Young Female Rats Research Articles

Tooth eruption status and bite force determine dental microwear texture gradients in albino rats (Rattus norvegicus forma domestica).

Dental microwear texture analysis (DMTA) is widely applied for inferring diet in vertebrates. Besides diet and ingesta properties, factors like wear stage and bite force may affect microwear formation, potentially leading to tooth position-specific microwear patterns. We investigated DMTA consistency along the upper cheek tooth row in young adult female rats at different growth stages, but with erupted adult dentitions. Bite forces for each molar (M) position were determined using muscle cross-sectional areas and lever arm mechanics. Rats were categorized into three size classes based on increasing skull length. Maximum bite force increased with size, while across all size classes, M3 bite force was almost 1.4 times higher than M1 bite force. In size class 1, M1 and M2 showed higher values than M3 for DMTA complexity, height, and volume parameters, while in size class 3, M1 had the lowest values. Comparing the same tooth position between size classes revealed opposing trends: M1 and M2 showed, for most parameters, decreasing roughness and complexity from size class 1-3, while M3 displayed the opposite trend, with size class 1 showing lowest, and either size class 2 or 3 the highest roughness and complexity values. This suggests that as rats age and M3 fully occludes, it becomes more utilized during mastication. DMTA, being a short-term diet proxy, is influenced by eruption and occlusion status changes. Our findings emphasize the importance of bite force and ontogenetic stage when interpreting microwear patterns and advise to select teeth in full occlusion for diet reconstruction.

Detrimental effect of prenatal progesterone exposure on anxiety and depressive-like responses in adult male and female rat offspring: role of plasma, hippocampal corticosterone and hippocampal progesterone receptors

In clinical practice, the use of exogenous progesterone (Pro) is often required in assisted reproduction programs due to reduced levels of the hormone and the risk of miscarriage. Exposure to the hormone reduces anxiety in rodents, but the long-term effects of prenatal exposure in adult offspring are unknown. Therefore, the present study was designed to investigate the effect of prenatal Pro treatment on anxiety- and depression-like behavior and the effect on plasma, hippocampal corticosterone (CORT) and hippocampal progesterone receptor (PR) in young adult male and female rat offspring. The behavioral responses of offspring of both sexes were tested in the open field, and the elevated plus maze tests, and for depressive-like behavior in the sucrose preference test, the forced swimming test and the splash test. CORT levels and PR expression were measured by ELISA. The results indicate that prenatal Pro exposure at low and high doses (10 and 50 mg/kg, s.c. during G0-G10) induces anxiogenic and depressive-like effects compared to vehicle-treated controls, which are associated with high plasma and hippocampal CORT levels and upregulated hippocampal PR in male and female adult offspring. Our results demonstrate that prenatal Pro exposure has detrimental effects on the emotional status of male and female adult offspring, which may be associated with long-term changes in hormonal homeostasis.

Metabolic and Reproductive Parameters in Young Female Rats Subjected to Feed Restriction and/or Ginger Oil Administration

Background It is well known that the medicinal plant ginger (Zingiber officinale) has anti-oxidative properties that shield tissues and organs against oxidative damage. Aims Forty-eight, 9-week-old Sprague Dawley female rats (159±13 g) were used to evaluate the effects of feed restriction and/or ginger oil supplementation on growth, reproductive parameters, and blood metabolites. Methods Animals were randomly divided into 4 treatment groups (12 rats/treatment) in 2 × 2 factorial arrangements: ad libitum feed (CON), 25% feed restriction (G2), ad libitum feeding with 0.2 mL/rat ginger oil (G3), and 25% feed restriction plus 0.2 mL/rat ginger oil (G4). Animals in groups G2 and G4 received 75% of their pre-treatment feed intake (25% restriction). Six rats from each group were sacrificed at the end of treatments for blood and tissue collection, while the remaining rats were mated with mature males. Results No ginger-by-feed restriction interactions were detected in any of the tested parameters. Body size and BW increased as the experiment advanced (P < 0.01). However, G2 had the lowest BW towards the end of the treatment. Glucose was greater (P < 0.05) in feed-restricted animals, while urea nitrogen was greater in animals on ad libitum feeding. Combined ovarian weights and reproductive tract weights were greater in ginger-supplemented than non-supplemented animals. Similarly, rats on ad libitum feeding had greater ovarian weights than those on restricted feeding. Conclusion Ginger oil supplementation appears to have favorable effects on reproductive tract development and ovarian weight regardless of feed restriction.

