Stages Of Estrous Cycle Research Articles

Digital workflows for pathological assessment of rat estrous cycle stage using images of uterine horn and vaginal tissue

Assessment of the estrous cycle of mature female mammals is an important component of verifying the efficacy and safety of drug candidates. The common pathological approach of relying on expert observation has several drawbacks, including laborious work and inter-viewer variability. The recent advent of image recognition technologies using deep learning is expected to bring substantial benefits to such pathological assessments. We herein propose 2 distinct deep learning-based workflows to classify the estrous cycle stage from tissue images of the uterine horn and vagina, respectively. These constructed models were able to classify the estrous cycle stages with accuracy comparable with that of expert pathologists. Our digital workflows allow efficient pathological assessments of the estrous cycle stage in rats and are thus expected to accelerate drug research and development.

Gene expression in the amygdala and hippocampus of cyclic and acyclic gilts.

Age at first estrus is the earliest phenotypic indicator of future reproductive success of gilts. Prebreeding anestrus is a major reason for reproductive failure leading to culling of replacement gilts. The two types of prebreeding anestrus are delay in attaining puberty (prepubertal anestrus, PPA) and silent ovulation (behavioral anestrus, BA). Neural tissues such as amygdala and hippocampus play a major role in regulating sexual behavior, social interactions, and receptivity to males. Differences in gene expression in the amygdala and hippocampus of gilts were analyzed in three comparisons: 1) PPA cases and cyclic controls at follicular phase of estrous cycle, 2) BA cases and cyclic controls at luteal phase of estrous cycle, and 3) gilts at different stages of the ovarian cycle (cyclic gilts at follicular phase and luteal phase of estrous cycle) to gain functional understanding of how these rarely studied tissues may differ between pubertal phenotypes and different stages of the estrous cycle of gilts. Differentially expressed genes (DEG) between PPA and BA cases and their respective cyclic controls were involved in neurological and behavioral disorders as well as nervous system functions that could directly or indirectly involved in development of behaviors related to estrus. The comparison between cyclic follicular and luteal phase control gilts identified the greatest number of DEG in the hippocampus and amygdala. These DEG were involved in adult neurogenesis and neural synapse (e.g., GABAergic, dopamine, cholinergic), suggesting that these tissues undergo structural changes and synaptic plasticity in gilts. This is the first report to demonstrate that the stage of estrous cycle is associated with dynamic changes in gene expression within porcine hippocampus and amygdala and indicates a role of gonadal steroids in regulating their biology.

Influence of genistein and diadizine on regularity of estrous cycle in cyclic female Wistar rat: interaction with estradiol receptors and vascular endothelial growth factor.

Isoflavones are estrogenic compounds that exist in soy, clover, and peanuts. They are selective estrogen receptor modulators. The study was planned to explain the interactions of isoflavones with estrogen receptors alpha (ERα), beta (ERβ), and vascular endothelial growth factor (VEGF) expressions in ovarian and uterine tissues during different stages of the estrous cycle of regular cyclic female Wistar rats. Thirty-two regular cyclic females were divided equally into control group: fed casein-based diet and isoflavones group: fed casein-based diet and gavaged 50 mg/kg/day soy isoflavones extract 40%. The regularity of estrus cycles was monitored. Final body weight (FBW), weight gain (BWG), and ovarian and uterine weights were estimated. Histopathology and immunohistochemistry for ERα, Erβ, and VEGF in ovarian and uterine tissues were performed. All females (100%, n = 16) in control group showed regularity in estrous cycle compared to 62.5% (n = 10) in isoflavones group. Estrus and diestrus phases revealed prolongation and shortening in isoflavones rats than control, respectively. Nonsignificant variation was noted in the duration of the whole cycle of both groups. FBW and BWG significantly decreased however, ovarian and uterine weights increased significantly in all estrous phases of isoflavones group than control. Histopathology demonstrated an increase in number of follicles/ovaries besides, hyperplasia and proliferation of luminal epithelium with hydropic degeneration in the isoflavones group. Also, uterine connective tissue stroma showed edema in the isoflavones group during all estrous phases. Immunostaining percentages of ERα, Erβ, and VEGF protein expression were significantly elevated in the isoflavones group during all estrous phases. Isoflavones induced irregularity of the estrous cycle that was encountered by increased and altered ERα, Erβ, and VEGF expressions in ovarian and uterine tissues.

