Female Rat Brain Research Articles

The Glutamine-Glutamate Cycle Contributes to Behavioral Feminization in Female Rats

Plain Language SummaryThe expression of female sexual behaviors in rodents relies on neuronal signaling within the ventromedial nucleus of the hypothalamus (VMH). Neurons located in the ventral lateral part of the VMH (vlVMH) release glutamate and use it as a mediator to transmit neuronal signals. These neurons are surrounded by astrocytes and may engage in metabolic interactions with them during the perinatal period. Astrocytes produce glutamine (Gln), which are transported into neurons as a precursor for producing glutamate. The vlVMH neurons that release glutamate depend on astrocytic Gln more heavily in female than in male pups. Perinatal disruption of Gln supply to neurons sex-differentially alters glutamate-mediated neuronal signaling and results in morphological changes in vlVMH neurons that resemble those of the opposite sex in adult animals. The present study reveals that perinatal blockade at various points of this metabolic pathway consistently decreased the expression of sex behavior of female rats, while it may only moderately reduce or left unaffected the sex behavior of male rats. Additionally, perinatal inhibition of Gln supply to neurons led to compensatory increases in a neuronal enzyme responsible for glutamate production in the hypothalamus of adult female rats. The results of the study demonstrate that an intact Gln-glutamate metabolic cycle between astrocytes and neurons during the perinatal period is necessary for the development of neuronal networks for proper sex behavior expression in female rats. The findings also suggest that behavioral defeminization could occur in the absence of high levels of E2 exposure in the brain of perinatal female rats.

Temporal sex specific brain gene expression pattern during early rat embryonic development.

Background: The classical concept of brain sex differentiation suggests that steroid hormones released from the gonads program male and female brains differently. However, several studies indicate that steroid hormones are not the only determinant of brain sex differentiation and that genetic differences could also be involved. Methods: In this study, we have performed RNA sequencing of rat brains at embryonic days 12 (E12), E13, and E14. The aim was to identify differentially expressed genes between male and female rat brains during early development. Results: Analysis of genes expressed with the highest sex differences showed that Xist was highly expressed in females having XX genotype with an increasing expression over time. Analysis of genes expressed with the highest male expression identified three early genes, Sry2, Eif2s3y, and Ddx3y. Discussion: The observed sex-specific expression of genes at early development confirms that the rat brain is sexually dimorphic prior to gonadal action on the brain and identifies Sry2 and Eif2s3y as early genes contributing to male brain development.

Role of tactile stimulation during the preweaning period on the development of the peripheral sensory sural (SU) nerve in adult artificially reared female rat.

Maternal deprivation, as a result of the artificial rearing (AR) paradigm, disturbs electrophysiological and histological characteristics of the peripheral sensory sural (SU) nerve of infant and adult male rats. Such changes are prevented by providing tactile or social stimulation during isolation. AR also affects the female rat's brain and behavior; however, it is unknown whether this early adverse experience also alters their SU nerve development or if tactile stimulation might prevent these possible developmental effects. To assess these possibilities, the electrophysiological and histological characteristics of the SU nerve from adult diestrus AR female rats that: (i) received no tactile stimulation (AR group), (ii) received tactile stimulation in the anogenital and body area (AR-Tactile group), or (iii) were mother reared (MR group) were determined. We found that the amplitude, but not the area, of the evoked compound action potential response in SU nerves of AR rats was lower than those of SU nerves of MR female rats. Tactile stimulation prevented these effects. Additionally, we found a reduction in the outer diameter and myelin thickness of axons, as well as a large proportion of axons with low myelin thickness in nerves of AR rats compared to the nerves of the MR and AR-Tactile groups of rats; however, tactile stimulation only partially prevented these effects. Our data indicate that maternal deprivation disturbs the development of sensory SU nerves in female rats, whereas tactile stimulation partially prevents the changes generated by AR. Considering that our previous studies have shown more severe effects of AR on male SU nerve development, we suggest that sex-associated factors may be involved in these processes.

