Considering sex as a biological variable in preclinical research

Effects of Six Sequential Charged Particle Beams on Behavioral and Cognitive Performance in B6D2F1 Female and Male Mice

The radiation environment astronauts are exposed to in deep space includes galactic cosmic radiation (GCR) with different proportions of all naturally occurring ions. To assist NASA with assessment of risk to the brain following exposure to a mixture of ions broadly representative of the GCR, we assessed the behavioral and cognitive performance of female and male C57BL/6J × DBA2/J F1 (B6D2F1) mice two months following rapidly delivered, sequential 6 beam irradiation with protons (1 GeV, LET = 0.24 keV, 50%), 4He ions (250 MeV/n, LET = 1.6 keV/μm, 20%), 16O ions (250 MeV/n, LET = 25 keV/μm 7.5%), 28Si ions (263 MeV/n, LET = 78 keV/μm, 7.5%), 48Ti ions (1 GeV/n, LET = 107 keV/μm, 7.5%), and 56Fe ions (1 GeV/n, LET = 151 keV/μm, 7.5%) at 0, 25, 50, or 200 cGy) at 4-6 months of age. When the activity over 3 days of open field habituation was analyzed in female mice, those irradiated with 50 cGy moved less and spent less time in the center than sham-irradiated mice. Sham-irradiated female mice and those irradiated with 25 cGy showed object recognition. However, female mice exposed to 50 or 200 cGy did not show object recognition. When fear memory was assessed in passive avoidance tests, sham-irradiated mice and mice irradiated with 25 cGy showed memory retention while mice exposed to 50 or 200 cGy did not. The effects of radiation passive avoidance memory retention were not sex-dependent. There was no effect of radiation on depressive-like behavior in the forced swim test. There was a trend toward an effect of radiation on BDNF levels in the cortex of males, but not for females, with higher levels in male mice irradiated with 50 cGy than sham-irradiated. Finally, sequential 6-ion irradiation impacted the composition of the gut microbiome in a sex-dependent fashion. Taxa were uncovered whose relative abundance in the gut was associated with the radiation dose received. Thus, exposure to sequential six-beam irradiation significantly affects behavioral and cognitive performance and the gut microbiome.

Antidepressant and anti-amnesic effects of the aqueous lyophilisate of the leaves of Leptadenia arborea on an animal model of cognitive deficit associated depression

Leptadenia arborea (Asclepiadaceae) is a plant used in traditional medicine to treat syphilis, migraine, and mental illnesses. The aim of our study was to investigate possible antidepressant and anti-amnesic effects of the aqueous lyophilisate of the leaves of Leptadenia arborea in an animal model of cognitive deficit associated depression. Swiss albino adult mice of both sexes were used for this study. A 14-day combined stress model was used to induce depression with early cognitive deficits. The forced swimming test, the open field test and plasma corticosterone level were used to assess antidepressant-like effect. The novel object recognition task (NORT), the Morris Water Maze (MWM) and neurochemical analysis of hippocampal acetylcholinesterase activity was also carried out to assess memory integrity. The aqueous lyophelisate of L. arborea increased swimming time and decreased immobility time in the forced swimming test. In the open field test they was no difference in the number of lines crossed between groups, and the lyophilisate-treated mice spent more time in the centre compared to the control. The lyophilisate decreased the plasma level of corticosterone compared to the control. The lyophilisate decreased the latency to reach the hidden platform and increased the time spent in the target quadrant in the MWM. The lyophilisate also increased the time of exploration of the novel object in the NORT and decreased the acetylcholinesterase activity in the hippocampus. L. arborea effects were decreased when it was co-administered with pCPA. Results suggest that the aqueous lyophilisate of the leaves of L. arborea possess antidepressant-like and anti-amnesic effects.

Reporting of sex as a variable in cardiovascular studies using cultured cells: A systematic review

Reporting the sex of biological material is critical for transparency and reproducibility in science. This study examined the reporting of the sex of cells used in cardiovascular studies. Articles from 16 cardiovascular journals that publish peer-reviewed studies in cardiovascular physiology and pharmacology in the year 2018 were systematically reviewed using terms "cultured" and "cells." Data were collected on the sex of cells, the species from which the cells were isolated, and the type of cells, and summarized as a systematic review. Sex was reported in 88 (38.6%) of the 228 studies meeting inclusion criteria. Reporting rates varied with Circulation, Cardiovascular Research and American Journal of Physiology: Heart and Circulatory Physiology having the highest rates of sex reporting (>50%). A majority of the studies used cells from male (54.5%) or both male and female animals (32.9%). Humans (31.8%), rats (20.4%), and mice (43.8%) were the most common sources for cells. Cardiac myocytes were the most commonly used cell type (37.0%). Overall reporting of sex of experimental material remains below 50% and is inconsistent among journals. Sex chromosomes in cells have the potential to affect protein expression and molecular signaling pathways and should be consistently reported.

Increased P3HB Accumulation Capacity of Methylorubrum sp. in Response to Discontinuous Methanol Addition

An alternative for non-biodegradable oil-based plastics has been the focus of many researchers throughout the years. Polyhydroxyalkanoates (PHAs) are potential substitutes due to their biodegradable characteristic and diversity of monomers that allow different biopolymer compositions and physical-chemical properties suitable for a variety of applications. The most well-known biopolymer from this class, poly(3-hydroxybutyrate) (P3HB), is already produced industrially, but its final price cannot compete with the oil-based plastics. As a low-volume high-value bioproduct, P3HB must be produced through a cheap and abundant feedstock, with high productivity and a feasible purity process in order to become an economically attractive bioproduct. In this scenario, we report a methylotrophic strain isolated from an estuarine contaminated site identified as Methylorubrum sp. highly tolerant to methanol and with great accumulation capacity of 60% (CDW) in 48 h through a simple strategy of batch fermentation with discontinuous methanol addition that could help lower P3HB's processing costs and final price.