Behavior and Fos activation reveal that male and female rats differentially assess affective valence during CTA learning and expression.

Females are more affected by psychiatric illnesses including eating disorders, depression, and post-traumatic stress disorder than males. However, the neural mechanisms mediating these sex differences are poorly understood. Animal models can be useful in exploring such neural mechanisms. Conditioned taste aversion (CTA) is a behavioral task that assesses how animals process the competition between associated reinforcing and aversive stimuli in subsequent task performance, a process critical to healthy behavior in many domains. The purpose of the present study was to identify sex differences in this behavior and associated neural responses. We hypothesized that females would value the rewarding stimulus (Boost®) relative to the aversive stimulus (LiCl) more than males in performing CTA. We evaluated behavior (Boost® intake, LiCl-induced behaviors, ultrasonic vocalizations (USVs), CTA performance) and Fos activation in relevant brain regions after the acute stimuli [acute Boost® (AB), acute LiCl (AL)] and the context-only task control (COT), Boost® only task (BOT) and Boost®-LiCl task (BLT). Acutely, females drank more Boost® than males but showed similar aversive behaviors after LiCl. Females and males performed CTA similarly. Both sexes produced 55 kHz USVs anticipating BOT and inhibited these calls in the BLT. However, more females emitted both 22 kHz and 55 kHz USVs in the BLT than males: the latter correlated with less CTA. Estrous cycle stage also influenced 55 kHz USVs. Fos responses were similar in males and females after AB or AL. Females engaged the gustatory cortex and ventral tegmental area (VTA) more than males during the BOT and males engaged the amygdala more than females in both the BOT and BLT. Network analysis of correlated Fos responses across brain regions identified two unique networks characterizing the BOT and BLT, in both of which the VTA played a central role. In situ hybridization with RNAscope identified a population of D1-receptor expressing cells in the CeA that responded to Boost® and D2 receptor-expressing cells that responded to LiCl. The present study suggests that males and females differentially process the affective valence of a stimulus to produce the same goal-directed behavior.

Luteal toxicity evaluation in rats.

The corpora lutea (CL) are endocrine glands that form in the ovary after ovulation and secrete the steroid hormone, progesterone (P4). P4 plays a critical role in estrous and menstrual cycles, implantation, and pregnancy. The incomplete rodent estrous cycle stably lasts 4–5 days and its morphological features can be distinguished during each estrous cycle stage. In rat ovaries, there are two main types of CL: newly formed ones due to the current ovulation (new CL), and CL remaining from prior estrous cycles (old CL). In the luteal regression process, CL were almost fully regressed after four estrous cycles in Sprague-Dawley rats. P4 secretion from CL in rodents is regulated by the balance between synthesis and catabolism. In general, luteal toxicity should be evaluated by considering antemortem and postmortem data. Daily vaginal smear observations provided useful information on luteal toxicity. In histopathological examinations, not only the ovaries and CL but also other related tissues and organs including the uterus, vagina, mammary gland, and adrenal glands, must be carefully examined for exploring luteal changes. In this review, histological and functional characteristics of CL in rats are summarized, and representative luteal toxicity changes are presented for improved luteal toxicity evaluation in preclinical toxicity research.

Sex differences in the expression of the endocannabinoid system within V1M cortex and PAG of Sprague Dawley rats

BackgroundSeveral chronic pain disorders, such as migraine and fibromyalgia, have an increased prevalence in the female population. The underlying mechanisms of this sex-biased prevalence have yet to be thoroughly documented, but could be related to endogenous differences in neuromodulators in pain networks, including the endocannabinoid system. The cellular endocannabinoid system comprises the endogenous lipid signals 2-AG (2-arachidonoylglycerol) and AEA (anandamide); the enzymes that synthesize and degrade them; and the cannabinoid receptors. The relative prevalence of different components of the endocannabinoid system in specific brain regions may alter responses to endogenous and exogenous ligands.MethodsBrain tissue from naïve male and estrous staged female Sprague Dawley rats was harvested from V1M cortex, periaqueductal gray, trigeminal nerve, and trigeminal nucleus caudalis. Tissue was analyzed for relative levels of endocannabinoid enzymes, ligands, and receptors via mass spectrometry, unlabeled quantitative proteomic analysis, and immunohistochemistry.ResultsMass spectrometry revealed significant differences in 2-AG and AEA concentrations between males and females, as well as between female estrous cycle stages. Specifically, 2-AG concentration was lower within female PAG as compared to male PAG (*p = 0.0077); female 2-AG concentration within the PAG did not demonstrate estrous stage dependence. Immunohistochemistry followed by proteomics confirmed the prevalence of 2-AG-endocannabinoid system enzymes in the female PAG.ConclusionsOur results suggest that sex differences exist in the endocannabinoid system in two CNS regions relevant to cortical spreading depression (V1M cortex) and descending modulatory networks in pain/anxiety (PAG). These basal differences in endogenous endocannabinoid mechanisms may facilitate the development of chronic pain conditions and may also underlie sex differences in response to therapeutic intervention.