Depression-like behavior is associated with deficits in cognition and hippocampal neurogenesis in a subset of spinally contused male, but not female, rats

Depression and cognitive deficits present at higher rates among people with spinal cord injury (SCI) compared to the general population, yet these SCI comorbidities are poorly addressed. Sex and age appear to play roles in depression incidence, but consensus on the direction of their effects is limited. Systemic and cortical inflammation and disruptions in hippocampal neurogenesis have been identified as potential treatment targets, but a comprehensive understanding of these mechanisms remains elusive.We used a rodent SCI model to interrogate these gaps in knowledge. We examined post-injury depression-like behavior and cognitive deficits, as well as the association between affect, cognition, chronic hippocampal inflammation and hippocampal neurogenesis, in young and middle-aged male and female Sprague-Dawley rats. Depression-like behavior manifested in male and female subsets of SCI rats irrespective of age, at rates commensurate with the incidence of clinical depression. Changes in components of behavior were driven by sex and age, and affective outcomes were independent of common post-injury pathophysiological outcomes including locomotor functional deficits and spinal lesion severity. Interestingly, however, only male depression-like SCI rats exhibited deficits in hippocampal-associated spatial cognition. Neurogenesis was also disrupted in only SCI males in regions of the hippocampus responsible for affective outcomes. Decreased neurogenesis among middle-aged male subjects coincided with increases in numbers of the pro-inflammatory markers CD86 and iNOS, while middle-aged females had increased numbers of cells expressing Iba-1 and anti-inflammatory marker CD206.Overall, the present data suggest that post-SCI depression and cognition may be affected, in part, by sex- and age-dependent changes in hippocampal neurogenesis and inflammation. Hippocampal neurogenesis is a potential target to address psychological wellbeing after SCI, but therapeutic strategies must carefully consider sex and age as biological variables.

Peripubertal antagonism of corticotropin-releasing factor receptor 1 results in sustained, sex-specific changes in behavioral plasticity and the transcriptomic profile of the amygdala.

Peripuberty is a significant period of neurodevelopment with long-lasting effects on the brain and behavior. Blocking type 1 corticotropin-releasing factor receptors (CRFR1) in neonatal and peripubertal rats attenuates detrimental effects of early-life stress on neural plasticity, behavior, and stress hormone action, long after exposure to the drug has ended. CRFR1 antagonism can also impact neural and behavioral development in the absence of stressful stimuli, suggesting sustained alterations under baseline conditions. To investigate this further, we administered a CRFR1 antagonist (CRFR1a), R121919, to young adolescent male and female rats across 4 days. Following each treatment, rats were tested for locomotion, social behavior, mechanical allodynia, or PPI of the acoustic startle reflex. Acute CRFR1 blockade immediately reduced PPI in peripubertal males, but not females. In adulthood, each assay was repeated without CRFR1a exposure to test for long-term effects of the adolescent treatment, with males continuing to experience deficits in PPI, while females displayed altered locomotion, PPI, and social behavior. The amygdala was collected to measure long-term effects on gene expression in pathways related to neural plasticity and neurodevelopmental disorders. Relative expression of cannabinoid type 1 receptors (CB1R), which mediate sensorimotor and HPA function, was also measured. In the adult amygdala, peripubertal CRFR1a induced alterations in pathways related to neural plasticity and stress in males and lower expression of CB1R protein in females. Understanding how acute exposure to neuropharmacological agents can have sustained impacts on brain and behavior, in the absence of further exposures, has important clinical implications for adolescent psychiatric treatment protocols.

Combination of low doses of mirtazapine plus venlafaxine produces antidepressant-like effects in rats, without affecting male or female sexual behavior.