Sex dependent effects of post-natal penicillin on brain, behavior and immune regulation are prevented by concurrent probiotic treatment

There is increasing awareness of the need to consider potential long-term effects of antibiotics on the health of children. In addition to being associated with immune and metabolic diseases, there is evidence that early-life antibiotic exposure can affect neurodevelopment. Here we investigated the effect of low dose of penicillin V on mice when administered for 1 week immediately prior to weaning. We demonstrated that exposure to the antibiotic during the pre-weaning period led to long-term changes in social behaviour, but not anxiety-like traits, in male mice only. The change in behaviour of males was associated with decreased hippocampal expression of AVPR1A and AVPR1B while expression of both receptors was increased in females. Spleens of male mice also showed an increase in the proportion of activated dendritic cells and a corresponding decrease in regulatory T cells with penicillin exposure. All changes in brain, behaviour and immune cell populations, associated with penicillin exposure, were absent in mice that received L. rhamnosus JB-1 supplementation concurrent with the antibiotic. Our study indicates that post-natal exposure to a clinically relevant dose of antibiotic has long-term, sex dependent effects on the CNS and may have implications for the development of neuropsychiatric disorders. Importantly, we also provide further evidence that probiotic based strategies may be of use in counteracting detrimental effects of early-life antibiotics on neurodevelopment.

Sex differences in the relationship between dietary pattern adherence and cognitive function among older adults: findings from the NuAge study

BACKGROUND

Consumption of a prudent dietary pattern rich in healthy nutrients is associated with enhanced cognitive performance in older adulthood, while a Western dietary pattern low in healthy nutrients is associated with poor age-related cognitive function. Sex differences exist in dietary intake among older adults; however, there is a paucity of research examining the relationship between sex-specific dietary patterns and cognitive function in later life.

METHODS

The current study aimed to investigate sex differences in the relationship between sex-specific dietary pattern adherence and global cognitive function at baseline and over a 3-year follow-up in 1268 community-dwelling older adults (M_age = 74 years, n = 664 women, n = 612 men) from the Quebec Longitudinal Study on Nutrition and Successful Aging (NuAge). A 78-item Food Frequency Questionnaire was used to estimate dietary intake over the previous year. Sex-specific dietary pattern scores were derived using principal component analysis. Global cognition was assessed using the Modified Mini-Mental State Examination (3MS).

RESULTS

Adjusted linear mixed effects models indicated that a healthy, prudent dietary pattern was not associated with baseline cognitive performance in men or women. No relationship was found between Western dietary pattern adherence and baseline cognitive function in women. Among men, adherence to an unhealthy, Western dietary pattern was associated with poorer baseline cognitive function (β = - 0.652, p = 0.02, 95% CI [- 1.22, - 0.65]). No association was found between prudent or Western dietary patterns and cognitive change over time in men or women.

CONCLUSIONS

These findings highlight the importance of conducting sex-based analyses in aging research and suggest that the relationship between dietary pattern adherence and cognitive function in late life may be sex-dependent.

A 10-year follow-up study of sex inclusion in the biological sciences

In 2016, to address the historical overrepresentation of male subjects in biomedical research, the US National Institutes of Health implemented a policy requiring investigators to consider sex as a biological variable. In order to assess the impact of this policy, we conducted a bibliometric analysis across nine biological disciplines for papers published in 34 journals in 2019, and compared our results with those of a similar study carried out by Beery and Zucker in 2009. There was a significant increase in the proportion of studies that included both sexes across all nine disciplines, but in eight of the disciplines there was no change in the proportion studies that included data analyzed by sex. The majority of studies failed to provide rationale for single-sex studies or the lack of sex-based analyses, and those that did relied on misconceptions surrounding the hormonal variability of females. Together, these data demonstrate that while sex-inclusive research practices are more commonplace, there are still gaps in analyses and reporting of data by sex in many biological disciplines.

Reproducibility of animal research in light of biological variation

Context-dependent biological variation presents a unique challenge to the reproducibility of results in experimental animal research, because organisms' responses to experimental treatments can vary with both genotype and environmental conditions. In March 2019, experts in animal biology, experimental design and statistics convened in Blonay, Switzerland, to discuss strategies addressing this challenge. In contrast to the current gold standard of rigorous standardization in experimental animal research, we recommend the use of systematic heterogenization of study samples and conditions by actively incorporating biological variation into study design through diversifying study samples and conditions. Here we provide the scientific rationale for this approach in the hope that researchers, regulators, funders and editors can embrace this paradigm shift. We also present a road map towards better practices in view of improving the reproducibility of animal research.

Collateral Development and Arteriogenesis in Hindlimbs of Swine After Ligation of Arterial Inflow

BACKGROUND

Development of collateral vasculature is key in compensating for arterial occlusions in patients with peripheral artery disease (PAD). We aimed to examine the development of collateral pathways after ligation of native vessels in a porcine model of PAD.

METHODS

Right hindlimb ischemia was induced in domestic swine (n = 11) using two versions of arterial ligation. Version 1 (n = 6) consisted of ligation with division of the right external iliac, profunda femoral, and superficial femoral arteries. Version 2 (n = 5) consisted of the ligation of version 1 with additional ligation with division of the right internal iliac artery. Development of collateral pathways was evaluated with standard angiography before arterial ligation and at termination (30 days later). Relative luminal diameter of the arteries supplying the ischemic right hind limb were determined by two-dimensional angiography.

RESULTS

The dominant collateral pathway that developed after version 1 ligation connected the right internal iliac artery to the right profunda femoral and then to the right superficial femoral and popliteal artery. Mean luminal diameter of the right internal iliac artery at termination increased by 38% compared with baseline. Two codominant collateral pathways developed in version 2 ligation: (i) from the left profunda femoral artery to the reconstituted right profunda femoral artery and (ii) from the common internal iliac trunk and the left internal iliac artery to the reconstituted right internal iliac artery, which then supplied the right profunda femoral and then the right superficial femoral and popliteal artery. The mean diameter of the left profunda and the left internal iliac artery increased at termination by 26% and 21%, respectively (P < 0.05).

CONCLUSIONS

Two versions of hindlimb ischemia induction (right ilio-femoral artery ligation with and without right internal iliac artery ligation) in swine produced differing collateral pathways, along with changes to the diameter of the inflow vessels (i.e., arteriogenesis).

Pregnancy, postpartum and parity: Resilience and vulnerability in brain health and disease

Risk and resilience in brain health and disease can be influenced by a variety of factors. While there is a growing appreciation to consider sex as one of these factors, far less attention has been paid to sex-specific variables that may differentially impact females such as pregnancy and reproductive history. In this review, we focus on nervous system disorders which show a female bias and for which there is data from basic research and clinical studies pointing to modification in disease risk and progression during pregnancy, postpartum and/or as a result of parity: multiple sclerosis (MS), depression, stroke, and Alzheimer's disease (AD). In doing so, we join others (Shors, 2016; Galea et al., 2018a) in aiming to illustrate the importance of looking beyond sex in neuroscience research.

