Female Prefrontal Cortex Research Articles

Microglial responses to inflammatory challenge in adult rats altered by developmental exposure to polychlorinated biphenyls in a sex-specific manner

Polychlorinated biphenyls are ubiquitous environmental contaminants linkedc with peripheral immune and neural dysfunction. Neuroimmune signaling is critical to brain development and later health; however, effects of PCBs on neuroimmune processes are largely undescribed. This study extends our previous work in neonatal or adolescent rats by investigating longer-term effects of perinatal PCB exposure on later neuroimmune responses to an inflammatory challenge in adulthood. Male and female Sprague-Dawley rats were exposed to a low-dose, environmentally relevant, mixture of PCBs (Aroclors 1242, 1248, and 1254, 1:1:1, 20 μg / kg dam BW per gestational day) or oil control during gestation and via lactation. Upon reaching adulthood, rats were given a mild inflammatory challenge with lipopolysaccharide (LPS, 50 μg / kg BW, ip) or saline control and then euthanized 3 hours later for gene expression analysis or 24 hours later for immunohistochemical labeling of Iba1+ microglia. PCB exposure did not alter gene expression or microglial morphology independently, but instead interacted with the LPS challenge in brain region- and sex–specific ways. In the female hypothalamus, PCB exposure blunted LPS responses of neuroimmune and neuromodulatory genes without changing microglial morphology. In the female prefrontal cortex, PCBs shifted Iba1+ cells from reactive to hyperramified morphology in response to LPS. Conversely, in the male hypothalamus, PCBs shifted cell phenotypes from hyperramified to reactive morphologies in response to LPS. The results highlight the potential for long-lasting effects of environmental contaminants that are differentially revealed over a lifetime, sometimes only after a secondary challenge. These neuroimmune endpoints are possible mechanisms for PCB effects on a range of neural dysfunction in adulthood, including mental health and neurodegenerative disorders. The findings suggest possible interactions with other environmental challenges that also influence neuroimmune systems.

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.

The Role of Microglia in Sex- and Region-Specific Blood-Brain Barrier Integrity During Nicotine Withdrawal

BackgroundSmoking is the largest preventable cause of death and disease in the United States, with <5% of quit attempts being successful. Microglia activation and proinflammatory neuroimmune signaling in reward neurocircuitry are implicated in nicotine withdrawal symptomology. Microglia are integral regulators of blood-brain barrier (BBB) functionality as well; however, whether the effects of nicotine withdrawal on microglia function impact BBB integrity is unknown. MethodsMice were treated with chronic nicotine (12 mg/kg/day) and subjected to 48 hours nicotine withdrawal. Regional BBB permeability, together with messenger RNA and protein expression of tight junction proteins, were assessed. PLX5622 chow was used to deplete microglia to evaluate the role of microglia in regulating BBB integrity and nicotine withdrawal symptomology. ResultsFemale mice had higher baseline BBB permeability in the prefrontal cortex and hippocampus than males. Nicotine withdrawal further exacerbated the BBB permeability selectively in the prefrontal cortex of females. These effects were concurrent with prefrontal cortex alterations in a subset of tight junction proteins with increased proinflammatory responses following nicotine withdrawal in females. Depletion of microglia via PLX5622 treatment prevented all these molecular effects and attenuated withdrawal-induced anxiety-like behavior in female mice. ConclusionsThese results are the first to show sex differences in regional BBB permeability during nicotine withdrawal. This represents a possible link to both the reduced smoking cessation success seen in women and women’s increased risk for smoking-related neurovascular disorders. Furthermore, these findings open an avenue for sex-specific therapeutics that target microglia and BBB dysfunction during nicotine withdrawal in women.

Impaired fear memory in a rat model of the brain-derived neurotrophic factor Val66Met polymorphism is reversed by chronic exercise

