Stages Of Estrous Cycle Research Articles

Tamm-Horsfall Protein Expression in Urine of Buffaloes at the Estrus and Diestrus Stages of Estrous Cycle

Background: Identifying buffaloes in estrus is crucial for enhancing the efficiency of reproduction as silent heat is a major concern in this species. Review of literature indicated the role of Tamm-Horsfall protein (THP) is associated with the physiological events around the estrus stage. Hence, the present study was aimed to quantify the expression level of THP in urine of buffaloes to ascertain its suitability as a marker for identifying buffaloes in estrus. Methods: The grouping of animals as mid-diestrus (Group-I/G-I/Control group), regular estrus (Group-II/G-II) and silent estrus (Group-III/G-III) buffaloes was done using a combinatorial approach. The expression of THP in the urine of three groups of animals was quantified by western blot. Result: The results of the present study revealed higher levels of urinary THP in G-II animals when compared to G-III and G-I animals, although it was statistically non-significant (p greater than 0.05). The present study revealing for increased urinary expression of THP in G-II and G-III animals when compared to G-I animals probably construes the antimicrobial role of THP in the female reproductive tract and its role during estrus to prevent microbiota population beyond the physiological levels. For THP to be considered as biomarker for detecting buffaloes in silent heat there is need for further studies involving large number of animals. Nonetheless, an easy method has been developed that facilitated THP detection and quantification in urine of buffaloes by western blot.

Distribution of degenerative changes in the equine endometrium as observed in a single versus two biopsies

Equine endometrial degeneration is diagnosed by microscopy of an endometrial biopsy but it is uncertain if findings in a single biopsy represent the state of the entire endometrium. Previous studies have compared samples from multiple sites but conclusions are inconsistent. Further clarification is therefore needed. In this study, presence and characteristics of endometrial degeneration were compared in two full thickness specimens from the ventral base of both uterine horns, obtained post mortem from cyclic mares (n = 82). Hematoxylin and eosin-stained sections were blinded evaluated for periglandular fibrosis, glandular nests, dilated glands, glandular dilation, excessive lymphatic vessels, and lymphatic lacunae. Each section was also assigned to a modified Kenney and Doig categorization. Statistical analysis included multiple logistic regression models for fraction of mares with disagreement in the modified Kenney and Doig category and fraction of mares with disagreement for each parameter, multiple generalized linear regression models for fraction of parameters with disagreement, and equivalence tests for agreement of a cumulative score of degenerative parameters. Possible effect of age, mare type and estrous cycle stage were included in the analyses. For the Kenney and Doig categorization, 49% of the mares had good agreement, 46% had moderate agreement and 5% had poor agreement between the two biopsies. Disagreement in the Kenney and Doig categorization between the two biopsies increased with age (OR = 1.1, P = 0.009). Disagreement within each parameter ranged from 10% of mares (glandular nests), to 31% (periglandular fibroblasts) and 37% (lymphatic lacunae). Disagreement for changes in endometrial glands increased with age (OR = 1.15–1.16, P < 0.040). Several mares (33%) had disagreement in at least two parameters, and the number of parameters with disagreement increased with age (HR = 1.04, P = 0.010). When tested for equivalence, the cumulative scores for paired endometrial samples did not differ for mares younger than 18 years (P = 0.011). In conclusion, the degenerative changes were not uniformly distributed, revealed by a disagreement between paired endometrial samples for individual parameters and for the Kenney and Doig categorization, which increased with age. This suggests that conclusions based on a single biopsy, particularly in mares over 17 years of age, should be interpreted with caution, and evaluation of two biopsies should be considered.

