Sex Differences In Vulnerability Research Articles

Altered immune response is associated with sex difference in vulnerability to Alzheimer's disease in human prefrontal cortex.

Alzheimer's disease (AD) is a neurodegenerative disorder with a higher risk incidence in females than in males, and there are also differences in AD pathophysiology between sexes. The role of sex in the pathogenesis of AD may be crucial, yet the cellular and molecular basis remains unclear. Here, we performed a comprehensive analysis using four public transcriptome datasets of AD patients and age-matched control individuals in prefrontal cortex, including bulk transcriptome (295 females and 402 males) and single-nucleus RNA sequencing (snRNA-seq) data (224 females and 219 males). We found that the transcriptomic profile in female control was similar to those in AD. To characterize the key features associated with both the pathogenesis of AD and sex difference, we identified a co-expressed gene module that positively correlated with AD, sex, and aging, and was also enriched with immune-associated pathways. Using snRNA-seq datasets, we found that microglia (MG), a resident immune cell in the brain, demonstrated substantial differences in several aspects between sexes, such as an elevated proportion of activated MG, altered transcriptomic profile and cell-cell interaction between MG and other brain cell types in female control. Additionally, genes upregulated in female MG, such as TLR2, MERTK, SPP1, SLA, ACSL1, and FKBP5, had high confidence to be identified as biomarkers to distinguish AD status, and these genes also interacted with some approved drugs for treatment of AD. These findings underscore the altered immune response in female is associated with sex difference in susceptibility to AD, and the necessity of considering sex factors when developing AD biomarkers and therapeutic strategies, providing a scientific basis for further in-depth studies on sex differences in AD.

Failure of senolytic treatment to prevent cognitive decline in a female rodent model of aging.

There are sex differences in vulnerability and resilience to the stressors of aging and subsequent age-related cognitive decline. Cellular senescence occurs as a response to damaging or stress-inducing stimuli. The response includes a state of irreversible growth arrest, the development of a senescence-associated secretory phenotype, and the release of pro-inflammatory cytokines associated with aging and age-related diseases. Senolytics are compounds designed to eliminate senescent cells. Our recent work indicates that senolytic treatment preserves cognitive function in aging male F344 rats. The current study examined the effect of senolytic treatment on cognitive function in aging female rats. Female F344 rats (12 months) were treated with dasatinib (1.2 mg/kg) + quercetin (12 mg/kg) or ABT-263 (12 mg/kg) or vehicle for 7 months. Examination of the estrus cycle indicated that females had undergone estropause during treatment. Senolytic treatment may have increased sex differences in behavioral stress responsivity, particularly for the initial training on the cued version of the watermaze. However, pre-training on the cue task reduced stress responsivity for subsequent spatial training and all groups learned the spatial discrimination. In contrast to preserved memory observed in senolytic-treated males, all older females exhibited impaired episodic memory relative to young (6-month) females. We suggest that the senolytic treatment may not have been able to compensate for the loss of estradiol, which can act on aging mechanisms for anxiety and memory independent of cellular senescence.

Lack of detectable sex differences in the mitochondrial function of Caenorhabditis elegans

BackgroundSex differences in mitochondrial function have been reported in multiple tissue and cell types. Additionally, sex-variable responses to stressors including environmental pollutants and drugs that cause mitochondrial toxicity have been observed. The mechanisms that establish these differences are thought to include hormonal modulation, epigenetic regulation, double dosing of X-linked genes, and the maternal inheritance of mtDNA. Understanding the drivers of sex differences in mitochondrial function and being able to model them in vitro is important for identifying toxic compounds with sex-variable effects. Additionally, understanding how sex differences in mitochondrial function compare across species may permit insight into the drivers of these differences, which is important for basic biology research. This study explored whether Caenorhabditis elegans, a model organism commonly used to study stress biology and toxicology, exhibits sex differences in mitochondrial function and toxicant susceptibility. To assess sex differences in mitochondrial function, we utilized four male enriched populations (N2 wild-type male enriched, fog-2(q71), him-5(e1490), and him-8(e1498)). We performed whole worm respirometry and determined whole worm ATP levels and mtDNA copy number. To probe whether sex differences manifest only after stress and inform the growing use of C. elegans as a mitochondrial health and toxicologic model, we also assessed susceptibility to a classic mitochondrial toxicant, rotenone.ResultsWe detected few to no large differences in mitochondrial function between C. elegans sexes. Though we saw no sex differences in vulnerability to rotenone, we did observe sex differences in the uptake of this lipophilic compound, which may be of interest to those utilizing C. elegans as a model organism for toxicologic studies. Additionally, we observed altered non-mitochondrial respiration in two him strains, which may be of interest to other researchers utilizing these strains.ConclusionsBasal mitochondrial parameters in male and hermaphrodite C. elegans are similar, at least at the whole-organism level, as is toxicity associated with a mitochondrial Complex I inhibitor, rotenone. Our data highlights the limitation of using C. elegans as a model to study sex-variable mitochondrial function and toxicological responses.

