Treatment of juvenile myasthenia gravis with tacrolimus: A cohort study.

BACKGROUND: We investigated the proper timing, efficacy and safety of tacrolimus for juvenile myasthenia gravis (JMG). METHODS: We conducted a retrospective cohort study for JMG patients treated with tacrolimus at Xiangya Hospital, Central South University, Changsha, China from 2010 to 2023. The clinical information of patients with a follow-up of more than 1 year was collected. Comparisons of clinical features between groups of patients who achieved therapeutic goal and those who did not achieve therapeutic goal as well as between groups of patients treated with tacrolimus within or after 1 year from JMG onset was carried out. RESULTS: Forty-three patients were enrolled, of whom 28 achieved therapeutic goal. Tacrolimus reduced glucocorticoids (GC) dosages for the 28 cases and 15 cases discontinued GC completely. Generalized myasthenia gravis (GMG) subtype had an association with a group of patients who achieved therapeutic goal (p = 0.001). Median duration from JMG onset to tacrolimus use was 10.50 months for those who achieved therapeutic goal and 36.00 months for those who did not achieve therapeutic goal (p = 0.010). The median Myasthenia Gravis Activities of Daily Living (MG-ADL) score improved significantly (p = 0.003). The initiation of tacrolimus within 1 year of JMG onset showed an association with achievement of therapeutic goal (p = 0.026). GMG subtype showed an association with a group of patients who received tacrolimus within 1 year (p = <0.001). Tacrolimus side effects were tolerable. CONCLUSION: The provision of tacrolimus within 1 year of JMG onset is effective and safe.

Exacerbation of Thyroid Eye Disease and Dysthyroid Optic Neuropathy During Pregnancy: A Case Report.

A 37-year-old, never-smoker, pregnant woman diagnosed with Graves' disease who had stable thyroid eye disease (TED) before pregnancy presented with aggravated proptosis and eyelid swelling at 13 weeks of pregnancy. Despite the administration of local triamcinolone and 3 cycles of corticosteroid pulse therapy from 25 to 28 weeks, the patient's visual acuity decline necessitated postpartum orbital decompression surgery. Although TSH receptor antibody (TRAb) levels decreased during the mid- to late term of pregnancy, the TED worsened. This finding suggests that factors other than anti-TSH receptor antibodies may have a significant effect on disease severity.

Current practice, trends and attitudes of rheumatologists towards glucocorticoids use for rheumatoid arthritis (GURANTEE): a national cross-sectional survey across China.

INTRODUCTION: To investigate current practices, changes, and perceptions of rheumatologists regarding GC use in RA patients. METHODS: A cross-sectional survey was conducted using a structured questionnaire between April and August 2023. Rheumatologists from 31 province-level regions of Mainland China were invited to participate. Chi-squared tests were adopted to investigate the differences by sociodemographic characteristics. RESULTS: 1,717 rheumatologists from 598 hospitals completed the survey with a response rate of 92%. Up to 60% of participants expressed currently infrequent initiation of GC co-therapy with csDMARDs (hardly ever 7.0%; occasionally 24.6%; sometimes 29.1%), accompanied by a decline of frequency over time reported in 64.2%. Regarding attitudes towards bridging therapy with GC, 604 (35.2%) participants supported this approach, 468 (27.3%) opposed it, and 645 (37.6%) remained inconclusive. Time to GC discontinuation in context of csDMARDs was commonly reported within 6 months in current practice which has been narrowed over time. Reasons for chronic GC use were mostly reported due to suboptimal disease control, followed by the need of RA complications, and pre-existing comorbidities. After failure of GC cessation, majority of respondents (84.4%) would escalate RA therapy (commonly by addition of JAK inhibitors, TNF inhibitors), which usually or often facilitated the GC cessation. The most frequently reported advantages and weaknesses of GC were rapid and strong efficacy, adverse events, respectively. Regarding long-term low-dose GC use for RA, the percentage of respondents who supported, opposed, or depended on the situation were 15.9%, 17.2%, and 66.9%, respectively. CONCLUSIONS: The current data demonstrate that GC initiation for RA treatment is not as frequent as before and the awareness of GC discontinuation is growing in current practice. Attitudes towards GC co-therapy with csDMARDs vary considerably and long-term low-dose GC use remain situation dependent.

