Juvenile Female Mice Research Articles

Impact of Dietary Isoflavones in Standard Chow on Reproductive Development in Juvenile and Adult Female Mice with Different Metabolic Phenotypes.

Two factors influencing female reproduction have been repeatedly studied in different animal species and humans, namely, 1. secondary plant compounds, especially phytoestrogens (mainly isoflavones (IFs)), and 2. the physical constitution/metabolic phenotype (e.g., obesity). So far, these research results have only been considered separately. In this study, we investigated the influence on reproduction of both phytochemicals, mainly dietary IFs, and the metabolic phenotype represented by three mouse models considered as three distinct genetic groups (a control group, a mouse model with high metabolic activity, and a mouse line with obese body weight). The IF content in different investigated standard chows with similar macronutrient profiles varied significantly (p < 0.005), leading to high mean total plasma IF levels of up to 5.8 µmol/L in juvenile and 6.7 µmol/L in adult female mice. Reproductive performance was only slightly affected; only an IF dose-dependent effect on gestation length was observed in all genetic groups, as well as an effect on pregnancy rate in obese mice. Dietary IF exposure, however, caused earlier onset of vaginal opening by 4-10 days in juvenile mice (p < 0.05), dependent on the genetic group, resulting in a slight acceleration of sexual maturation in the already precocious obese model and to a strong earlier maturation in the otherwise late-maturing sporty model, bred for high treadmill performance. Therefore, our results may help to draw the missing line between the effect of dietary secondary plant constituents, such as IFs, and metabolic phenotype on sexual development.

Age and sex-dependent gut alterations in mice induced by neonatal immune activation with lipopolysaccharide

Neonatal immune activation (NIA) through exposure to lipopolysaccharide (LPS) induces adult behavioral changes in rodents that resemble symptoms of developmental disorders, such as autism spectrum disorder. The neonatal timing of LPS exposure appears to play a crucial role in determining the nature and extent of long-term changes. This study aims to explore whether a 3-day LPS-NIA triggers sex- and age-related changes in gut function, potentially linking LPS-NIA to gastrointestinal dysfunction. Male and female Swiss mice received intraperitoneal injections of LPS or saline on postnatal days (PN) 3, 5, and 7. At PN35 (juvenile) and PN70 (adult), gut inflammation and oxidative stress were evaluated in addition to assessments of working memory, depressive-like symptoms, sociability, and repetitive behavior. Gut examination showed elevated C-X-C motif chemokine receptor 3 (CXCR3) in LPS-NIA mice, while MyD88 and Zonulin expressions were significantly higher only in adult LPS-NIA females. Interleukin (IL)-23 expression increased in juvenile and adult male and juvenile female LPS-NIA mice. Oxidative changes included decreased duodenal reduced glutathione (GSH) in juvenile females and ileal GSH in adult females exposed to LPS-NIA. Regarding behavioral alterations, adult LPS-NIA females exhibited depressive-like behavior. Working memory deficits were observed across all LPS-NIA groups. Only juvenile LPS-NIA females increased grooming, while rearing was higher in adult LPS-NIA mice of both sexes. The findings imply that LPS-NIA impacts intestinal barrier function and causes gut inflammatory alterations that are sex- and age-specific. These findings pave the way for exploring potential mechanisms that could contribute to LPS-induced gastrointestinal disturbances among individuals with ASD.

Sex-based differences in persistent lung inflammation following influenza infection of juvenile outbred mice.