Magnitude and predictors of elasticity of demand for morphine are similar in male and female rats.

Sex differences in vulnerability to opioid use disorder (OUD) have been reported in some clinical and preclinical studies, but findings are mixed and further research is needed in this area. The goal of this study was to compare elasticity of demand (reinforcement efficacy) in an i.v. morphine self-administration (SA) model in male and female rats using a translationally relevant behavioral economics approach. Rate of acquisition and predictors of individual differences in demand (e.g., cumulative morphine infusions during acquisition) were also evaluated in both sexes. Acquisition of morphine SA (0.4 mg/kg/infusion) under a fixed ratio (FR) 1 schedule of reinforcement was slower and infusions earned were lower in females than in males (n = 30-31/sex), but infusions earned did not differ between sexes during the FR 2 and FR 3 phases of acquisition. Increases in the FR response requirement across sessions during demand testing (FR 1-FR 96) resulted in a progressive reduction in morphine infusions in both sexes. Morphine consumption was well-described by an exponential demand function in both sexes and was associated with considerable individual vulnerability. There were no sex differences in elasticity of demand (rate of decline in morphine consumption with increasing price) or intensity of demand (consumption at zero price). A higher number of infusions earned during the FR 2 and FR 3 phases of acquisition and greater maximum response rates during demand testing were associated with lower demand elasticity (i.e., greater reinforcing efficacy) in both males and females, whereas other relationships were sex-specific (e.g., higher intensity of demand was associated with lower elasticity of demand in males but not in females). Our findings indicate similar elasticity of demand and predictors of individual differences in demand for morphine in male and female rats, although sex differences were observed in initial rate of acquisition and in some correlations between morphine SA measures. These data are consistent with findings of similar OUD vulnerability in males and females in some human and animal studies.

Divergent Population-Specific Effects of Chronic Ethanol Exposure on Excitability and Inhibitory Transmission in Male and Female Rat Central Amygdala.

The central nucleus of the amygdala (CeA) is implicated in alcohol use disorder (AUD) and AUD-associated plasticity. The CeA is a primarily GABAergic nucleus that is subdivided into lateral and medial compartments with genetically diverse subpopulations. GABAA receptors are heteromeric pentamers with subunits conferring distinct physiological characteristics. GABAA receptor signaling in the CeA has been implicated in ethanol-associated plasticity; however, population-specific changes in inhibitory signaling and subunit expression remain unclear. Here, we combined electrophysiology with single-cell gene expression analysis of population markers and GABAA receptor subunits to examine population-specific changes in inhibitory control in male and female rats following chronic ethanol exposure. We found that chronic ethanol exposure and withdrawal produced global changes in GABAA receptor subunit expression at the transcript and protein levels, increased excitability in female CeA neurons, and increased inhibitory synaptic transmission in male CeA neurons. When we examined CeA neurons at the single-cell level we found heterogenous populations, as previously reported. We observed ethanol-induced increases in excitability only in somatostatin neurons in the CeA of females, decreases in excitability only in the protein kinase C delta (PKCd) population in males, and ethanol-induced increases in inhibitory transmission in male PKCd and calbindin 2-expressing CeA neurons. There were no population-specific differences in GABAA receptor (Gabr) subunits in males but reduced GabrA5 expression in female somatostatin neurons. Collectively, these findings suggest that defined CeA populations display differential ethanol sensitivity in males and females, which may play a role in sex differences in vulnerability to AUD or expression of AUD pathology.SIGNIFICANCE STATEMENT The CeA is involved in the effects of ethanol in the brain; however, the population-specific changes in CeA activity remain unclear. We used recordings of CeA neuronal activity and single-cell gene expression to examine population-specific changes in inhibitory control in male and female rats following chronic ethanol exposure and found sex- and population-specific effects of chronic ethanol exposure and withdrawal. Specifically, female CeA neurons displayed increased excitability in the somatostatin CeA population, whereas male CeA neurons displayed increased inhibitory control in both PKCd and calbindin populations and decreased excitability in the PKCd population. These findings identify CeA populations that display differential sensitivity to ethanol exposure, which may contribute to sex differences in vulnerability to alcohol use disorder.