Hedgehog signaling is required for endometrial remodeling and myometrial homeostasis in the cycling mouse uterus

Decades of work demonstrate that the mammalian estrous cycle is controlled by cycling steroid hormones. However, the signaling mechanisms that act downstream, linking hormonal action to the physical remodeling of the cycling uterus, remain unclear. To address this issue, we analyzed gene expression at all stages of the mouse estrous cycle. Strikingly, we found that several genetic programs well-known to control tissue morphogenesis in developing embryos displayed cyclical patterns of expression. We find that most of the genetic architectures of Hedgehog signaling (ligands, receptors, effectors, and transcription factors) are transcribed cyclically in the uterus, and that conditional disruption of the Hedgehog receptor smoothened not only elicits a failure of normal cyclical thickening of the endometrial lining but also induces aberrant deformation of the uterine smooth muscle. Together, our data shed light on the mechanisms underlying normal uterine remodeling specifically and cyclical gene expression generally.

Collection and Analysis of Vaginal Smears to Assess Reproductive Stage in Mice.

An increasing number of scientific studies include female mice to assess possible sex differences. As such, for reproducibility by others, it is important to consider hormonal levels, i.e., report the reproductive status of the female mice used. The mouse estrous cycle can be divided in 4 stages, all characterized by a different proportion of 3 cell types found in vaginal secretions. Observation of the mouse vaginal opening and collection of vaginal smears for analysis of cytology can be done in order to determine puberty onset and estrus stage. This protocol describes the characteristics of each estrus stage and details a quick and low-invasive method for collection of vaginal secretions. Examples of estrous cycle stages are included to help the investigator visualize patterns of cyclicity, which can provide important information about the reproductive health of the mice. Published 2023. This article is a U.S. Government work and is in the public domain in the USA. Basic Protocol 1: Visual assessment of vaginal opening Basic Protocol 2: Collection of vaginal secretion (smears).

Estrous cycle dependent expression of oxycodone conditioned reward in rats

Oxycodone is one of the most widely prescribed and misused opioid painkillers in the United States. Evidence suggests that biological sex and hormonal status can impact drug reward in humans and rodents, but the extent to which these factors can influence the rewarding effects of oxycodone is unclear. The purpose of this study was to utilize place conditioning to determine the effects of sex and female hormonal status on the expression of oxycodone conditioned reward in rats. Gonadally intact adult Sprague-Dawley male and female rats were used to test: (1) whether both sexes express conditioned reward to oxycodone at similar doses, (2) the impact of conditioning session length on oxycodone conditioned reward expression in both sexes, and (3) the influence of female estrous cycle stage on oxycodone conditioned reward expression. Both sexes expressed conditioned reward at the same doses of oxycodone. Increasing the length of conditioning sessions did not reveal an effect of sex and resulted in lower magnitude conditioned reward expression. Importantly however, female stage of estrous cycle significantly influenced oxycodone conditioned reward expression. These results suggest that female hormonal status can impact the rewarding effects of opioids and thus have important implications for prescription opioid treatment practices.

Efecto de la fase del ciclo estral en la maduración in vitro de ovocitos de gatas domésticas criadas en condiciones tropicales

Oocyte maturation is a critical step for in vitro embryo production. In female cats, findings on the influence of the estrous cycle stage on oocyte quality and maturation are contradictory. Little is known about this phenomenon in female cats in the tropics. This study aimed to assess the effect of the estrous cycle stage on oocyte quality and subsequent capacity to complete nuclear maturation in cats in a tropical environment. Ovaries from 18 sexually matured cats were collected during ovariohysterectomy. Cumulus–oocyte complexes (COCs) were released from follicles by slicing and fragmentation of the ovarian cortex. According to morphological characteristics, COCs were classified into grades I–II (suitable) and III–IV (no suitable). Only suitable COCs from each cat were cultured for in vitro maturation. Nuclear oocyte maturation was assessed by the presence of a telophase I or metaphase II plate with extrusion of the first polar corpuscle. A significantly greater number of oocytes per ovary were collected from queens in inactive than in follicular or luteal phase. Proportions of suitable COCs were similar among groups. Rate of oocyte maturation did not differ among stages of the estrous cycle, nor did the proportion of non–matured or degenerated oocytes. The age of the queens did not affect the percentage of oocyte maturation. In conclusion, the quality and rate of oocytes maturation were similar in the three stages of estrous cycle examined.