Faecal microbiome analysis reveals Clostridiales and Bacteroidales as signature gut microbes during estrus of buffalo

The non-pathogenic intestinal microbes that conquer our intestines are not an accidental jumble of organisms, but rather a disparate community of microbes that coexist, and sustain a mutualistic and symbiotic relationship with the host. The gut microbiome has been shown to be influenced by animal physiology and vice versa. However, information is still scanty. The present study aimed to analyse the variation between faecal bacteria of three different stages (proestrus, estrus and postestrus) of the estrous cycle of Murrah buffalos. A phylogenetic study of buffalo faeces derived from three different stages of estrous cycle was conducted in order to compare the bacterial diversity among these three stages. We performed an exploratory microbiome analysis of buffalo faeces using 16S rRNA sequencing during these stages of the buffalo estrous cycle. A total of three bacterial phyla with six different bacterial orders and twenty-three different genera were identified among all the three comparative phases of the estrous cycle. Among them, the Clostridiales were found to be the most abundant, and Bacteroidales were present exclusive during the estrus phase. As faeces is a source of gut microbes and a non-invasive representative of the metabolic steroids and perceptible pheromones, the profiling of gut microbes during estrous cycle would provide clues towards the major microbes contributing to the perceptible pheromones during estrus stage. To the best of our knowledge, this is the first ever report describing the faecal bacterial diversity during estrous cycle of any ruminant species. Although future studies are required to understand the role of Clostridiales and Bacteroidales in faecal pheromone metabolism.

A Novel Mouse Model for Studying the Effects of Cyp17 Overexpression in a Temporal- and Spatial-Specific Manner

Background: Cyp17 plays a key role in theca cells (TCs) to produce androgens, which, in turn, are converted to estrogens in granulosa cells. Intrinsic alterations in ovarian steroidogenesis contribute to excessive ovarian androgen production that characterizes polycystic ovary disease (PCOS)1,2. Hyperandrogenism has been associated with higher levels of Cyp17 in TCs, and correlate with increased numbers of antral follicles3. While androgen excess is one of the hallmark features of PCOS, its putative role in the follicular development and function remains poorly known. Most efforts have used androgen administration or Cyp19 blockade approach to study how androgens prolong folliculogenesis4. Although some insights have been made, it is not clear if these models accurately address the cascade of effects that follow ovarian hyperandrogenism. Aim: Here, we aim to study the specific effects of hyperandrogenemia on ovarian morphology, follicle function and fertility with a new transgenic (TG) mouse model expressing elevated Cyp17 levels exclusively in TCs. Methods: We generated a breeding line of triple TG mice using a combination of the Tet-dependent expression system and the Cre/LoxP gene control system. Specifically, we used Cyp17 promoter-iCre mice crossed with trans-activator mice (R26-STOP-rtTA-IRES-EGFP transgene, Jackson Lab) and with a responder mouse carrying the TRE-Cyp17 transgene. Cyp17 promoter-iCre mice were used to ensure rtTA/EGFP is expressed specifically in TCs of secondary follicles. After the DNA segment between the two LoxP sites is excised by Cyp17iCre specifically in TCs, the R26-STOP-rtTA gene remains activated in all daughter TCs. Only upon treatment with Doxycycline (DOX) can suppression be relieved and active transcription of TRE-Cyp17 be induced in a dose-dependent manner. Results: Cyp17 mRNA expression levels in TCs of TG mice treated with 20, 100 or 200 mg/Kg DOX compared with corresponding untreated control mice showed a modulation in a dose-dependent manner (P=0.01 ANOVA). Confocal and RNAscope analysis validated (i) the effective combination of the Cyp17iCre/rtTA expression system visualizing the rtTA/EGFP specifically expressed in ovarian TCs and (ii) the DOX-induced increase of Cyp17 expression compared with the WT mice. DOX treated TG females were acyclic, being mostly arrested in diestrus. Analysis of estrous cycle stages revealed that treated TG females spent significantly more time in diestrus than control females (P=0.007, ANOVA). Conclusions: Our new in vivo model is the first that analyzes androgen impact independent of any extraovarian source of androgen, complementing current clinical efforts to study the occurrences of TCs elevated androgen levels in normal and PCOS women. 1 Rosenfield, R. L. et al. Endocr Rev (2016)2 Azziz, R. et al. Nat Rev Dis Primers (2016)3 Comim, F. V., et al. Hum Reprod (2013)4 Stener-Victorin, E. et al. Endocr Rev (2020)