Pharmacological treatments for depression are not always effective and produce unwanted side effects. Male and female sexual dysfunction is one of these side effects, which can lead to treatment withdrawal. Combination of two antidepressants with different mechanisms of action, like mirtazapine (MTZ) and venlafaxine (VLF) have been shown to be effective for treatment-resistant depression in humans. Combination of low doses of these drugs may still exert antidepressant-like effects without altering sexual behavior. To investigate the potential antidepressant-like effect of the chronic administration of low doses of MTZ plus VLF combined, as well as its impact on male and female sexual behavior in rats. The antidepressant-like effect of a 14-day treatment with combinations of MTZ plus VLF (0/0, 2.5/3.75 or 5/7.5mg/kg) was assessed in young adult male and female rats in the forced swim test (FST). The 5/7.5mg/kg MTZ/VLF combination was also tested in the chronic mild stress (CMS) test, in both males and females treated for 21days. The sexual effects of this last treatment were assessed in sexually experienced males and in gonadally-intact females during proestrus. The 5/7.5mg/kg MTZ/VLF combination produced an antidepressant-like effect in the FST and reversed the CMS-induced anhedonia in both male and female rats. This combination did not alter male sexual behavior, female proceptive and receptive behaviors or the regularity of the estrous cycle. The combination of low doses of MTZ and VLF might be a promising therapeutic alternative to treat depression without affecting the sexual response.

Distribution and morphologic characterization of telocytes in rat ovary and uterus: insights from ultrastructural and immunohistochemical analysis

Telocytes (TCs) are characterized by a small oval-shaped cell body with long prolongations that are called telopods (Tps). PDGFR-β and c-kit markers may assist for the immunohistochemical identification of TCs; however, by these means they cannot be identified with absolute specificity. Transmission electron microscopy (TEM) is considered as a gold standard method for TCs observation. Studies on TCs in the female reproductive system are limited, and there is a lack of awareness regarding TCs in rat ovaries. We aimed to demonstrate the existence and morphology of TCs in rat ovaries, alongside previously studied TCs in rat uteri. Thus, ovaries and uteri from young adult Sprague–Dawley female rats (n = 8) with regular estrous cycles were collected. Then, left ovaries and uteri were proccessed for TEM analysis, while the right ones were used for immunohistochemistry. As a result, TCs were seen throughout the rat’s ovarian stroma with their characteristic cell bodies, Tps, podomes (Pds) and podomers (Pdms). Tps were situated within the thecal layer of the follicles, surrounding the corpus luteum and blood vessels. Ovarian TCs were recognized to have relationship with other TCs/stromal cells. Subsequently, TCs were seen in stroma of endometrium with surrounding blood vessels and uterine glands, myometrium and perimetrium in rat uteri. There was also no statistical significance between the number of c-kit+ and PDGFR-β+ telocyte-like cells in both rat ovarian (p = 0.137) and endometrial stroma (p = 0.450). Further investigation of the roles and functions of TCs in the female reproductive system is needed.

The Liver of Young and Old Female Rats Exhibits Heightened Susceptibility to Dichlorvos Exposure

Exposure to industrial and agricultural environmental contaminants has been shown to produce deleterious effects on different organs of the human body. Dichlorvos [O, O-dimethyl O-(2,2-dichlorovinyl) phosphate, DDVP] is a major organophosphate pesticide used mostly in developing countries for domestic and agricultural insect control. The toxic effects of DDVP have been reported on many organs. However, its gender and age-dependent effects on the liver are yet to be documented. This study investigated the influence of gender and age on liver damage in male and female rats exposed to DDVP. Animals were divided into control and experimental groups with age and gender classification. Using age, rats were classified into young, middle-aged, and old age groups. Rats in the experimental groups were exposed to DDVP from 8 am to 12 noon for five weeks. Rats were subsequently euthanized and liver tissues were harvested for biochemical assay. Glutamyl transferase (GGT), Alanine aminotransferase (ALT), Aspartate aminotransferase (AST), Alkaline phosphatase (ALP), Lactate dehydrogenase (LDH), Albumin, and conjugated bilirubin were assayed using ELISA kits. Statistical analysis was done using two-way ANOVA, followed by Tukey post-Hoc test at significance level of p<0.05. Our study found that DDVP exposure caused liver damage in female rats only with significant elevation in liver enzymes such as ALP, ALT, AST, and LDH. However, the male rats showed more resistance to DDVP exposure. The liver damage observed in female rats was age-dependent, with young and old rats showing higher susceptibility compared to middle-aged female rats. Nutritional and pharmacological strategies are recommended to mitigate the effect of DDVP exposure, particularly in populations at higher risk of exposure.