Sex bias and omission in neuroscience research is influenced by research model and journal, but not reported NIH funding

Neuroscience research has historically demonstrated sex bias that favors male over female research subjects, as well as sex omission, which is the lack of reporting sex. Here we analyzed the status of sex bias and omission in neuroscience research published across six different journals in 2017. Regarding sex omission, 16% of articles did not report sex. Regarding sex bias, 52% of neuroscience articles reported using both males and females, albeit only 15% of articles using both males and females reported assessing sex as an experimental variable. Overrepresentation of the sole use of males compared to females persisted (26% versus 5%, respectively). Sex bias and omission differed across research models, but not by reported NIH funding status. Sex omission differed across journals. These findings represent the latest information regarding the complex status of sex in neuroscience research and illustrate the continued need for thoughtful and informed action to enhance scientific discovery.

Reference Intervals for and the Effects of Sample Handling and Sex on Rotational Thromboelastometry in Healthy Adult Pigs

Accurate assessment of coagulation in porcine studies is essential. We sought to establish normal values for porcine rotational thromboelastometry (ROTEM) according to the American Society for Veterinary Clinical Pathology guidelines and to assess the effects of various preanalytical parameters on those measurements. Healthy Yorkshire-cross pigs (n = 81; 46 males and 35 females) were anesthetized. By using a 18-gauge needle attached to a vacuum phlebotomy tube, blood was acquired from the cranial vena cava. Tubes were filled in the following order: evacuation clot tube, EDTA tube, heparin tube, and 2 citrate tubes. The citrate tubes were randomly assigned to 30 min with or without constant agitation on a rocker. The following parameters were reported according to the manufacturer's recommendations: clotting time, clot formation time, α, (tangent to the clot formation curve when the clot firmness is 20 mm), clot firmness after 10 and 20 min, maximal clot firmness, maximum lysis, and lysis indexes at 30 and 45 min. Reference intervals were reported as mean ± 2 SD (parametric distribution) or 2.5th and 97.5th percentile of the population's results (nonparametric distribution). The effects of sex, sampling order, and agitation on ROTEM results were analyzed through linear regression. Neither sex nor sample agitation influenced any of the ROTEM parameters. Combined reference intervals were established for each ROTEM parameter by pooling data from the nonagitated tubes for both male and female pigs. This study is the first to establish ROTEM reference intervals from a large number of male and female adult Yorkshire-cross pigs and to provide a detailed description of preanalytical sample processing.

Synthesizing Views to Understand Sex Differences in Response to Early Life Adversity

Sex as a biological variable (SABV) is critical for understanding the broad range of physiological, neurobiological, and behavioral consequences of early life adversity(ELA). The study of the interaction of SABV and ELA ties into several current debates, including the importance of taking into account SABV in research, differing strategies employed by males and females in response to adversity, and the possible evolutionary and developmental mechanisms of altered development in response to adversity. This review highlights the importance of studying both sexes, of understanding sex differences (and similarities) in response to ELA, and provides a context for the debate surrounding whether the response to ELA may be an adaptive process.

The radiotherapy cancer patient: female inclusive, but male dominated

Background: The sex-neutral language used in preclinical and clinical research intends to be inclusive of both the female and the male population, but the practice of data pooling prevents the detection of the impact of sex on cancer biology and response to medications and treatment. This study aimed to examine the consideration of sex as biological variable in the evaluation of radiation therapy in preclinical and clinical studies.Methods: Preclinical and clinical studies published over a 12-month period were reviewed for the reporting of cells, animal or patient sex and the inclusion of sex as a biological variable in both study design and data analysis.Results: A total of 321 articles met the inclusion criteria: 41 (13%) preclinical and 280 (87%) clinical studies. Two articles reported separate outcome data for males and females. Where the sex of participants was stated (230/280 (82%), 81% reported a larger number of male participants, compared to females. Less than half (45%) of studies used sex as a variable in data analysis. Sex disparity was not dependent on study location but may be more prominent in certain cancer sites. In preclinical studies, sex was at best stated in those reporting on animals (48% of studies).Conclusion: Referring to a radiotherapy cancer patient, the literature is female inclusive, but a gap does exist when it comes to consideration of sex in data analysis. The pooled analysis of female and male data could introduce statistical biases and prevent the identification of key sex-specific biological subtilities that do affect radiation responses.

Widespread sex dimorphism in aging and age-related diseases

Although aging is a conserved phenomenon across evolutionary distant species, aspects of the aging process have been found to differ between males and females of the same species. Indeed, observations across mammalian studies have revealed the existence of longevity and health disparities between sexes, including in humans (i.e. with a female or male advantage). However, the underlying mechanisms for these sex differences in health and lifespan remain poorly understood, and it is unclear which aspects of this dimorphism stem from hormonal differences (i.e. predominance of estrogens vs. androgens) or from karyotypic differences (i.e. XX vs. XY sex chromosome complement). In this review, we discuss the state of the knowledge in terms of sex dimorphism in various aspects of aging and in human age-related diseases. Where the interplay between sex differences and age-related differences has not been explored fully, we present the state of the field to highlight important future research directions. We also discuss various dietary, drug or genetic interventions that were shown to improve longevity in a sex-dimorphic fashion. Finally, emerging tools and models that can be leveraged to decipher the mechanisms underlying sex differences in aging are also briefly discussed.

Safety of Human Adipose Stromal Vascular Fraction Cells Isolated with a Closed System Device in an Immunocompetent Murine Pressure Ulcer Model

Pressure ulcers (PUs) result in part due to ischemia-reperfusion injury to the skin and present frequently in elderly or quadriplegic patients with reduced mobility. Despite the high economic and societal cost of this condition, PU therapy relies primarily on preventive strategies and invasive surgical intervention. A growing body of clinical literature suggests that localized injection of adipose-derived cells can accelerate and enhance the closure of PUs. The current study systematically evaluated the safety of human adipose stromal vascular fraction (SVF) cells isolated using a closed system device when injected into a murine PU injury model. The human SVF cells were characterized by colony-forming unit-fibroblast and differentiation assays before use. Young (2 months) immunocompetent C57BL/6 mice subjected to a magnet-induced ischemia-reperfusion injury were injected subcutaneously with human SVF cells at increasing doses (0.25-2 million cells). The size of the PU was monitored over a 20-day period. Both female and male mice tolerated the concentration-dependent injection of the SVF cells without complications. While male mice trended toward more rapid wound closure rates in response to lower SVF cell concentrations (0.25-0.5 million cells), female mice responded favorably to higher SVF cell concentrations (1-2 million cells); however, outcomes did not reach statistical significance in either sex. Overall, the study demonstrates that human SVF cells prepared with a closed system device designed for use at point of care can be safely administered for PU therapy in an immunocompetent host animal model.