The Influence of Circulating Sex Hormones on Severe Intermittent Hypoxia‐Induced Phrenic Long‐Term Facilitation in Female and Male Rats

Multiple, stimulus-specific cellular mechanisms give rise to phrenic long-term facilitation (pLTF), a well-studied form of respiratory neuroplasticity. We recently demonstrated that circulating sex hormones are critical for induction of pLTF following moderate acute intermittent hypoxia (mAIH; 35-45mmHG PaO2) in adult female rats; mAIH-induced pLTF is not expressed during estrous cycle stages with low circulating 17β-estradiol (the most neuroactive form of estrogen) or following removal of the ovaries, the primary source of circulating sex hormones. Castrated male rats also do not express mAIH-induced pLTF supporting a link between circulating sex hormones and pLTF expression in males as well. More severe AIH protocols (sAIH; 25-35mmHg PaO2) induce pLTF through a unique set of cellular pathways. However, all studies of sAIH-induced pLTF to date have been completed in young-adult, gonadally-intact male rats. Our primary Aims for these studies were two-fold: 1) determine if sAIH-induced pLTF was expressed in female rats across stages of the estrous cycle; and 2) determine if removal of the gonads (ovaries or testicles) influenced expression of sAIH-induced pLTF. We hypothesized that sAIH-induced pLTF would be expressed in females regardless of estrous cycle stage, and that sAIH-induced pLTF would be expressed in both females and males following removal of the gonads. Young adult (12-13 weeks) female and male Sprague-Dawely rats were used for each study. In study 1, pLTF was quantified in female rats on the morning of estrus (low circulating 17β-estradiol) or proestrus (high circulating 17β-estradiol) based on examination of vaginal cell characteristics in vaginal smears using light microscopy. In study 2, ovariectomy or castration was completed at least 7 days prior to pLTF assessments. Contrary to our hypothesis, preliminary results suggest that sAIH-induced pLTF may be significantly influenced by circulating sex hormones. Though female rats exhibited sAIH-induced plasticity across estrous cycle stages, the magnitude of pLTF was associated with circulating estradiol levels. Additionally, removal of the gonads abolished the expression of sAIH-induced pLTF in both female and male rats, suggesting a direct influence of sex hormones on sAIH mechanisms to pLTF. These data provide further evidence that sex hormones may play a critical role in expression of AIH-induced respiratory neuroplasticity.

Sex Differences in Acute Alcohol Sensitivity of Naïve and Alcohol Dependent Central Amygdala GABA Synapses.

Alcohol use disorder (AUD) is linked to hyperactivity of brain stress systems, leading to withdrawal states which drive relapse. AUD differs among the sexes, as men are more likely to have AUD than women, but women progress from casual use to binge and heavy alcohol use more quickly and are more likely to relapse into repetitive episodes of heavy drinking. In alcohol dependence animal models of AUD, the central amygdala (CeA) functions as a hub of stress and anxiety processing and gamma-Aminobutyric acid (GABA)ergic signaling within the CeA is involved in dependence-induced increases in alcohol consumption. We have shown dysregulation of CeA GABAergic synaptic signaling in alcohol dependence animal models, but previous studies have exclusively used males. Here, we used whole-cell patch clamp electrophysiology to examine basal CeA GABAergic spontaneous inhibitory postsynaptic currents (sIPSC) and the effects of acute alcohol in both naïve and alcohol dependent rats of both sexes. We found that sIPSC kinetics differ between females and males, as well as between naïve and alcohol-dependent animals, with naïve females having the fastest current kinetics. Additionally, we find differences in baseline current kinetics across estrous cycle stages. In contrast to the increase in sIPSC frequency routinely found in males, acute alcohol (11-88mM) had no effect on sIPSCs in naïve females, however the highest concentration of alcohol increased sIPSC frequency in dependent females. These results provide important insight into sex differences in CeA neuronal function and dysregulation with alcohol dependence and highlight the need for sex-specific considerations in the development of effective AUD treatment.