Children are susceptible to influenza infections and can experience severe disease presentation due to a lack of or limited pre-existing immunity. Despite the disproportionate impact influenza has on this population, there is a lack of focus on pediatric influenza research, particularly when it comes to identifying the pathogenesis of long-term outcomes that persist beyond the point of viral clearance. In this study, juvenile outbred male and female mice were infected with influenza and analyzed following viral clearance to determine how sex impacts the persistent inflammatory responses to influenza. It was found that females maintained a broader cytokine response in the lung following clearance of influenza, with innate, type I and type II cytokine signatures in almost all mice. Males, on the other hand, had higher levels of IL-6 and other macrophage-related cytokines, but no evidence of a type I or type II response. The immune landscape was similar in the lungs between males and females postinfection, but males had a higher regulatory T cell to TH1 ratio compared with female mice. Cytokine production positively correlated with the frequency of TH1 cells and exudate macrophages, as well as the number of cells in the bronchoalveolar lavage fluid. Furthermore, female lungs were enriched for metabolites involved in the glycolytic pathway, suggesting glycolysis is higher in female lungs compared with males after viral clearance. These data suggest juvenile female mice have persistent and excessive lung inflammation beyond the point of viral clearance, whereas juvenile males had a more immunosuppressive phenotype.NEW & NOTEWORTHY This study identifies sex-based differences in persistent lung inflammation following influenza infection in an outbred, juvenile animal model of pediatric infection. These findings indicate the importance of considering sex and age as variable in infectious disease research.

Naringenin modulates GABA mediated response in a sexdependent manner in substantia gelatinosa neurons of trigeminal subnucleus caudalis in immature mice.

The substantia gelatinosa (SG) within the trigeminal subnucleus caudalis (Vc) is recognized as a pivotal site of integrating and modulating afferent fibers carrying orofacial nociceptive information. Although naringenin (4',5,7-thrihydroxyflavanone), a natural bioflavonoid, has been proven to possess various biological effects in the central nervous system (CNS), the activity of naringenin at the orofacial nociceptive site has not been reported yet. In this study, we explored the influence of naringenin on GABA response in SG neurons of Vc using whole-cell patch-clamp technique. The application of GABA in a bath induced two forms of GABA responses: slow and fast. Naringenin enhanced both amplitude and area under curve (AUC) of GABA-mediated responses in 57% (12/21) of tested neurons while decreasing both parameters in 33% (7/21) of neurons. The enhancing or suppressing effect of naringenin on GABA response have been observed, with enhancement occurring when the GABA response was slow, and suppression when it was fast. Furthermore, both the enhancement of slower GABA responses and the suppression of faster GABA responses by naringenin were concentration dependent. Interestingly, the nature of GABA response was also found to be sex-dependent. A majority of SG neurons from juvenile female mice exhibited slower GABA responses, whereas those from juvenile males predominantly displayed faster GABA responses. Taken together, this study indicates that naringenin plays a partial role in modulating orofacial nociception and may hold promise as a therapeutic target for treating orofacial pain, with effects that vary according to sex.

THU480 Loss Of Selenof And A Western Diet Promote Mammary Tumorigenesis

Abstract Disclosure: B. Flowers: None. A. Zigrossi: None. A. Diamond: None. I. Kastrati: None. SELENOF is an understudied selenium-containing protein which has previously been postulated to behave as a tumor suppressor in the breast. Examination of patient databases showed that SELENOF levels were lowest in tumors from patients with aggressive late-stage breast cancers. Whether loss of SELENOF drives breast tumorigenesis remains to be determined. To address this question, we used juvenile female wild type or systemic Selenof knockout mice and exposed them to 7,12-Dimethylbenz[a]anthracene (DMBA), a carcinogen which replicates the multistep process of breast tumorigenesis. Previous reports have shown that loss of Selenof led to glucose and metabolic dysregulation in mice suggesting a link between Selenof and metabolism. Because obesity is a risk factor in breast cancer, we challenged the mice with a western diet, high in fats and in calories, to mimic obesity. We hypothesized that loss of Selenof would promote DMBA-induced tumorigenesis and the western diet would exacerbate it. We found that tumor incidence was in fact highest in the Selenof knockout mice and western diet group. The Selenof knockout mice exhibited higher weights and higher fasting glucose levels consistent with metabolic dysfunction. These findings indicate that lower or loss of SELENOF expression may predispose a subset of women, especially obese ones, to increased risk of breast cancer. The link between SELENOF, obesity, and breast cancer warrants further investigation. Presentation: Thursday, June 15, 2023

THU297 Metformin Treatment Of Juvenile Mice Alters Aging-Related Developmental And Metabolic Phenotypes In Sex-Dependent And -Independent Manners

