sex hormone produced by testicular Leydig cells in males. Blood testosterone concentrations increase at three time-periods in male life-fetal, neonatal (which can be separated into newborn and infant periods), and pubertal stages. After peaking in the early 20s, the blood bioactive testosterone level declines by 1-2% each year. It is increasingly apparent that a low testosterone level impairs general physical and mental health in men. Here, this review summarizes recent systematic reviews and meta-analyses of epidemiological studies in males (including cross-sectional, longitudinal, and androgen deprivation studies, and randomized controlled testosterone replacement trials) in relation to testosterone and obesity,  body composition, metabolic syndrome, type 2 diabetes, cardiovascular disease, and longevity. Furthermore, underlying mechanisms are discussed using data from rodent studies involving castration or androgen receptor knockout. This review provides an update understanding of the role of testosterone in energy metabolism. Abbreviations AR: androgen receptor; CV: cardiovascular; FDA: US Food and Drug Administration; HFD: high-fat diet; KO: knockout; MetS: metabolic syndrome; RCT: randomized controlled trial; SHBG: sex hormone binding globulin; SRMA: systematic review and meta-analysis; TRT: testosterone replacement therapy; T2DM:type 2 diabetes mellitus.

Elevated androstenedione in young adult but not early adolescent prenatally androgenized female rats

Background

Elevated testosterone (T) is routinely reported as a marker of hyperandrogenemia in rodent models for polycystic ovary syndrome (PCOS). In women with PCOS, elevated serum androstenedione (A4) is associated with more severe phenotypes, including a positive correlation with serum T, DHEAS, free androgen index (FAI), LH, and LH/FSH ratio. Furthermore, A4, along with calculated free T and FAI, was identified as one of the best predictors of PCOS in adult women of all ages (18 to > 50 y).

Objective

The objective of this study was to investigate serum A4 levels in early adolescent and young adult prenatally androgenized (PNA) female rats, a model for PCOS.

Methods

Pregnant rats were injected with 5 mg T daily during gestational days 16–19 (PNA rats, experimental group) or an equal volume of vehicle (control group). Female offspring of both groups had tail vein blood drawn for serum analysis at 8 and 16 weeks of age. ELISAs were used to quantify serum A4 and T levels.

Results

Serum A4 and T were elevated in 16-week-old PNA rats compared to controls. There was no significant difference in either hormone at 8 weeks of age.

Conclusions

The PNA rats demonstrated elevated serum A4 and T in young adulthood, as has been observed in women with PCOS, further validating this as a model for PCOS and underscoring the importance of serum A4 elevation as a parameter inherent to PCOS and a rodent model for the disorder. Significant A4 elevation develops between early adolescence and early adulthood in this PNA rat model.

Sex-Specific Effects of Combined Exposure to Chemical and Non-chemical Stressors on Neuroendocrine Development: a Review of Recent Findings and Putative Mechanisms

PURPOSE OF REVIEW

Environmental toxicants and psychosocial stressors share many biological substrates and influence overlapping physiological pathways. Increasing evidence indicates stress-induced changes to the maternal milieu may prime rapidly developing physiological systems for disruption by concurrent or subsequent exposure to environmental chemicals. In this review, we highlight putative mechanisms underlying sex-specific susceptibility of the developing neuroendocrine system to the joint effects of stress or stress correlates and environmental toxicants (bisphenol A, alcohol, phthalates, lead, chlorpyrifos, and traffic-related air pollution).

RECENT FINDINGS

We provide evidence indicating that concurrent or tandem exposure to chemical and non-chemical stressors during windows of rapid development is associated with sex-specific synergistic, potentiated and reversed effects on several neuroendocrine endpoints related to hypothalamic-pituitary-adrenal axis function, sex steroid levels, neurotransmitter circuits, and innate immune function. We additionally identify gaps, such as the role that the endocrine-active placenta plays, in our understanding of these complex interactions. Finally, we discuss future research needs, including the investigation of non-hormonal biomarkers of stress. We demonstrate multiple physiologic systems are impacted by joint exposure to chemical and non-chemical stressors differentially among males and females. Collectively, the results highlight the importance of evaluating sex-specific endpoints when investigating the neuroendocrine system and underscore the need to examine exposure to chemical toxicants within the context of the social environment.

Sex Differences in Early Postnatal Microglial Colonization of the Developing Rat Hippocampus Following a Single-Day Alcohol Exposure

Microglia are involved in various homeostatic processes in the brain, including phagocytosis, apoptosis, and synaptic pruning. Sex differences in microglia colonization of the developing brain have been reported, but have not been established following alcohol insult. Developmental alcohol exposure represents a neuroimmune challenge that may contribute to cognitive dysfunction prevalent in humans with Fetal Alcohol Spectrum Disorders (FASD) and in rodent models of FASD. Most studies have investigated neuroimmune activation following adult alcohol exposure or following multiple exposures. The current study uses a single day binge alcohol exposure model (postnatal day [PD] 4) to examine sex differences in the neuroimmune response in the developing rat hippocampus on PD5 and 8. The neuroimmune response was evaluated through measurement of microglial number and cytokine gene expression at both time points. Male pups had higher microglial number compared to females in many hippocampal subregions on PD5, but this difference disappeared by PD8, unless exposed to alcohol. Expression of pro-inflammatory marker CD11b was higher on PD5 in alcohol-exposed (AE) females compared to AE males. After alcohol exposure, C-C motif chemokine ligand 4 (CCL4) was significantly increased in female AE pups on PD5 and PD8. Tumor necrosis factor-α (TNF-α) levels were also upregulated by AE in males on PD8. The results demonstrate a clear difference between the male and female neuroimmune response to an AE challenge, which also occurs in a time-dependent manner. These findings are significant as they add to our knowledge of specific sex-dependent effects of alcohol exposure on microglia within the developing brain.