Estrous Cycle Plasticity in the Central Clock Output to Kisspeptin Neurons: Implications for the Preovulatory Surge.

Coordination of ovulation and behavior is critical to reproductive success in many species. During the female estrous cycle, the preovulatory gonadotropin surge occurs when ovarian follicles reach maturity and, in rodents, it begins just before the daily onset of activity, ensuring that ovulation coincides with sex behavior. Timing of the surge relies on projections from the suprachiasmatic nucleus (SCN), the locus of the central circadian clock, to hypothalamic circuits that regulate gonadotropin secretion. The cellular mechanisms through which the SCN controls these circuits and gates the preovulatory surge to the appropriate estrous cycle stage, however, are poorly understood. We investigated in mice the functional impact of SCN arginine-vasopressin (AVP) neuron projections to kisspeptin (Kiss1) neurons in the rostral periventricular area of the third ventricle (RP3VKiss1), responsible for generating the preovulatory surge. Conditional anterograde tracing revealed that SCNAVP neurons innervate approximately half of the RP3VKiss1 neurons. Optogenetic activation of SCNAVP projections in brain slices caused an AVP-mediated stimulation of RP3VKiss1 action potential firing in proestrus, the cycle stage when the surge is generated. This effect was less prominent in diestrus, the preceding cycle stage, and absent in estrus, following ovulation. Remarkably, in estrus, activation of SCNAVP projections resulted in GABA-mediated inhibition of RP3VKiss1 neuron firing, an effect rarely encountered in other cycle stages. Together, these data reveal functional plasticity in SCNAVP neuron output that drives opposing effects on RP3VKiss1 neuron activity across the ovulatory cycle. This might contribute to gating activation of the preovulatory surge to the appropriate estrous cycle stage.

In vivo effects of AZD4547, a novel fibroblast growth factor receptor inhibitor, in a mouse model of endometriosis.

Endometriosis is a chronic disease, characterized by the growth of endometrial‐like cells outside the uterine cavity. Due to its complex pathophysiology, a totally resolving cure is yet to be found. The aim of this study was to compare the therapeutic efficacy of AZD4547, a novel fibroblast growth factor receptor inhibitor (FGFRI), with a well‐characterized progestin, etonogestrel (ENG) using a validated in vivo mouse model of endometriosis. Endometriosis was induced by transplanting uterine fragments from donor mice in proestrus into the peritoneal cavity of recipient mice, which then developed into cyst‐like lesions. AZD4547 and ENG were administered systemically either from the day of endometriosis induction or 2‐weeks post‐surgery. After 20 days of treatment, the lesions were harvested; their size and weight were measured and analyzed histologically or by qRT‐PCR. Stage of estrous cycle was monitored throughout. Compared to vehicle, AZD4547 (25 mg/kg) was most effective in counteracting lesion growth when treating from day of surgery and 2 weeks after; ENG (0.8 mg/kg) was similarly effective in reducing lesion growth but only when administered from day of surgery. Each downregulated FGFR gene expression (p < 0.05). AZD4547 at all doses and ENG (0.008 mg/kg) caused no disturbance to the estrous cycle. ENG at 0.08 and 0.8 mg/kg was associated with partial or complete estrous cycle disruption and hyperemia of the uteri. AZD4547 and ENG both attenuated endometriotic lesion size, but only AZD4547 did not disrupt the estrous cycle, suggesting that targeting of FGFR is worthy of further investigation as a novel treatment for endometriosis.