Age-related sex differences in tongue strength and muscle morphometry in a rat model

ObjectiveTo investigate potential effects of sex on voluntary tongue strength, evoked twitch and tetanic tension, speed of contraction, and muscle fiber cross-sectional area in the muscles of the rat tongue. Additionally, we aimed to determine whether estrous cycle stage impacts any of the dependent variables as a pilot investigation into the use of female rats in a model of tongue exercise and aging. DesignFischer 344-Brown Norway male and female rats in two age groups (16 middle-aged, 16 young-adult) were trained to use a tongue force operandum. Tongue muscle contraction, myosin heavy chain (MyHC) composition, and cross section area of the genioglossus and styloglossus muscles were examined. Vaginal lavage determined estrous cycle stage of the female rats daily. ResultsThe female group had significantly lower evoked twitch and tetanic tension, longer contraction times, and a smaller proportion of MyHC type IIa and MyHC type IIx in the styloglossus muscle. There was no significant sex effect in maximal voluntary tongue force (MVTF) despite a significant weight difference between the male and female groups. There were no significant age or sex effects in the genioglossus. Estrous cycle stage did not have a significant effect on any of the dependent variables. ConclusionsSex and age both have a significant effect on tongue muscle structure and physiology. While the female group showed reduced contraction speed and maximal twitch and tetanic tension relative to the male group, differences in muscle morphology appeared to vary by muscle.

Lower female survival from an opportunistic infection reveals progesterone-driven sex bias in trained immunity

Immune responses differ between females and males, although such sex-based variance is incompletely understood. Observing that bacteremia of the opportunistic pathogen Burkholderia gladioli caused many more deaths of female than male mice bearing genetic deficiencies in adaptive immunity, we determined that this was associated with sex bias in the innate immune memory response called trained immunity. Female attenuation of trained immunity varies with estrous cycle stage and correlates with serum progesterone, a hormone that decreases glycolytic capacity and recall cytokine secretion induced by antigen non-specific stimuli. Progesterone receptor antagonism rescues female trained immune responses and survival from controlled B.gladioli infection to magnitudes similar to those of males. These data demonstrate progesterone-dependent sex bias in trained immunity where attenuation of female responses is associated with survival outcomes from opportunistic infection.

Rat brown adipose tissue thermogenic markers are modulated by estrous cycle phases and short-term fasting.

Brown adipose tissue (BAT) converts chemical energy into heat to maintain body temperature. Although fatty acids (FAs) represent a primary substrate for uncoupling protein 1 (UCP1)-dependent thermogenesis, BAT also utilizes glucose for the same purpose. Considering that estrous cycle effects on BAT are not greatly explored, we examined those of 6-h fasting on interscapular BAT (iBAT) thermogenic markers in proestrus and diestrus. We found that the percentage of multilocular adipocytes was lower in proestrus than in diestrus, although it was increased after fasting in both analyzed estrous cycle stages. Furthermore, the percentage of paucilocular adipocytes was increased by fasting, unlike the percentage of unilocular cells, which decreased in both analyzed stages of the estrous cycle. The UCP1 amount was lower in proestrus irrespectively of the examined dietary regimens. Regarding FA transporters, it was shown that iBAT CD36 content was increased in fasted rats in diestrus. In contrast to GLUT1, the level of GLUT4 was interactively modulated by selected estrous cycle phases and fasting. There was no change in insulin receptor and ERK1/2 activation, while AKT activation was interactively modulated by fasting and estrous cycle stages. Our study showed that iBAT exhibits morphological and functional changes in proestrus and diestrus. Moreover, iBAT undergoes additional dynamic functional and morphological changes during short-term fasting to modulate nutrient utilization and adjust energy expenditure.

Estrous cycle state-dependent renewal of appetitive behavior recruits unique patterns of Arc mRNA in female rats.