Novel androgen-induced activity of an antimicrobial β-defensin: Regulation of Wolffian duct morphogenesis

The Wolffian duct (WD) undergoes morphological changes induced by androgens to form the epididymis, which is an organ essential for sperm maturation. Androgen action in WD epithelium involves paracrine factors of mesenchymal origin that function by still poorly understood mechanisms. Here we studied the antimicrobial β-defensin SPAG11C as a new player in duct morphogenesis, localized prenatally in the WD mesenchyme. Organotypic culture of rat WDs and tissues from Androgen Receptor (AR) knockout mice (ARKO) were used. Our results show that androgen/AR signaling differentially regulated SPAG11C expression at mRNA and protein levels in the developing WD. WDs incubated with recombinant human SPAG11C were shorter and less coiled as a result of reduced epithelial cell proliferation, but not increased apoptosis. Our results suggested β-defensin SPAG11C as an androgen-target required for WD morphogenesis. This highlights the multifunctional repertoire of the β-defensin protein family and their potential contribution to the in utero environment that determines male reproductive success.

ALL OUR SONS: THE DEVELOPMENTAL NEUROBIOLOGY AND NEUROENDOCRINOLOGY OF BOYS AT RISK

Why are boys at risk? To address this question, I use the perspective of regulation theory to offer a model of the deeper psychoneurobiological mechanisms that underlie the vulnerability of the developing male. The central thesis of this work dictates that significant gender differences are seen between male and female social and emotional functions in the earliest stages of development, and that these result from not only differences in sex hormones and social experiences but also in rates of male and female brain maturation, specifically in the early developing right brain. I present interdisciplinary research which indicates that the stress-regulating circuits of the male brain mature more slowly than those of the female in the prenatal, perinatal, and postnatal critical periods, and that this differential structural maturation is reflected in normal gender differences in right-brain attachment functions. Due to this maturational delay, developing males also are more vulnerable over a longer period of time to stressors in the social environment (attachment trauma) and toxins in the physical environment (endocrine disruptors) that negatively impact right-brain development. In terms of differences in gender-related psychopathology, I describe the early developmental neuroendocrinological and neurobiological mechanisms that are involved in the increased vulnerability of males to autism, early onset schizophrenia, attention deficit hyperactivity disorder, and conduct disorders as well as the epigenetic mechanisms that can account for the recent widespread increase of these disorders in U.S. culture. I also offer a clinical formulation of early assessments of boys at risk, discuss the impact of early childcare on male psychopathogenesis, and end with a neurobiological model of optimal adult male socioemotional functions.

Enduring, Sexually Dimorphic Impact of In Utero Exposure to Elevated Levels of Glucocorticoids on Midbrain Dopaminergic Populations

Glucocorticoid hormones (GCs) released from the fetal/maternal glands during late gestation are required for normal development of mammalian organs and tissues. Accordingly, synthetic glucocorticoids have proven to be invaluable in perinatal medicine where they are widely used to accelerate fetal lung maturation when there is risk of pre-term birth and to promote infant survival. However, clinical and pre-clinical studies have demonstrated that inappropriate exposure of the developing brain to elevated levels of GCs, either as a result of clinical over-use or after stress-induced activation of the fetal/maternal adrenal cortex, is linked with significant effects on brain structure, neurological function and behaviour in later life. In order to understand the underlying neural processes, particular interest has focused on the midbrain dopaminergic systems, which are critical regulators of normal adaptive behaviours, cognitive and sensorimotor functions. Specifically, using a rodent model of GC exposure in late gestation (approximating human brain development at late second/early third trimester), we demonstrated enduring effects on the shape and volume of the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) (origins of the mesocorticolimbic and nigrostriatal dopaminergic pathways) on the topographical organisation and size of the dopaminergic neuronal populations and astrocytes within these nuclei and on target innervation density and neurochemical markers of dopaminergic transmission (receptors, transporters, basal and amphetamine-stimulated dopamine release at striatal and prefrontal cortical sites) that impact on the adult brain. The effects of antenatal GC treatment (AGT) were both profound and sexually-dimorphic, not only in terms of quantitative change but also qualitatively, with several parameters affected in the opposite direction in males and females. Although such substantial neurobiological changes might presage marked behavioural effects, in utero GC exposure had only a modest or no effect, depending on sex, on a range of conditioned and unconditioned behaviours known to depend on midbrain dopaminergic transmission. Collectively, these findings suggest that apparent behavioural normality in certain tests, but not others, arises from AGT-induced adaptations or compensatory mechanisms within the midbrain dopaminergic systems, which preserve some, but not all functions. Furthermore, the capacities for molecular adaptations to early environmental challenge are different, even opponent, in males and females, which may account for their differential resilience or failure to perform adequately in behavioural tests. Behavioural "normality" is thus achieved by the midbrain dopaminergic network operating outside its normal limits (in a state of allostasis), rendering it at greater risk to malfunction when challenged in later life. Sex-specific neurobiological programming of midbrain dopaminergic systems may, therefore, have psychopathological relevance for the sex bias commonly found in brain disorders associated with these systems, and which have a neurodevelopmental component, including schizophrenia, ADHD (attention/deficit hyperactivity disorders), autism, depression and substance abuse.