The brain-derived neurotrophic factor (BDNF) Val66Met polymorphism is associated with reduced activity-dependent BDNF release in the brain and has been implicated in fear and anxiety disorders, including post-traumatic stress disorder. Exercise has been shown to have benefits in affective disorders but the role of BDNF Val66Met remains unclear. Male and female BDNF Val66Met rats were housed in automated running-wheel cages from weaning while controls were housed in standard cages. During adulthood, all rats underwent standard three-day fear conditioning testing, with three tone/shock pairings on day 1 (acquisition), and extinction learning and memory (40 tones/session) on day 2 and day 3. Expression of BDNF and stress-related genes were measured in the frontal cortex. Extinction testing on day 2 revealed significantly lower freezing in response to initial cue exposure in control Met/Met rats, reflecting impaired fear memory. This deficit was reversed in both male and female Met/Met rats exposed to exercise. There were no genotype effects on acquisition or extinction of fear, however chronic exercise increased freezing in all groups at every stage of testing. Exercise furthermore led to increased expression of Bdnf in the prefrontal cortex of females and its isoforms in both sexes, as well as increased expression of FK506 binding protein 51 (Fkpb5) in females and decreased expression of Serum/glucocorticoid-regulated kinase (Sgk1) in males independent of genotype. These results show that the Met/Met genotype of the Val66Met polymorphism affects fear memory, and that chronic exercise selectively reverses this genotype effect. Chronic exercise also led to an overall increase in freezing in all genotypes which may contribute to results.

Prospective Investigation of Glutamate Levels and Percentage Gray Matter in the Medial Prefrontal Cortex in Females at Risk for Postpartum Depression.

The substantial female hormone fluctuations associated with pregnancy and postpartum have been linked to a greater risk of developing depressive symptoms, particularly in high-risk women (HRW), i.e. those with histories of mood sensitivity to female hormone fluctuations. We have shown that glutamate (Glu) levels in the medial prefrontal cortex (MPFC) decrease during perimenopause, a period of increased risk of developing a major depressive episode. Our team has also demonstrated that percentage gray matter (%GM), another neural correlate of maternal brain health, decreases in the MPFC during pregnancy. To investigate MPFC Glu levels and %GM from late pregnancy up to 7 weeks postpartum in HRW and healthy pregnant women (HPW). Single-voxel spectra were acquired from the MPFC of 41 HPW and 22 HRW using 3- Tesla in vivo proton magnetic resonance spectroscopy at five different time points. We observed a statistically significant interaction between time and group for the metabolite Glu, with Glu levels being lower for HRW during pregnancy and early postpartum (p<0.05). MPFC %GM was initially lower during pregnancy and then significantly increased over time in both groups (p<0.01). This investigation suggests that the vulnerability towards PPD is associated with unique fluctuations of MPFC Glu levels during pregnancy and early postpartum period. Our results also suggest that the decline in MPFC %GM associated with pregnancy seems to progressively recover over time. Further investigations are needed to determine the specific role that female hormones play on the physiological changes in %GM during pregnancy and postpartum.

Age Worsens the Cognitive Phenotype in Mice Carrying the Thr92Ala-DIO2 Polymorphism.

The Thr92Ala-Dio2 polymorphism has been associated with reduced cognition in 2-month-old male mice and increased risk for cognitive impairment and Alzheimer’s disease in African Americans. This has been attributed to reduced thyroid hormone (TH) signaling and endoplasmic reticulum (ER) stress in the brain. Here we studied the Thr92Ala-Dio2 mouse model and saw that older male mice (7–8-month-old) exhibited a more severe cognition impairment, which extended to different aspects of declarative and working memories. A similar phenotype was observed in 4–5-month-old female mice. There were no structural alterations in the prefrontal cortex (PFC) and hippocampus of the Thr92Ala-Dio2 mouse. Nonetheless, in both male and female PFC, there was an enrichment in genes associated with TH-dependent processes, ER stress, and Golgi apparatus, while in the hippocampus there was additional enrichment in genes associated with inflammation and apoptosis. Reduced TH signaling remains a key mechanism of disease given that short-term treatment with L-T3 rescued the cognitive phenotype observed in males and females. We conclude that in mice, age is an additional risk factor for cognitive impairment associated with the Thr92Ala-Dio2 polymorphism. In addition to reduced TH signaling, ER-stress, and involvement of the Golgi apparatus, hippocampal inflammation and apoptosis were identified as potentially important mechanisms of a disease.