Abstract Disclosure: Y. Zhu: None. M. Engmann: None. D. Medina: None. A. Bartke: None. B.S. Ellsworth: None. R. Yuan: None. Metformin is a widely used drug for the treatment of type 2 diabetes that also has a strong potential for long-term effects which may extend healthspan and longevity. In the current study, C57BL/6J (B6) juvenile female and male mice were treated with metformin between the ages of 15 and 56 days. Saline was used as the control. The results show that early-life treatment with metformin has profound effects on developmental and metabolic traits. Body weight was significantly reduced by metformin treatment in both sexes (P&amp;lt;0.05, t test). At 10 weeks of age, mice were euthanized, and organ weights were recorded. In treated males, weights of epididymal, perirenal, and brown fat depots were significantly reduced (P&amp;lt;0.05, t test). Pancreas weight was significantly reduced in both sexes (P&amp;lt;0.05, t test). Hypothalamus weight was significantly reduced in the females, and whole brain weight was significantly reduced in the males. Tail length as well as age of sexual maturation were not significantly altered in either sex. No significant difference was found in circulating insulin-like growth factor 1 (IGF1) or adiponectin. Circulating insulin was significantly reduced by the treatment under fasting and non-fasting conditions in the male mice, while in the females no significant difference was detected. Insulin sensitivity, calculated by the quantitative insulin-sensitivity check index (QUICKI), was suggestively increased in the male mice (P=0.062, t test). Glucose tolerance test (GTT) did not show a significant difference in treated female mice; however, comparing the area under curve, metformin treatment significantly improved the glucose tolerance of male mice (P=0.014, t test). Insulin tolerance test (ITT) showed no significant difference in the male mice; but, unexpectedly, in female mice, metformin treatment significantly reduced insulin sensitivity. This study revealed that early-life metformin treatment alters development and metabolism of mice in both sex-specific and non-specific manners, which may have long-term impacts on metabolism in aging. Interestingly, comparing the results of this study with previous studies of metformin-treated heterogenous UM-HET3 mice, further analyses revealed that metformin effects on body weight, age of sexual maturation, body size, IGF1, adiponectin, insulin, GTT, and ITT, are genetically dependent. Funding: SIU collaborative grant to Rong Yuan and Buffy S. Ellsworth. SIU Geriatric foundation by Andrzej Bartke Presentation: Thursday, June 15, 2023

Progesterone Receptor Activation Regulates Sensory Sensitivity and Migraine Susceptibility

Women develop chronic pain during their reproductive years more often than men, and estrogen and progesterone regulate this susceptibility. We tested whether brain progesterone receptor (PR) signaling regulates pain susceptibility. During the estrous cycle, animals were more sensitive to mechanical stimulus during the estrus stage than in the diestrus stage, suggesting a role for reproductive hormones, estrogen, and progesterone. Progesterone treatment of ovariectomized and estrogen-primed mice caused a delayed reduction in the mechanical threshold. Segesterone, a specific agonist of PRs replicated this effect, whereas, the segesterone-induced reduction in mechanical threshold was blocked in the mice lacking PRs in the nervous system. Segesterone treatment also did not alter mechanical threshold in adult male and juvenile female mice. PR activation increased the cold sensitivity but did not affect the heat and light sensitivity. We evaluated whether PR activation altered experimental migraine. Segesterone and nitroglycerin when administered sequentially, reduced the pain threshold but not when given separately. PRs were expressed in several components of the migraine ascending pain pathway, and their deletion blocked the painful effects of nitroglycerin. PR activation also increased the number of active neurons in the components of the migraine ascending pain pathway. These studies have uncovered a pain-regulating function of PRs. Targeting PRs may provide a novel therapeutic avenue to treat chronic pain and migraine in women. PerspectiveThis article provides evidence for the role of progesterone receptors in regulating pain sensitivity and migraine susceptibility in females. Progesterone receptors may be a therapeutic target to treat chronic pain conditions more prevalent in women than men.