β-defensins and the epididymis: contrasting influences of prenatal, postnatal, and adult scenarios

β-defensins are components of host defense, with antimicrobial and pleiotropic immuno-modulatory properties. Research over the last 15 years has demonstrated abundant expression of a variety of β-defensins in the postnatal epididymis of different species. A gradient of region- and cell-specific expression of these proteins is observed in the epithelium of the postnatal epididymis. Their secretion into the luminal fluid and binding to spermatozoa as they travel along the epididymis has suggested their involvement in reproduction-specific tasks. Therefore, continuous attention has been given to various β-defensins for their role in sperm function and fertility. Although β-defensins are largely dependent on androgens, the underlying mechanisms regulating their expression and function in the epididymis are not well understood. Recent investigation has pointed out to a new and interesting scenario where β-defensins emerge with a different expression pattern in the Wolffian duct, the embryonic precursor of the epididymis, as opposed to the adult epididymis, thereby redefining the concept concerning the multifunctional roles of β-defensins in the developing epididymis. In this review, we summarize some current views of β-defensins in the epididymis highlighting our most recent data and speculations on their role in the developing epididymis during the prenatal-to-postnatal transition, bringing attention to the many unanswered questions in this research area that may contribute to a better understanding of epididymal biology and male fertility.

Mammary Gland Evaluation in Juvenile Toxicity Studies: Temporal Developmental Patterns in the Male and Female Harlan Sprague-Dawley Rat

There are currently no reports describing mammary gland development in the Harlan Sprague-Dawley (HSD) rat, the current strain of choice for National Toxicology Program (NTP) testing. Our goals were to empower the NTP, contract labs, and other researchers in understanding and interpreting chemical effects in this rat strain. To delineate similarities/differences between the female and male mammary gland, data were compiled starting on embryonic day 15.5 through postnatal day 70. Mammary gland whole mounts, histology sections, and immunohistochemically stained tissues for estrogen, progesterone, and androgen receptors were evaluated in both sexes; qualitative and quantitative differences are highlighted using a comprehensive visual timeline. Research on endocrine disrupting chemicals in animal models has highlighted chemically induced mammary gland anomalies that may potentially impact human health. In order to investigate these effects within the HSD strain, 2,3,7,8-tetrachlorodibenzo-p-dioxin, diethylstilbestrol, or vehicle control was gavage dosed on gestation day 15 and 18 to demonstrate delayed, accelerated, and control mammary gland growth in offspring, respectively. We provide illustrations of normal and chemically altered mammary gland development in HSD male and female rats to help inform researchers unfamiliar with the tissue and may facilitate enhanced evaluation of both male and female mammary glands in juvenile toxicity studies.

Effect of prenatal ethanol exposure on sexual motivation in adult rats

Maternal alcohol use during pregnancy adversely affects prenatal and postnatal growth and increases the risk of behavioral deficits. The aim of the present study was to evaluate the effect of prenatal exposure to a moderate dose of alcohol on sexual motivation during adulthood. Rats were prenatally exposed to ethanol by feeding pregnant dams a liquid diet containing 25% ethanol-derived calories on days 6 through 19 of gestation. The controls consisted of pair-fed dams (receiving an isocaloric liquid diet containing 0% ethanol-derived calories) and dams with ad libitum access to a liquid control diet. The sexual motivation of offspring was evaluated during adulthood. The results revealed that the male and female pups of dams treated with alcohol exhibited reduced weight gain, which persisted until adulthood. Both male and female adult animals from dams that were exposed to alcohol showed a reduction in the preference score in the sexual motivation test. Taken together, these results provide evidence of the damaging effects of prenatal alcohol exposure on sexual motivation responses in adulthood.

Activational action of testosterone on androgen receptors protects males preventing temporomandibular joint pain

BACKGROUND

Testosterone protects male rats from Temporomandibular Joint (TMJ) pain. This study investigated whether this protective effect is mediated by an organizational action of testosterone during nervous system development, by central estrogen and androgen receptors and by the 5α-reduced metabolite of testosterone, dihydrotestosterone.

METHODS

A pharmacological approach was used to assess the ability of the androgen receptor antagonist flutamide, the estrogen receptor antagonist ICI 182 780 and the 5-α reductase inhibitor dutasteride to block the protective effect of testosterone, evaluated through the behavioral response induced by a TMJ injection of 0.5% formalin. Flutamide and ICI 182 780 were injected into the medullary subarachnoid space, and dutasteride and testosterone were systemically administered.