Moving beyond the mean: an analysis of faecal corticosterone metabolites shows substantial variability both within and across white-tailed deer populations.

Glucocorticoid (GC) levels have significant impacts on the health and behaviour of wildlife populations and are involved in many essential body functions including circadian rhythm, stress physiology and metabolism. However, studies of GCs in wildlife often focus on estimating mean hormone levels in populations, or a subset of a population, rather than on assessing the entire distribution of hormone levels within populations. Additionally, explorations of population GC data are limited due to the tradeoff between the number of individuals included in studies and the amount of data per individual that can be collected. In this study, we explore patterns of GC level distributions in three white-tailed deer (Odocoileus virginianus) populations using a non-invasive, opportunistic sampling approach. GC levels were assessed by measuring faecal corticosterone metabolite levels ('fCMs') from deer faecal samples throughout the year. We found both population and seasonal differences in fCMs but observed similarly shaped fCM distributions in all populations. Specifically, all population fCM cumulative distributions were found to be very heavy-tailed. We developed two toy models of acute corticosterone elevation in an effort to recreate the observed heavy-tailed distributions. We found that, in all three populations, cumulative fCM distributions were better described by an assumption of large, periodic spikes in corticosterone levels every few days, as opposed to an assumption of random spikes in corticosterone levels. The analyses presented in this study demonstrate the potential for exploring population-level patterns of GC levels from random, opportunistically sampled data. When taken together with individual-focused studies of GC levels, such analyses can improve our understanding of how individual hormone production scales up to population-level patterns.

High-Dose Corticosteroid Use in Severe to Critically Ill Patients With COVID-19: A Nationwide Population-Based Matched Cohort Study.

BACKGROUND: Systemic corticosteroids have become the standard of care for severe to critically ill patients with coronavirus disease 2019 (COVID-19). However, the real-world efficacy and safety outcomes associated with a higher dose of corticosteroids remain uncertain. METHODS: We conducted a nationwide, population-based, matched cohort study of severe to critically ill adult patients with COVID-19 between January 2020 and June 2021 in Korea using the National Health Information Database. Patients using systemic corticosteroids were included and high-dose corticosteroid use was defined as a daily mean prescribed dose of more than 6 mg of dexamethasone. We then employed a proportional hazard regression model to identify prognostic factors for 28-day all-cause mortality and conducted a Fine and Gray regression model to assess risk factors for developing COVID-19-associated pulmonary aspergillosis (CAPA). RESULTS: During the study period, 102,304 patients with COVID-19 were screened, 5,754 met the eligibility criteria, and 2,138 were successfully matched. The mean prescribed daily dose was 4.2 mg and 13.4 mg in the standard- and high-dose groups, respectively, and the mean duration of use was not different between the groups. High-dose corticosteroid use independently increased all-cause mortality at 28 days (adjusted hazard ratio [aHR], 1.48; 95% confidence interval [CI], 1.25-1.76) and 90 days (aHR, 1.63; CI, 1.44-1.85) after admission. Subgroup analysis revealed a statistically significant elevation in the risk of mortality among patients using low-flow or high-flow nasal cannulas, with aHRs of 1.41 and 1.46, respectively. No significant impact of high-dose steroids was observed, even in patients who underwent mechanical ventilation at 28 days (aHR, 1.17; CI, 0.79-1.72). As a safety outcome, high-dose corticosteroid use showed an association with the development of CAPA (aHR, 2.97; 95% CI, 0.94-9.43). CONCLUSION: Among severe to critically ill patients with COVID-19, high-dose corticosteroid use was associated with increased 28-day all-cause mortality and showed a trend toward the development of CAPA.