Large sex differences in vulnerability to circulatory-system disease under current and future climate in Bucharest and its rural surroundings

Circulatory-system diseases (CSDs) are responsible for 50–60% of all deaths in Romania. Due to its continental climate, with cold winters and very warm summers, there is a strong temperature dependence of the CSD mortality. Additionally, within its capital Bucharest, the urban heat island (UHI) is expected to enhance (reduce) heat (cold)-related mortality. Using distributed lag non-linear models, we establish the relation between temperature and CSD mortality in Bucharest and its surroundings. A striking finding is the strong temperature-related response to high urban temperatures of women in comparison with men from the total CSDs mortality. In the present climate, estimates of the CSDs attributable fraction (AF) of mortality at high temperatures is about 66% higher in Bucharest than in its rural surroundings for men, while it is about 100% times higher for women. Additionally, the AF in urban areas is also significantly higher for elderly people, and for those with hypertensive and cerebrovascular diseases than in the rural surroundings. On the other hand, in rural areas, men but especially women are currently more vulnerable with respect to low temperatures than in the urban environment. In order to project future thermal-related mortality, we have used five bias-corrected climate projections from regional circulation models under two climate-change scenarios, RCP4.5 and RCP8.5. Analysis of the temperature-mortality associations for future climate reveals the strongest signal under the scenario RCP8.5 for women, elderly people as well as for groups with hypertensive and cerebrovascular diseases. The net AF increase is much larger in urban agglomeration for women (8.2 times higher than in rural surroundings) and elderly people (8.5 times higher than in rural surroundings). However, our estimates of thermal attributable mortality are most likely underestimated due to the poor representation of UHI and future demography.

Hippocampal subfields’ sex differences in EOAD

AbstractBackgroundIn healthy ageing, there is evidence of sex differences in vulnerability of hippocampal subfields to volume loss. However, this has not been investigated in early‐onset Alzheimer’s disease (<65 years; EOAD).MethodWe included 106 subjects: 62 EOAD (A+T+N+, MMSE>15) and 44 healthy controls (HC; A‐T‐N‐) that underwent lumbar puncture for analysis of AD biomarkers, 3T‐MRI scan and neuropsychological assessment. Hippocampal subfield segmentation was performed using T1‐weighted images and Freesurfer 6.0. Volume was adjusted by intracranial volume. Adjusted linear models were used to analyze differences between EOAD and HC and differences between sexes. We calculated Cohen’s d as a measure of the effect size of volume change by sex, restricted to volume differences between EOAD and HC. In EOAD, we used linear models adjusted by age and education to investigate the association of volume loss with 18 cognition z‐scores. Results were adjusted using Bonferroni correction for multiple comparisons.ResultThere were no demographic differences across groups. APOEε4 carriers were higher in EOAD‐female/EOAD‐male than HC‐female. EOAD‐female showed higher T‐Tau and P‐Tau levels than EOAD‐male (all p<0.05; Table1). Comparing EOAD vs. HC, differences were found in volume of all subfields and hippocampus (p<0.05, Bonferroni corrected), except for bilateral parasubiculum and right cornu ammonis (CA) 2/3. No differences were found between EOAD‐female and EOAD‐male (p>0.05). When compared to HC of the same sex, EOAD‐female showed differences in the same regions as the whole sample, while EOAD‐male showed differences in bilateral hippocampal tail and left presubiculum and hippocampus (all p<0.05, Bonferroni corrected, Figure 1). We observed larger effect sizes than in women in these regions, except for left hippocampus (Figure 2).In EOAD, higher volume in left CA2/3 predicted higher memory z‐scores, including free and total learning and delayed total recall (p<0.05 Bonferroni corrected; Figure 3). No associations were found in EOAD‐female nor EOAD‐male.ConclusionIn EOAD, the pattern of volume loss in hippocampal subfields was similar between sexes. However, females showed more marked differences from HC, except for bilateral hippocampal tail and left presubiculum. Further studies are necessary to elucidate the existence of sex differences in EOAD and their implication for cognitive impairment.

Psilocybin sex-dependently reduces alcohol consumption in C57BL/6J mice.