Vascular and blood-brain barrier-related changes underlie stress responses and resilience in female mice and depression in human tissue

Prevalence, symptoms, and treatment of depression suggest that major depressive disorders (MDD) present sex differences. Social stress-induced neurovascular pathology is associated with depressive symptoms in male mice; however, this association is unclear in females. Here, we report that chronic social and subchronic variable stress promotes blood-brain barrier (BBB) alterations in mood-related brain regions of female mice. Targeted disruption of the BBB in the female prefrontal cortex (PFC) induces anxiety- and depression-like behaviours. By comparing the endothelium cell-specific transcriptomic profiling of the mouse male and female PFC, we identify several pathways and genes involved in maladaptive stress responses and resilience to stress. Furthermore, we confirm that the BBB in the PFC of stressed female mice is leaky. Then, we identify circulating vascular biomarkers of chronic stress, such as soluble E-selectin. Similar changes in circulating soluble E-selectin, BBB gene expression and morphology can be found in blood serum and postmortem brain samples from women diagnosed with MDD. Altogether, we propose that BBB dysfunction plays an important role in modulating stress responses in female mice and possibly MDD.

Sex-Based Impact of Creatine Supplementation on Depressive Symptoms, Brain Serotonin and SSRI Efficacy in an Animal Model of Treatment-Resistant Depression.

Background: Rates of major depressive disorder (MDD) increase with living at altitude. In our model, rats housed at moderate altitude (in hypobaric hypoxia) exhibit increased depression-like behavior, altered brain serotonin and a lack of antidepressant response to most selective serotonin reuptake inhibitors (SSRIs). A forebrain deficit in the bioenergetic marker creatine is noted in people living at altitude or with MDD. Methods: Rats housed at 4500 ft were given dietary creatine monohydrate (CRMH, 4% w/w, 5 weeks) vs. un-supplemented diet, and impact on depression-like behavior, brain bioenergetics, serotonin and SSRI efficacy assessed. Results: CRMH significantly improved brain creatine in a sex-based manner. At altitude, CRMH increased serotonin levels in the female prefrontal cortex and striatum but reduced male striatal and hippocampal serotonin. Dietary CRMH was antidepressant in the forced swim test and anti-anhedonic in the sucrose preference test in only females at altitude, with motor behavior unchanged. CRMH improved fluoxetine efficacy (20 mg/kg) in only males at altitude: CRMH + SSRI significantly improved male striatal creatine and serotonin vs. CRMH alone. Conclusions: Dietary CRMH exhibits sex-based efficacy in resolving altitude-related deficits in brain biomarkers, depression-like behavior and SSRI efficacy, and may be effective clinically for SSRI-resistant depression at altitude. This is the first study to link CRMH treatment to improving brain serotonin.

Sex-based changes in rat brain serotonin and behavior in a model of altitude-related vulnerability to treatment-resistant depression.

Rates of depression and suicide increase with altitude. In our animal model, rats housed at moderate altitude vs. at sea level exhibit increased depressive symptoms in the forced swim test (FST) and lack of response to selective serotonin reuptake inhibitors (SSRIs). Depression and SSRI resistance are linked to disrupted serotonergic function, and hypobaric hypoxia may reduce the oxygen-dependent synthesis of serotonin. We therefore tested brain serotonin in rats housed at altitude. Sprague-Dawley rats were housed at altitude (4,500 ft, 10,000 ft) vs. sea level for 7-36days. Brain serotonin was measured by ELISA, or behavior evaluated in the FST, sucrose preference (SPT), or open-field tests (OFT). After 2weeks at 4,500 ft or 10,000ft vs. sea level, serotonin levels decreased significantly at altitude in the female prefrontal cortex, striatum, hippocampus, and brainstem, but increased with altitude in the male hippocampus and brainstem. Female brain serotonin decreased from 7 to 36days at 4,500 ft, but males did not vary. At 2weeks and 24days, females at altitude exhibit lower brain serotonin and increased depressive symptoms in the FST and SPT, with motor behavior unaltered. In males, serotonin, passive coping in the FST and OFT immobility increased with altitude at 2weeks, but not at 24days. Male SPT behavior did not change with altitude. Females may be more vulnerable to depressive symptoms at altitude, while males may be resilient. Chronic hypoxic stress at altitudes as low as 4,500 ft may cause a brain serotonin imbalance to worsen vulnerability to depression and SSRI resistance, and potentially worsen suicide risk.

Sex-specific role for prefrontal cortical protein interacting with C kinase 1 in cue-induced cocaine seeking.