Androgens suppress corticosteroid binding globulin in male mice, affecting the endocrine stress response.

Biological sex affects the activity of the hypothalamus-pituitary-adrenal (HPA) axis. However, how androgen deprivation affects this axis remains largely unknown. In this study, we investigated the effect of androgen status on different components of the HPA axis in male mice. Two weeks of androgen deprivation did not affect total plasma corticosterone levels but led to increased pituitary adrenocorticotropic hormone (ACTH) levels. Stress-induced total plasma corticosterone levels were increased, while the suppression of corticosterone after dexamethasone treatment under basal conditions was attenuated. Androgen-deprived mice displayed a 2-fold increase in plasma levels of corticosteroid binding globulin (CBG). A similar increase in CBG was observed in global androgen receptor (AR) knock-out animals, compared to wild-type litter mates. Androgen deprivation was associated with a 6-fold increase in CBG mRNA in the liver and enhanced transcriptional activity at CBG regulatory regions, as evidenced by increased H3K27 acetylation. We propose that the induction of CBG as a consequence of androgen deprivation, together with the unaltered total corticosterone levels, results in lower free corticosterone levels in plasma. This is further supported by mRNA levels of androgen-independent GR target genes in the liver. The reduction in negative feedback on the HPA axis under basal condition would suffice to explain the enhanced stress reactivity after androgen deprivation. Overall our data demonstrate that, in mice, tonic AR activation affects CBG levels, in conjunction with effects on gene expression and HPA-axis reactivity.

Cardiometabolic Aspects of Congenital Adrenal Hyperplasia.

Treatment of classic congenital adrenal hyperplasia (CAH) is directed at replacing deficient hormones and reducing androgen excess. However, even in the era of early diagnosis and lifelong hormonal substitution, the presence of CAH is still associated with numerous complications and also with increased mortality. The aim of this article was to create an authoritative and balanced review concerning cardiometabolic risk in patients with CAH. The authors searched all major databases and scanned reference lists of all potentially eligible articles to find relevant articles. The risk was compared with that in other forms of adrenal insufficiency. The reviewed articles, most of which were published recently, provided conflicting results, which can be partially explained by differences in the inclusion criteria and treatment, small sample sizes and gene-environmental interactions. However, many studies showed that the presence of CAH is associated with an increased risk of weight gain, worsening of insulin sensitivity, high blood pressure, endothelial dysfunction, early atherosclerotic changes in the vascular wall and left ventricular diastolic dysfunction. These complications were more consistently reported in patients with classic than non-classic CAH and were in part related to hormonal and functional abnormalities associated with this disorder and/or to the impact of over- and undertreatment. An analysis of available studies suggests that individuals with classic CAH are at increased cardiometabolic risk. Excess cardiovascular and metabolic morbidity is likely multifactorial, related to glucocorticoid overtreatment, imperfect adrenal hormone replacement therapy, androgen excess and adrenomedullary failure. Cardiometabolic effects of new therapeutic approaches require future targeted studies.

METHODS: Validating an immunoassay to measure fecal glucocorticoid metabolites in yellow-bellied marmots.

Quantifying physiological stress in wild animals is essential for understanding their health, reproductive success, and survival in a variable environment. The yellow-bellied marmot (Marmota flaviventer) study at the Rocky Mountain Biological Laboratory near Crested Butte, Colorado, USA is the world's second longest study of free-living mammals. Historically, we used a validated corticosterone radioimmunoassay (RIA) to measure fecal glucocorticoid metabolites (FGMs) as a proxy for physiological stress. However, the costs and risks associated with working with radioisotopes drove us to consider a more sustainable method. Here we evaluate the suitability of two competitive corticosterone enzyme-linked assays (EIA), one from Cayman Chemical Company (CCC) and one from Arbor Assays (AA), to measure marmot FGMs via its cross-reaction. The findings revealed that the AA EIA better matched the RIA in terms of accuracy across high and low FGM concentrations, had superior assay parameters, showed the highest correlations with RIA results and effectively captured the annual variations in FGM concentrations, thus demonstrating its reliability for use in longitudinal studies. We further analytically validated the AA EIA for FGMs and confirmed its efficacy and lack of matrix effects, thus establishing its suitability for ongoing and future studies of FGMs in marmots. The transition to the AA EIA from the RIA ensures continued data integrity while enhancing safety and environmental sustainability.