Renewal is a behavioral phenomenon wherein extinction learning fails to generalize between different contextual environments, thereby representing a significant challenge to extinction-based rehabilitative therapies. Previously, we have shown that renewal of extinguished appetitive behavior differs across the estrous cycle of the female rat. In this experiment that effect is replicated and extended upon to understand how the estrous cycle may modulate contextual representation at the neuronal population level to drive renewal. Estrous cycle stage [i.e., proestrus (P, high hormone) or metestrus/diestrus (M/D, low hormone)] was considered during two important learning and behavioral expression windows: at extinction training and during long-term memory (LTM)/renewal testing. Cellular compartment analysis of temporal activity using fluorescence in situ hybridization (catFISH) for Arc mRNA was conducted after the distinct context-stimulus exposures. Rats in P during context-dependent extinction training but in a different stage of the estrous cycle during LTM and renewal testing (P-different) were shown to exhibit more renewal of conditioned foodcup (but not conditioned orienting) behavior compared to rats in other estrous cycle groups. Importantly, we discovered this depends on the order of tests. P-different rats showed differential Arc mRNA expression in regions of the prefrontal cortex (PFC), amygdala, and hippocampus (HPC). For each case P-different rats had more co-expression (i.e., expression of both nuclear and cytoplasmic) of Arc mRNA compared to other groups; specific to the dorsal HPC, P-different rats also had a more robust Arc mRNA response to the extinction context exposure. These data suggest female rats show estrous cycle state-dependent renewal of appetitive behavior, and differences in context and conditioned stimulus representation at the neuronal level may drive this effect.

Are degenerative changes in a single endometrial biopsy representative for the endometrial state?

Equine endometrial fibrosis is diagnosed by microscopy of an endometrial biopsy. It is however uncertain how representative a single biopsy is for the state of the entire endometrium. While previous studies have compared samples from multiple sites, further clarification is needed on specific degenerative changes that may vary in severity between sites. Histopathology was compared, with an emphasis on degenerative changes, in two full thickness specimens from the ventral base of the left and right uterine horns, collected post slaughter from cyclic mares (n=82). Hematoxylin and eosin-stained sections were blinded evaluated by the same evaluator for layers of periglandular fibroblasts (mild[0-3], moderate[4-10], severe[>10]), glandular nests per view (mild[0-2], moderate[3-4], severe[>4]), dilated glands per view (mild[0-3], moderate[4-6], severe[>6]), degree of glandular dilation (mild, moderate, severe), excessive lymphatic vessels (absent, present), and lymphatic lacunae (absent, present). In addition, each section was scored according to a modified Kenney and Doig classification. Statistical analysis included a multiple logistic regression model for fraction of mares with disagreement in Kenney and Doig category, a multiple generalized linear regression model for fraction of parameters with disagreement, a multiple logistic regression model for fraction of mares with disagreement within each parameter, and equivalence tests for agreement of a cumulative score ofdegenerative parameters. Possible effect of age, breed and estrous cycle stage on disagreement between paired uterine horns were included in the analysis. In 49% of mares, specimens from paired uterine horns were assigned the same Kenney and Doig category, and in 46% of mares, the specimens were assigned either of two adjacent categories. In 5% of mares, the specimens varied with two categories. Disagreement in Kenney and Doig category between paired uterine horns increased with each year of age (OR=1.1, p=0.012). Analysis of degenerative parameters showed a disagreement in at least two parameters in 39% of mares, and the number of parameters with disagreement increased with age (HR=1.04, p=0.005). Disagreement within each parameter ranged from 10% of mares (glandular nests), to 31% (periglandular fibroblasts) and 38% (excessive lymphatic vessels). Disagreement increased with age for parameters involving glands (OR=1.14-1.16, p<0.04). When tested for equivalence, the cumulative scores for paired uterine horns did not differ for mares younger than 20 years (p<0.001). In conclusion, although cumulative scores of degenerative changes were equal for paired samples in mares under 20 years of age, the changes were not uniformly distributed. This suggests that conclusions based on a single biopsy, particularly in mares over 20 years of age, should be interpreted with caution, and evaluation of two biopsies is recommended.

Sex and estrous cycle stage shape left-right asymmetry in chronic hippocampal seizures in mice.