Disruption of prefrontal glutamate receptor interacting protein (GRIP), which anchors GluA2-containing AMPA receptors (AMPARs) into the synaptic membrane, potentiates cue-induced cocaine seeking in both males and females. Protein interacting with C kinase 1 (PICK1) plays an opposing role to that of GRIP, removing AMPARs from the synapse. Consistent with our hypothesis that disruption of PICK1 in the mPFC would lead to a decrease in addiction-like behaviour, we found that conditional deletion of PICK1 in the mPFC attenuates cue-induced cocaine seeking in male mice. However, prefrontal PICK1 deletion had the opposite effect in females, leading to an increase in cue-induced reinstatement of cocaine seeking. We did not see any effects of PICK1 knockdown on sucrose taking or seeking, suggesting the sex-specific effects do not generalise to natural reinforcers. These findings suggest the role of PICK1 in the prefrontal cortex of females may not be consistent with its accepted role in males. To determine whether these sex differences were influenced by gonadal hormones, we gonadectomised a cohort of males and found that removal of circulating androgens eliminated the effect of prefrontal PICK1 knockdown. As there was no effect of gonadectomy on its own on any of the behavioural measures collected, our results suggest that androgens may be involved in compensatory downstream effects of PICK1 knockdown. Taken together, these results highlight the need for consideration of sex as a biological variable when examining mechanisms underlying all behaviours, as convergent sex differences can reveal different mechanisms where behavioural sex differences do not exist.

Synaptic and behavioral effects of chronic stress are linked to dynamic and sex-specific changes in microglia function and astrocyte dystrophy

Emerging evidence indicates that males and females display different neurobiological responses to chronic stress which contribute to varied behavioral adaptations. In particular, pyramidal neurons undergo dendritic atrophy and synapse loss in the prefrontal cortex (PFC) of male, but not female, mice. Our recent work shows that chronic stress also provokes microglia-mediated neuronal remodeling, which contributes to synaptic deficits in the PFC and associated behavioral consequences in males. Separate studies indicate that chronic stress promotes astrocyte dystrophy in the PFC which is associated with behavioral despair. Notably, these prior reports focused primarily on stress effects in males. In the present studies, male and female mice were exposed to 14 or 28 days of chronic unpredictable stress (CUS) to assess molecular and cellular adaptations of microglia, astrocytes, and neurons in the medial PFC. Consistent with our recent work, male, but not female, mice displayed behavioral and cognitive deficits with corresponding perturbations of neuroimmune factors in the PFC after 14 days of CUS. Fluorescence-activated cell sorting and gene expression analyses revealed that CUS increased expression of select markers of phagocytosis in male PFC microglia. Confocal imaging in Thy1-GFP(M) mice showed that CUS reduced dendritic spine density, decreased GFAP immunolabeling, and increased microglia-mediated neuronal remodeling only in male mice. After 28 days of CUS, both male and female mice displayed behavioral and cognitive impairments. Interestingly, there were limited stress effects on neuroimmune factors and measures of microglial phagocytosis in the PFC of both sexes. Despite limited changes in neuroimmune function, reduced GFAP immunolabeling and dendritic spine deficits persisted in male mice. Further, GFAP immunolabeling and dendritic spine density remained unaltered in the PFC of females. These findings indicate that chronic stress causes sex-specific and temporally dynamic changes in microglial function which are associated with different neurobiological and behavioral adaptations. In all, these results suggest that microglia-mediated neuronal remodeling, astrocyte dystrophy, and synapse loss contribute to stress-induced PFC dysfunction and associated behavioral consequences in male mice.

Sex- and Brain Region-specific Changes in Gene Expression in Male and Female Rats as Consequences of Methamphetamine Self-administration and Abstinence

Sex differences in METH use exist among human METH users and in animal models of METH addiction. Herein, we tried to identify potential differences in gene expression between female and male rats after Methamphetamine self-administration (METH SA). Rats were trained to self-administer METH using two 3-hours daily sessions for 20 days. Cue-induced drug seeking was measured on withdrawal days 3 (WD3) and 30 (WD30). Rats were euthanized twenty-four hours after WD30. Prefrontal cortex (PFC) and hippocampus (HIP) were dissected to measure mRNA expression. Both female and male rats increased their METH intake and showed increased METH seeking during withdrawal. Female had higher basal level expression of hypocretin receptor 1 (Hcrtr1) and prodynorphin (Pdyn) mRNAs in the PFC and HIP. Basal corticotropin releasing hormone receptor 1 (Crhr1), Crh receptor 2 (Crhr2), hypocretin receptor 2 (Hcrtr2) and opioid receptor kappa 1 (Oprk1) mRNA levels were higher in the PFC of females. Male rats had higher basal levels of Crh and Crhr1 in HIP. METH SA was associated with increased Crh and Crhr1 in the HIP of both sexes and Crhr2 only in female HIP. Importantly, increased Crh and Crhr1 mRNA levels correlated positively with incubation of METH craving in both sexes, supporting their potential involvement, in part, in the regulation of this behavioral phenomenon. When taken together, our results identified sexual dimorphic baseline differences in rats. We also detected dimorphic responses in animals that had self-administered METH. These observations highlight the importance of understanding the molecular neurobiology of sex differences when therapeutic interventions are planned against METH addiction.