The classical psychedelic psilocybin is of interest as a treatment for alcohol use disorder (AUD). This study investigated the effects of psilocybin on voluntary ethanol consumption in adult male and female C57BL/6J mice administered saline or psilocybin intraperitoneally as a single dose of 0.1, 0.5, 1.0 or 2.0mg/kg and provided 20% ethanol utilizing a two-bottle choice alcohol drinking paradigm. Ethanol was provided continuously for 3days immediately following the administration of psilocybin, then withheld for 2days, and then provided continuously for two subsequent additional days. A multilevel model (MLM) for repeated measures was used to compare ethanol consumption and preference in psilocybin-treated groups versus controls. Ethanol consumption and preference were reduced in male mice during the 3-day interval that immediately followed psilocybin administration. The effect of psilocybin on ethanol consumption was dose-related and was consistent across the 3-day interval at dosages of 0.5mg/kg or greater. Psilocybin had no effect on consumption or preference when ethanol was subsequently reintroduced after 2days of withdrawal. In contrast to males, psilocybin had no significant effect on ethanol consumption or preference in female mice at any dosage or time point. The lack of an effect of psilocybin on quinine preference, and its limited interaction with locomotor activity indicated that the observed reduction in voluntary ethanol consumption was not attributable to altered taste perception or motor effects. Total fluid consumption was increased in males at some time points and psilocybin dosages and unchanged in females, and the absence of any decrease in either group at any time point indicated that the observed reduction in ethanol consumption was not mediated by nonspecific effects on consummatory behavior. The finding of a sex-dependent effect of psilocybin on ethanol consumption suggests that the C57BL/6J mouse may provide a useful experimental approach to modeling sex differences in vulnerability to AUD in addition to investigation of the neurobiological basis of the effect of classical psychedelics on alcohol drinking behavior.

Predictors of psychological and physiological measures of graduate student health during COVID-19

IntroductionThe COVID-19 pandemic brought on higher-than-normal levels of anxiety and depression, especially among graduate students whose academic trajectory was disrupted. However, not all graduate students were affected and therefore, it is important to identify potential protective factors.MethodWe recruited 61 graduate students whose research was directly impacted by the pandemic and examined their change in academic stressors since the onset of the pandemic. Hierarchical regression analyses were used to evaluate how perceived academic stressors brought on by the COVID-19 pandemic impacted anxiety, depression, and heart rate variability (HRV), and whether physical activity and trait resiliency independently buffered against the effects of stress.ResultsGraduate students who reported greater changes in academic stressors since the onset for the pandemic were more anxious and depressed. Moderate-intensity physical activity explained significant variance in anxiety whereas resiliency explained significant variance in both anxiety and depression. HRV was higher in males than females, aligning with sex differences in vulnerability to stress and mental illness.ConclusionOverall, the results suggest that resiliency and physical activity may offer unique protection against symptoms of anxiety and depression in graduate students experiencing increased academic stress during COVID-19. Institutions of higher education should consider investing in programs that encourage physical activity and promote resiliency by teaching mindfulness, stress management, and cognitive behavioral approaches.

Impact of chronic exposure to 5-alpha reductase inhibitors on the risk of hospitalization for COVID-19: a case-control study in male population from two COVID-19 regional centers of Lombardy, Italy.

There are sex differences in vulnerability to Coronavirus disease 2019 (COVID-19). The coronavirus S protein mediates viral entry into target cells employing the host cellular serine protease TMPRSS2 for S-protein priming. The TMPRSS2 gene expression is responsive to androgen stimulation and it could partially explain sex differences. We hypothesized that men chronically exposed to 5-alpha reductase inhibitors (5ARIs) for benign prostate hyperplasia (BPH) have a lower risk of hospitalization for COVID-19. This is a population-based case-control study on consecutive patients positive for SARS-CoV-2 virus who required hospitalization for COVID-19 (cases), age-matched to beneficiaries of the Lombardy Regional Health Service (controls). Data were collected by two high-volume COVID-19 regional centers of Lombardy (Italy). The primary outcome was to compare the prevalence of patients chronically exposed to 5ARIs, who required hospitalization for COVID-19, with the one of controls. Overall, 943 males were enrolled; 45 (4.77%) were exposed to 5ARI. COVID-19 patients aged >55 years under 5ARI treatment were significantly less than expected on the basis of the prevalence of 5ARI treatment among age-matched controls (5.57 vs. 8.14%; P=0.0083, 95% CI: 0.75-3.97%). This disproportion was higher for men aged >65 (7.14 vs. 12.31%; P=0.0001, 95% CI: 2.83-6.97%). Eighteen 5ARIs-patients died; the mean age of men who died was higher than those who did not: 75.98±9.29 vs. 64.78±13.57 (P<0.001). Cox-regression and multivariable models did not show correlation between 5ARIs exposure and protection against intensive care unit admission/death. Men exposed to 5ARIs might be less vulnerable to severe COVID-19, supporting its use in disease prophylaxis.