ANGIOTENSIN RECEPTOR - NEPRILYSIN INHIBITION IS SUPERIOR TO ANGIOTENSIN RECEPTOR INHIBITION ALONE FOR THE TREATMENT OF SEXUAL DYSFUNCTION IN FEMALE SPONTANEOUSLY HYPERTENSIVE RATS

Abstract Objective: We investigate the effect of angiotensin receptor - neprilysin inhibition on sexual dysfunction (SD) for female SHR rats. Design and method: A total of 50 female SHR rats were randomly divided into 5 groups (n = 10/group): Wistar rats (no medication); SHR rats (no medication); Valsartan (30 mg/kg/day p.o.); Sacubitril / valsartan (SAC/VAL) (60 mg/kg/day p.o.); SAC/VAL + A799 (100ng/kg/day i.v.). The blood pressure was measured before intervention and after 1-month intervention. Vaginal smears were performed and examined daily via light microscopy for determination of the stage of each rat's estrous cycle. Paced mating behavior is observed in nighttime, including number of mounts, intromissions, smelling female vagina, and rejection by kicking male rats. Results: Blood pressure in SHR rats received SAC/VAL was obviously lower than SHR rats without intervention, but similar to valsartan. The different cell populations across the cycle were improved in SAC/VAL, and worse in SHR rats without intervention. The numbers of mounts, intromissions, smelling and kicking male rats for rejection were significantly superior to Valsartan and SHR without intervention, and the difference was significant statistic. Conclusions: SAC/VAL is a novel drug of angiotensin receptor - neprilysin inhibition to improve blood pressure and SD.

Production of IL-1β, IL-6 and CXCL8 by endometrium of crossbred heifers stimulated with various pathogen-associated molecular patterns

Uterine bacterial infections are common during the post-partum period of dairy herds and, apparently, incidences in crossbred cattle are less than in Holsteins. The aims of this study were (I) to evaluate production of interleukin 1-β (IL-1β), interleukin-6 (IL-6) and chemokine CXCL8 using endometrial explants from Bos indicus crossbred heifers at diestrous, stimulated by various pathogen-associated molecular patterns (PAMP), and (II) assess production of these cytokines by lipopolysaccharide-stimulated endometrial explants from heifers when samples were collected at different stages of estrous cycle. In the first experiment, endometrial explants from heifers at diestrous were stimulated by ten-fold serial dilutions of lipopolysaccharide (LPS), triacylated lipopeptide (PAM3) or peptidoglycan (PGN). In the second experiment, endometrial explants collected at different stages of the estrous cycle were treated with LPS. Concentrations of IL-1β, IL-6 and CXCL8 were quantified in supernatant. There was a marked (P < 0.05) production of IL-1β, IL-6, and CXCL8 in response to LPS treatment. There was also production of IL-1β (P < 0.05) in response to PGN treatment. Explant samples collected at different stages of the estrous cycle responded to LPS treatment with production of IL-1β and IL-6, but with no differences (P > 0.05) between stages of estrous cycle. In conclusion, endometrial samples of crossbred Zebu-based heifers collected during diestrous produced IL-1β, IL-6 and CXCL8 in response to LPS and IL-1β in response to PGN. The cytokine production in response to LPS, however, was not affected by the stage of the estrous cycle in Bos indicus crossbred heifers.

Effects of spaceflight aboard the International Space Station on mouse estrous cycle and ovarian gene expression

Ovarian steroids dramatically impact normal homeostatic and metabolic processes of most tissues within the body, including muscle, bone, neural, immune, cardiovascular, and reproductive systems. Determining the effects of spaceflight on the ovary and estrous cycle is, therefore, critical to our understanding of all spaceflight experiments using female mice. Adult female mice (n = 10) were exposed to and sacrificed on-orbit after 37 days of spaceflight in microgravity. Contemporary control (preflight baseline, vivarium, and habitat; n = 10/group) groups were maintained at the Kennedy Space Center, prior to sacrifice and similar tissue collection at the NASA Ames Research Center. Ovarian tissues were collected and processed for RNA and steroid analyses at initial carcass thaw. Vaginal wall tissue collected from twice frozen/thawed carcasses was fixed for estrous cycle stage determinations. The proportion of animals in each phase of the estrous cycle (i.e., proestrus, estrus, metestrus, and diestrus) did not appreciably differ between baseline, vivarium, and flight mice, while habitat control mice exhibited greater numbers in diestrus. Ovarian tissue steroid concentrations indicated no differences in estradiol across groups, while progesterone levels were lower (p < 0.05) in habitat and flight compared to baseline females. Genes involved in ovarian steroidogenic function were not differentially expressed across groups. As ovarian estrogen can dramatically impact multiple non-reproductive tissues, these data support vaginal wall estrous cycle classification of all female mice flown in space. Additionally, since females exposed to long-term spaceflight were observed at different estrous cycle stages, this indicates females are likely undergoing ovarian cyclicity and may yet be fertile.