Sex differences in the effectiveness of buprenorphine to decrease rates of responding in rhesus monkeys

Sex differences in μ-opioid receptor (MOR) agonist-induced antinociception have been reported in nonhuman primates. The degree to which μ-opioid receptor agonist sex differences in nonhuman primates extend to other behavioral endpoints remains unknown. The present study compared the behavioral effects of three MOR ligands (fentanyl, buprenorphine, and naltrexone) that varied in efficacy to stimulate [S]-GTPγS binding (from highest to lowest: fentanyl, buprenorphine, and naltrexone) in male and female rhesus monkeys. Male (n=3) and female (n=3) monkeys were trained to respond under a fixed-ratio 10 schedule of food presentation during daily sessions consisting of multiple components. Once rates of responding were stable, cumulative dose-effect functions were determined for intramuscular fentanyl (0.00032-0.032 mg/kg), buprenorphine (0.001-1 mg/kg), and naltrexone (0.01-0.1 mg/kg). Fentanyl dose-dependently decreased rates of responding in both sexes and the corresponding ED50 values were not significantly different. Buprenorphine dose-dependently decreased rates of responding in females, but not males. Naltrexone did not significantly alter behavior in either females or males. Overall, these results suggest that the expression of sex differences in MOR pharmacology depends upon both the efficacy of the MOR ligand and the behavioral endpoint.

Safety and Efficacy of Human Adipose-Derived Stromal/Stem Cell Therapy in an Immunocompetent Murine Pressure Ulcer Model

Pressure injuries/ulcers are frequent complications in elderly, paraplegic, and quadriplegic patients, which account for considerable cost to the international health care economy and remain refractory to current treatment options. Autologous or allogeneic adult stromal/stem cells represent an alternative therapeutic approach. The current study extends prior findings by exploring the safety and efficacy of human adipose-derived stromal/stem cell (ASC) therapy in an established immunocompetent murine skin pressure ulcer model where dermal fibroblast cells (DFCs) served as a control. Human adipose tissue was processed using a closed system device designed for point-of-care use in the operating room and on file with the Food and Drug Administration. Cell characterization was performed using colony-forming unit-fibroblast, differentiation, and immunophenotypic assays in vitro. Wound healing was assessed over a 20-day period based on photomicrographs, histology, and immunohistochemistry. The isolated human ASCs displayed significantly greater colony formation relative to DFCs while both populations exhibited comparable immunophenotype and differentiation potential. Both fresh and cryopreserved human ASCs significantly accelerated and enhanced wound healing in young (2 month) mice of both sexes relative to DFC controls based on tissue architecture and CD68⁺ cell infiltration. In contrast, while injection of either fresh or cryopreserved human ASCs was safe in older mice, the fresh ASCs significantly enhanced wound closure relative to the cryopreserved ASCs. Overall, these findings support the safety and efficacy of human ASCs isolated using a closed system device designed for clinical procedures in the future treatment of pressure injuries.

Prenatal low-dose penicillin results in long-term sex-specific changes to murine behaviour, immune regulation, and gut microbiota

Growing evidence suggests that environmental disruptors of maternal microbes may have significant detrimental consequences for the developing fetus. Antibiotic exposure during early life can have long-term effects on neurodevelopment in mice and humans. Here we explore whether exposure to low-dose penicillin during only the last week of gestation in mice has long-term effects on offspring behaviour, brain, immune function, and gut microbiota. We found that this treatment had sex-specific effects in the adult mouse offspring. Female, but not male, mice demonstrated decreased anxiety-like behaviours, while male, but not female, mice had abnormal social behaviours which correlated with altered brain expression of AVPR1A, AVPR1B, and OXTR, and decreases in the balance of splenic FOXP3⁺ regulatory T cells. Prenatal penicillin exposure also led to distinct microbiota compositions that clustered differently by sex. These data suggest that exposure of pregnant mice to even a low dose of penicillin through only the last week before birth is nonetheless sufficient to induce long-term sex-specific developmental changes in both male and female offspring.

Sexual Dimorphisms in Innate Immunity and Responses to Infection in Drosophila melanogaster

The sexes show profound differences in responses to infection and the development of autoimmunity. Dimorphisms in immune responses are ubiquitous across taxa, from arthropods to vertebrates. Drosophila melanogaster shows strong sex dimorphisms in immune system responses at baseline, upon pathogenic challenge, and over aging. We have performed an exhaustive survey of peer-reviewed literature on Drosophila immunity, and present a database of publications indicating the sex(es) analyzed in each study. While we found a growing interest in the community in adult immunity and in reporting both sexes, the main body of work in this field uses only one sex, or does not stratify by sex. We synthesize evidence for sexually dimorphic responses to bacterial, viral, and fungal infections. Dimorphisms may be mediated by distinct immune compartments, and we review work on sex differences in behavioral, epithelial, cellular, and systemic (fat body-mediated) immunity. Emerging work on sexually dimorphic aging of immune tissues, immune senescence, and inflammation are examined. We consider evolutionary drivers for sex differences in immune investment, highlight the features of Drosophila biology that make it particularly amenable to studies of immune dimorphisms, and discuss areas for future exploration.

Sex as a Biological Variable: A 5-Year Progress Report and Call to Action

A little over 5 years ago, the U.S. National Institutes of Health (NIH) announced the intention to develop policies to require applicants to report plans to balance male and female cells and animals in preclinical investigations. Soon thereafter, the NIH issued a request for information from the scientific community and consulted with various stakeholders. The feedback received was considered during development of policy requiring the consideration of sex as a biological variable (SABV) in NIH-funded research on vertebrate animals and humans, which went into effect for applications due on or after January 25, 2016. We identified NIH programs related to SABV and reviewed SABV-relevant scientific literature. We find that the application of SABV throughout the research process can serve as a guiding principle to improve the value of biomedical science. The NIH is engaged in ongoing efforts to develop resources to help investigators consider SABV in their research. We also provide an update on lessons learned, highlight ways that different disciplines consider SABV, and describe the opportunities for scientific discovery that applying SABV offers. We call on NIH's various stakeholders to redouble their efforts to integrate SABV throughout the biomedical research enterprise. Sex- and gender-aware investigations are critical to the conduct of rigorous and transparent science and the advancement of personalized medicine. This kind of research achieves its greatest potential when sex and gender considerations are integrated into the biomedical research enterprise in an end-to-end manner, from basic and preclinical investigations, through translational and clinical research, to improved health care delivery.