Effect of treadmill exercise on serum corticosterone, serum and hippocampal BDNF, hippocampal apoptosis and anxiety behavior in an ovariectomized rat model of post-traumatic stress disorder (PTSD)

There is a sex difference in vulnerability to PTSD and in response to therapeutic interventions. Since relation between gonadal hormones and PTSD has been revealed, this study aimed to understand the severity of PTSD-induced impairments after ovarian hormone deficiency and the influence of exercise on PTSD accompanied by ovarian hormone deficiency. Female adult Wistar rats were subjected to ovariectomy, PTSD, or combination ovariectomy plus PTSD. Twenty days after ovariectomy, PTSD was induced by single prolonged stress (SPS) model. The exercise started 14 days after SPS and continued for 4 weeks. Thirty minutes moderate treadmill exercise was planned for 5 days per week. On day 65, after assessing rats using the elevated plus-maze (EPM) test, corticosterone, BDNF, and apoptotic markers were tested. p < 0.05 was considered as significant level. The results showed that ovariectomy worsened the effect of SPS on hippocampal BDNF and led to greater increase in serum corticosterone and hippocampal caspase 3 and BAX in SPS rats. Also, ovariectomy exacerbated anxiety-like behavior in SPS rats. Exercise improved the alterations of hippocampal BDNF, corticosterone, caspase 3, and BAX in SPS ovariectomized rats. However, exercise had no statistically significant effect on anxiety-like behavior in this group. According to the results, exercise is effective to attenuate SPS-induced impairments in molecular and cellular responses even when the condition becomes more complicated due to ovarian hormone deficiency. However, exercise alone cannot help to improve behavior impairments in PTSD combined with an ovarian hormone deficiency. Therefore, exercise could likely be considered as a complementary intervention to strengthen other treatments.

Acute heart failure: a mechanism underscoring sex differences in outcomes following acute coronary syndromes

Abstract Background It remains uncertain whether female sex is itself a strong risk factor for worse outcomes in acute coronary syndromes (ACS). Purpose We hypothesized that sex differences in vulnerability to heart failure after ACS may modify the association between sex and outcomes. Methods Data were drawn from the ISACS-Archives network of registries. The study population consisted of 87,812 patients with known time from symptom onset to hospital presentation. Participants were stratified by ACS subtypes: STEMI and NSTE-ACS Data on presenting heart failure symptoms were collected from medical record abstraction. Heart failure was categorized as Killip class &amp;gt;2. Time from symptom onset to hospital presentation was categorized as early (≤120 minutes) or late (&amp;gt;120 minutes). Primary outcome measure was 30-day mortality. Estimates were performed using a parametric balancing strategy by weighting and compared by test of interaction on the log scale. Results Among the study sample, 30922 (35.2%) patients were women. Patient outcomes varied according to subtype of ACS. The mortality rates at 30-days were significantly higher among women vs men in STEMI (RR:1.65; 95% CI: 1.56–1.73) compared with NSTE-ACS (RR:1.18; 95% CI: 1.09–1.28; P interaction &amp;lt;0.0001). Similarly, the women vs men RR of heart failure was higher in STEMI (RR: 1.24; 95% CI: 1.20–1.29) compared with NSTE-ACS (RR:1.02; 95% CI: 0.97–1.08; P interaction &amp;lt;0.0001). Sex difference in heart failure rates with STEMI presentation were independent (P&amp;lt;0.0001) of early (34.3% in women vs 24.2% in men) or late (35.5% in women vs 30.7% in men) hospital presentation. The same finding was not seen in NSTE-ACS patients. Overall, women presenting with heart failure was had higher 30-day mortality than did their male counterparts with heart failure (29.8% vs 25.5%; RR: 1.24; 95% CI: 1.17–1.31). Conclusions Women exhibit substantially more vulnerability to heart failure in STEMI than men: a greater percentage of women have heart failure, and women with heart failure have higher 30-day mortality than men with heart failure. This finding was not seen in NSTE-ACS. heart failure on initial assessment is a key feature to explain the sex gap in mortality after ACS. Funding Acknowledgement Type of funding sources: None.