Polyethylene glycol fusion repair of severed rat sciatic nerves reestablishes axonal continuity and reorganizes sensory terminal fields in the spinal cord.

JOURNAL/nrgr/04.03/01300535-202507000-00030/figure1/v/2024-09-09T124005Z/r/image-tiff Peripheral nerve injuries result in the rapid degeneration of distal nerve segments and immediate loss of motor and sensory functions; behavioral recovery is typically poor. We used a plasmalemmal fusogen, polyethylene glycol (PEG), to immediately fuse closely apposed open ends of severed proximal and distal axons in rat sciatic nerves. We have previously reported that sciatic nerve axons repaired by PEG-fusion do not undergo Wallerian degeneration, and PEG-fused animals exhibit rapid (within 2-6 weeks) and extensive locomotor recovery. Furthermore, our previous report showed that PEG-fusion of severed sciatic motor axons was non-specific, i.e., spinal motoneurons in PEG-fused animals were found to project to appropriate as well as inappropriate target muscles. In this study, we examined the consequences of PEG-fusion for sensory axons of the sciatic nerve. Young adult male and female rats (Sprague-Dawley) received either a unilateral single cut or ablation injury to the sciatic nerve and subsequent repair with or without (Negative Control) the application of PEG. Compound action potentials recorded immediately after PEG-fusion repair confirmed conduction across the injury site. The success of PEG-fusion was confirmed through Sciatic Functional Index testing with PEG-fused animals showing improvement in locomotor function beginning at 35 days postoperatively. At 2-42 days postoperatively, we anterogradely labeled sensory afferents from the dorsal aspect of the hindpaw following bilateral intradermal injection of wheat germ agglutinin conjugated horseradish peroxidase. PEG-fusion repair reestablished axonal continuity. Compared to unoperated animals, labeled sensory afferents ipsilateral to the injury in PEG-fused animals were found in the appropriate area of the dorsal horn, as well as inappropriate mediolateral and rostrocaudal areas. Unexpectedly, despite having intact peripheral nerves, similar reorganizations of labeled sensory afferents were also observed contralateral to the injury and repair. This central reorganization may contribute to the improved behavioral recovery seen after PEG-fusion repair, supporting the use of this novel repair methodology over currently available treatments.

Serine racemase expression profile in the prefrontal cortex and hippocampal subregions during aging in male and female rats.

Aging is associated with a decrease in N-methyl-D-aspartate (NMDA) receptor function, which is critical for maintaining synaptic plasticity, learning, and memory. Activation of the NMDA receptor requires binding of the neurotransmitter glutamate and also the presence of co-agonist D-serine at the glycine site. The enzymatic conversion of L-serine to D-serine is facilitated by the enzyme serine racemase (SR). Subsequently, SR plays a pivotal role in regulating NMDA receptor activity, thereby impacting synaptic plasticity and memory processes in the central nervous system. As such, age-related changes in the expression of SR could contribute to decreased NMDA receptor function. However, age-associated changes in SR expression levels in the medial and lateral prefrontal cortex (mPFC, lPFC), and in the dorsal hippocampal subfields, CA1, CA3, and dentate gyrus (DG), have not been thoroughly elucidated. Therefore, the current studies were designed to determine the SR expression profile, including protein levels and mRNA, for these regions in aged and young male and female Fischer-344 rats. Our results demonstrate a significant reduction in SR expression levels in the mPFC and all hippocampal subfields of aged rats compared to young rats. No sex differences were observed in the expression of SR. These findings suggest that the decrease in SR levels may play a role in the age-associated reduction of NMDA receptor function in brain regions crucial for cognitive function and synaptic plasticity.