Relationship between growth and ambulation loss in Duchenne muscular dystrophy boys on steroids.

BACKGROUND AND PURPOSE: Treatment with glucocorticoids (GCs) is part of the standard of care in Duchenne muscular dystrophy, but excess weight gain and height stunting are common side-effects. It is still unclear how these growth-related side-effects affect motor function. METHODS: This retrospective cohort study utilized 2228 observations from 648 participants in the UK NorthStar database who had growth and ambulation data recorded between 2006 and 2020. Joint modelling was used to analyse the effect of longitudinal growth centiles on loss of ambulation with respect to GC type and regimen. RESULTS: Loss of ambulation was observed in 113 patients. National estimates of loss of ambulation age were updated by GC group and showed no significant association between loss of ambulation risk and absolute growth centile. However, yearly drift in weight and/or height centile had an associated risk effect on loss of ambulation. Over a 2-year period, a yearly drift in weight from the 50th to the 75th, 75th to the 90th and 90th to the 95th centile was associated with 138%, 118% and 64% increased risk of loss of ambulation, respectively. Conversely, a 2-year drift in height from the 50th to the 25th, 25th to the 10th and 10th to the 5th centile was associated with 53%, 49% and 35% decreased risk of loss of ambulation, respectively. CONCLUSIONS: Our results suggest a complex relationship between growth and loss of ambulation in Duchenne muscular dystrophy boys on chronic GCs, the first step in understanding the effects of drugs which also affect growth patterns.

Jintiange capsule ameliorates glucocorticoid-induced osteonecrosis of the femoral head in rats by regulating the activity and differentiation of BMSCs.

Background and aim: A surplus of glucocorticoids (GC) is a main cause of non-traumatic osteonecrosis of the femoral head (ONFH), and Jintiange (JTG), as one of the traditional Chinese medicines (TCM), also plays an instrumental role in the alleviation of bone loss simultaneously. Therefore, JTG was thought to be able to reverse GC-induced ONFH (GC-ONFH) to a certain extent. Experimental procedure: In vivo, the effect of JTG on trabeculae in the subchondral bone of the femoral head was investigated using micro-computed tomography (micro-CT), TdT-mediated dUTP nick end labeling (TUNEL) and histological staining; in vitro, proliferation, viability, apoptosis, and senescence of purified bone mesenchymal stem cells (BMSCs) were examined to demonstrate the direct impact of JTG on these cells. Meanwhile after using a series of interventions, the function of JTG on BMSC differentiation could be assessed by measuring of osteogenic and adipogenic markers at levels of protein and mRNA. Results: Our final results demonstrated that with the involvement of Wnt/ß-catenin pathway, JTG was able to significantly promote osteogenesis, restrain adipogenesis, delay senescence in BMSCs, reduce osteoclast number, weaken apoptosis, and enhance proliferation of osteocytes, all of which could mitigate the progression of subchondral osteonecrosis. Conclusion: According to the results of experiments in vitro and vivo, JTG was deemed to relieve the early GC-ONFH using the prevention of destruction of subchondral bone, which was contributed to regulating the differentiation of BMSCs and the number of osteoclasts.

Glucocorticoid treatment increases cholesterol availability during critical illness: effect on adrenal and muscle function.