Placental Expression of ACE2 and TMPRSS2 in Maternal Severe Acute Respiratory Syndrome Coronavirus 2 Infection: Are Placental Defenses Mediated by Fetal Sex?

BackgroundExpression of angiotensin-converting enzyme 2 (ACE2) and type II transmembrane serine protease (TMPRSS2), host molecules required for viral entry, may underlie sex differences in vulnerability to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We investigated whether placental ACE2 and TMPRSS2 expression vary by fetal sex in the presence of maternal SARS-CoV-2 infection.MethodsPlacental ACE2 and TMPRSS2 expression was quantified by quantitative reverse transcription polymerase chain reaction (RT-PCR) and by Western blot in 68 pregnant women (38 SARS-CoV-2 positive, 30 SARS-CoV-2 negative) delivering at Mass General Brigham from April to June 2020. The impact of fetal sex and maternal SARS-CoV-2 exposure on ACE2 and TMPRSS2 was analyzed by 2-way analysis of variance (ANOVA).ResultsMaternal SARS-CoV-2 infection impacted placental TMPRSS2 expression in a sexually dimorphic fashion (2-way ANOVA interaction, P = .002). We observed no impact of fetal sex or maternal SARS-CoV-2 status on ACE2. TMPRSS2 expression was significantly correlated with ACE2 expression in males (Spearman ρ = 0.54, P = .02) but not females (ρ = 0.23, P = .34) exposed to maternal SARS-CoV-2.ConclusionsSex differences in placental TMPRSS2 but not ACE2 were observed in the setting of maternal SARS-CoV-2 infection, which may have implications for offspring vulnerability to placental infection.

Delay Discounting of Cocaine‐Food Choice in Socially Housed Female and Male Cynomolgus Macaques

At present, there are no FDA-approved pharmacological treatments for cocaine use disorders (CUD). Because there is evidence of sex differences in vulnerability to cocaine abuse (O’Brien and Anthony, 2005) and treatment outcomes (Sugarman et al., 2017), research needs to include both sexes in evaluating treatment strategies. Weafer and de Wit (2014) have suggested that impulsivity is a stronger predictor of drug abuse in females compared to males and lack of inhibitory control may be a mechanism mediating the faster progression of drug use in women compared to men. The overarching goal of the present research is to utilize a “personalized medicine” approach to evaluating the role of environmental and pharmacological interventions on the reinforcing effects of cocaine. In this study, socially housed female (N=5) and male (N=6) cynomolgus monkeys, each implanted with an indwelling intravenous catheter and self-administering cocaine (0.01-0.1 mg/kg/injection) under a concurrent schedule with food (1.0-g banana-flavored pellets) as the alternative, served as subjects. Under these conditions, the frequency of cocaine choice increases in a dose-dependent manner, from <20% choice when 0.01 mg/kg/injection cocaine was available as an alternative to food, to >80% choice when 0.1 mg/kg/injection was the alternative to food; in this preliminary study, no sex or social rank differences were noted. Next, environmental manipulations were studied at both ends of the cocaine dose-response curve in order to assess whether there were sex differences in sensitivity to the reinforcing effects of cocaine. To study impulsivity, we used a delay discounting procedure similar to that described by Woolverton and colleagues (Huskinson et al., 2015, 2016). Differences in sensitivity to changes in cocaine preference when the preferred cocaine dose was available would provide information as to potential sex differences in the reinforcing strength of cocaine. In contrast, when low, non-preferred, cocaine doses were studied and food reinforcement was delayed, sex differences would provide information related to sensitivity of adverse environmental changes on vulnerability to cocaine abuse. In preliminary findings, when delays were imposed on high-dose cocaine, the indifference points (IP; 50% choice between cocaine and food) were not different between males and females (168.88 ± 75.6 seconds vs. 154.94 ± 39.1 seconds, respectively). However, when low-dose cocaine was available and food reinforcement was delayed, males were more sensitive to changes in the environment, as represented by lower IP values (46.74 ± 16.8 seconds vs. 114.39 ± 44.9 seconds, respectively). Studies are currently underway to determine if pharmacological manipulations, with and without delays, would provide additional reductions in cocaine choice, at both ends of the cocaine dose-response curve. An interesting behavioral pharmacology study would involve examine drug effects under conditions in which delayed high-dose cocaine and food-delayed low-dose cocaine produce similar behaviors (i.e., % cocaine choice).