Xanthotoxin affects depression-related behavior and neurotransmitters content in a sex-dependent manner in mice

The present study aimed to evaluate xanthotoxin's influence on male and female Swiss mice's depression-like behaviors and investigate the potential mechanism of this effect. Naturally derived furanocoumarin (the Apiaceae family), xanthotoxin, administered acutely (12.5 mg/kg), diminished the immobility level in the forced swim test only in males. The immobility level was lower in females than males, which may be associated with a higher serotonin level in the female prefrontal cortex. A dose-dependent increase of serotonin and noradrenaline was reported in the reverse-phase ion-pair liquid chromatography in the female prefrontal cortex but not in the hippocampus. We suggest that xanthotoxin may exert antidepressant properties and affect males and females differently. The increasing level of serotonin in the male and female prefrontal cortex may underlie this effect.

The prefrontal cortex conscious and unconscious response to social/emotional facial expressions involve sex, hemispheric laterality, and selective activation of the central cardiac modulation

The human prefrontal cortex (PFC) processes complex sensory information for the elaboration of social behaviors. The non-invasive neuroimaging technique near-infrared spectroscopy (NIRS) identifies hemodynamic changes and concentration of oxygenated (HbO2) and deoxygenated (HHb) hemoglobin in the cerebral cortex. We studied the responses detected by NIRS in the right and left PFC activation of 28 participants (n = 14 adult young females and males) while processing social/emotional facial expressions, i.e., in conscious perception of different expressions (neutral, happy, sad, angry, disgust, and fearful) and in unconscious/masked perception of negative expressions (fearful and disgust overlapped by neutral). The power spectral analysis from concomitant ECG signals revealed the sympathetic and parasympathetic modulation of cardiac responses. We found higher HbO2 values in the right PFC of females than in males during, and in the left PFC after, following the conscious perception of the happy face. In males, the left PFC increased and the right PFC decreased HbO2 while viewing the happy expression. In both sexes, HHb values were higher during the masked presentation of disgust than fearful expression, and after the masked presentation of fearful expression than during it. Higher sympathetic and lower parasympathetic activity (LF/ HF components) occurred in females when consciously and unconsciously processing negative emotions (p < 0.05 in all cases). These results demonstrate that the human PFC displays a selective activation depending on sex, hemispheric laterality, attention, time for responding to conscious and unconscious emotionally loaded stimuli with simulataneous centrally modulated cardiovascular responses.

Sensitivity and Resilience to Stress‐Induced Alcohol Intake Enhancement Produces Sex Differences in the Corticotropin Releasing Factor System in Male and Female C57BL/6J Mice