The Effects of Puberty Blocking Treatment (Gonadotropin Releasing Hormone Agonist) on Reproductive Function in Young Female Rats

The number of adolescents identifying as transgender has been increasing with many transgender youth receiving treatment with a gonadotropin releasing hormone agonist (GnRHa) that suppresses sex hormone production (i.e., puberty blocker). Transgender individuals taking a GnRHa to block puberty have reported improved mental wellbeing, but the physiological impact on reproductive function needs to be examined. Objective: To investigate the effects of puberty blocking treatment using GnRHa on reproductive morphology and function in young female rats. It was hypothesized that puberty blocking treatment would decrease fertility. Methods: Four-week old female Sprague Dawley rats were given daily subcutaneous injections of the GnRHa triptorelin or saline as control. After four weeks of treatment a group of rats were euthanized and the uterus and ovaries were removed for H&E staining to assess morphology. An additional group was taken off GnRHa treatment for 4-weeks to examine recovery of reproductive organ morphology. The final group was taken off GnRHa treatment and housed with fertile males to determine reproductive performance. Results: GnRHa treatment led to a reduction in the mass of uteri and ovaries which recovered after 4-weeks of drug withdrawal. The myometrial and endometrial thickness of the uterus was reduced in GnRHa treated animals. The ovaries of puberty blocked animals exhibited a disruption in follicle development and corpora lutea health. The morphology of the uterus and ovaries recuperated after 4-weeks of drug withdrawal. No significant difference in pregnancy rate was detected; however, both the number of days until pregnancy detection and number of days until giving birth were considerably longer in GnRHa rats following withdrawal. The number of pups per litter was also significantly reduced by puberty blocking treatment but no abnormalities were observed in the pups. Conclusion: Young female rats treated with a GnRHa had significantly delayed development of the reproductive organs. After 4 weeks of GnRHa withdrawal reproductive organ mass and morphology recovered. A minor disruption in reproductive function was detected immediately following GnRHa withdrawal. These physiological effects on reproductive health should be considered when administering a GnRHa to block puberty. No external funding was used to support this research. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A pilot exploring the impact of paternal puberty blocking on offspring voluntary wheel running

Previous work from our lab has shown puberty blocking treatment in young female rats followed by discontinued use (or detransition) leads to decreased voluntary wheel running activity in their offspring. The purpose of the present study was to determine if puberty blocking and detransition in young male rats affects offspring voluntary wheel running activity. We hypothesized that offspring of previously puberty blocked male rats will have lower wheel running activity than offspring of control rats. Four week old, male Sprague-Dawley rats received either 100 μg of the gonadotropin releasing hormone agonist triptorelin daily as a puberty blocker or 0.9% saline daily as a control. At the end of the 4 week treatment period, injections ceased, and each male rat was paired with an age-matched female rat for breeding. The breeding period lasted approximately 8 weeks and resulted in pregnancy of each paired female. At 6 weeks of age, a portion of the offspring were randomly assigned to the following voluntary wheel running groups: male offspring of previously puberty blocked males (M-PBO, n=2), female offspring of previously puberty blocked males (F-PBO, n=2), male offspring of control males (M-CON, n=5), and female offspring of control males (F-CON, n=5). Offspring were housed in cages outfitted with voluntary running wheels, received food and water ad libitum, and were maintained on a12:12 hour light:dark cycle. Voluntary wheel running activity was monitored for 8 weeks, and between-group comparisons were made via Welch’s t-test. Voluntary wheel running activity is presented as number of wheel running rotations, and data are shown as mean ± standard error. For total wheel running activity over 8 weeks, M-PBO had significantly lower voluntary wheel running activity than M-CON (107,453 ± 50,683 rotations vs. 456,011 ± 62,970 rotations, respectively, p=0.0122). There were no differences observed, however, between F-PBO and F-CON for total 8-week wheel running activity (376,582 ± 1,847 rotations vs. 472,271 ± 116,017 rotations, p=0.4559). Additionally, M-PBO ran significantly less than M-CON in weeks 1, 2, 3, 6, 7, and 8 (Week 1: 5,606 ± 225 rotations vs. 17,824 ± 2,544 rotations, p=0.0084; Week 2: 11,537 ± 3,129 rotations vs. 51,882 ± 6,494 rotations, p=0.0025; Week 3: 10,157 ± 2,639 rotations vs. 79,257 ± 5,842 rotations, p=0.0001; Week 6: 15,816 ± 7,865 rotations vs. 64,425 ± 11,755 rotations, p=0.0207; Week 7: 14,068 ± 6,999 rotations vs. 58,112 ± 9,781 rotations, p=0.0178; Week 8: 13,234 ± 6351 rotations vs. 67,349 ± 16,142 rotations, p=0.0272, respectively). No differences were observed in weekly wheel running activity between F-PBO and F-CON. Based on the observed voluntary wheel running activity, puberty blocking male rats prior to breeding negatively impacted physical activity of male offspring but not female offspring. This is contrary to our previous work showing that puberty blocking treatment followed by detransition in female rats prior to breeding negatively impacted physical activity of both male and female offspring. Our hypothesis was therefore partially supported as M-PBO had significantly less wheel running activity than M-CON, but F-PBO and F-CON had similar wheel running activity. Supported by a University of Northern Colorado Provost's Seed Grant awarded to DSH. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Metabolic-Dysfunction Associated Liver Disease Progresses Independent of Weight in a Rodent Model