Role of linagliptin, a dipeptidyl peptidase-4 inhibitor against oxidative stress and neuronal damage in experimental diabetic aging brain of female rats of different age groups.

Role of linagliptin, a dipeptidyl peptidase-4 inhibitor against oxidative stress and neuronal damage in experimental diabetic aging brain of female rats of different age groups.

Abstract LB155: Intra-cranial administration of MTL-004, a promising post-resection treatment for glioblastoma

Abstract Objectives Gliomas (GBM), are exceptionally hard to treat, aggressive and genetically heterogeneous tumors. This study reports the control of tumor recurrence and improved survival in male and female rats by combining a single intra-cranial dose of MTL-004 (5-(aziridine-1- yl)-4 hydroxylamino-2-nitrobenzamide), in a bioresorbable paste (a blend of poly DL-lactic acid-co-glycolic acid; (PLGA) and poly ethylene glycol; (PEG)) to surgical resection of primary glioma tumors. Comparison is made with oral temozolomide (TMZ), the current standard of care (SOC), following resection. Experimental procedures On day 0, 2 mm3 tumor fragments were implanted into the brains of healthy female and male Fischer rats. On day 5 rats the growing tumors were removed using microsurgery. Treatments started as follows: •Group 1 (Placebo) received a single intracranial dose of excipient powder in PGLA/PEG paste; •Group 2 (SOC) received 5 daily oral doses of TMZ at 50 mg/kg; •Group 3 (MTL-004) received a single intracranial dose of excipient powder containing 1 mg/kg MTL-004 in PGLA/PEG paste. Results Body Weight Between day 0 and 5, no groups had statistically significant body weight changes. Between days 5 to 9, mean body weight of rats receiving TMZ was significantly reduced. Tumor Volumes Tumor volumes from MRI were evaluated when at least 80% of rats were still alive in each group (day 14 post tumor resection/treatment initiation). Mean tumor volume was significantly higher in the placebo groups compared to MTL-004 and TMZ treatments. Survival Rats were studied for 58-days post tumor resection/treatment. At this time out of twelve rats per group, none or one survived on TMZ, two or no animals were still alive on placebo, and seven or ten rats treated with MTL-004 were still alive (male or female respectively). Post resection median survival time was between 20.5 to 27.5 days for rats treated with oral placebo or TMZ. Rats treated with MTL-004 had a significantly higher survival compared to both placebo and TMZ groups and remained in apparent good health for the 58 days of the study. Conclusions Consistent trends were observed in each group of male and female rats following tumor resection. •PGLA/PEG paste with MTL-004 or without (placebo) or were both well tolerated. •Treatment with MTL-004 in PGLA/PEG paste provided good tumor control, was better tolerated and led to significantly greater survival than oral TMZ or placebo. •Oral TMZ (SOC) provided control of tumor volume but was associated with significant, transient body weight losses and no significant survival gain compared to placebo. Our data highlight significant survival benefits associated with a single intracranial dose of MTL-004 with PLGA/PEG paste post-surgery. In conclusion, surgery followed by MTL-004 in PGLA/PEG paste is a well-tolerated and promising treatment for glioblastoma, suitable for clinical evaluation. Citation Format: Mike Hudson, Sylvie Maubant, Elisabeth Bertrand, Marie Lux, Jordan Longin, Elodie Marie Dit Chatel, Maxime Ramelet, Olivier Duchamp. Intra-cranial administration of MTL-004, a promising post-resection treatment for glioblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB155.