Selected Hematological and Biochemical of the Peranakan Ongole (PO) Cattle in Different Stage of Reproductive in Indonesian Tropical Environment

This research aimed to determine the proportional hematology and biochemistry in a different stage of estrous cycles and period of gestation and lactation in the Peranakan Ongole (PO) cattle in Indonesia’s tropical environment. Thirty-three clinically healthy PO cattle were used in this research. Blood was collected for estrous, diestrus, metestrus, proestrus, pregnancy, and lactation groups for hematology and biochemistry analysis. The lymphocyte higher in estrous stages and lower in the lactation period (p<0.05). The triglyceride highest in all estrous cycles and pregnancy period and lowest in the lactation period (p<0.05). The highest glucose was found in lactation and lowest in proestrus (p<0.05). The potassium highest in proestrus and the lowest in estrous and lactation (p<0.05). This finding has revealed that fluctuations in the lymphocytes, triglyceride, and glucose in different stages of estrous cycles and pregnancy and lactation period. Blood and biochemical are affected by the stage of reproduction in the PO cattle in Indonesia’s tropical environment.

Abstract P422: Chronic Nicotine Exposure Increases Hematoma Growth Following Intracerebral Hemorrhage in Young Rats of Both Sexes

Spontaneous intracerebral hemorrhage (sICH) is the deadliest stroke subtype. There is strong evidence that tobacco use / smoking increases the risk of sICH, and some epidemiological studies have observed sex differences in sICH outcomes. However, systematic controlled studies on the effect of tobacco / smoking on post-sICH outcomes in both sexes are lacking. Therefore, we determined the effect of nicotine exposure on outcomes following collagenase-induced sICH both sexes. Young animals of both sexes were randomly divided into nicotine (4.5 mg / kg / day b.w.) and vehicle (saline) treatment groups (using osmotic pumps for two to three weeks). sICH in females was induced during the diestrous stage of estrous cycle. sICH was induced by collagenase injection into the right striatum and ~24 hours later, neurological scores were evaluated, rats were euthanized, and brains were sectioned to measure hematoma volume. Hematoma volumes for male rats was 42% higher (p&lt;0.01) in the nicotine-treated group (139 ± 9 mm 3 , n=10) versus vehicle-treated group (98 ± 9 mm 3 , n=10). Hematoma volumes for female rats was 48% higher (p&lt;0.01) in the nicotine-treated group (134 ± 11 mm 3 , n=10) versus vehicle-treated group (90 ± 7 mm 3 , n=10). Hematoma volumes for the vehicle and nicotine-treated male groups were not different from their respective female groups. The neurological score for the nicotine-treated male group (9.3 ± 0.6) was significantly higher (p&lt;0.05) when compared to vehicle group (7.4 ± 0.6). The neurological score for the nicotine-treated female group (10.7 ± 0.2) was significantly higher (p&lt;0.001) than the vehicle group (7.7 ± 0.7). The neurological score for the vehicle-treated male group was not different from its respective female group. However, the neurological score for the nicotine-treated male group was significantly lower than the female group. Our results show that chronic nicotine exposure increases hematoma volume post-sICH in animals of both sexes. Future studies into the mechanism of nicotine-induced increase in hematoma growth following sICH are required. Support: James and Esther King Biomedical Research Grant 9JK08

Influence of estrous cycle stage on acquisition and expression of fear conditioning in female rats

It is unclear whether all animal models of anxiety-like states developed using males are appropriate for use in females. In females, tests involving a learning component might be influenced not only by estrous cycle stage on the test day but also by the stage during the conditioning process. We used two tests - conditioned freezing (CF) and fear potentiated startle (FPS) to compare responsiveness of male rats and females conditioned and/or tested in proestrus (P) or late diestrus (LD). For CF all rats displayed a similar freezing response regardless of sex or estrous cycle stage. In terms of FPS, males and females conditioned in P and tested in P or LD, and females conditioned in LD and tested in LD all showed potentiated startle. The response waned during the test session in males and in females conditioned in P, but not in those conditioned in LD. In contrast, FPS was not apparent in the first half of the test session in females conditioned in LD and tested in P but developed in the second half. We suggest that fear learning during P and LD is robust but may be initially be obscured in rats tested in P because of generalization to the CS due to high estrogen. Estrous cycle stage is an important consideration which must be taken into account in designing behavioural tests in females.