Post‐traumatic stress disorder (PTSD) and alcohol use disorder (AUD) are prevalent disorders with higher lifetime comorbidity among females. Stress has been shown to increase alcohol drinking, along with evidence confirming associations between PTSD and AUD. We developed a model of traumatic stress and PTSD using predator odor stress (PS) wherein repeated PS exposures significantly increased anxiety‐related behavior, corticosterone levels, and neuronal activation in the hippocampus (HIPP) and prefrontal cortex (PFC) in naïve C57BL/6J mice. Intermittent PS exposure (30 min dirty rat bedding) also significantly increased subsequent alcohol drinking in “sensitive” mice, with heterogeneity of responses as seen with comorbid PTSD and AUD. The purpose of our present study was to determine whether PS‐enhanced drinking in “sensitive” mice produced sex differences in several proteins important for CRF system function based on previous evidence regarding sex differences in the responsivity to stress and the CRF system. Drinking preference (10% ethanol vs water) was measured for 7 weeks in adult male and female mice (4 weeks baseline, 2 weeks with intermittent PS, 1 week post‐stress). Median and interquartile ranges were used to identify “sensitive” (&gt; 20% increase in alcohol drinking over baseline) and “resilient” (no change or decrease in drinking from baseline) subgroups. In the “sensitive” subgroup, alcohol drinking was increased by 69% in males and by 46% in females, with heterogeneity in response (17.5% of males, 12.5% of females were “PS‐sensitive”). Brains were harvested 24 hrs from the final drinking session, PFC and HIPP were dissected and frozen for Western Blot analyses of CRF receptor 1 (CRF‐R1), CRF‐R2, CRF binding protein (CRF‐BP), and glucocorticoid receptor (GR) vs separate naïve age‐matched mice, quantifying protein levels for each subgroup. In female PFC, all 4 proteins were significantly increased (17–28%) in the “sensitive” subgroup vs naïve, and these differences were significantly higher than in the “resilient” subgroup. In contrast, there were no significant increases in protein levels in “sensitive” male PFC vs naïve, and a significant “sensitive” vs “resilient” subgroup difference in CRF‐R2 and CRF‐BP was due to lower protein levels in the “resilient” subgroup. In male and female HIPP, CRF‐R1 levels were significantly decreased by 20% and 25%, respectively, in the “resilient” subgroup vs naïve. CRF‐R1 and GR levels were significantly lower in the “resilient” vs “sensitive” female subgroup. In contrast, CRF‐BP levels were significantly lower in “resilient vs “sensitive” males, while both male and female “resilient” vs “sensitive” subgroups had significantly lower levels for CRF‐R2. Taken together, these results continue to support the suggestion that a history of ethanol drinking and stress interact to increase the risk for harm from subsequent drinking in “sensitive” mice, with important sex differences in drinking behaviors and brain protein changes relevant to CRF system function.Support or Funding InformationSupported by BX002966 (DF) from the Department of Veteran Affairs

Neural basis of romantic partners\u2019 decisions about participation in leisure activity

Leisure activity is one of key ingredients for individual happiness and life satisfaction. Enjoying leisure activity with one’s partner can increase marital satisfaction. This study aimed to identify the neural basis of making decisions on participation in a leisure activity with one’s romantic partner as well as the relationship between leisure activity and satisfaction with life. Thirty-seven soon-to-be married heterosexual couples were participated in functional MRI while deciding participation in specific leisure activities in the individual, partner, with-friend, and with-partner conditions. We constructed analysis of variance models and investigated couple characteristics such as personality similarity, leisure activity matching rate, and spatial similarity in the bilateral frontoparietal network. The results showed decreased activity in the bilateral hippocampus during the task in the with-partner condition. Individual leisure activity was correlated with quality of life in males, whereas participation in leisure activity might require more cognitive loading on the dorsolateral prefrontal cortex in females. The leisure activity matching rate was correlated with courtship period, personality similarity, and spatial similarity of the right frontoparietal network during the task. These findings suggest that although there are different activation pattern in making decisions on leisure activity between romantic couples, spatial similarity of the partner’s social brain networks may be a marker that predicts how well the couple enjoys leisure activity together. In addition, our couples’ data analysis provides a scientific basis for the saying that romantic couples become more similar the longer they are together.

Drinking patterns and alterations in several brain protein levels after binge drinking during adolescence followed by intermittent stress and ethanol drinking during adulthood in male and female C57BL/6J mice