Background: Metabolic dysfunction associated steatotic liver disease (MASLD) is the most prevalent liver disease worldwide with an estimated 25% of U.S. adults having MASLD. MASLD is typically regarded as a diet driven disease, with the Western diet (high fat, high sugar, low fiber) being a major driver. Recently, evidence suggests MASLD can be present regardless of body weight. There is not good evidence on how prevalent this is, but reports suggest it could be as high as nearly 30% of MASLD patients. As such, there is a critical need to better understand MASLD independent of weight to ensure all individuals with the disease are receiving proper diagnosis and treatment. Methods: Young female rats were fed either a Control (AIN-93G) or Western (45% fat, 34% sugar) diet for 8 weeks. Histology, RT-qPCR, and standard biological assays were performed to analyze differences in hepatic function and fatty acid analysis was used to analyze fatty acid deposition in the liver, adipose tissue, and brain. Results: There were no statistically significant differences in the weights of rats consuming a Control or Western diet. However, consuming a Western diet had increased histological evidence of fat deposition and inflammation compared to Control. Rats consuming a Western diet also displayed increased ( p<0.05) hepatic triglyceride content and relative expression of several key genes involved in lipogenesis and oxidative stress. Fatty acid analysis found Western diet rats to have increased (p<0.05) hepatic monounsaturated fatty acid (MUFA) content, while adipose tissue of those same animals had decreased (p<0.05) MUFAs. Conclusions: The Western diet plays a significant role in the development of MASLD independent of differences in weight. This model may serve to better elucidate mechanisms at play in lean MASLD. We are currently conducting additional experiments on the role of alcohol in this phenomenon. WVU Davis College Dean's Opportunity Fund and the UVM Food Systems Research Center. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

A new bicornuate model of rat uterus transplantation.

Uterus transplantation has revolutionized reproductive medicine for women with absolute uterine factor infertility, resulting in more than 40 reported successful live births worldwide to date. Small animal models are pivotal to refine this surgical and immunological challenging procedure aiming to enhance safety for both the mother and the child. We established a syngeneic bicornuate uterus transplantation model in young female Lewis rats. All surgical procedures were conducted by an experienced and skilled microsurgeon who organized the learning process into multiple structured steps. Animals underwent meticulous preoperative preparation and postoperative care. Transplant success was monitored by sequential biopsies, monitoring graft viability and documenting histological changes long-term. Bicornuate uterus transplantation were successfully established achieving an over 70% graft survival rate with the passage of time. The bicornuate model demonstrated safety and feasibility, yielding outcomes comparable to the unicornuate model in terms of ischemia times and complications. Longitudinal biopsies were well-tolerated, enabling comprehensive monitoring throughout the study. Our novel bicornuate rat uterus transplantation model provides a distinctive opportunity for sequential biopsies at various intervals after transplantation and, therefore, comprehensive monitoring of graft health, viability, and identification of potential signs of rejection. Furthermore, this model allows for different interventions in each horn for comparative studies without interobserver differences contrary to the established unicornuate model. By closely replicating the clinical setting, this model stands as a valuable tool for ongoing research in the field of uterus transplantation, promoting further innovation and deeper insights into the intricacies of the uterus transplant procedure.

Ethanolic extract of Persea americana Mill. (Lauraceae) seeds induced antiestrogenic effects in young female Wistar rats.