BACKGROUND: Hypocholesterolemia hallmarks critical illness though the underlying pathophysiology is incompletely understood. As low circulating cholesterol levels could partly be due to an increased conversion to cortisol/corticosterone, we hypothesized that glucocorticoid treatment, via reduced de novo adrenal cortisol/corticosterone synthesis, might improve cholesterol availability and as such affect adrenal gland and skeletal muscle function. METHODS: In a matched set of prolonged critically ill patients (n = 324) included in the EPaNIC RCT, a secondary analysis was performed to assess the association between glucocorticoid treatment and plasma cholesterol from ICU admission to day five. Next, in a mouse model of cecal ligation and puncture-induced sepsis, septic mice were randomized to receive either hydrocortisone (1.2 mg/day) (n = 17) or placebo (n = 15) for 5 days, as compared with healthy mice (n = 18). Plasma corticosterone, cholesterol, and adrenocortical and myofiber cholesterol were quantified. Adrenal structure and steroidogenic capacity were evaluated. Muscle force and markers of atrophy, fibrosis and regeneration were quantified. In a consecutive mouse study with identical design (n = 24), whole body composition was assessed by EchoMRI to investigate impact on lean mass, fat mass, total and free water. RESULTS: In human patients, glucocorticoid treatment was associated with higher plasma HDL- and LDL-cholesterol from respectively ICU day two and day three, up to day five (P < 0.05). Plasma corticosterone was no longer elevated in hydrocortisone-treated septic mice compared to placebo, whereas the sepsis-induced reduction in plasma HDL- and LDL-cholesterol and in adrenocortical cholesterol was attenuated (P < 0.05), but without improving the adrenocortical ACTH-induced CORT response and with increased adrenocortical inflammation and apoptosis (P < 0.05). Total body mass was further decreased in hydrocortisone-treated septic mice (P < 0.01) compared to placebo, with no additional effect on muscle mass, force or myofiber size. The sepsis-induced rise in markers of muscle atrophy and fibrosis was unaffected by hydrocortisone treatment, whereas markers of muscle regeneration were suppressed compared to placebo (P < 0.05). An increased loss of lean body mass and total and free water was observed in hydrocortisone-treated septic mice compared to placebo (P < 0.05). CONCLUSIONS: Glucocorticoid treatment partially attenuated critical illness-induced hypocholesterolemia, but at a cost of impaired adrenal function, suppressed muscle regeneration and exacerbated loss of body mass.

Further insights into anti-IgLON5 disease: a case with complex clinical presentation.

BACKGROUND: Anti-IgLON5 disease is an autoimmune encephalitis overlapping with neurodegenerative disorders due to pathological accumulation of hyperphosphorylated tau. It is characterized by several clinical manifestations determined by involvement of different brain areas, and mild response to first-line immunotherapies. We report a case of anti-IgLON5 disease with a multifaceted semiology and an unusually good response to glucocorticoid monotherapy. CASE PRESENTATION: A 68-year-old man with type 2 diabetes was evaluated for an 8-month history of progressive gait disorder causing frequent falls. He also suffered from obstructive sleep apneas and complained of dysphonia, dysarthria, occasional dysphagia, urinary incontinence, and upper limb action tremor. Neurological examination demonstrated bilateral eyelid ptosis, limitation of ocular horizontal smooth pursuit movements, slow horizontal saccades, and lack of inhibition of the vestibulo-ocular reflex during rapid horizontal head torsions. The patient also displayed involuntary, slow, rhythmic movements of the left periorbital and perioral muscles, spreading to the ipsilateral hemipalate and hemitongue, along with bilateral negative upper limb myoclonus. There were proximal muscle wasting in the upper limbs, proximal weakness of the four limbs, and diffuse fasciculations. Ataxia of stance and gait and of the four limbs was noted. MRI of the brain and spine was unremarkable; nerve conduction studies revealed a chronic, predominantly demyelinating, sensory-motor polyneuropathy, probably due to diabetes. Routine CSF examination was unrevealing and serum GFAP level was 89.6 pg/mL; however, the autoimmunity tests revealed a high-titer positivity for anti-IgLON5 autoantibodies in both CSF and serum, leading to the diagnosis of anti-IgLON5 disease. Symptoms improved significantly after intravenous methylprednisolone. CONCLUSIONS: Hemifacial and hemiorolingual myorhythmia along with peculiar oculomotor abnormalities characterizes the multifaceted clinical picture of our case. The complex semiology of our patient may reflect multifocal targeting of the autoimmune process or sequential spreading of tau inclusions in different brain areas. Our patient's optimal response to glucocorticoid monotherapy could be underpinned by a slightly different phenotype in which autoimmunity plays a greater pathogenic role than tauopathy, with a lower burden of tau deposition. In such patients, neurodegeneration and tau accumulation could be merely secondary to immune-mediated neuronal dysfunction, supporting the existence of a group of glucocorticoid-responsive patients.