Paternal cadmium exposure affects estradiol synthesis by impairing intracellular cholesterol homeostasis and mitochondrial function in offspring female mice

Cadmium (Cd) is a toxic heavy metal commonly found in nature and an endocrine disrupting chemical (EDC). Previous studies found that Cd can damage several organs, including the kidneys, bones, cardiovascular system and reproductive system. However, the effect of paternal Cd exposure on the offspring is unclear. In this study, 1 mg/kg of cadmium chloride (CdCl2) was injected intraperitoneally every other day in 8-week-old C57BL/6 J male mice to study the effects on their female offspring. Our results showed an increase in body weight, water intake and food intake in F1 female mice from the Cd-exposed group. The development of secondary follicles and antral follicles in the ovaries of Cd-treated was inhibited. Serum estradiol (E2) was found to be decreased. Further analysis revealed significant downregulation of StAR, P450scc, 17β-HSD, CYP17A1 and CYP19A1, which are related to E2 synthesis. Serum total cholesterol was increased and free cholesterol was reduced. Total cholesterol in ovarian tissue was decreased. qRT-PCR and Western blot analysis revealed a decrease in the mRNA and protein expression of HMGCR, LDLR, and ABCA1, which are associated with cholesterol homeostasis. Oil red O staining indicated that lipid droplets (LDs) were accumulated in ovarian tissues, while the expression of ATGL and HSL proteins associated with lipid droplet degradation was significantly downregulated. In juvenile female mice, ultrastructural alterations of mitochondria in the ovaries were observed by transmission electron microscopy (TEM). In adult female mice, the expression of proteins associated with mitochondrial dynamics (DRP1 and MFN2) was significantly reduced in the ovaries. Overall, our study suggests that paternal Cd exposure inhibits follicular development, and affects serum E2 synthesis by impairing cholesterol homeostasis and affecting mitochondrial function.

Developmental age and fatty acid amide hydrolase genetic variation converge to mediate fear regulation in female mice.

Anxiety disorders are more prevalent in females than in males, yet a majority of basic neuroscience studies are performed in males. Furthermore, anxiety disorders peak in prevalence during adolescence, yet little is known about neurodevelopmental trajectories of fear expression, particularly in females. To examine these factors, we fear conditioned juvenile, adolescent, and adult female mice and exposed them to fear extinction and a long-term recall test. For this, we used knock-in mice containing a common human mutation in the gene for fatty acid amide hydrolase (FAAH), the primary catabolic enzyme for the endocannabinoid anandamide (FAAH-IN). This mutation has been shown to impart a low-anxiety phenotype in humans, and in rodents relative to their wild-type littermates. We find an impact of the FAAH polymorphism on developmental changes in fear behavior. Specifically, the FAAH polymorphism appears to induce a state of hypervigilance (increased fear) during adolescence. We also used markerless pose estimation software to classify alternative behaviors outside of freezing. These analyses revealed age differences in vigilance to indicators of threat and in the propensity of mice to explore an aversive environment, though genotypic differences were minimal. These findings address a gap in the literature regarding developmental patterns of fear learning and memory as well as the mechanistic contributions of the endocannabinoid system in females.

Differential gene expression in the calvarial and cortical bone of juvenile female mice.

Both the calvarial and the cortical bones develop through intramembranous ossification, yet they have very different structures and functions. The calvaria enables the rapid while protected growth of the brain, whereas the cortical bone takes part in locomotion. Both types of bones undergo extensive modeling during embryonic and post-natal growth, while bone remodeling is the most dominant process in adults. Their shared formation mechanism and their highly distinct functions raise the fundamental question of how similar or diverse the molecular pathways that act in each bone type are. To answer this question, we aimed to compare the transcriptomes of calvaria and cortices from 21-day old mice by bulk RNA-Seq analysis. The results revealed clear differences in expression levels of genes related to bone pathologies, craniosynostosis, mechanical loading and bone-relevant signaling pathways like WNT and IHH, emphasizing the functional differences between these bones. We further discussed the less expected candidate genes and gene sets in the context of bone. Finally, we compared differences between juvenile and mature bone, highlighting commonalities and dissimilarities of gene expression between calvaria and cortices during post-natal bone growth and adult bone remodeling. Altogether, this study revealed significant differences between the transcriptome of calvaria and cortical bones in juvenile female mice, highlighting the most important pathway mediators for the development and function of two different bone types that originate both through intramembranous ossification.