Identification of Differentially Expressed MicroRNAs in the Rat Hippocampus during Adolescence through an Epigenome-Wide Analysis

Introduction: Epigenetic mechanisms involving microRNAs (miRNAs) play a fundamental role in many biological processes, particularly during prenatal and early postnatal development. Their role in adolescent brain development, however, has been poorly described. The present study aimed to explore miRNA expression in the hippocampus during adolescence compared to adulthood in rats. Method: The brains of female and male Wistar rats were extracted, and the hippocampus was freshly dissected at postnatal day 41 (adolescence) and postnatal day 98 (adulthood). An epigenome-wide analysis was conducted to identify the miRNAs significantly expressed in adolescence compared to adulthood. Additionally, target genes of such miRNAs were considered to perform an exploratory Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Results: We identified 16 differentially expressed miRNAs in adolescent male rats compared with adult male rats and 4 differentially expressed miRNAs in adolescent females compared with adult females. Enrichment analysis reinforced that the target genes found are related to neurodevelopmental processes such as cell proliferation, cell migration, and nervous system development. Conclusion: Our findings suggest a complex pattern of miRNA expression during adolescence, which differs from that in adulthood. The differential expression of miRNA in the hippocampus during adolescence may be associated with the late developmental changes occurring in this brain region. Furthermore, the observed sex differences in miRNA expression patterns indicate potential sexual differentiation in hippocampal development. Further comprehensive investigations are needed to elucidate the roles of miRNA in normal brain development.

Bacterial lipopolysaccharide forms aggregates with apolipoproteins in male and female rat brains after ethanol binges

Alcohol binge drinking allows the translocation of bacterial lipopolysaccharide (LPS) from the gut to the blood, which activates the peripheral immune system with consequences in neuroinflammation. A possible access/direct signaling of LPS to/in the brain has not yet been described under alcohol abuse conditions. Apolipoproteins are compounds altered by alcohol with high affinity to LPS which may be involved in its transport to the brain or in its elimination. Here, we explored the expression of small components of LPS, in its free form or bound to apolipoproteins, in the brain of female and male rats exposed to alcohol binges. Animals received ethanol oral gavages (3 g/kg every 8 h) for 4 days. LPS or its components (Lipid A and core), LPS-binding protein, corticosterone, lipoproteins (HDL, LDL), apolipoproteins (ApoAI, ApoB, and ApoE), and their receptors were measured in plasma and/or in nonperfused prefrontal cortex (PFC) and cerebellum. Brain LipidA-apolipoprotein aggregates were determined by Western blotting and confirmed by co-immunoprecipitation. In animals exposed to alcohol binges: 1) plasma LPS-binding protein was elevated in both sexes; 2) females showed elevations in plasma ApoAI and corticosterone levels; 3) Lipid A formed aggregates with ApoAI in the female PFC and with ApoB in males, the latter showing Toll-like receptor 4 upregulation in PFC but not females. These results suggest that small bacterial components are present within the brain, forming aggregates with different apolipoproteins, depending on the sex, after alcohol binge intoxications. Results may have implications for the crosstalk between alcohol, LPS, and neuroinflammation.

Acute, but not repeated, cocaine exposure alters allopregnanolone levels in the midbrain of male and female rats.

Multiple psychiatric disorders are associated with altered brain and serum levels of neuroactive steroids, including the endogenous GABAergic steroid, allopregnanolone. Clinically, chronic cocaine use was correlated with decreased levels of pregnenolone. Preclinically, the effect of acute cocaine on allopregnanolone levels in rodents has had mixed results, showing an increase or no change in allopregnanolone levels in some brain regions. We hypothesized that cocaine acutely increases allopregnanolone levels, but repeated cocaine exposure decreases allopregnanolone levels compared to controls. We performed two separate studies to determine how systemic administration of 15mg/kg cocaine (1) acutely or (2) chronically alters brain (olfactory bulb, frontal cortex, dorsal striatum, and midbrain) and serum allopregnanolone levels in adult male and female Sprague-Dawley rats. Cocaine acutely increased allopregnanolone levels in the midbrain, but not in olfactory bulb, frontal cortex, or dorsal striatum. Repeated cocaine did not persistently (24h later) alter allopregnanolone levels in any region in either sex. However, allopregnanolone levels varied by sex across brain regions. In the acute study, we found that females had significantly higher allopregnanolone levels in serum and olfactory bulb relative to males. In the repeated cocaine study, females had significantly higher allopregnanolone levels in olfactory bulb, frontal cortex, and serum. Finally, acute cocaine increased allopregnanolone levels in the frontal cortex of females in proestrus, relative to non-proestrus stages. Collectively these results suggest that allopregnanolone levels vary across brain regions and by sex, which may play a part in differential responses to cocaine by sex.