Canine pigmented viral plaques associated with application of potent topical glucocorticoids.

A six-year-old atopic boxer presented with pigmented viral plaques on the interdigital spaces and pinnae following treatment with potent topical glucocorticoids. The lesions regressed after treatment was discontinued, and recurred each time a topical glucocorticoid was resumed. A Chipapillomavirus was amplified from lesional tissue.

Can biosampling really be "non-invasive"? An examination of the socially invasive nature of physically non-invasive biosampling in urban and rural Malawi.

Glucocorticoids are understood to represent useful biomarkers of stress and can be measured in saliva, hair, and breastmilk. The collection of such biosamples is increasingly included in biobank and cohort studies. While collection is considered "non-invasive" by biomedical researchers (compared to sampling blood), community perspectives may differ. This cross-sectional, qualitative study utilising eight focus groups aimed to determine the feasibility and acceptability of collecting ostensibly "non-invasive" biological samples in Malawi. Breastfeeding women, couples, field workers, and healthcare providers were purposively sampled. Data about prior understandings of, barriers to, and feasibility of "non-invasive" biosampling were analysed. Participants described biomaterials intended for "non-invasive" collection as sometimes highly sensitive, with sampling procedures raising community concerns. Sampling methods framed as physically "non-invasive" within biomedicine can consequently be considered socially "invasive" by prospective sample donors. Biomedical and community framings of "invasiveness' can therefore diverge, and the former must respond to and be informed by the perspectives of the latter. Further, considerations of collection procedures are shaped by therapeutic misconceptions about the immediate health-related utility of biomedical and public health research. When researchers engage with communities about biosampling, they must ensure they are not furthering therapeutic misconceptions and actively seek to dispel these.

Salivary cortisol captures endocrine response to an acute stressor in captive female tufted capuchin monkeys (Sapajus apella).

Measuring glucocorticoids such as cortisol is a useful tool for exploring relationships among behavior, physiology, and well-being in primates. As cortisol circulates in blood, it moves into biological matrices such as hair, urine, feces, and saliva. Saliva sampling is a simple, noninvasive method to measure cortisol that can be easily implemented by training animals to voluntarily provide samples. The temporal lag between elevation of cortisol in the blood and elevation of cortisol in saliva likely varies by species and must be characterized to identify appropriate sampling regimens. In the present study we characterized the time course of cortisol changes in saliva following an acute psychological stressor in captive tufted capuchin monkeys (Sapajus apella). We trained eight free-moving female tufted capuchin monkeys to voluntarily produce clean saliva samples. We exposed them to the acute stressor of a veterinary catch net and observed behavior pre and post exposure. We collected salivary samples immediately pre exposure (0 min) and 30, 45, 60, 75, 90, and 120 min after exposure. Salivary cortisol was quantified using a Salimetrics kit. Behavioral and cortisol measures were compared within individuals to a control condition in which no stressor was presented. Capuchins showed a clear behavioral response to the stressor by demonstrating increased freezing and pacing, decreased feed foraging, nonsocial play, and scratching, and decreased willingness to provide saliva samples after stressor presentation. After stressor presentation, average salivary cortisol began to increase at 30 min and continued to increase through the 120 min sample period. There was individual variation in absolute cortisol levels, the timing of the cortisol increase, and the timing of the peak. Our results suggest that no single time-point can be reliably used to evaluate salivary cortisol response to an acute stressor across individuals, and instead we recommend the collection of a prolonged time series.