Lateralization of hippocampal function is indicated by varied outcomes of patients with neurological disorders that selectively affect one hemisphere of this structure, such as temporal lobe epilepsy (TLE). The intrahippocampal kainic acid (IHKA) injection model of TLE allows for targeted damage to the left or right hippocampus, enabling systematic comparison of effects of left-right asymmetry on seizure and non-seizure outcomes. Although varying non-seizure phenotypic outcomes based on injection side in dorsal hippocampus were recently evaluated in this model, differences in chronic seizure patterns in left- (IHKA-L) vs. right-injected (IHKA-R) IHKA animals have yet to be evaluated. Here, we assessed hippocampal seizure incidence in male and female IHKA-L and IHKA-R mice. Females displayed increased electrographic seizure activity compared to males at both 2 and 4 months post-injection. In addition, IHKA-L females showed higher seizure frequency than IHKA-R on diestrus and estrus at 2 months post-injection, but seizure duration and percent time in seizures were only higher in IHKA-L females on diestrus. These cycle stage-associated changes, however, did not persist to 4 months post-injection. Furthermore, this lateralized difference in seizure burden was not observed in males. These results indicate for the first time that the side of IHKA injection can shape chronic electrographic seizure burden. Overall, these results demonstrate a female-specific left-right asymmetry in hippocampal function can interact with estrous cycle stage to shape chronic seizures in mice with epilepsy, with implications for neural activity and behavior in both normal and disease states.Significance StatementSeizures in temporal lobe epilepsy often originate in the hippocampus, and patient outcomes can depend on whether the seizures initiate in the left or right hippocampus. Although rodent brain function appears less lateralized than in humans, emerging evidence indicates stronger lateralization of hippocampal function in mice than previously thought. Here, we systematically compared chronic epilepsy profiles in mice based on whether left or right hippocampus is the main site of seizure generation. Males did not show a left-right asymmetry in epilepsy severity, but females showed effects of seizure initiation side that varied with estrous cycle stage. These results thus suggest a female-specific lateralization of hippocampal function can interact with the estrous cycle to shape chronic seizures in mice with epilepsy.

Exploring sex differences in inhibitory synaptic transmission in the kolliker-fuse of rett syndrome mice

Rett Syndrome (RTT) is a rare neurodevelopmental disorder characterized by severe motor impairments including breathing problems. RTT is caused by mutations in the methyl CpG binding protein 2 (MeCP2) gene located on the X chromosome. Accordingly, girls and women account for the majority of RTT patients. The genetic nature of RTT lends itself to study in mice with loss of function mutations in the MeCP2 gene. Importantly, RTT mice display breathing irregularities similar to human patients. Insufficient inhibitory neurotransmission in the brainstem respiratory network is thought to contribute to the breathing problems in RTT. In the pontine Kölliker-Fuse (KF) area of RTT mice, there are fewer GABAergic neurites and injection of a GABA reuptake antagonist alleviates breathing irregularity in vivo. However, no one has examined the physiology of inhibitory synaptic transmission in the KF of RTT mice. In the present work, we tested the hypothesis that inhibitory synaptic transmission was deficient in the respiratory-controlling KF of MeCP2Bird mice. Although girls and women make up the majority of RTT patients, most studies examining synaptic physiology in the brainstem have been performed using male MeCP2-deficient mice. Hemizygous male MeCP2Bird mice lack MeCP2 protein and exhibit rapid onset of severe RTT symptoms which leads to short life spans. Due to partial X-inactivation, MeCP2 expression in heterozygous female MeCP2-deficient mice is mosaic, leading to variable symptom severity and delayed onset, which more closely resembles the human condition. In the present study, we examined inhibitory synaptic transmission in the KF of female heterozygous MeCP2Bird mice compared to male hemizygous MeCP2Bird mice and wild type littermates. Whole-cell voltage-clamp recordings from KF neurons contained in acute brain slices were used to measure inhibitory currents. Most notably, the frequency of spontaneous inhibitory postsynaptic currents is reduced in the KF of male, but not female, MeCP2Bird mice compared to wild type littermates. To better understand this sex difference in inhibitory neurotransmission, we assessed the influence of estrous cycle stage and MeCP2 expression status in the recorded neuron. The outcomes of this research will increase our understanding of synaptic function in respiratory control neurons in female Rett Syndrome mice. This research was supported by the International Rett Syndrome Foundation Basic Research Grant 3608. This is the full abstract presented at the American Physiology Summit 2023 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.