RESULTS

The TMJ injection of 0.5% formalin induced a significant nociceptive behavioral response in gonadectomized male and naïve female, but not in sham gonadectomized male rats, confirming that endogenous testosterone prevents TMJ nociception in males. Testosterone administration prevented formalin-induced TMJ nociception in males gonadectomized either in the neonatal (at the day of birth) or adult period and in naïve female rats, suggesting that the protective effect of testosterone on TMJ nociception does not depend on its organizational actions during critical periods of development. The administration of flutamide and dutasteride but not of ICI 182 780 blocked the protective effect of testosterone.

CONCLUSIONS

We conclude that the protective effect of testosterone on TMJ nociception depends on activational actions of dihydrotestosterone on androgen receptors rather than on organizational androgenic actions during central nervous system development or estrogenic actions.

Prenatal programming of neuroendocrine reproductive function

It is now well recognized that the gestational environment can have long-lasting effects not only on the life span and health span of an individual but also, through potential epigenetic changes, on future generations. This article reviews the "prenatal programming" of the neuroendocrine systems that regulate reproduction, with a specific focus on the lessons learned using ovine models. The review examines the critical roles played by steroids in normal reproductive development before considering the effects of prenatal exposure to exogenous steroid hormones including androgens and estrogens, the effects of maternal nutrition and stress during gestation, and the effects of exogenous chemicals such as alcohol and environment chemicals. In so doing, it becomes evident that, to maximize fitness, the regulation of reproduction has evolved to be responsive to many different internal and external cues and that the GnRH neurosecretory system expresses a degree of plasticity throughout life. During fetal life, however, the system is particularly sensitive to change and at this time, the GnRH neurosecretory system can be "shaped" both to achieve normal sexually differentiated function but also in ways that may adversely affect or even prevent "normal function". The exact mechanisms through which these programmed changes are brought about remain largely uncharacterized but are likely to differ depending on the factor, the timing of exposure to that factor, and the species. It would appear, however, that some afferent systems to the GnRH neurons such as kisspeptin, may be critical in this regard as it would appear to be sensitive to a wide variety of factors that can program reproductive function. Finally, it has been noted that the prenatal programming of neuroendocrine reproductive function can be associated with epigenetic changes, which would suggest that in addition to direct effects on the exposed offspring, prenatal programming could have transgenerational effects on reproductive potential.

Sex-specific prenatal stress effects on the rat reproductive axis and adrenal gland structure

Social stress during pregnancy has profound effects on offspring physiology. This study examined whether an ethologically relevant social stress during late pregnancy in rats alters the reproductive axis and adrenal gland structure in post-pubertal male and female offspring. Prenatally stressed (PNS) pregnant rats (n=9) were exposed to an unfamiliar lactating rat for 10 min/day from day 16 to 20 of pregnancy inclusive, whereas control pregnant rats (n=9) remained in their home cages. Gonads, adrenal glands and blood samples were obtained from one female and one male from each litter at 11 to 12-weeks of age. Anogenital distance was measured. There was no treatment effect on body, adrenal or gonad weight at 11-12 weeks. PNS did not affect the number of primordial, secondary or tertiary ovarian follicles, numbers of corpora lutea or ovarian FSH receptor expression. There was an indication that PNS females had more primary follicles and greater ovarian aromatase expression compared with control females (both P=0.09). PNS males had longer anogenital distances (0.01±0.0 cm/g vs 0.008±0.00 cm/g; P=0.007) and higher plasma FSH concentrations (0.05 ng/mL vs 0.006 ng/mL; s.e.d.=0.023; P=0.043) compared with control males. There were no treatment effects on the number of Sertoli cells or seminiferous tubules, seminiferous tubule area, plasma testosterone concentration or testis expression of aromatase, FSH receptor or androgen receptor. PNS did not affect adrenal size. These data suggest that the developing male reproductive axis is more sensitive to maternal stress and that PNS may enhance aspects of male reproductive development.

Prenatal alcohol exposure and prenatal stress differentially alter glucocorticoid signaling in the placenta and fetal brain

Adverse intrauterine environments increase vulnerability to chronic diseases across the lifespan. The hypothalamic-pituitary-adrenal (HPA) axis, which integrates multiple neuronal signals and ultimately controls the response to stressors, may provide a final common pathway linking early adversity and adult diseases. Both prenatal alcohol exposure (PAE) and prenatal stress (PS) induce a hyperresponsive HPA phenotype in adulthood. As glucocorticoids are pivotal for the normal development of many fetal tissues including the brain, we used animal models of PAE and PS to investigate possible mechanisms underlying fetal programing of glucocorticoid signaling in the placenta and fetal brain at gestation day (GD) 21. We found that both PAE and PS dams had higher corticosterone (CORT) levels than control dams. However, 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) enzyme levels were increased in PAE and unchanged in PS placentae, although there were no differences in 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) levels. Moreover, only PAE fetuses showed decreased body weight and increased placental weight, and hence a lower fetal/placental weight ratio, a marker of placenta efficiency, compared to all other prenatal groups. Importantly, PAE and PS differentially altered corticosteroid receptor levels in placentae and brains. In the PS condition, maternal CORT was negatively correlated with both 11β-HSD1 and mineralocorticoid receptor (MR) protein levels in male and female placentae, whereas in the PAE condition, there were trends for a positive correlation between maternal CORT and 11β-HSD1, regardless of sex, and a negative correlation between maternal alcohol intake and MR in male placentae. In fetal brains, sexually dimorphic changes in MR and glucocorticoid receptor (GR) levels, and the MR/GR ratio seen in C fetuses were absent in PAE and PS fetuses. In addition, PS but not PAE female fetuses had higher MR and lower GR expression levels in certain limbic areas compared to C female fetuses. Thus the similar adult HPA hyperresponsive phenotype in PAE and PS animals likely occurs through differential effects on glucocorticoid signaling in the placenta and fetal brain.