Journey through discovery of 75 years glucocorticoids: evolution of our knowledge of glucocorticoid receptor mechanisms in rheumatic diseases.

For three-quarters of a century, glucocorticoids (GCs) have been used to treat rheumatic and autoimmune diseases. Over these 75 years, our understanding of GCs binding to nuclear receptors, mainly the glucocorticoid receptor (GR) and their molecular mechanisms has changed dramatically. Initially, in the late 1950s, GCs were considered important regulators of energy metabolism. By the 1970s/1980s, they were characterised as ligands for hormone-inducible transcription factors that regulate many aspects of cell biology and physiology. More recently, their impact on cellular metabolism has been rediscovered. Our understanding of cell-type-specific GC actions and the crosstalk between various immune and stromal cells in arthritis models has evolved by investigating conditional GR mutant mice using the Cre/LoxP system. A major achievement in studying the complex, cell-type-specific interplay is the recent advent of omics technologies at single-cell resolution, which will provide further unprecedented insights into the cell types and factors mediating GC responses. Alongside gene-encoded factors, anti-inflammatory metabolites that participate in resolving inflammation by GCs during arthritis are just being uncovered. The translation of this knowledge into therapeutic concepts will help tackle inflammatory diseases and reduce side effects. In this review, we describe major milestones in preclinical research that led to our current understanding of GC and GR action 75 years after the first use of GCs in arthritis.

Fetal endocrine axes mRNA expression levels are related to sex and intrauterine position.

BACKGROUND: The hypothalamic-pituitary-adrenal (HPA) and -gonadal (HPG) axes are two major pathways that connect the neural and endocrine systems in vertebrates. Factors such as prenatal stress and maternal exposure to exogenous steroids have been shown to affect these pathways during fetal development. Another less studied factor is the transfer of hormones across fetuses in multifetal pregnancies. This form of transfer has been shown to influence the morphology, anatomy, physiology, and behavior of the offspring in litter-bearing mammals, an influence termed the intrauterine position (IUP) effect. In this study, we sought to delineate how the IUP effects HPA and HPG brain receptors, peptides, and enzymes (hereafter components) in utero and how these influences may differ between males and females. METHODS: We utilized the unconventional model of culled free-ranging nutria (Myocastor coypus), with its large natural variation. We collected brain tissues from nutria fetuses and quantified the expression of key HPA and HPG components in three brain regions: prefrontal cortex, hypothalamus, and striatum. RESULTS: We found an interaction between sex and IUP in the mineralocorticoid receptor (MR), gonadotropin-releasing hormone receptor (GNRHR), androgen receptor (AR), and estrogen receptor alpha (ESR1). IUP was significant in both gonadotropin-releasing hormone (GnRH) and its receptor GNRHR, but in different ways. In the hypothalamus, fetuses adjacent to same-sex neighbors had higher expression of GnRH than fetuses neighboring the opposite sex. Conversely, in the cortex, GNRHR exhibited the inverse pattern, and fetuses that were neighboring the opposite sex had higher expression levels than those neighboring the same sex. Regardless of IUP, in most components that showed significant sex differences, female fetuses had higher mRNA expression levels than male fetuses. We also found that HPA and HPG components were highly related in the early stages of gestation, and that there was an interaction between sex and developmental stage. In the early stages of pregnancy, female component expression levels were more correlated than males', but in the last trimester of pregnancy, male components were more related to each other than female's. CONCLUSIONS: This study suggests that there are sexually different mechanisms to regulate the HPA and HPG axes during fetal development. Higher mRNA expression levels of endocrine axes components may be a mechanism to help females cope with prolonged androgen exposure over a long gestational period. Additionally, these findings suggest different coordination requirements of male and female endocrine axes during stages of fetal development.