Thyroid Hormone Metabolites Quantified in Pup and Adult Rat Cerebellum, Cortex and Whole-Brain Samples Using an Automated Online SPE-LC-MS/MS Method.

Changes in thyroid hormone (TH) levels in rat brain at early developmental stages are correlated with adverse effects on offspring development. To characterize the ability of substances to interfere with the TH concentrations in, e.g., rat brain, it is essential to know the mean TH concentrations in this tissue under control conditions. In this publication, an online solid-phase extraction (SPE) liquid chromatography (LC) tandem mass spectrometry (MS/MS) method was validated and used to measure TH metabolites (T4, T3, rT3, T2 and T1) in the brains of untreated rats. Data on TH concentrations in the whole brain and separate data from the cerebellum and the cortex are shown. The corresponding samples were gathered from young rats at postnatal days (PND) 4 and 21/22 and from adult rats. The results show inter alia the high accuracy and precision of the method, and LOQs of 0.02 ng/mL were determined for T1, T2 and rT3 and of 0.15 ng/mL for T3 and T4. Technical variability is low, as shown by the relative standard deviations of 7.5-20%. For our rat model, we found that T4, T3 and T2 concentrations rise from PND4 to PND21, whereas the rT3 concentration decreases; as well as there is no statistical difference between TH concentrations in the male and female rat brain. This method is suitable to analyze TH metabolites in the brain and build up a database of historical TH concentrations in control rats. Together, this yields a robust diagnostic tool to detect potentially adverse disturbances of TH homeostasis in the most vulnerable anatomic structure.

High intensity interval training exercise increases dopamine D2 levels and modulates brain dopamine signaling.

Previous research has outlined the health benefits of exercise including its therapeutic potential for substance use disorders (SUD). These data have already been utilized and it is now common to find exercise as part of SUD treatment and relapse prevention programs. However, we need to better understand different exercise regimens and determine which would be the most beneficial for SUDs. Recently, high intensity interval training (HIIT) has gained attention in comparison with aerobic and resistance exercise. Little is known regarding the neurobiological mechanisms of HIIT, including its effects on dopamine signaling and receptor levels in the brain. The present study examined the effects of chronic HIIT exercise on dopamine signaling as measured by dopamine type 1-like receptor (D1R)-like, dopamine type 2-like receptor (D2R)-like, and tyrosine hydroxylase (TH) quantification in the brains of male and female rats as measured by [3H] SCH 23390 and [3H] spiperone autoradiography, and TH-immunoreactive optical density values. Rats were separated in two groups: sedentary and HIIT exercise. Exercise was on a treadmill for 30 min daily (10 3 min cycles) for six weeks with progressive speed increased up to 0.8 mph (21.5 m/min). Results showed for D2R-like binding, a significant effect across the ventral caudate putamen (V CPU) between sexes, such that mean D2R-like binding was 14% greater for males than females. In the nucleus accumbens shell (Nac Shell), the HIIT Exercise rats showed 16% greater D2R-like binding as compared to the sedentary rats. No significant effects of HIIT exercise were found across groups for brain D1R-like binding levels or TH expression. These results suggest that HIIT exercise can modulate dopamine signaling by way of increased D2R. These findings support the premise that HIIT exercise plays an important role in dopamine signaling and, may provide a potential mechanism for how HIIT exercise can impact the brain and behavior.

Astrocyte Reactivity and Neurodegeneration in the Female Rat Brain Following Alcohol Dependence.