The ethanol extract of Persea americana seeds was found to inhibit the development of estrogen-dependent conditions in female Wistar rats, suggesting the ability of its secondary metabolites to interact with estrogen receptors (ERs), either as partial agonists or as antagonists. To test this hypothesis, the abovementioned extract was assessed for its ability to mimic and/or antagonize estradiol effects. Two experiments were conducted in ovariectomized (OVX) rats: (1) animals were treated with estradiol valerate (E2V; 1 mg/kg) or P.americana at doses of 25 and 50 mg/kg; (2) animals were treated with E2V alone (0.75 mg/kg) or in combination with P.americana at the abovementioned doses. Treatments were given orally for 3days and animals were sacrificed for biochemical and histological analyses of the uterus and vagina. When administered alone, P.americana did not change the histomorphology of both organs (uterus and vagina). In combination with E2V, P.americana decreased uterine weight [30 % decrease (p<0.001) at 25 mg/kg and 24 % (p<0.01) at 50 mg/kg] and epithelium height (37 % decrease). This was associated with decreased estradiol levels (at least 86 % decrease, p<0.001) in the uterus. Similarly, vagina epithelium height decreased by at least 34 % (p<0.05) when E2V was co-administered with P.americana. The seed extract of P.americana contains ER antagonist secondary metabolites accounting for its ability to inhibit the development of estrogen-dependent conditions in female rats.

Mitochondrial remodeling underlying age-induced skeletal muscle wasting: let’s talk about sex

Sarcopenia is associated with reduced quality of life and premature mortality. The sex disparities in the processes underlying sarcopenia pathogenesis, which include mitochondrial dysfunction, are ill-understood and can be decisive for the optimization of sarcopenia-related interventions. To improve the knowledge regarding the sex differences in skeletal muscle aging, the gastrocnemius muscle of young and old female and male rats was analyzed with a focus on mitochondrial remodeling through the proteome profiling of mitochondria-enriched fractions. To the best of our knowledge, this is the first study analyzing sex differences in skeletal muscle mitochondrial proteome remodeling. Data demonstrated that age induced skeletal muscle atrophy and fibrosis in both sexes. In females, however, this adverse skeletal muscle remodeling was more accentuated than in males and might be attributed to an age-related reduction of 17beta-estradiol signaling through its estrogen receptor alpha located in mitochondria. The females-specific mitochondrial remodeling encompassed increased abundance of proteins involved in fatty acid oxidation, decreased abundance of the complexes subunits, and enhanced proneness to oxidative posttranslational modifications. This conceivable accretion of damaged mitochondria in old females might be ascribed to low levels of Parkin, a key mediator of mitophagy. Despite skeletal muscle atrophy and fibrosis, males maintained their testosterone levels throughout aging, as well as their androgen receptor content, and the age-induced mitochondrial remodeling was limited to increased abundance of pyruvate dehydrogenase E1 component subunit beta and electron transfer flavoprotein subunit beta. Herein, for the first time, it was demonstrated that age affects more severely the skeletal muscle mitochondrial proteome of females, reinforcing the necessity of sex-personalized approaches towards sarcopenia management, and the inevitability of the assessment of mitochondrion-related therapeutics.

Age and Sex in the Development of Hepatic Encephalopathy: Role of Alcohol.

Hepatic encephalopathy (HE) is a neurological condition linked to liver failure. Acute HE (Type A) occurs with acute liver failure, while chronic HE (Type C) is tied to cirrhosis and portal hypertension. HE treatments lag due to gaps in understanding its development by gender and age. We studied how sex and age impact HE and its severity with combined liver toxins. Our findings indicate that drug-induced (thioacetamide, TAA) brain edema was more severe in aged males than in young males or young/aged female rats. However, adding alcohol (ethanol, EtOH) worsens TAA's brain edema in both young and aged females, with females experiencing a more severe effect than males. These patterns also apply to Type A HE induced by azoxymethane (AZO) in mice. Similarly, TAA-induced behavioral deficits in Type C HE were milder in young and aged females than in males. Conversely, EtOH and TAA in young/aged males led to severe brain edema and fatality without noticeable behavioral changes. TAA metabolism was slower in aged males than in young or middle-aged rats. When TAA-treated aged male rats received EtOH, there was a slow and sustained plasma level of thioacetamide sulfoxide (TASO). This suggests that with EtOH, TAA-induced HE is more severe in aged males. TAA metabolism was similar in young, middle-aged, and aged female rats. However, with EtOH, young and aged females experience more severe drug-induced HE as compared to middle-aged adult rats. These findings strongly suggest that gender and age play a role in the severity of HE development and that the presence of one or more liver toxins may aggravate the severity of the disease progression.