The influence of alpha-lipoic acid on ovarian follicle growth in induced aging mice

The ovary contains follicles at various developmental stages. The present study aimed to investigate the antioxidant efficiency of alpha-lipoic acid (α-LA) on follicle growth in induced aging ovaries. Juvenile female mice (n=24) were allocated into four groups (n=6, each); the control group received distilled water, and the induced aging group (T1) received D-galactose (300 mg/kg). The co-administrated group (T2) was treated with α-LA (300 mg/kg) and D-galactose (100 mg/kg), while the fourth group (T3) was treated with α-LA (100 mg/kg). At the end of treatments (8 weeks), animals were sacrificed, and ovaries were processed for hematoxylin and eosin staining and immunostaining for proliferating cell nuclear antigen (PCNA). PCNA was detectable in oocytes but only in granulosa cells of activated follicles. The D-galactose treatment successfully induced ovarian aging as the proportion of primordial and growing follicles was significantly reduced accompanied by massively increased atretic follicles. Additionally, only numerous PCNA positively stained follicles were recognized. The co-administrated α-LA moderately rescued the characteristics of ovarian aging. Mice treated with α-LA demonstrated a substantial increase in the population of atretic follicles, antral follicles, and PCNA positively stained follicles. There was no change in oocyte size at any follicle growth stage among groups. In conclusion, α-LA moderately rescued the detrimental impacts of induced ovarian aging. For the first time, the expression of PCNA was linked with ovarian aging, where PCNA-staining has been recognized as a valuable tool to evaluate the proliferative activity of the granulosa cells.

Maternal immune activation accelerates puberty initiation and alters mechanical allodynia in male and female C57BL6/J mice.

The mechanisms that link maternal immune activation (MIA) with the onset of neurodevelopmental disorders remain largely unclear. Accelerated puberty is also associated with a heightened risk for psychopathology in later life, but there is a dearth of evidence on the impacts of maternal infection on pubertal timing. We examined the effects of MIA on reproductive development, mechanical allodynia, and sensorimotor gating in juvenile, adolescent, and adult male and female mice. Moreover, we investigated hypothalamic neural markers associated with the reproductive and stress axes. Finally, we tested the mitigating effects of environmental enrichment (EE), which has clinical relevancy in human rehabilitation settings. Our results show that administration of polyinosinic-polycytidylic acid (poly(I:C)) on gestational day 12.5 led to early preputial separation, vaginal openings, and age of first estrus in offspring. MIA exposure altered pain sensitivity across development and modestly altered prepulse inhibition. The downregulation of Nr3c1 and Oprk mRNA in the hypothalamus of juvenile mice suggests that MIA's effects may be mediated through disruption of hypothalamic-pituitary-adrenal axis activity. In contrast, life-long housing with EE rescued many of these MIA-induced consequences. Overall, our findings suggest that accelerated puberty may be associated with the deleterious effects of infection during pregnancy and the onset of psychopathology.