Relationship between cognitive performance and social rank in male and female cynomolgus macaques: Implications for the role of cognition in vulnerability to cocaine use disorder

Cocaine use disorder (CUD) currently has no FDA-approved pharmacological treatment. One of the most promising behavioral interventions is cognitive behavioral therapy. Still, there is a continuing need to understanding what makes an individual susceptible to CUD. A major goal of this study is to determine if cognitive performance can serve as a behavioral biomarker related to vulnerability to cocaine abuse. Previous studies have shown sex differences in vulnerability to cocaine based on social rank (Morgan et al., 2002; Nader et al., 2012). The goal of the present study is to evaluate cognitive performance as a potential biomarker for vulnerability to cocaine abuse, in socially housed cocaine-naïve female and male monkeys. In an earlier study involving newly formed social groups of female monkeys, performance on one cognitive domain, working memory using a delayed-match-to-sample task, showed social rank differences only during establishment of the social hierarchy; once the hierarchies were stable, there were no differences in working memory across social ranks (Kromrey et al., 2016). The present study differs from our earlier work by studying several cognitive domains in well-established, same-sex, male and female social groups (N=8/sex). Monkeys were trained to complete a battery of cognitive tasks which evaluated learning and memory (stimulus discrimination; SD and compound discrimination; CD), executive function (reversal learning; SDR) and behavioral flexibility (interdimensional shifting; ID, extradimensional shifting; and reversal, ED, EDR). The test battery consisted of monkeys performing all tasks (SD/SDR, CD, ID, ED/EDR) in 1-3 sessions; criteria for moving to the next task was 12/15 trials correct. All studies were performed in accordance with the FASEB Statement of Principles for the Use of Vertebrate Animals in Research and Education and Wake Forest's IACUC. We hypothesized that because earlier work had shown subordinate males and dominant females were more vulnerable to cocaine reinforcement, that they would show poorer cognitive performance relative to dominant males and subordinate females. In preliminary findings, dominant male and female monkeys made fewer total errors and required less trials to complete the battery compared with subordinate animals, in contrast to our hypothesis. Next, acquisition of cocaine reinforcement will be examined in an effort to replicate earlier findings and then the test battery will be repeated at various timepoints in order to evaluate the effects of cocaine on cognitive performance as a function of sex and social rank.

A buprenorphine-validated rat model of opioid use disorder optimized to study sex differences in vulnerability to relapse.

RationaleOpioid use disorder (OUD) is a major epidemic in the USA. Despite evidence indicating that OUD may be particularly severe for women, preclinical models have yet to establish sex as a major factor in OUD.ObjectivesHere, we examined sex differences in vulnerability to relapse following intermittent access fentanyl self-administration and protracted abstinence and used buprenorphine, the FDA-approved treatment for OUD, to test the validity of our model.MethodsFollowing acquisition of fentanyl self-administration under one of two training conditions, male and female rats were given extended, 24-h/day access to fentanyl (0.25 μg/kg/infusion, 10 days) using an intermittent access procedure. Vulnerability to relapse was assessed using an extinction/cue-induced reinstatement procedure following 14 days of abstinence; buprenorphine (0 or 3 mg/kg/day) was administered throughout abstinence.ResultsLevels of drug-seeking were high following extended-access fentanyl self-administration and abstinence; buprenorphine markedly decreased drug-seeking supporting the validity of our relapse model. Females self-administered more fentanyl and responded at higher levels during subsequent extinction testing. Buprenorphine was effective in both sexes and eliminated sex and estrous phase differences in drug-seeking. Interestingly, the inclusion of a time-out during training had a major impact on later fentanyl self-administration in females, but not males, indicating that the initial exposure conditions can persistently impact vulnerability in females.ConclusionsThese findings demonstrate the utility of this rat model for determining sex and hormonal influences on the development and treatment of OUD.

Astroglial cells as neuroendocrine targets in forebrain development: Implications for sex differences in psychiatric disease

Astroglial cells are the most abundant cell type in the mammalian brain. They are implicated in almost every aspect of brain physiology, including maintaining homeostasis, building and maintaining the blood brain barrier, and the development and maturation of neuronal networks. Critically, astroglia also express receptors for gonadal sex hormones, respond rapidly to gonadal hormones, and are able to synthesize hormones. Thus, they are positioned to guide and mediate sexual differentiation of the brain, particularly neuronal networks in typical and pathological conditions. In this review, we describe astroglial involvement in the organization and development of the brain, and consider known sex differences in astroglial responses to understand how astroglial cell-mediated organization may play a role in forebrain sexual dimorphisms in human populations. Finally, we consider how sexually dimorphic astroglial responses and functions in development may lead to sex differences in vulnerability for neuropsychiatric disorders.