Adolescent activity-based anorexia has a substantial and prolonged impact on social behavior in young adult female rats

Activity-based anorexia (ABA) is a rodent model of anorexia nervosa (AN) that induces several key components of AN, including voluntary reduction in food intake, reduced body weight, hyperactivity, and alterations to the hypothalamic-pituitary-adrenal (HPA) axis. Previous research has demonstrated persistently increased anxiety-like behavior in the elevated plus maze (EPM), a test measuring avoidance of novel and open areas in adult female rats that experienced ABA during adolescence and are weight-restored in adulthood. Whether the same behavioral effects of two bouts of adolescent ABA emerge in response to different anxiety-provoking stimuli, however, has not been explored. We used the social partition (SP), novelty suppressed feeding (NSF), marble burying, and EPM tests to explore whether two bouts of adolescent ABA have persistent effects on anxiety-like behavior in weight restored young adult female rats. One-way ANOVA analyses revealed that female rats that experienced two bouts of ABA during adolescence had increased anxiety-like behavior in the EPM and SP tests in young adulthood following weight restoration compared with controls. These data demonstrate that the enduring behavioral effects of two bouts of adolescent ABA are specific to particular anxiety-provoking stimuli and suggest that adolescent ABA has enduring effects on social relationships.

Complex alterations in inflammatory pain and analgesic sensitivity in young and ageing female rats: involvement of ASIC3 and Nav1.8 in primary sensory neurons.

Our aim was to determine an age-dependent role of Nav1.8 and ASIC3 in dorsal root ganglion (DRG) neurons in a rat pre-clinical model of long-term inflammatory pain. We compared 6 and 24months-old female Wistar rats after cutaneous inflammation. We used behavioral pain assessments over time, qPCR, quantitative immunohistochemistry, selective pharmacological manipulation, ELISA and in vitro treatment with cytokines. Older rats exhibited delayed recovery from mechanical allodynia and earlier onset of spontaneous pain than younger rats after inflammation. Moreover, the expression patterns of Nav1.8 and ASIC3 were time and age-dependent and ASIC3 levels remained elevated only in aged rats. In vivo, selective blockade of Nav1.8 with A803467 or of ASIC3 with APETx2 alleviated mechanical and cold allodynia and also spontaneous pain in both age groups with slightly different potency. Furthermore, in vitro IL-1β up-regulated Nav1.8 expression in DRG neurons cultured from young but not old rats. We also found that while TNF-α up-regulated ASIC3 expression in both age groups, IL-6 and IL-1β had this effect only on young and aged neurons, respectively. Inflammation-associated mechanical allodynia and spontaneous pain in the elderly can be more effectively treated by inhibiting ASIC3 than Nav1.8.

Differential Effect of Chronic Morphine on Neuronal Degeneration in Male vs. Female Mice.

Opioid abuse in the United States has been increasing at an alarming rate over the past 20 years. Sex differences are documented for the rates of opioid-related overdoses, abuse patterns, and drug-induced physiological effects. In our previous study, we demonstrated that chronic oxycodone administration in young female rats is associated with neurodegeneration in the brain. Males and females are susceptible to neurodegenerative diseases via differing mechanisms. To investigate whether opioid exposure affects males and females differently, we treated young mice with chronic morphine. We observed that females had stronger antinociceptive responses to acute morphine and showed a delayed development of tolerance. Males had a higher basal Bax level in the brain that correlated with a higher number of apoptotic cells. Morphine increased Bax levels in both males and females without affecting the numbers of apoptotic cells. Morphine increased activated caspase 3 in axons and increased the MBP level in plasma only in females, suggesting a demyelination process. Our data suggest that males are protected from demyelination by having a higher basal BDNF level. Altogether, our results suggest that males and females have different molecular signaling underlying their patterns in the development of morphine tolerance and drug-induced neuronal degeneration.