Effect of honey on the reproductive system of male rat offspring exposed to prenatal restraint stress

Exposure to prenatal stress is associated with impaired reproductive function in male rat offspring. Honey is traditionally used by the Malays for enhancement of fertility. The aim of this study was to determine the effect of honey on reproductive system of male rat offspring exposed to prenatal restraint stress. Dams were divided into four groups (n = 10/group): control, honey, stress and honey + stress groups. Dams from honey and honey + stress groups received oral honey (1.2 g kg(-1) body weight) daily from day 1 of pregnancy, meanwhile dams from stress and honey + stress groups were subjected to restraint stress (three times per day) from day 11 of pregnancy until delivery. At 10 weeks old, each male rat offspring was mated with a regular oestrus cycle female. Male sexual behaviour and reproductive performance were evaluated. Then, male rats were euthanised for assessment on reproductive parameters. Honey supplementation during prenatal restraint stress significantly increased testis and epididymis weights as well as improved the percentages of abnormal spermatozoa and sperm motility in male rat offspring. In conclusion, this study might suggest that supplementation of honey during pregnancy seems to reduce the adverse effects of restraint stress on reproductive organs weight and sperm parameters in male rat offspring.

Dynamic changes in the spatio-temporal expression of the β-defensin SPAG11C in the developing rat epididymis and its regulation by androgens

Herein, we characterized the spatio-temporal expression, cellular distribution and regulation by androgens of the β-defensin SPAG11C, the rat ortholog of the human SPAG11B isoform C, in the developing epididymis by using RT-PCR, in situ hybridization and immunohistochemistry. We observed that Spag11c mRNA was ubiquitously expressed in rat fetuses, but preferentially detected in male reproductive tissues at adulthood. SPAG11C (mRNA and protein) was prenatally mainly detected in the mesenchyme of the Wolffian duct, switching gradually after birth to a predominant localization in the epididymis epithelium during postnatal development. In the adult epididymis, smooth muscle and interstitial cells were also identified as sources of SPAG11C. Furthermore, SPAG11C was differentially immunolocalized on spermatozoa surface during their transit from testis throughout caput and cauda epididymis. Developmental and surgical castration studies suggested that androgens contribute to the epididymal cell type- and region-specific modulation of SPAG11C mRNA levels and immunolocalization. Together our findings provide novel insights into the potential role of β-defensins in the epididymis.

Sexually dimorphic outcomes and inflammatory responses in hypoxic-ischemic encephalopathy

Background

Neonatal hypoxic-ischemic encephalopathy (HIE) is an important cause of motor and cognitive impairment in children. Clinically, male infants are more vulnerable to ischemic insults and suffer more long-term deficits than females; however, the mechanisms underlying this sex difference remain elusive. Inflammatory processes initiated by microglial activation are fundamental in the pathophysiology of ischemia. Recent studies report a sexual dimorphism in microglia numbers and expression of activation markers in the neonatal brain under normal conditions. How these basal sex differences in microglia affect HIE remains largely unexplored. This study investigated sex differences in ischemic outcomes and inflammation triggered by HIE. We hypothesize that ischemia induces sex-specific brain injury in male and female neonates and that microglial activation and inflammatory responses play an important role in this sexual dimorphism.

Methods

Male and female C57BL6 mice were subjected to 60-min Rice-Vanucci modeling (RVM) at post-natal day 10 (P10) to induce HIE. Stroke outcomes were measured 1, 3, 7, and 30 days after stroke. Microglial activation and inflammatory responses were evaluated by flow cytometry and cytokine analysis.

Results

On day 1 of HIE, no difference in infarct volumes or seizure scores was seen between male and female neonates. However, female neonates exhibited significantly smaller infarct size and fewer seizures compared to males 3 days after HIE. Females also had less brain tissue loss and behavioral deficits compared to males at the chronic stage of HIE. Male animals demonstrated increased microglial activation and up-regulated inflammatory response compared to females at day 3.

Conclusions

HIE leads to an equivalent primary brain injury in male and female neonates at the acute stage that develops into sexually dimorphic outcomes at later time points. An innate immune response secondary to the primary injury may contribute to sexual dimorphism in HIE.