Sex differences in neurodevelopmental abnormalities caused by early-life anaesthesia exposure: a narrative review

Exposure to anaesthetic drugs during the fetal or neonatal period induces widespread neuronal apoptosis in the brains of rodents and non-human primates. Hundreds of published preclinical studies and nearly 20 clinical studies have documented cognitive and behavioural deficits many months or years later, raising the spectre that early life anaesthesia exposure is a long-term, perhaps permanent, insult that might affect the quality of life of millions of humans. Although the phenomenon of anaesthesia-induced developmental neurotoxicity is well characterised, there are important and lingering questions pertaining to sex differences and neurodevelopmental sequelae that might occur differentially in females and males. We review the relevant literature on sex differences in the field of anaesthesia-induced developmental neurotoxicity, and present an emerging pattern of potential sex-dependent neurodevelopmental abnormalities in rodent models of human infant anaesthesia exposure.

Gender medicine: Towards a gender-specific treatment of neuropsychiatric disorders

Sex and gender are increasingly recognized as major influencing factors in disorders across all medical specialties. Even though there is ample evidence of sex and gender differences in neuropsychiatric disorders, a sex and gender-differentiated approach has not yet been sufficiently applied to diagnostics and management. Therefore, there is an urgent need to establish general recommendations and guidelines toward precision and sex/gender medicine, with regard to dosage, tolerability, interactions and side effects, sensitivity of diagnostic tests, and distinct treatment strategies. This chapter illustrates the current knowledge about sex and gender aspects in neuropsychiatric disorders, providing a base not only to assist the clinician in the handling of specific pathologic entities, but also to sensitize medical practitioners to consider sex and gender in clinical decision-making. As such, the chapter is a call to action to physicians and researchers to produce more sex- and gender-stratified evidence, leading to an acceleration of guideline development. Such novel guidelines will provide a base for medical education, of both medical students and specialists, as well as a reference point for practitioners, toward precision medicine.

Animal Models for Functional Gastrointestinal Disorders

Functional gastrointestinal disorders (FGID), such as functional dyspepsia (FD) and irritable bowel syndrome (IBS) are characterized by chronic abdominal symptoms in the absence of an organic, metabolic or systemic cause that readily explains these complaints. Their pathophysiology is still not fully elucidated and animal models have been of great value to improve the understanding of the complex biological mechanisms. Over the last decades, many animal models have been developed to further unravel FGID pathophysiology and test drug efficacy. In the first part of this review, we focus on stress-related models, starting with the different perinatal stress models, including the stress of the dam, followed by a discussion on neonatal stress such as the maternal separation model. We also describe the most commonly used stress models in adult animals which brought valuable insights on the brain-gut axis in stress-related disorders. In the second part, we focus more on models studying peripheral, i.e., gastrointestinal, mechanisms, either induced by an infection or another inflammatory trigger. In this section, we also introduce more recent models developed around food-related metabolic disorders or food hypersensitivity and allergy. Finally, we introduce models mimicking FGID as a secondary effect of medical interventions and spontaneous models sharing characteristics of GI and anxiety-related disorders. The latter are powerful models for brain-gut axis dysfunction and bring new insights about FGID and their comorbidities such as anxiety and depression.

Modulation of the NOP receptor signaling affects resilience to acute stress

BACKGROUND

The peptide nociceptin/orphanin FQ (N/OFQ) and its receptor (NOP) are implicated in the modulation of emotional states. Previous human and rodent findings support NOP antagonists as antidepressants. However, the role played by the N/OFQ-NOP receptor system in resilience to stress is unclear.

AIMS

The present study investigated the effects of activation or blockade of NOP receptor signaling before exposure to acute stress.

METHODS

The behavioral effects of the administration before stress of the NOP agonists Ro 65-6570 (0.01-1 mg/kg) and MCOPPB (0.1-10 mg/kg), and the NOP antagonist SB-612111 (1-10 mg/kg) were assessed in mice exposed to inescapable electric footshock and forced swim as stressors. The behavioral phenotype of mice lacking the NOP receptor (NOP(-/-)) exposed to inescapable electric footshock was also investigated.

RESULTS

The activation of NOP receptor signaling with the agonists increased the percentage of mice developing helpless behavior and facilitated immobile posture. In contrast, the blockade of NOP receptor reduced the acquisition of depressive-like phenotypes, and similar resistance to develop helpless behaviors was observed in NOP(-/-) mice. Under the same stressful conditions, the antidepressant nortriptyline (20 mg/kg) did not change the acquisition of helpless behavior and immobile posture.

CONCLUSIONS

These findings support the view that NOP activation during acute stress facilitates the development of depressive-related behaviors, whereas NOP blockade has a protective outcome. This study showed for first time that NOP antagonists are worthy of investigation as preemptive treatments in patients with severe risk factors for depression.

FAM19A1, a brain-enriched and metabolically responsive neurokine, regulates food intake patterns and mouse behaviors

Cytokines and chemokines play diverse roles in different organ systems. Family with sequence similarity 19, member A1-5 (FAM19A1-A5; also known as TAFA1-5) is a group of conserved chemokine-like proteins enriched in the CNS of mice and humans. Their functions are only beginning to emerge. Here, we show that the expression of Fam19a1-a5 in different mouse brain regions are induced or suppressed by unfed and refed states. The striking nutritional regulation of Fam19a family members in the brain suggests a potential central role in regulating metabolism. Using a knockout (KO) mouse model, we show that loss of FAM19A1 results in sexually dimorphic phenotypes. In male mice, FAM19A1 deficiency alters food intake patterns during the light and dark cycle. Fam19a1 KO mice are hyperactive, and locomotor hyperactivity is more pronounced in female KO mice. Behavior tests indicate that Fam19a1 KO female mice have reduced anxiety and sensitivity to pain. Spatial learning and exploration, however, is preserved in Fam19a1 KO mice. Altered behaviors are associated with elevated norepinephrine and dopamine turnover in the striatum. Our results establish an in vivo function of FAM19A1 and highlight central roles for this family of neurokines in modulating animal physiology and behavior.-Lei, X., Liu, L., Terrillion, C. E., Karuppagounder, S. S., Cisternas, P., Lay, M., Martinelli, D. C., Aja, S., Dong, X., Pletnikov, M. V., Wong, G. W. FAM19A1, a brain-enriched and metabolically responsive neurokine, regulates food intake patterns and mouse behaviors.