Exercise During Childhood Protects Against Cardiac Dysfunction Later in Life

Cardiovascular disease continues to be a major cause of morbidity and mortality, particularly in aging populations. Exercise is amongst the most cardioprotective interventions identified to date, with early in life exercise such as during the juvenile period potentially imparting even more cardioprotective outcomes due to the plasticity of the developing heart. To test the hypothesis that juvenile exercise would impart later in life cardioprotection, we exercised juvenile male and female mice via voluntary wheel running from 3-5 weeks of age and then exposed them to cardiac stress by isoproterenol (ISO) at 4-6 and 18 months of age in adulthood and older age, respectively. We compared cardiac function and remodeling to sedentary control animals, sedentary animals who received ISO, and adult and aged mice that exercised for two weeks immediately before ISO exposure. Juvenile mice engaged in voluntarily wheel running, with male mice running 1.3 ± 0.8 km and female mice 2.8 ± 1.0 km a day. Echocardiography suggested that these juvenile animals underwent running-induced cardiac remodeling as evidenced by higher ejection fraction and stroke volume compared to sedentary controls. Exercise in the juvenile period attenuated ISO-induced cardiac hypertrophy and remodeling later in life compared to sedentary animals and those that exercised immediately before ISO administration. The mechanisms by which early versus late exercise is protective in adult and aged mice are under investigation. Further ongoing work will identify the adaptations induced by exercise in the juvenile heart that may help improve cardiac aging.

Sex-specific behavioral and structural alterations caused by early-life stress in C57BL/6 and BTBR mice

Lately, the development of various mental illnesses, such as depression, personality disorders, and autism spectrum disorders, is often associated with traumatic events in childhood. Nonetheless, the mechanism giving rise to this predisposition is still unknown. Because the development of a disease often depends on a combination of a genetic background and environment, we decided to evaluate the effect of early-life stress on BTBR mice, which have behavioral, neuroanatomical, and physiological features of autism spectrum disorders. As early-life stress, we used prolonged separation of pups from their mothers in the first 2 weeks of life (3 h once a day). We assessed effects of the early-life stress on juvenile (postnatal day 23) and adolescent (postnatal days 37–38) male and female mice of strains C57BL/6 (B6) and BTBR. We found that in both strains, the early-life stress did not lead to changes in the level of social behavior, which is an important characteristic of autism-related behavior. Nonetheless, the early-life stress resulted in increased locomotor activity in juvenile BTBR mice. In adolescent mice, the stress early in life caused a low level of anxiety in B6 males and BTBR females and increased exploratory activity in adolescent BTBR males and females. In addition, adolescent B6 male and female mice with a history of the early-life stress tended to have a thinner motor cortex as assessed by magnetic resonance imaging. As compared to B6 mice, BTBR mice showed reduced levels of social behavior and exploratory activity but their level of locomotor activity was higher. BTBR mice had smaller whole-brain, cortical, and dorsal hippocampal volumes; decreased motor cortex thickness; and increased ventral-hippocampus volume as compared to B6 mice, and these parameters correlated with the level of exploratory behavior of BTBR mice. Overall, the effects of early postnatal stress are sex- and strain-dependent.

Transcriptomic analysis of cardiac gene expression across the life course in male and female mice.

Risk for heart disease increases with advanced age and differs between sexes, with females generally protected from heart disease until menopause. Despite these epidemiological observations, the molecular mechanisms that underlie sex‐specific differences in cardiac function have not been fully described. We used high throughput transcriptomics in juvenile (5 weeks), adult (4–6 months), and aged (18 months) male and female mice to understand how cardiac gene expression changes across the life course and by sex. While male gene expression profiles differed between juvenile‐adult and juvenile‐aged (254 and 518 genes, respectively), we found no significant differences in adult‐aged gene expression. Females had distinct gene expression changes across the life course with 1835 genes in juvenile‐adult and 1328 in adult‐aged. Analysis of differentially expressed genes (DEGs) suggests that juvenile to adulthood genes were clustered in cell cycle and development‐related pathways in contrast to adulthood‐aged which were characterized by immune‐and inflammation‐related pathways. Analysis of sex differences within each age suggests that juvenile and aged cardiac transcriptomes are different between males and females, with significantly fewer DEGs identified in adult males and females. Interestingly, the male–female differences in early age were distinct from those in advanced age. These findings are in contrast to expected sex differences historically attributed to estrogen and could not be explained by estrogen‐direct mechanisms alone as evidenced by juvenile sexual immaturity and reproductive incompetence in the aged mice. Together, distinct trajectories in cardiac transcriptomic profiles highlight fundamental sex differences across the life course and demonstrate the need for the consideration of age and sex as biological variables in heart disease.