Age- and Sex-Dependent Changes in Androgen Receptor Expression in the Developing Mouse Cortex and Hippocampus

During the perinatal period, male mice are exposed to higher levels of testosterone (T) than females, which promotes sexual dimorphism in their brain structures and behaviors. In addition to acting via estrogen receptors after being locally converted into estradiol by aromatase, T also acts directly through androgen receptor (AR) in the brain. Therefore, we hypothesized that AR expression in the developing mouse cortex and hippocampus was sexually dimorphic. To test our hypothesis, we measured and determined AR mRNA and protein levels in mouse cortex/hippocampus collected on the day of birth (PN0) and 7 (PN7), 14 (PN14), and 21 (PN21) days after birth. We demonstrated that, as age advanced, AR mRNA levels increased in the cortex/hippocampus of both sexes but showed no sex difference. Two AR proteins, the full-length (110 kDa) and a smaller isoform (70 kDa), were detected in the developing mouse cortex/hippocampus with an age-dependent increase in protein levels of both AR isoforms at PN21 and a transient masculine increase in expression of the full-length AR protein on PN7. Thus, we conclude that the postnatal age and sex differences in AR protein expression in combination with the sex differences in circulating T may cause sexual differentiation of the mouse cortex/hippocampus.

Prenatal and Perinatal Factors Related to Autism, IQ, and Adaptive Functioning

This study focused on prenatal and perinatal factors related to autism spectrum disorder (ASD). The authors hypothesized that mothers who exposed their infants to intrauterine toxicity or who had complications with labor or delivery would be more likely to give birth to individuals with lower IQ scores, higher scores on a measure of ASD, and lower scores on a measure of adaptive functioning. This clinical sample consisted of 33 children who presented for neuropsychological assessment with symptoms of ASD. Results indicated that individuals with a history of intrauterine toxicity had lower IQ scores than individuals who did not have a history of intrauterine toxicity. However, no significant effects were found for intrauterine toxicity and ASD or adaptive functioning. Results indicated that individuals with a history of complications during labor and delivery had lower IQ scores, higher scores on a measure of ASD, and lower scores on a measure of adaptive functioning. Findings may lend support to the oxidative stress theory of ASD.

Environmental and genetic contributors to salivary testosterone levels in infants

Transient activation of the hypothalamic-pituitary-gonadal axis in early infancy plays an important role in male genital development and sexual differentiation of the brain, but factors contributing to individual variation in testosterone levels during this period are poorly understood. We measured salivary testosterone levels in 222 infants (119 males, 103 females, 108 singletons, 114 twins) between 2.70 and 4.80 months of age. We tested 16 major demographic and medical history variables for effects on inter-individual variation in salivary testosterone. Using the subset of twins, we estimated genetic and environmental contributions to salivary testosterone levels. Finally, we tested single nucleotide polymorphisms (SNPs) within ±5 kb of genes involved in testosterone synthesis, transport, signaling, and metabolism for associations with salivary testosterone using univariate tests and random forest (RF) analysis. We report an association between 5 min APGAR scores and salivary testosterone levels in males. Twin modeling indicated that individual variability in testosterone levels was primarily explained by environmental factors. Regarding genetic variation, univariate tests did not reveal any variants significantly associated with salivary testosterone after adjusting for false discovery rate. The top hit in males was rs10923844, an SNP of unknown function located downstream of HSD3B1 and HSD3B2. The top hits in females were two SNPs located upstream of ESR1 (rs3407085 and rs2295190). RF analysis, which reflects joint and conditional effects of multiple variants, indicated that genes involved in regulation of reproductive function, particularly LHCGR, are related to salivary testosterone levels in male infants, as are genes involved in cholesterol production, transport, and removal, while genes involved in estrogen signaling are related to salivary testosterone levels in female infants.

Periadolescent maturation of the prefrontal cortex is sex-specific and is disrupted by prenatal stress

The prefrontal cortex (PFC) undergoes dramatic, sex-specific maturation during adolescence. Adolescence is a vulnerable window for developing mental illnesses that show significant sexual dimorphisms. Gestational stress is associated with increased risk for both schizophrenia, which is more common among men, and cognitive deficits. We have shown that male, but not female, rats exposed to prenatal stress develop postpubertal deficits in cognitive behaviors supported by the prefrontal cortex. Here we tested the hypothesis that repeated variable prenatal stress during the third week of rat gestation disrupts periadolescent development of prefrontal neurons in a sex-specific fashion. Using Golgi-Cox stained tissue, we compared dendritic arborization and spine density of prelimbic layer III neurons in prenatally stressed and control animals at juvenile (day 20), prepubertal (day 30), postpubertal (day 56), and adult (day 90) ages (N = 115). Dendritic ramification followed a sex-specific pattern that was disrupted during adolescence in prenatally stressed males, but not in females. In contrast, the impact of prenatal stress on the female PFC was not evident until adulthood. Prenatal stress also caused reductions in brain and body weights, and the latter effect was more pronounced among males. Additionally, there was a trend toward reduced testosterone levels for adult prenatally stressed males. Our findings indicate that, similarly to humans, the rat PFC undergoes sex-specific development during adolescence and furthermore that this process is disrupted by prenatal stress. These findings may be relevant to both the development of normal sex differences in cognition as well as differential male-female vulnerability to psychiatric conditions.