064 Oviductal magnetic spheroid is an effective in vitro culture system to study the estrous cycle stage effect in the oviduct

064 Oviductal magnetic spheroid is an effective in vitro culture system to study the estrous cycle stage effect in the oviduct

Noninvasive Monitoring of Blood Pressure and Heart Rate during Estrous Cycle Phases in Normotensive Wistar-Kyoto and Spontaneously Hypertensive Female Rats.

Since 2015, the National Institutes of Health has called for its funded preclinical research to include both male and female subjects. However, much of the basic animal research that has studied heart rate and blood pressure in the past has used male rats. Male rats have been preferred for these studies to avoid the possible complicating effects of the female estrous cycle. The aim of the current study was to determine whether blood pressure and heart rates vary as a function of the estrous cycle phase of young normotensive Wistar-Kyoto (WKY) and Spontaneously Hypertensive (SHR) female rats. Blood pressure and heart rate were measured at the same time of day throughout the estrous cycle by using a noninvasive tail cuff sphygmomanometric technique. As expected, 16-wk-old female SHR rats had higher blood pressure and heart rates than did age-matched female WKY rats. However, no significant differences in mean, systolic, or diastolic arterial blood pressure or heart rate were detected across the different stages of the estrous cycle in either strain of female rats. Consistent with previous reports, heart rates were higher and showed less variation in the hypertensive SHR female rats as compared with the normotensive WKY female rats. These results indicate that studies measuring blood pressure and heart rate can include young female SHR and WKY rats with no effect of estrous cycle stage.

Sex and estrous cycle affect experience-dependent plasticity in mouse primary visual cortex.

Sex hormones can affect cellular physiology and modulate synaptic plasticity, but it is not always clear whether or how sex-dependent differences identified in vitro express themselves as functional dimorphisms in the brain. Historically, most experimental neuroscience has been conducted using only male animals and the literature is largely mute about whether including female mice in will introduce variability due to inherent sex differences or endogenous estrous cycles. Though this is beginning to change following an NIH directive that sex should be included as a factor in vertebrate research, the lack of information raises practical issues around how to design experimental controls and apply existing knowledge to more heterogeneous populations. Various lines of research suggest that visual processing can be affected by sex and estrous cycle stage. For these reasons, we performed a series of in vivo electrophysiological experiments to characterize baseline visual function and experience-dependent plasticity in the primary visual cortex (V1) of male and female mice. We find that sex and estrous stage have no statistically significant effect on baseline acuity measurements, but that both sex and estrous stage have can modulate two mechanistically distinct forms of experience dependent cortical plasticity. We also demonstrate that resulting variability can be largely controlled with appropriate normalizations. These findings suggest that V1 plasticity can be used for mechanistic studies focusing on how sex hormones effect experience dependent plasticity in the mammalian cortex.

Importance of Induction Endometritis and Vaginal Cytology in Rat Model: A Narrative Review Article

Introduction: Endometritis is a female reproductive disease characterized by the inflammation of the endometrial glandular and stromal tissues. It is usually occurred due to uterine contamination with infectious causes. Animal models of clinical endometritis are very important to prevent the incidence and treatment of endometritis. Vaginal cytology method is considered as a golden standard for determining the estrous cycle stage in female rats. The aim of this study was to induce endometritis in a rat model and determine the stages of the estrous cycle of this animal using vaginal cytology method in order to successfully induce this condition in this animal model.&#x0D; Conclusion: Inflammation changes the production of endometrial cytokines, which may result in menstrual disorders and decreased endometrial reception by impaired endometrial tissue dysfunction. Increased expression of specific cytokines genes such as IL-6, IL-8 and TNF-α can be used to detect the severity and degree of endometritis. Uterine infections are known as a result of damage to the defense mechanisms of the uterine tissue, which are caused by physiological changes in the postpartum period. Another change that occurs in the postpartum period is the increase in the production of reactive oxygen species. The imbalance between the production of reactive oxygen species and its clearance leads to the creation of oxidative stress conditions. On the other hand, there is a significant relationship between inflammatory diseases such as endometritis and oxidative stress. On other hand, by accurately determining the estrous cycle of rats by using vaginal cytology, endometritis can be well induced in this species.