In vivo magnetic resonance imaging reveals the effect of gonadal hormones on morphological and functional brain sexual dimorphisms in adult sheep

Sex differences in the brain and behavior are produced by the perinatal action of testosterone, which is converted into estradiol by the enzyme aromatase in the brain. Although magnetic resonance imaging (MRI) has been widely used in humans to study these differences, the use of animal models, where hormonal status can be properly manipulated, is necessary to explore the mechanisms involved. We used sheep, a recognized model in the field of neuroendocrinology, to assess brain morphological and functional sex differences and their regulation by adult gonadal hormones. To this end, we performed voxel-based morphometry and a resting-state functional MRI approach to assess sex differences in gonadally intact animals. We demonstrated significant sex differences in gray matter concentration (GMC) at the level of the gonadotropic axis, i.e., not only within the hypothalamus and pituitary but also within the hippocampus and the amygdala of intact animals. We then performed the same analysis one month after gonadectomy and found that some of these differences were reduced, especially in the hypothalamus and amygdala. By contrast, we found few differences in the organization of the functional connectome between males and females either before or after gonadectomy. As a whole, our study identifies brain regions that are sexually dimorphic in the sheep brain at the resolution of the MRI and highlights the role of gonadal hormones in the maintenance of these differences.

Sex differences in the burden of type 2 diabetes and cardiovascular risk across the life course

By 2017 estimates, diabetes mellitus affects 425 million people globally; approximately 90-95% of these have type 2 diabetes. This narrative review highlights two domains of sex differences related to the burden of type 2 diabetes across the life span: sex differences in the prevalence and incidence of type 2 diabetes, and sex differences in the cardiovascular burden conferred by type 2 diabetes. In the presence of type 2 diabetes, the difference in the absolute rates of cardiovascular disease (CVD) between men and women lessens, albeit remaining higher in men. Large-scale observational studies suggest that type 2 diabetes confers 25-50% greater excess risk of incident CVD in women compared with men. Physiological and behavioural mechanisms that may underpin both the observed sex differences in the prevalence of type 2 diabetes and the associated cardiovascular burden are discussed in this review. Gender differences in social behavioural norms and disparities in provider-level treatment patterns are also highlighted, but not described in detail. We conclude by discussing research gaps in this area that are worthy of further investigation.

3Rs friendly study designs facilitate rat liver and blood micronucleus assays and Pig-a gene mutation assessments: Proof-of-concept with 13 reference chemicals

Regulatory guidance documents stress the value of assessing the most appropriate endpoints in multiple tissues when evaluating the in vivo genotoxic potential of chemicals. However, conducting several independent studies to evaluate multiple endpoints and/or tissue compartments is resource intensive. Furthermore, when dependent on visual detection, conventional approaches for scoring genotoxicity endpoints can be slow, tedious, and less objective than the ideal. To address these issues with current practices we attempted to (1) devise resource sparing treatment and harvest schedules that are compatible with liver and blood micronucleus endpoints, as well as the Pig-a gene mutation assay, and (2) utilize flow cytometry-based methods to score each of these genotoxicity biomarkers. Proof-of-principle experiments were performed with 4-week-old male and female Crl:CD(SD) rats exposed to aristolochic acids I/II, benzo[a]pyrene, cisplatin, cyclophosphamide, diethylnitrosamine, 1,2-dimethylhydrazine, dimethylnitrosamine, 2,6-dinitrotoluene, hydroxyurea, melphalan, temozolomide, quinoline, or vinblastine. These 13 chemicals were each tested in two treatment regimens: one 3-day exposure cycle, and three 3-day exposure cycles. Each exposure, blood collection, and liver harvest was accomplished during a standard Monday-Friday workweek. Key findings are that even these well-studied, relatively potent genotoxicants were not active in both tissues and all assays (indeed only cisplatin was clearly positive in all three assays); and whereas the sensitivity of the Pig-a assay clearly benefitted from three versus one treatment cycle, micronucleus assays yielded qualitatively similar results across both study designs. Collectively, these results suggest it is possible to significantly reduce animal and other resource requirements while improving assessments of in vivo genotoxicity potential by simultaneously evaluating three endpoints and two important tissue compartments using fit-for-purpose study designs in conjunction with flow cytometric scoring approaches. Environ. Mol. Mutagen., 60:704-739, 2019. © 2019 Wiley Periodicals, Inc.

Enhanced Renal Vascular Responsiveness to Angiotensin II and Norepinephrine: A Unique Feature of Female Rats with Congestive Heart Failure

Background/Aims: We found recently that the aortocaval fistula (ACF)-induced heart failure (HF) results in higher mortality in female than in male rats. Possibly, the development of renal dysfunction in the females, unlike in males, is associated with altered renal vascular responsiveness to angiotensin II (ANG II). Methods: Five or 20 weeks after ACF creation (compensated and decompensated HF, respectively), we assessed renal blood flow (RBF) responses to intrarenal administration of ANG II, norepinephrine (NE), and acetylcholine (Ach) in female ACF and sham-operated rats. Results: In ACF females, ANG II decreased RBF more than in healthy animals, unlike with earlier published data in male ACF rats that responded similarly. Also, NE decreased RBF more in female ACF rats, whereas Ach increased RBF to the same extent in female ACF and sham-operated rats. RBF responses to intravenous administration of NE and Ach were almost identical in female and male ACF rats. Conclusion: Female ACF rats studied at the onset of HF decompensation reveal, in contrast to male rats, enhanced renal vascular responsiveness to both NE and ANG II. When associated with the demonstrated increased intrarenal ANG II and NE concentrations, such hyperresponsiveness might promote the development of renal dysfunction and accelerate HF decompensation.