Serotonin transporter genotype modulates resting state and predator stress-induced amygdala perfusion in mice in a sex-dependent manner

The serotonin transporter (5-HTT) is a key molecule of serotoninergic neurotransmission and target of many anxiolytics and antidepressants. In humans, 5-HTT gene variants resulting in lower expression levels are associated with behavioral traits of anxiety. Furthermore, functional magnetic resonance imaging (fMRI) studies reported increased cerebral blood flow (CBF) during resting state (RS) and amygdala hyperreactivity. 5-HTT deficient mice as an established animal model for anxiety disorders seem to be well suited for investigating amygdala (re-)activity in an fMRI study. We investigated wildtype (5-HTT+/+), heterozygous (5-HTT+/-), and homozygous 5-HTT-knockout mice (5-HTT-/-) of both sexes in an ultra-high-field 17.6 Tesla magnetic resonance scanner. CBF was measured with continuous arterial spin labeling during RS, stimulation state (SS; with odor of rats as aversive stimulus), and post-stimulation state (PS). Subsequently, post mortem c-Fos immunohistochemistry elucidated neural activation on cellular level. The results showed that in reaction to the aversive odor CBF in total brain and amygdala of all mice significantly increased. In male 5-HTT+/+ mice amygdala RS CBF levels were found to be significantly lower than in 5-HTT+/- mice. From RS to SS 5-HTT+/+ amygdala perfusion significantly increased compared to both 5-HTT+/- and 5-HTT-/- mice. Perfusion level changes of male mice correlated with the density of c-Fos-immunoreactive cells in the amygdaloid nuclei. In female mice the perfusion was not modulated by the 5-Htt-genotype, but by estrous cycle stages. We conclude that amygdala reactivity is modulated by the 5-Htt genotype in males. In females, gonadal hormones have an impact which might have obscured genotype effects. Furthermore, our results demonstrate experimental support for the tonic model of 5-HTTLPR function.

Prevention of Unwanted Pregnancy using Diethylstilbestrol in Mismated Bitches

Efficiency of diethylstilbestrol (DES) was evaluated for preventing unwanted pregnancy following misalliance in eight bitches of different breeds, age, and bodyweight along with use of vaginal cytology on the day of case registration for retrospective confirmation of stage of estrous cycle and time of mating. All the bitches were injected with diethylstilbestrol (DES) @ 2.0 mg/kg b. wt., i/m (Max. 20 mg) on day three and five post-mating and were subjected to blood examination on day zero and seven of DES injection. An ultra-sonographic scan was carried out in each of the bitch on day 30-35 post-mating to rule out the pregnancy status of the animal and success of therapy. All the bitches were followed up for 70-100 days post-treatment for any untoward effects. The major exfoliative cells found in vaginal cytology were of large intermediate/anuclear cells (94.37 ± 0.57 %) characteristics of a peak estrus phase, and 6 of 8 bitches also showed presence of sperm in the smear evinced mating. All the bitches were found to be non-pregnant on USG scan 30-35 days post-treatment and had no serious side effect during the follow-up period. The pre- and post-treatment mean values of hemoglobin (g/dL), WBCs (×103/?L) and RBCs (×106/?L) were 15.58 ± 0.59 vs. 15.33 ± 0.60, 9.10 ± 0.44 vs. 11.33 ± 1.60 and 6.94 ± 0.12 vs. 6.83 ± 0.22, respectively, differing non-significantly. It was concluded that the exfoliative vaginal cytology in bitches having fully cornified superficial/anuclear cells as predominant cells with sperm presence indicates misalliance during estrus phase. Injection diethylstilbestrol twice could prevent the conception and establishment of pregnancy in bitches having misalliance, with minimal effect on their health.