Sex differences in the associations between maternal prenatal distress and infant cortisol reactivity and recovery

Previous research suggests that maternal prenatal psychological distress (PPD) is related to altered cortisol reactivity in the exposed child. There are indications for the sex differences in vulnerability for prenatal adversities that depend on the exposure and child outcome. Still, it is not known whether the association between maternal PPD and infant cortisol stress response is moderated by sex. In addition, the recovery phase of the cortisol stress response has not been given as much attention as reactivity. Our aim was to study the sex differences in the associations between self-reported maternal prenatal depressive-, anxiety- and pregnancy-related anxiety symptoms through gestational weeks 14, 24 and 34 and the saliva cortisol reactivity to and recovery from the acute stress among 10-week-old infants. The study population comprised of 363 mother-infant pairs from the FinnBrain Birth Cohort Study. We found evidence for sex-dependent associations between PPD exposure and infant cortisol response. A less steep recovery slope (-10 % per one SD increase in PPD [95 % CI = -18 to -2 %] and -8 % [-16 to 0 %] depending on the exposure) and a possibly less steep reactivity slope (-14 % [95 % CI = -25 to 0 %] and -10 % [-21 to 3 %]) were associated with higher PPD exposure in females. Of the PPD measures, the strongly intercorrelated, and thus combined, depressive and anxiety symptom score provided the most robust prediction of infant cortisol recovery. Our results demonstrate sexually dimorphic alterations in the functioning of the infant hypothalamus-pituitary-adrenal axis and especially in the functioning of the negative feedback loop of the axis after prenatal PPD exposure among healthy babies.

Sex Differences in Proatherogenic Cytokine Levels.

Background: It has been shown that sex affects immunity, including cytokine production. Given that atherosclerosis is an inflammatory disease promoted by specific cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, we aimed at evaluating whether sex could affect the levels of these proatherogenic cytokines in a group of healthy adults. In this analysis, we also included other cytokines and peptides that have been implicated in atherosclerosis development and progression. Methods: A total of 104 healthy adults were recruited; we measured circulating levels of IL-1β, IL-6, TNF-α, angiotensins and angiotensin-converting enzyme-2 (ACE2), as well as osteoprotegerin and receptor activator of nuclear factor κB ligand (RANKL). Results: IL-1β, IL-6, and TNF-α were significantly higher in men as compared to women. They were all associated with testosterone and the testosterone/estradiol ratio. They remained significantly associated with sex (but not with hormones) after being tested for potential confounders. Conclusions: Sex seems to influence the levels of proatherogenic cytokines. This is consistent not only with sex differences in vulnerability to infections but also with the higher cardiovascular risk exhibited by the male gender as compared to the female gender. Nevertheless, this association is only partly explained by hormone levels.

Alterations of neural network organization during REM sleep in women: implication for sex differences in vulnerability to mood disorders

BackgroundSleep plays an important role in vulnerability to mood disorders. However, despite the existence of sex differences in vulnerability to mood disorders, no study has yet investigated the sex effect on sleep network organization and its potential involvement in vulnerability to mood disorders. The aim of our study was to empirically investigate the sex effect on network organization during REM and slow-wave sleep using the effective connectivity measured by Granger causality.MethodsPolysomnographic data from 44 healthy individuals (28 men and 16 women) recruited prospectively were analysed. To obtain the 19 × 19 connectivity matrix of all possible pairwise combinations of electrodes by Granger causality method from our EEG data, we used the Toolbox MVGC multivariate Granger causality. The computation of the network measures was realized by importing these connectivity matrices into EEGNET Toolbox.ResultsIn men and women, all small-world coefficients obtained are compatible with a small-world network organization during REM and slow-wave sleep. However, compared to men, women present greater small-world coefficients during REM sleep as well as for all EEG bands during this sleep stage, which indicates the presence of a small-world network organization less marked during REM sleep as well as for all EEG bands during this sleep stage in women. In addition, in women, these small-world coefficients during REM sleep as well as for all EEG bands during this sleep stage are positively correlated with the presence of subclinical symptoms of depression.ConclusionsThus, the highlighting of these sex differences in network organization during REM sleep indicates the presence of differences in the global and local processing of information during sleep between women and men. In addition, this small-world network organization less marked during REM sleep appears to be a marker of vulnerability to mood disorders specific to women, which opens up new perspectives in understanding sex differences in the occurrence of mood disorders.