Alcohol abuse is a serious problem in our society with stress likely increasing the risk for escalation to harmful drinking. We are continuing to explore the effect of prior binge drinking on subsequent drinking behaviors and the response to intermittent predator odor stress (PS) exposure (a model of traumatic stress). We assessed responses in mice that were adolescent at the time of the binge drinking sessions, as we are aware that the adolescent brain is particularly vulnerable to ethanol. Male and female C57BL/6J adolescent mice had either 7 binge ethanol sessions (binge) or drank water (control). Following an abstinence period, all mice (now adults) were provided free access to 10% ethanol (10E) and water via lickometers for 4 weeks, with 30 min exposure to PS during the middle 2 weeks (2X/week). For mice exposed to the binge paradigm during adolescence, drinking levels changed across time after repeated PS. In males, ethanol intake increased over baseline by 34% in the binge group vs unchanged in the control group. In females, ethanol intake was increased by 57% (binge) and 38% (control) over baseline. At 24 hr after the final drinking session, brains were harvested and frozen for Western Blot analyses versus separate naïve age‐matched mice. Prefrontal cortex (PFC) and hippocampus (HIPP) were assayed for levels of the GABAA receptor (GABAAR) alpha2 and alpha 4 subunits, P450scc (a steroidogenesis enzyme), and CRF R1 (corticotropin releasing factor receptor) with values compared to naïve mice. We found divergent responses across proteins by sex and brain area. In male PFC, there reduced levels for GABAAR alpha 4 subunit levels (to 0.86 ± 0.04% for control and 0.85 ± 0.04% for binge vs naïve) and a decrease in P450scc levels of 084 ± 0.04% (control) and 0.89 ± 0.04% (binge) whereas the male HIPP also showed a trend towards reduced levels of the GABAAR alpha 4 subunit (0.90 ± 0.04% and 0.85 ± 0.03% for control and binge, respectively) but an increase in CRF‐R1 levels to 1.26 ± 0.05% for control and 1.28 ± 0.04% for binge. In contrast, the female PFC had decreased levels of the GABAAR alpha 2 subunit (0.77 ± 0.12% for control and 0.74 ± 0.07% for binge) with a similar decrease in alpha 4 subunit levels as in male PFC (0.84 ± 0.11% for control and 0.78 ± 0.09% for binge). Also similar to male, female HIPP had increased levels for CRF‐R1 levels of 1.14 ± 0.05% for control and 1.15 ± 0.05% for binge. And while P450scc levels were decreased (0.84 ± 0.04% for both groups) in female HIPP, a similar change was only observed in male PFC. The similar changes in the binge and control groups vs naïve animals suggest that the repeated PS and ethanol drinking history during adulthood influenced neuroadaptations in brain proteins more than the adolescent binge drinking experience. Taken together, these data continue to support the suggestion that a history of ethanol drinking and stress may interact to increase the risk for harm from subsequent drinking with important sex differences in drinking behaviors and brain protein changes.Support or Funding InformationSupported by BX001070 and BX002966 (DF) from the Department of Veteran AffairsThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Sex‐selective effects of prior binge‐like drinking followed by intermittent stress and ethanol drinking on alterations in several brain protein levels and neurosteroids

Alcohol misuse and abuse are serious problems in our society and stress may increase the risk for escalation of drinking from recreational to problematic. We are continuing to explore the effect of prior binge drinking on subsequent drinking behaviors and the response to intermittent predator odor stress exposure, which is a model of traumatic stress. Adult male and female C57BL/6 mice had either 7 binge ethanol sessions (binge) or drank water (control). Following a 30‐day abstinence period, all mice were provided free access to 10% ethanol (10E) and water via lickometers for 4 weeks, with 30 min exposure to predator odor during the middle 2 weeks (2X/week). At 24 hrs after the final drinking session, mice were euthanized, and brains were harvested and frozen for Western Blot analyses vs separate naïve age‐matched mice. Dissected prefrontal cortex (PFC) and hippocampus (HIPP) were assayed for levels of the GABAA receptor a2 and a4 subunits, P450scc (an enzyme involved in steroidogenesis), and synaptophysin and ARC (activity‐regulated cytoskeletal protein), two proteins involved in synaptic plasticity. Western blot analyses found divergent responses across proteins and by sex. For the GABAA receptor a2 and a4 subunits, treatments (binge and control) decreased levels by 20–25% in male PFC but not HIPP versus naïve mice. Binge and control females displayed a similar decrease in PFC levels of the a4 subunit, whereas PFC levels of the a2 GABAA receptor subunit were increased by 25% compared to naïve mice. Additional sex differences were observed for the effect of the binge and control treatment groups versus naïve mice on P450scc levels: a 20% decrease in relative protein levels in male PFC versus a 15–30% increase in levels for both the female PFC and HIPP. Treatments also increased levels of synaptophysin in male and female HIPP by 20–30%, compared to naïve mice, with only the female PFC having a 30% increase in ARC levels. Alterations in relative protein levels were similar for the control and binge animals versus naïve mice, suggesting that the repeated predator odor stress and ethanol drinking had the greatest influence on assayed neuroaptations in the PFC and HIPP. Simultaneous analysis of ten plasma neurosteroid levels by gas chromatography‐mass spectrometry showed that treatment significantly increased levels of several GABAA receptor active neurosteroids in these male and female mice versus naïve animals. Taken together, these data reinforce the importance of assessing sex differences, as there were divergent neurochemical responses between males and females. These data also implicate the influence of neurosteroids on responses to the impact of prior binge‐like drinking on subsequent ethanol drinking and effects of stress.Support or Funding InformationSupported by BX001070 and BX002966 (DF) from the Department of Veteran AffairsThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Sex differences in behavioral and neurochemical effects of gonadectomy and aromatase inhibition in rats