Recent evidence suggests that alcohol use disorder (AUD) may manifest itself differently in women compared to men. Women experience AUDs on an accelerated timeline and may have certain regional vulnerabilities. In male rats, neuronal cell death and astrocyte reactivity are noted following induction of alcohol dependence in an animal model of an AUD. However, the regional and temporal patterns of neurodegeneration and astrocyte reactivity have yet to be fully examined in females using this model. Therefore, adult female rats were exposed to a 4-day binge model of alcohol dependence followed by different periods of abstinence. Histological markers for FluoroJade B, a label of degenerating neurons, and vimentin, a marker for reactive astrocytes, were utilized. The expression of these markers in cortical and limbic regions was quantified immediately after their last dose (e.g., T0), or 2, 7, and 14days later. Significant neuronal cell death was noted in the entorhinal cortex and the hippocampus, similar to previous reports in males, but also in several cortical regions not previously observed. Vimentin immunoreactivity was noted in the same regions as previously reported, in addition to three novel regions. Vimentin immunoreactivity also occurred at earlier and later time points in some cortical and hippocampal regions. These data suggest that both neuronal cell death and astrocyte reactivity could be more widespread in females compared to males. Therefore, this study provides a framework for specific regions and time points which should be examined in future studies of alcohol-induced damage that include female rats.

Early Alterations of PACAP and VIP Expression in the Female Rat Brain Following Spinal Cord Injury

Previous evidence shows that rapid changes occur in the brain following spinal cord injury (SCI). Here, we interrogated the expression of the neuropeptides pituitary adenylyl cyclase-activating peptide (PACAP), vasoactive intestinal peptides (VIP), and their binding receptors in the rat brain 24 h following SCI. Female Sprague-Dawley rats underwent thoracic laminectomy; half of the rats received a mild contusion injury at the level of the T10 vertebrate (SCI group); the other half underwent sham surgery (sham group). Twenty-four hours post-surgery, the hypothalamus, thalamus, amygdala, hippocampus (dorsal and ventral), prefrontal cortex, and periaqueductal gray were collected. PACAP, VIP, PAC1, VPAC1, and VPAC2 mRNA and protein levels were measured by real-time quantitative polymerase chain reaction and Western blot. In SCI rats, PACAP expression was increased in the hypothalamus (104–141% vs sham) and amygdala (138–350%), but downregulated in the thalamus (35–95%) and periaqueductal gray (58–68%). VIP expression was increased only in the thalamus (175–385%), with a reduction in the amygdala (51–68%), hippocampus (40–75%), and periaqueductal gray (74–76%). The expression of the PAC1 receptor was the least disturbed by SCI, with decrease expression in the ventral hippocampus (63–68%) only. The expression levels of VPAC1 and VPAC2 receptors were globally reduced, with more prominent reductions of VPAC1 vs VPAC2 in the amygdala (21–70%) and ventral hippocampus (72–75%). In addition, VPAC1 downregulation also extended to the dorsal hippocampus (69–70%). These findings demonstrate that as early as 24 h post-SCI, there are region-specific disruptions of PACAP, VIP, and related receptor transcript and protein levels in supraspinal regions controlling higher cognitive functions.

Gestational intermittent hypoxia increases FosB-immunoreactive perikaryas in the paraventricular nucleus of the hypothalamus of adult male (but not female) rats.