Operant, oral alcohol self-administration: Sex differences in Sardinian alcohol-preferring rats

Sardinian alcohol-preferring (sP) rats have been selectively bred, over almost 40 years, for high alcohol preference and consumption. sP rats have served as an animal model for more than 120 published studies. With very few exceptions, however, these studies have always employed male sP rats, and little is known about alcohol-related behaviors in female sP rats. The present study was designed to fill, at least in part, this gap. Accordingly, alcohol self-administration under the fixed ratio 4 schedule of reinforcement was compared among male, intact female, and ovariectomized female sP rats. Additionally, it was investigated whether i) estrous cycle influenced alcohol self-administration, and ii) alcohol self-administration in the three sP rat groups differed in sensitivity to pharmacological manipulation. Lever-responding for alcohol was steadily higher in male than intact and ovariectomized female sP rats; conversely, because of large sex differences in rat body weight, estimated amount of self-administered alcohol (in g/kg) did not differ among the three sP rat groups or occasionally was higher in intact female than male and ovariectomized female sP rats. Blood alcohol levels derived from self-administered alcohol i) did not differ among the three sP rat groups and ii) were positively correlated with the number of lever-responses for alcohol and the estimated amount of self-administered alcohol. Treatment with the opioid receptor antagonist, naloxone (0, 0.3, 1, and 3 mg/kg, i.p. [intraperitoneally]), and the positive allosteric modulator of the GABA_B receptor, GS39783 (0, 25, 50, and 100 mg/kg, i.g. [intragastrically]), reduced alcohol self-administration with comparable potency and efficacy in the three sP rat groups. The impact of the estrous cycle on alcohol self-administration was relatively modest, limited to a tendency toward a reduction in the number of lever-responses for alcohol and the estimated amount of self-administered alcohol in estrus and metestrus. Together, these results provide the first characterization of alcohol-seeking and -taking behavior in female sP rats.

Sex-linked differences in the mortality in Ren-2 transgenic hypertensive rats with aorto-caval fistula: effects of treatment with angiotensin converting enzyme alone and combined with inhibitor of soluble epoxide hydrolase

We found recently that in Ren-2 transgenic hypertensive rats (TGR) addition of soluble epoxide hydrolase inhibitor (sEHi) to treatment with angiotensin-converting enzyme inhibitor (ACEi), surprisingly, increased the mortality due to heart failure (HF) induced by creation of the aorto-caval fistula (ACF). Since TGR exhibit sex-related differences in mortality, we examined here if such differentiation exists also in the response to the treatment with ACEi (trandolapril), alone or combined with sEHi [cis-4-[4-(3-adamantan-1-yl-ureido)cyclohexyloxy]benzoic acid, (c-AUCB)]. ACEi improved survival in males to 74 % (vs. 0 %) and in females to 65 % (vs. 32 %). ACEi and sEHi combined also improved the survival in male ACF TGR, however, it was significantly less (38 %) than after ACEi alone. In contrast, in females the combined treatment significantly improved the final survival rate (84 %). There were no significant sex-linked differences in survival rate in untreated or treated normotensive Hannover Sprague-Dawley rats. In conclusion, in HF patients with co-existing hypertension and RAS hyperactivity, the sex may co-determine the rate of HF progression, and can influence the effectiveness of the therapeutic measures applied. Therefore, in the relevant pre-clinical studies the sex-linked differences should be seriously considered. Our data indicate that TGR might be an optimal model for such studies.

Sex differences in α-pyrrolidinopentiophenone (α-PVP)-induced taste avoidance, place preference, hyperthermia and locomotor activity in rats

RATIONALE

The majority of synthetic cathinone research has used only male subjects, and as a result there are few studies assessing the impact of biological sex on their effects.

OBJECTIVES

The current work extends the characterization of the second-generation synthetic cathinone, α-PVP, by investigating how biological sex impacts α-PVP's aversive and rewarding effects important to its use and potential abuse.

METHODS

A combined conditioned taste avoidance/conditioned place preference preparation was utilized in which adult male and female Sprague Dawley rats were injected with 1.5, 3 or 6 mg/kg of racemic α-PVP or vehicle (saline) (IP). Following a 24-day washout period, rats were then tested for thermoregulatory effects of α-PVP using subcutaneous microchips to measure body temperature changes over the course of 8 h. This was followed 21 days later by assessments for α-PVP-induced locomotor activity and stereotypies over a 1-h session.

RESULTS

Dose-dependent conditioned taste avoidance was evident in both males and females, although females displayed weaker avoidance at 3 mg/kg compared to males. Males displayed a dose-dependent conditioned place preference, while females did not form a place preference at any dose. α-PVP elicited dose- and time-dependent hyperthermia, with males displaying a faster on-set and delayed off-set compared to females. α-PVP also produced dose- and time-dependent increases in locomotor activity (F > M) and stereotypies (M > F).

CONCLUSIONS

As described, males displayed greater rewarding (as indexed by place preference conditioning) and aversive (as indexed by taste avoidance, hyperthermia and stereotypies) effects of α-PVP. Although comparisons between males and females in α-PVP self-administration have not been reported, these data suggest that males may be more likely to use the drug. The implications for sex differences in human use of α-PVP were discussed.

Sex still matters: has the prevalence of male-only studies of drug effects on rodent behaviour changed during the past decade?

During the past 10 years, for a number of biomedical disciplines, including behavioural pharmacology, there have been appeals to include both sexes in animal studies of processes that are not sex specific. In 2007, a survey of experimental studies of drug or other chemical effects on rodent behaviour, published in five prominent journals over 20 months (February 2005 to September 2006, inclusive), revealed that 85% of these conducted with rats and 78% of these conducted with mice involved males only. This was in spite of the evidence of sex differences in responsiveness to an increasing number of compounds. To see if the situation has improved, the survey was repeated with the same journals for a comparable period namely, February 2016 to September 2017 (inclusive). Even though there have been repeated appeals for biomedical research that is not sex specific to involve both sexes, it was apparent that little has changed since 2005-2006, as 82% of rat and 75% of mouse studies were again conducted with males only. However, there was an increase in studies with mice, which may be owing to a greater interest in genetic factors. The male-only situation could be rectified by appropriate funding agencies and journals that publish behavioural pharmacological research insisting that both sexes must be included in research that is not sex specific along with valid scientific justification for single-sex studies, as now typifies some other disciplines.

Sex differences in transcriptomic profiles in aged kidney cells of renin lineage

Renin expressing cells in the kidney’s juxta-glomeruluar compartment likely also serve as progenitors for adult glomerular cells in disease. Although these cells of renin lineage (CoRL) decrease in number with advancing kidney age, accompanied by less responsiveness to typical stimuli such as ACE-inhibition, mechanisms and the impact of sex as a biological variable with age are not known. Accordingly, labeled CoRL were sorted from individual young (2m) and aged (27m) male and female Ren1cCre|ZsGreen reporter mice, and their transcriptomic profiles analyzed by RNA seq. When both aged female and male mice were combined, there were 48 differentially expressed genes (DEG) compared to young mice. However, when compared to their young sex-matched mice, aged female and male mice had 159 and 503 DEGs respectively. In addition to marked differences in individual genes between aged female and male mice, gene ontology analysis showed major pathway differences by sex. The majority of DEGs in one sex did not significantly change or changed in the opposite direction in the other sex. These results show that in CoRL of advanced age, individual genes and gene ontologies change, but differ between female and male mice, highlighting sex related differences the aging process.