Aromatase inhibitors, which are widely used for the treatment of estrogen-dependent cancers, have been associated with psychiatric side effects ranging from mania to depression. In the present study, we investigated sex differences in the behavioral and neurochemical effects of aromatase inhibition on male and female, sham-operated or gonadectomized adult rats. Three weeks after surgery, rats received chronic treatment with the aromatase inhibitor letrozole or vehicle and were then subjected to the open field test, which assesses general activity. Half of the subjects were subsequently exposed to the stressful procedure of the forced swim test (FST), which is also a test of antidepressant activity. Aromatase activity was analyzed in the hypothalamus and testosterone and corticosterone were assayed in the blood serum of all rats. The hippocampus and prefrontal cortex (PFC) were analyzed for monoamine (noradrenaline, dopamine and serotonin), as well as amino acid (GABA, glutamate, glycine, taurine, alanine and histidine) levels. The observed decrease in hypothalamic aromatase activity confirmed the efficacy of letrozole treatment in both sexes. Moreover, letrozole enhanced testosterone levels in sham-operated females. In the open field test, females were overall more active and explorative than males and gonadectomy eliminated this sex difference. In the FST, females exhibited overall higher immobility than males and gonadectomy further enhanced this passive behavior in both sexes. However, sustained aromatase inhibition had no effect on open field and FST behaviors. Head shakes during FST, which were fewer in females than in males, were reduced by castration in males and by letrozole treatment in ovariectomized females, suggesting a role of testosterone and extra-gonadal estrogens in the expression of this behavior. Sustained aromatase inhibition also decreased noradrenaline and the dopaminergic turnover rates [DOPAC/DA, HVA/DA] in the hippocampus and PFC of male and female rats, irrespectively of gonadectomy. Moreover, letrozole treatment enhanced the serotonergic turnover [5HIAA/5HT] rate in the hippocampus of males and females, irrespectively of gonadectomy. Amino acid levels were not influenced by letrozole, but sex differences were demonstrated with higher levels in the PFC of females vs. males. Present findings suggest that the neuropsychiatric effects of aromatase inhibition can be attributed to the inhibition of extragonadal estrogen synthesis, presumably in the brain, and could be further associated with serotonergic and catecholaminergic changes in brain regions involved in mood and cognition. Importantly, present data could be linked with the neurobiology of affective side-effects in post-menopausal women receiving aromatase inhibitors.

Two-hit model of schizophrenia induced by neonatal immune activation and peripubertal stress in rats: Study of sex differences and brain oxidative alterations

Schizophrenia is considered to be a developmental disorder with distinctive sex differences. Aiming to simulate the vulnerability of the third trimester of human pregnancy to the developmental course of schizophrenia, an animal model was developed, using neonatal poly(I:C) as a first-hit, and peripubertal stress as a second-hit, i.e. a two-hit model. Since, to date, there have been no references to sex differences in the two-hit model, our study sought to determine sex influences on the development of behavior and brain oxidative change in adult rats submitted to neonatal exposure to poly(I:C) on postnatal days 5–7 as well as peripubertal unpredictable stress (PUS). Our results showed that adult two-hit rats present sex-specific behavioral alterations, with females showing more pronounced deficits in prepulse inhibition of the startle reflex and hyperlocomotion, while males showing more deficits in social interaction. Male and female animals exhibited similar working memory deficits. The levels of the endogenous antioxidant, reduced glutathione, were decreased in the prefrontal cortex (PFC) of both male and female animals exposed to both poly(I:C) and poly(I:C) + PUS. Only females presented decrements in GSH levels in the striatum. Nitrite levels were increased in the PFC of male and in the striatum of female poly(I:C) + PUS rats. Increased lipid peroxidation was observed in the PFC of females and in the striatum of males and females exposed to poly(I:C) and poly(I:C) + PUS. Thus, the present study presents evidence for sex differences in behavior and oxidative brain change induced by a two-hit model of schizophrenia.