Sleep-disordered breathing is a respiratory disorder commonly experienced by pregnant women. The recurrent hypoxaemic events associated with sleep-disordered breathing have deleterious consequences for the mother and fetus. Adult male (but not female) rats born to dams subjected to gestational intermittent hypoxia (GIH) have a higher resting blood pressure than control animals and show behavioural/neurodevelopmental disorders. The origin of this persistent, sex-specific effect of GIH in offspring is unknown, but disruption of the neuroendocrine stress pathways is a key mechanism by which gestational stress increases disease risk in progeny. Using FosB immunolabelling as a chronic marker of neuronal activation, we determined whether GIH augments basal expression of FosB in the perikaryas of cells in the paraventricular nucleus of the hypothalamus (PVN), a key structure in the regulation of the stress response and blood pressure. From gestational day 10, female rats were subjected to GIH for 8h/day (light phase) until the day before delivery (gestational day 21); GIH consisted of 2min hypoxic bouts (10.5% O2 ) alternating with normoxia. Control rats were exposed to intermittent normoxia over the same period (GNX). At adulthood (10-15weeks), the brains of male and female rats were harvested for FosB immunohistochemistry. In males, GIH augmented PVN FosB labelling density by 30%. Conversely, PVN FosB density in GIH females was 28% lower than that of GNX females. We conclude that GIH has persistent and sex-specific impacts on the development of stress pathways, thereby offering a plausible mechanism by which GIH can disturb neural development and blood pressure homeostasis in adulthood. NEW FINDINGS: What is the central question of this study? In pregnant women, sleep apnoea increases the risk of disease for the offspring at various life stages. Given that gestational stress disrupts the programming of the stress pathways, we determined whether exposing female rats to gestational intermittent hypoxia (GIH) activates hypothalamic neurons regulating the stress response in adult rats. What is the main finding and its importance? Using FosB immunolabelling as a marker of marker of neuronal activation, we showed that GIH augmented basal activation of the paraventricular nucleus of the hypothalamus in males, but not females. Disruption of the stress pathways is a new hypothesis to explain the persistent and sex-specific impacts of GIH on offspring health.

Levels of neurotrophins in the brain of female rats in an experimental model of malignant tumor growth under conditions of hypothyroidism

Objective. Studying the levels of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF-β), and neurotrophin 3 (NT3) in the cerebral cortex and subcortical substance of female rats in an experimental model of extracerebral growth of malignant tumor under conditions of induced hypothyroidism.Materials and methods. An experiment was performed on 47 white non-linear female rats: 10 rats each in the intact group, control group 1 (induced hypothyroidism), control group 2 (subcutaneous growth of Guerin’s carcinoma), main group (combination of pathologies); 7 rats in the group with subcutaneous tumor growth to assess life expectancy. Hypothyroidism was induced by per os administration of thiamazole (mercazolil, Akrikhin, Russia), daily dose of 2.5 mg/100 g of body weight, course of 30 days; total thyroxine and thyroid stimulating hormone were determined in blood serum by RIA (Immunotech, Czech Republic). When persistent hypothyroidism was achieved, Guerin’s carcinoma was transplanted under the skin as standard. Aſter decapitation on the 18th day aſter transplantation, the content of BDNF, NGF-β, NT3 (R&D System, RayBiotech, USA) was determined in 10 % homogenates of the cortex and subcortical substance subcortex of the brain (R&D System, RayBiotech, USA).Results. In the cortex in control groups 1 and 2, the level of BDNF was 2.6- and 1.6-fold lower, respectively, and NGF-β was 2.2-fold higher on average than in the intact group. NT3 levels in the control group 1 were 3.0- and 1.6-fold lower in the cortex and subcortical substance, respectively. In the control group 2, the levels of NT3 and NGF-β were higher in the subcortical matter than in the intact group by 2.4-fold and 3.1-fold, respectively. In the cortex and subcortical substance in the main group, only NGF-β levels were higher on average by 1.7 times, with values being intermediate between the corresponding values in control groups 1 and 2.Conclusion. Changes in the levels of all neurotrophins in hypothyroidism were most pronounced in the cortex, while in independent tumor growth, NGF-β in the cortex and subcortical substance and NT3 only in subcortical substance changed the most. When the pathologies were combined, only NGF-β was altered in the cortex and subcortical substance. Apparently, there is an interaction of the tumor and the CNS with changes in the balance of regulatory signals in the subcortical areas of the brain, that reflecting the connection with the biological characteristics of an active or inhibited (in presence of hypothyroidism) tumor growth.