Prenatal maternal restraint stress exposure alters the reproductive hormone profile and testis development of the rat male offspring

Several studies have demonstrated that the presence of stressors during pregnancy induces adverse effects on the neuroendocrine system of the offspring later in life. In the present work, we investigated the effects of early programming on the male reproductive system, employing a prenatal stress (PS) paradigm. This study found that when pregnant dams were placed in a plastic restrainer three times a day during the last week of pregnancy, the offspring showed reduced anogenital distance and delayed testicular descent. Serum luteinising hormone (LH) and follicle-stimulating hormone (FSH) levels were decreased at postnatal day (PND) 28 and testosterone was decreased at PND 75. Increased testosterone plus dihydrotestosterone (T + DHT) concentrations correlated with increased testicular 5α Reductase-1 (5αR-1) mRNA expression at PND 28. Moreover, PS accelerated spermatogenesis at PND 35 and 60, and increased mean seminiferous tubule diameter in pubertal offspring and reduced Leydig cell number was observed at PND 35 and 60. PS offspring had increased androgen receptor (AR) mRNA level at PND 28, and at PND 35 had increased the numbers of Sertoli cells immunopositive for AR. Overall, the results confirm that stress during gestation can induce long-term effects on the male offspring reproductive system. Of particular interest is the pre-pubertal imbalance of circulating hormones that probably trigger accelerated testicular development, followed by an increase in total androgens and a decrease in testosterone concentration during adulthood. Exposure to an unfavourable intrauterine environment might prepare for harsh external conditions by triggering early puberty, increasing reproductive potential.

Prenatal ethanol exposure delays the onset of spermatogenesis in the rat

BACKGROUND

During late prenatal and early postnatal life, the reproductive system in males undergoes an extensive series of physiological and morphological changes. Prenatal ethanol (EtOH) exposure has marked effects on the development of the reproductive system, with long-term effects on function in adulthood. The present study tested the hypothesis that prenatal EtOH exposure will delay the onset of spermatogenesis.

METHODS

Development of the seminiferous tubules and the onset of spermatogenesis were examined utilizing a rat model of fetal alcohol spectrum disorder (FASD). Male offspring from ad libitum-fed control (C), pair-fed (PF), and EtOH-fed (prenatal alcohol exposure [PAE]) dams were terminated on postnatal (PN) days 5, 15, 18, 20, 25, 35, 45, and 55, to investigate morphological changes through morphometric analysis of the testes from early neonatal life through young adulthood.

RESULTS

PAE males had lower relative (adjusted for body weight) testis weights compared with PF and/or C males from PN15 through puberty (PN45). In addition, fewer gonocytes (primordial germ cells) were located on the basal lamina on PN5, while more of those touching the basal lamina were dividing in PAE compared with PF and C males, suggesting delayed cell division and migration processes. As well, the percentage of tubules with open lumena was lower in PAE compared with PF and C males on PN18 and 20, and PAE males had fewer primary spermatocytes per tubule on PN18 and round spermatids per tubule on PN25 compared with C males. Finally, the percentage of tubules at stages VII and VIII, when mature spermatids move to the apex of the epithelium and are released, was lower in PAE compared with PF and/or C males in young adulthood (PN55).

CONCLUSIONS

Maternal EtOH consumption appears to delay both reproductive development and the onset of spermatogenesis in male offspring, with effects persisting at least until young adulthood.

Steroid hormones, stress and the adolescent brain: a comparative perspective

Steroid hormones, including those produced by the gonads and the adrenal glands, are known to influence brain development during sensitive periods of life. Until recently, most brain organisation was assumed to take place during early stages of development, with relatively little neurogenesis or brain re-organisation during later stages. However, an increasing body of research has shown that the developing brain is also sensitive to steroid hormone exposure during adolescence (broadly defined as the period from nutritional independence to sexual maturity). In this review, we examine how steroid hormones that are produced by the gonads and adrenal glands vary across the lifespan in a range of mammalian and bird species, and we summarise the evidence that steroid hormone exposure influences behavioural and brain development during early stages of life and during adolescence in these two taxonomic groups. Taking a cross-species, comparative perspective reveals that the effects of early exposure to steroid hormones depend upon the stage of development at birth or hatching, as measured along the altricial-precocial dimension. We then review the evidence that exposure to stress during adolescence impacts upon the developing neuroendocrine systems, the brain and behaviour. Current research suggests that the effects of adolescent stress vary depending upon the sex of the individual and type of stressor, and the effects of stress could involve several neural systems, including the serotonergic and dopaminergic systems. Experience of stressors during adolescence could also influence brain development via the close interactions between the stress hormone and gonadal hormone axes. While sensitivity of the brain to steroid hormones during early life and adolescence potentially leaves the developing organism vulnerable to external adversities, developmental plasticity also provides an opportunity for the developing organism to respond to current circumstances and for behavioural responses to influence the future life history of the individual.