Male and female mice show equal variability in food intake across 4-day spans that encompass estrous cycles

The exclusion of female rodents from biomedical research is well documented and persists in large part due to perceptions that ovulatory cycles render female traits more variable than those of males, and females must be tested at each of four stages of the estrous cycle to generate reliable data. These beliefs are not empirically based. The magnitude of trait variance associated with the estrous cycle may be sufficiently low and of little impact, or trait variability of males tested on 4 consecutive days may be as great as that of females over the 4 days of the estrous cycle. Here, we analyzed food intake data from mice in 4-day blocks, corresponding to the females' 4-day estrous cycle in several schedules of food procurement or reward. Variance was compared within and across individual mice. In no instance did the overall variance differ by sex under any of the food reward schedules. This extends earlier observations of trait variability in body temperature and locomotor activity of mice and supports the claim that there is no empirical basis for excluding female rodents from biomedical research.

Role of estrogen and its receptors mediated-autophagy in cell fate and human diseases

Studies have shown that morbidity of several diseases varies between males and females. This difference likely arises due to sex-related hormones. Estrogen, a primary female sex steroid hormone, plays a critical role in mediating many of the physiological functions like growth, differentiation, metabolism, and cell death. Recently, it has been demonstrated that estrogen mediates autophagy through its receptors (ERs) namely ERα, ERβ, and G-protein coupled estrogen receptor (GPER). However, the specific role of estrogen and its receptors mediated-autophagy in cell fate and human diseases such as cancers, cardiovascular disease and nervous system disease remains unclear. In this review, we comprehensively summarize the complex role of estrogen and its receptors-mediated autophagy in different cell lines and human diseases. In addition, we further discuss the key signaling molecules governing the role of ERs in autophagy. This review will serve as the basis for a proposed model of autophagy constituting a new frontier in estrogen-related human diseases. Here, we discuss the dual role of ERα in classical and non-classical autophagy through B-cell lymphoma 2 (BCL2)-associated athanogene 3 (BAG3). Next, we review the role of ERβ in pro-survival pathways through the promotion of autophagy under stress conditions. We further discuss activation of GPER via estrogen often mediates autophagy or mitophagy suppression, respectively. In summary, we believe that understanding the relationship between estrogen and its receptors mediated-autophagy on cell fate and human diseases will provide insightful knowledge for future therapeutic implications.

Challenges of the heterogeneous nutrition response: interpreting the group mean

Extensive research demonstrates unequivocally that nutrition plays a fundamental role in maintaining health and preventing disease. In parallel nutrition research provides evidence that the risks and benefits of diet and lifestyle choices do not affect people equally, as people are inherently variable in their responses to nutrition and associated interventions to maintain health and prevent disease. To simplify the inherent complexity of human subjects and their nutrition, with the aim of managing expectations for dietary guidance required to ensure healthy populations and individuals, nutrition researchers often seek to group individuals based on commonly used criteria. This strategy relies on demonstrating meaningful conclusions based on comparison of group mean responses of assigned groups. Such studies are often confounded by the heterogeneous nutrition response. Commonly used criteria applied in grouping study populations and individuals to identify mechanisms and determinants of responses to nutrition often contribute to the problem of interpreting the results of group comparisons. Challenges of interpreting the group mean using diverse populations will be discussed with respect to studies in human subjects, in vivo and in vitro model systems. Future advances in nutrition research to tackle inter-individual variation require a coordinated approach from funders, learned societies, nutrition scientists, publishers and reviewers of the scientific literature. This will be essential to develop and implement improved study design, data recording, analysis and reporting to facilitate more insightful interpretation of the group mean with respect to population diversity and the heterogeneous nutrition response.

Enrollment and Retention of Men and Women in Health Services Research and Development Trials

INTRODUCTION

Sex- and gender-specific science is essential to inform patient-centered, evidence-based care. Developing such evidence requires adequate inclusion of both women and men in trials. We sought to describe study participation of women and men in Department of Veterans Affairs Health Services Research and Development trials.

METHODS

We identified recent health services research trials from one Health Services Research and Development Center of Innovation and compared the participation of women and men from trial recruitment to study completion. We also calculated the participation to prevalence ratio (PPR) by sex for each trial.

RESULTS

We included eight trials that started recruitment between 2011 and 2014. Only one study purposefully attempted to boost the recruitment of women. Overall, the PPR for women ranged from 0.2 to 4.5, with seven studies having a PPR of greater than 1, indicating that women participated in these trials at proportions greater than their prevalence in the disease population within the Department of Veterans Affairs. The PPR for men ranged from 0.8 to 1.1. Retention was best with those studies that used administrative data for final outcomes assessment. No studies provided results stratified by sex or conducted analyses to explore treatment effect by sex.

CONCLUSIONS

At a single site, women participated in Health Services Research and Development trials at similar or greater rates to men without cross-study efforts to enrich the recruitment or retention of women. Adding strategic recruitment approaches could further boost the proportion of women in Department of Veterans Affairs trials and enable adequately powered sex-based analyses.

Sex as a biological variable in the pathology and pharmacology of neurodegenerative and neurovascular diseases

The incidence of dementia, most commonly caused by cerebrovascular and neurodegenerative diseases, continues to grow as our population ages. Alzheimer disease (AD) and vascular cognitive impairment (VCI) are responsible for more than 80% of all cases of dementia. There are few effective, long-term treatments for AD and VCI-related conditions (e.g., stroke and cerebral amyloid angiopathy (CAA)). This review focuses on AD (as the most common "neurodegenerative" cause of dementia), CAA (as an "emerging" cause of dementia), and stroke (as the most common cause of "vascular" dementia). We will discuss the available literature on the pharmacological therapies that demonstrate sex differences, which refer to any combination of structural, chromosomal, gonadal, or hormonal differences between males and females. We will emphasize the importance of considering sex as a biological variable in the design of preclinical and clinical studies that investigate underlying pathologies or response to pharmacological interventions in dementia. LINKED ARTICLES: This article is part of a themed section on The Importance of Sex Differences in Pharmacology Research. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.21/issuetoc.