Changes in Microcirculation in the Brain, Heart, and Liver in Female Rats with Translational Model of Alcoholic Cardiomyopathy.

We studied some features of blood and lymph microcirculation in the brain, heart, and liver of female rats with developed alcoholic cardiomyopathy. In female rats after 24-week forced consumption of 10% ethanol solution, the size and inotropic function of the heart were measured by echocardiography. Microcirculation in the brain, myocardium, and liver was assessed by laser Doppler flowmetry using LAKK-OP2 and LAZMA-D computerized laser analyzers. Using spectral wavelet analysis, we determined the absolute and normalized to total perfusion amplitudes of microcirculation oscillations reflecting various regulatory mechanisms. Intact animals served as controls. In rats of the experimental group, alcoholic cardiomyopathy completely developed. Under these conditions, the index of microcirculation in the brain, myocardium, and liver significantly decreased. At the same time, there was a redistribution in the brain between shunting and nutritive blood flow in favor of the latter. In the myocardium and liver, this ratio did not change.

Machine learning reveals common transcriptomic signatures across rat brain and placenta following developmental organophosphate ester exposure.

Toxicogenomics is a critical area of inquiry for hazard identification and to identify both mechanisms of action and potential markers of exposure to toxic compounds. However, data generated by these experiments are highly dimensional and present challenges to standard statistical approaches, requiring strict correction for multiple comparisons. This stringency often fails to detect meaningful changes to low expression genes and/or eliminate genes with small but consistent changes particularly in tissues where slight changes in expression can have important functional differences, such as brain. Machine learning offers an alternative analytical approach for "omics" data that effectively sidesteps the challenges of analyzing highly dimensional data. Using 3 rat RNA transcriptome sets, we utilized an ensemble machine learning approach to predict developmental exposure to a mixture of organophosphate esters (OPEs) in brain (newborn cortex and day 10 hippocampus) and late gestation placenta of male and female rats, and identified genes that informed predictor performance. OPE exposure had sex specific effects on hippocampal transcriptome, and significantly impacted genes associated with mitochondrial transcriptional regulation and cation transport in females, including voltage-gated potassium and calcium channels and subunits. To establish if this holds for other tissues, RNAseq data from cortex and placenta, both previously published and analyzed via a more traditional pipeline, were reanalyzed with the ensemble machine learning methodology. Significant enrichment for pathways of oxidative phosphorylation and electron transport chain was found, suggesting a transcriptomic signature of OPE exposure impacting mitochondrial metabolism across tissue types and developmental epoch. Here we show how machine learning can complement more traditional analytical approaches to identify vulnerable "signature" pathways disrupted by chemical exposures and biomarkers of exposure.

Proteome Profiling of Rat Brain Cortical Changes during Early Postnatal Brain Development.

Label-free quantitation (LFQ) was applied to proteome profiling of rat brain cortical development during the early postnatal period. Male and female rat brain extracts were prepared using a convenient, detergent-free sample preparation technique at postnatal days (PND) 2, 8, 15, and 22. The PND protein ratios were calculated using Proteome Discoverer, and the PND protein change profiles were constructed separately for male and female animals for key presynaptic, postsynaptic, and adhesion brain proteins. The profiles were compared to the analogous profiles assembled from the published mouse and rat cortex proteomic data, including the fractionated-synaptosome data. The PND protein-change trendlines, Pearson correlation coefficient (PCC), and linear regression analysis of the statistically significant PND protein changes were used in the comparative analysis of the datasets. The analysis identified similarities and differences between the datasets. Importantly, there were significant similarities in the comparison of the rat cortex PND (current work) vs mouse (previously published) PND profiles, although in general, a lower abundance of synaptic proteins in mice than in rats was found. The male and female rat cortex PND profiles were expectedly almost identical (98-99% correlation by PCC), which also substantiated this LFQ nanoflow liquid chromatography-high-resolution mass spectrometry approach.