Maternal androgen excess reduces placental and fetal weights, increases placental steroidogenesis, and leads to long-term health effects in their female offspring

Here, we tested the hypothesis that excess maternal androgen in late pregnancy reduces placental and fetal growth, increases placental steroidogenesis, and adversely affects glucose and lipid metabolism in adult female offspring. Pregnant Wistar rats were randomly assigned to treatment with testosterone (daily injections of 5 mg of free testosterone from gestational days 16 to 19) or vehicle alone. In experiment 1, fetal and placental weights, circulating maternal testosterone, estradiol, and corticosterone levels, and placental protein expression and distribution of estrogen receptor-α and -β, androgen receptor, and 17β-hydroxysteroid dehydrogenase 2 were determined. In experiment 2, birth weights, postnatal growth rates, circulating testosterone, estradiol, and corticosterone levels, insulin sensitivity, adipocyte size, lipid profiles, and the presence of nonalcoholic fatty liver were assessed in female adult offspring. Treatment with testosterone reduced placental and fetal weights and increased placental expression of all four proteins. The offspring of testosterone-treated dams were born with intrauterine growth restriction; however, at 6 wk of age there was no difference in body weight between the offspring of testosterone- and control-treated rats. At 10-11 wk of age, the offspring of the testosterone-treated dams had less fat mass and smaller adipocyte size than those born to control rats and had no difference in insulin sensitivity. Circulating triglyceride levels were higher in the offspring of testosterone-treated dams, and they developed nonalcoholic fatty liver as adults. We demonstrate for the first time that prenatal testosterone exposure alters placental steroidogenesis and leads to dysregulation of lipid metabolism in their adult female offspring.

Prenatal hyperandrogenization induces metabolic and endocrine alterations which depend on the levels of testosterone exposure

Prenatal hyperandrogenism is able to induce polycystic ovary syndrome (PCOS) in rats. The aim of the present study was to establish if the levels of prenatal testosterone may determine the extent of metabolic and endocrine alterations during the adult life. Pregnant Sprague Dawley rats were prenatally injected with either 2 or 5 mg free testosterone (groups T2 and T5 respectively) from day 16 to day 19 day of gestation. Female offspring from T2 and T5 displayed different phenotype of PCOS during adult life. Offspring from T2 showed hyperandrogenism, ovarian cysts and ovulatory cycles whereas those from T5 displayed hyperandrogenism, ovarian cysts and anovulatory cycles. Both group showed increased circulating glucose levels after the intraperitoneal glucose tolerance test (IPGTT; an evaluation of insulin resistance). IPGTT was higher in T5 rats and directly correlated with body weight at prepubertal age. However, the decrease in the body weight at prepubertal age was compensated during adult life. Although both groups showed enhanced ovarian steroidogenesis, it appears that the molecular mechanisms involved were different. The higher dose of testosterone enhanced the expression of both the protein that regulates cholesterol availability (the steroidogenic acute regulatory protein (StAR)) and the protein expression of the transcriptional factor: peroxisome proliferator-activated receptor gamma (PPAR gamma). Prenatal hyperandrogenization induced an anti-oxidant response that prevented a possible pro-oxidant status. The higher dose of testosterone induced a pro-inflammatory state in ovarian tissue mediated by increased levels of prostaglandin E (PG) and the protein expression of cyclooxygenase 2 (COX2, the limiting enzyme of PGs synthesis). In summary, our data show that the levels of testosterone prenatally injected modulate the uterine environment and that this, in turn, would be responsible for the endocrine and metabolic abnormalities and the phenotype of PCOS during the adult life.

Postnatal aromatase blockade increases c-fos mRNA responses to acute restraint stress in adult male rats

Recent evidence suggests that the aromatization of testosterone to estrogen is important for the organizing effects of neonatal testosterone on neuroendocrine responses to acute challenges. However, the extent to which neonatal inhibition of aromatase alters the stress-induced activation of neural pathways has not been examined. Here we assessed central patterns of c-fos mRNA induced by 30 min of restraint in 65-d-old adult male rats that were implanted with sc capsules of the aromatase inhibitor 1,4,6-androstatriene-3,17-dione (ATD), introduced within 12 h of birth and removed on d 21 of weaning. Neonatal ATD decreased the expression of arginine vasopressin within extrahypothalamic regions in adults, confirming reduced estrogen exposure during development. As adults, ATD-treated animals showed higher corticosterone responses at 30 min of restraint exposure compared with control animals as well as higher c-fos expression levels in the paraventricular nucleus of the hypothalamus. ATD treatment also increased stress-induced c-fos within several limbic regions of the forebrain, in addition to areas involved in somatosensory processing. Based on these results, we propose that the conversion of testosterone to estrogen during the neonatal period exerts marked, system-wide effects to organize adult neuroendocrine responses to homeostatic threat.

Gestational restraint stress and the developing dopaminergic system: an overview

Prenatal stress exerts a strong impact on fetal brain development in rats impairing adaptation to stressful conditions, subsequent vulnerability to anxiety, altered sexual function, and enhanced propensity to self-administer drugs. Most of these alterations have been attributed to changes in the neurotransmitter dopamine (DA). In humans; dysfunction of dopaminergic system is associated with development of several neurological disorders, such as Parkinson disease, schizophrenia, attention-deficit hyperactivity disorder, and depression. Evidences provided by animal research, as well as retrospective studies in humans, pointed out that exposure to adverse events in early life can alter adult behaviors and neurochemical indicators of midbrain DA activity, suggesting that the development of the DA system is sensitive to disruption by exposure to early stressors. The purpose of this article is to provide a general overview of published studies and our own study related to the effect of prenatal insults on the development of DA metabolism and biology, focusing mainly in articles involving prenatal-restraint stress protocols in rats. We will also attempt to make a correlation between theses alterations and DA-related pathological processes in humans.