CaMKIV Signaling Is Not Essential for the Maintenance of Intrinsic or Synaptic Properties in Mouse Visual Cortex.

Pyramidal neurons in rodent visual cortex homeostatically maintain their firing rates in vivo within a target range. In young cultured rat cortical neurons, Ca2+/calmodulin-dependent kinase IV (CaMKIV) signaling jointly regulates excitatory synaptic strength and intrinsic excitability to allow neurons to maintain their target firing rate. However, the role of CaMKIV signaling in regulating synaptic strength and intrinsic excitability in vivo has not been tested. Here, we show that in pyramidal neurons in visual cortex of juvenile male and female mice, CaMKIV signaling is not essential for the maintenance of basal synaptic or intrinsic properties. Neither CaMKIV conditional knock-down nor viral expression of dominant negative CaMKIV (dnCaMKIV) in vivo disrupts the intrinsic excitability or synaptic input strength of pyramidal neurons in primary visual cortex (V1), and CaMKIV signaling is not required for the increase in intrinsic excitability seen following monocular deprivation (MD). Viral expression of constitutively active CaMKIV (caCaMKIV) in vivo causes a complex disruption of the neuronal input/output function but does not affect synaptic input strength. Taken together, these results demonstrate that although augmented in vivo CaMKIV signaling can alter neuronal excitability, either endogenous CaMKIV signaling is dispensable for maintenance of excitability, or impaired CaMKIV signaling is robustly compensated.

Transcriptomic Analysis Of Cardiac Gene Expression Across The Life‐Course In Male And Female Mice

Risk for heart disease increases with advanced age and differs between sexes, with females generally protected from heart disease until menopause. Despite these epidemiological and clinical observations, however, the molecular mechanisms of the cardiac aging life-course and how it differs between sexes is not fully described. We used high throughput transcriptomics in juvenile (5 weeks), adult (4-6 months), and aged (18 months) to understand how cardiac gene expression changes across the life-course and by sex. Age-related changes in cardiac gene expression differed significantly between males and females. While male gene expression changed from the juvenile-adult and juvenile-aged period (203 and 395 genes, respectively), adult-old gene expression was unchanged. Female gene expression changed across the life-course with 2009 genes from juvenile-adult and 1656 from adult-aged. Gene enrichment analysis of differentially expressed genes (DEG) suggests that juvenile to adulthood genes are clustered in cell-cycle and development-related pathways in contrast to adulthood to aged shift with immune and inflammation-related pathways. Within age, significant sex differences existed as well. Juvenile and aged male and female mice displayed significantly different gene expression, while adult male and female gene expression was similar. Interestingly, there was very little overlap in differently expressed genes juvenile and aged mice, suggesting sex differences in early age are distinct from those in advanced age. Gene enrichment analysis shows early juvenile DEGs clustering in cell-differentiation and development pathways, aged mice DEGs clustering in protein metabolism and its regulation, and suppression of some immune response pathways. These findings are contrary to expected sex differences historically attributed to estrogen, given that juvenile female mice are not yet sexually mature and the aged female cohort demonstrates cessation of estrous cycle. Thus, we suggest that mechanisms beyond sex hormones likely explain these significant sex-specific differences across the mouse life-course. Together, distinct trajectories in transcriptomic profile hints to fundamental age-sex-differences in cardiac aging and demonstrates the need for consideration of age and sex as biological variables in heart disease.

Cardiac response to adrenergic stress differs by sex and across the lifespan.