Pre and postnatal exposure to 900 MHz electromagnetic fields induce inflammation and oxidative stress, and alter renin-angiotensin system components differently in male and female offsprings

AimsThis study was designed to investigate inflammation, oxidative stress and renin-angiotensin system components in brain and kidney tissues of female and male rats prenatally and/or postnatally exposed to 900 MHz electromagnetic field (EMF). It is aimed to evaluate the biological effects of 900 MHz EMF exposure due to the increase in mobile phone use and especially the more widespread use of the GSM 900 system. Main methodsMale and female Wistar albino offsprings were divided into four groups of control, prenatal, postnatal, and prenatal+postnatal exposed to 900 MHz EMF for 1 h/day (23 days during pregnancy for prenatal period, 40 days for postnatal period). The brain and kidney tissues were collected when they reached puberty. Key findingsIt was found that the total oxidant status, IL-2, IL-6, and TNF-α levels increased (p < 0.001) and the total antioxidant status levels decreased (p < 0.001) in all three EMF groups comparing to controls in both male and female brain and kidney tissues. The renin- angiotensin system components such as angiotensinogen, renin, angiotensin type 1 and type 2 receptors, and MAS1-like G protein-coupled receptor expression were higher (p < 0.001) in all three EMF exposure groups comparing to controls in both male and female brain and kidney tissues. Although there are some differences of the levels of proinflammatory markers, ROS components and RAS components in brain and kidney tissues between males and females, the common result of all groups was increase in oxidative stress, inflammation markers and angiotensin system components with exposure to 900 MHz EMF. SignificanceIn conclusion, our study suggested that the 900 MHz EMF can activate brain and kidney renin-angiotensin system, and this activation is maybe related to inflammation and oxidative stress in both male and female offsprings.

DNA topoisomerase Top3β is impacted by early life stress in the developing female and male rat brain

DNA topoisomerases are essential for preserving genomic integrity. DNA topoisomerases induce breakage of DNA to facilitate replication and transcription by relaxing DNA and relieving supercoiling. Aberrant expression and deletions of topoisomerases are associated with psychiatric disorders such as schizophrenia and autism. Our study investigated the effects of early life stress (ELS) on three topoisomerases, Top1, Top3α, and Top3β in the developing rat brain. Newborn rats were exposed to a predator odor stress on postnatal days 1, 2, and 3; brain tissue was collected either 30 min after the last stressor on postnatal day 3 or during the juvenile period. We found that exposure to predator odor resulted in a decrease in Top3β expression levels in the neonatal male amygdala and in the juvenile prefrontal cortex of males and females. These data suggest that developing males and females respond differently to predator odor-induced stress. As ELS results in lower Top3β levels, these data suggest that ELS experienced during development may have consequences for genomic structural integrity and increased mental health risk.

Intrinsic macroscale oscillatory modes driving long range functional connectivity in female rat brains detected by ultrafast fMRI

Spontaneous fluctuations in functional magnetic resonance imaging (fMRI) signals correlate across distant brain areas, shaping functionally relevant intrinsic networks. However, the generative mechanism of fMRI signal correlations, and in particular the link with locally-detected ultra-slow oscillations, are not fully understood. To investigate this link, we record ultrafast ultrahigh field fMRI signals (9.4 Tesla, temporal resolution = 38 milliseconds) from female rats across three anesthesia conditions. Power at frequencies extending up to 0.3 Hz is detected consistently across rat brains and is modulated by anesthesia level. Principal component analysis reveals a repertoire of modes, in which transient oscillations organize with fixed phase relationships across distinct cortical and subcortical structures. Oscillatory modes are found to vary between conditions, resonating at faster frequencies under medetomidine sedation and reducing both in number, frequency, and duration with the addition of isoflurane. Peaking in power within clear anatomical boundaries, these oscillatory modes point to an emergent systemic property. This work provides additional insight into the origin of oscillations detected in fMRI and the organizing principles underpinning spontaneous long-range functional connectivity.