Cnih3 Deletion Dysregulates Dorsal Hippocampal Transcription across the Estrous Cycle.

In females, the hippocampus, a critical brain region for coordination of learning, memory, and behavior, displays altered physiology and behavioral output across the estrous or menstrual cycle. However, the molecular effectors and cell types underlying these observed cyclic changes have only been partially characterized to date. Recently, profiling of mice null for the AMPA receptor trafficking gene Cnih3 have demonstrated estrous-dependent phenotypes in dorsal hippocampal synaptic plasticity, composition, and learning/memory. We therefore profiled dorsal hippocampal transcriptomes from female mice in each estrous cycle stage, and contrasted it with that of males, across wild-type (WT) and Cnih3 mutants. In wild types, we identified only subtle differences in gene expression between the sexes, while comparing estrous stages to one another revealed up to >1000 differentially expressed genes (DEGs). These estrous-responsive genes are especially enriched in gene markers of oligodendrocytes and the dentate gyrus, and in functional gene sets relating to estrogen response, potassium channels, and synaptic gene splicing. Surprisingly, Cnih3 knock-outs (KOs) showed far broader transcriptomic differences between estrous cycle stages and males. Moreover, Cnih3 knock-out drove subtle but extensive expression changes accentuating sex differential expression at diestrus and estrus. Altogether, our profiling highlights cell types and molecular systems potentially impacted by estrous-specific gene expression patterns in the adult dorsal hippocampus, enabling mechanistic hypothesis generation for future studies of sex-differential neuropsychiatric function and dysfunction. Moreover, these findings suggest an unrecognized role of Cnih3 in buffering against transcriptional effects of estrous, providing a candidate molecular mechanism to explain estrous-dependent phenotypes observed with Cnih3 loss.

Effects of the estrous cycle on impulsive choice and interval timing in female rats

Research in humans and animals shows differences in impulsive choice, which is a failure to wait for larger, delayed rewards, when comparing males and females. It is possible that fluctuations in sex hormones (estradiol and progesterone) across the reproductive cycle contribute to sex differences in impulsive choice. The current study delivered an impulsive choice task with peak interval trials to female rats while estrous cycles, the rodent reproductive cycle, were tracked over the course of the task. Female rats were more sensitive to changes in delay in the proestrus phase of the estrous cycle and made more larger-later choices when in estrus, particularly when the delay to the smaller reward was short. Estradiol increases dramatically during proestrus while progesterone peaks during estrus, suggesting that estradiol and progesterone may affect impulsive choice through mechanisms such as delay discounting, delay aversion, and/or timing processes. Analyses of timing of the choice task delays showed inconsistent effects of the estrous cycle across delays, suggesting that reward-timing interactions may have complicated how hormone fluctuations affected interval timing. Further research is needed to determine the mechanism underlying increased larger-later choices during the estrus phase, increased delay sensitivity during the proestrus phase, and variability in interval timing across delays and estrous cycle stages.

Evaluating the interplay between estrous cyclicity and flurothyl-induced seizure susceptibility in Scn2a K1422E mice.

Recently, we demonstrated that Scn2a K1422E female mice showed a distinct distribution of flurothyl-induced seizure thresholds. To evaluate whether the estrous cycle contributes to this effect, estrous cycle monitoring was performed in mice that had undergone ovariectomy, sham surgery, or no treatment prior to seizure induction. Ovariectomy did not affect the non-unimodal distribution of flurothyl seizure thresholds observed in Scn2a K1422E females. Additionally, seizure thresholds were not associated with estrous cycle stage in mice that underwent sham surgery or in non-surgerized (intact) mice. Interestingly, intact Scn2a K1422E females showed evidence of disrupted estrous cyclicity, an effect not previously described in a genetic epilepsy model.