The aging heart is well-characterized by a diminished responsiveness to adrenergic activation. However, the precise mechanisms by which age and sex impact adrenergic-mediated cardiac function remain poorly described. In the current investigation, we compared the cardiac response to adrenergic stress to gain mechanistic understanding of how the response to an adrenergic challenge differs by sex and age. Juvenile (4 weeks), adult (4-6 months), and aged (18-20 months) male and female mice were treated with the β-agonist isoproterenol (ISO) for 1 week. ISO-induced morphometric changes were age- and sex-dependent as juvenile and adult mice of both sexes had higher left ventricle weights while aged mice did not increase cardiac mass. Adults increased myocyte cell size and deposited fibrotic matrix in response to ISO, while juvenile and aged animals did not show evidence of hypertrophy or fibrosis. Juvenile females and adults underwent expected changes in systolic function with higher heart rate, ejection fraction, and fractional shortening. However, cardiac function in aged animals was not altered in response to ISO. Transcriptomic analysis identified significant differences in gene expression by age and sex, with few overlapping genes and pathways between groups. Fibrotic and adrenergic signaling pathways were upregulated in adult hearts. Juvenile hearts upregulated genes in the adrenergic pathway with few changes in fibrosis, while aged mice robustly upregulated fibrotic gene expression without changes in adrenergic genes. We suggest that the response to adrenergic stress significantly differs across the lifespan and by sex. Mechanistic definition of these age-related pathways by sex is critical for future research aimed at treating age-related cardiac adrenergic desensitization.

Vocalizations of infant brown rats, but not infant house mice, enhance rodent captures in sex pheromone-baited traps

Synthetic replica of rat pup, Rattus norvegicus, vocalizations reportedly increase captures of wild rats in traps baited with natural scent of adult female rats. Here we tested the hypotheses (1) that synthetic calls of house mouse pups, Mus musculus, increase captures of wild house mice in traps baited with synthetic sex pheromones of mice, and (2) that synthetic rat pup calls increase captures of wild rats in traps baited with synthetic rat sex pheromones. Analyses of vocalizations from isolated 2- to 4-day-old mouse pups revealed frequency components almost exclusively in the ultrasonic range. In laboratory experiments, playback recordings of these calls, and synthetic replica thereof, each tested versus a silent control or a constant 60-kHz tone, induced phonotactic, arrestment and speaker-contact responses by both “pup-experienced” and “pup-naïve” adult female and adult male mice. In field experiments, synthetic mouse pup calls had no effect on captures of adult and juvenile male mice in female mouse pheromone-baited traps, and reduced captures of juvenile female mice in male mouse pheromone-baited traps. In analogous field experiments with brown rats, traps baited with both synthetic rat pup calls and synthetic rat sex pheromones captured 3.75-times (15 vs 4) more male rats and 2.5-times (15 vs 6) more female rats than traps baited with synthetic sex pheromone alone. We show that synthetic mouse pup vocalizations cannot be exploited as a trap lure to enhance trap captures of mice. Conversely, synthetic rat pup vocalizations enhance the attractiveness of synthetic sex pheromone lures to male and female rats and could become part of integrated brown rat management.

Early postnatal l-Dopa treatment causes behavioral alterations in female vs. male young adult Swiss mice

Dopaminergic signaling and neurodevelopment alterations are associated with several neuropsychiatric disorders. Knockout mice for dopamine transporters (DAT) as well as site-specific knockout mice lacking dopaminergic D2 autoreceptors in dopaminergic neurons (DA-D2RKO) display behavioral alterations such as hyperlocomotion and abnormal prepulse inhibition. However, it is possible that dopaminergic imbalances may have different effects during varied neurodevelopmental windows. In our previous study, we observed that elevated levels of dopamine during the perinatal developmental window increased exploratory behavior of juvenile (4-week-old) Swiss female mice and impaired hedonic behavior in males. In this study, we investigated whether these behavioral alterations persist through young adulthood. In order to do so, we administered daily doses of l-Dopa to mice pups beginning from postnatal day 1 (PD1) to PD5. At the age of 8 weeks, we submitted the young adult males and females to the open field test, elevated plus maze, forced swimming test, and sucrose preference test. We observed that augmentation of dopamine levels during the perinatal developmental window increased locomotor behavior in females, but not males. We also observed an increase in anxiety-behavior in females and anxiolytic-like behavior in males. In addition, we observed stress-coping behavior in males and an increase of hedonic behavior in females. Our results show that dopamine signaling is important for behavioral development and that transient imbalances of dopamine levels can cause permanent behavioral alterations – alterations which are different in males than in females. These data may help in better understanding the spectrum of symptoms associated with different neuropsychiatric disorders.