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Toxicologic Pathology Aug 2015Microscopic evaluation of the types of cells present in vaginal smears has long been used to document the stages of the estrous cycle in laboratory rats and mice and as... (Review)
Review
Microscopic evaluation of the types of cells present in vaginal smears has long been used to document the stages of the estrous cycle in laboratory rats and mice and as an index of the functional status of the hypothalamic-pituitary-ovarian axis. The estrous cycle is generally divided into the four stages of proestrus, estrus, metestrus, and diestrus. On cytological evaluation, these stages are defined by the absence, presence, or proportion of 4 basic cell types as well as by the cell density and arrangement of the cells on the slide. Multiple references regarding the cytology of the rat and mouse estrous cycle are available. Many contemporary references and studies, however, have relatively abbreviated definitions of the stages, are in reference to direct wet mount preparations, or lack comprehensive illustrations. This has led to ambiguity and, in some cases, a loss of appreciation for the encountered nuances of dividing a steadily moving cycle into 4 stages. The aim of this review is to provide a detailed description, discussion, and illustration of vaginal cytology of the rat and mouse estrous cycle as it appears on smears stained with metachromatic stains.
Topics: Animals; Coloring Agents; Estrous Cycle; Female; Mice; Rats; Vagina; Vaginal Smears
PubMed: 25739587
DOI: 10.1177/0192623315570339 -
Frontiers in Microbiology 2022The physiological state of the host affects the gut microbes. The estrus cycle is critical to the reproductive cycle of sows. However, the association between gut...
The physiological state of the host affects the gut microbes. The estrus cycle is critical to the reproductive cycle of sows. However, the association between gut microbes and animal estrus is poorly understood. Here, high-throughput 16S rRNA sequencing and liquid chromatography-mass spectrometry (LC-MS) non-targeted metabolome technology were used to study the estrous cycles in Diannan small ear pigs. Significantly different gut microbiota and metabolites of sows at estrous and diestrus were screened out and the correlation was analyzed. We found that the intestinal microbial composition and microbial metabolism of Diannan small ear sows were significantly different at diestrus and metestrus. The abundances of , , , , , , and in intestinal microorganisms of Diannan small ear sows at metestrus are significantly higher than that at diestrus. Propionic acid, benzyl butyrate, sucrose, piperidine, and 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) were significantly enriched at metestrus compared with diestrus, which were involved in the energy metabolism-related pathways and activated protein kinase (AMPK) signaling pathway. At diestrus and metestrus, differential microbiota of , , , , and differential metabolites of piperidine, propionic acid, and benzyl butyrate, sucrose, 4-methyl catechol, and AICAR exist a certain degree of correlation. Therefore, , , and may have a potential role at metestrus of the Diannan small ear sows. AICAR may be apotential marker of estrus Diannan small ear sows feces, but further studies about the specific mechanism are needed. These findings provide a new perspective for sows production management and improving sows reproductive performance.
PubMed: 35516431
DOI: 10.3389/fmicb.2022.826881 -
Behavioural Brain Research Jan 2021Low concentrations of ovarian hormones, among other factors, are associated with greater vulnerability to negative effects of environmental stressors and may trigger...
Low concentrations of ovarian hormones, among other factors, are associated with greater vulnerability to negative effects of environmental stressors and may trigger anxiety symptoms in females. The flavonoid chrysin (5,7-dihydroxyflavone) exerts anxiolytic-like effects in male and ovariectomized female rats, but it is unknown if chrysin could reduce anxiety-like behavior that naturally occurs through the ovarian cycle phases. The present study evaluated the effect of chrysin on anxiety-like behavior associated with the ovarian cycle phases in rats and the participation of γ-aminobutyric acid-A (GABA) receptors in these actions. The acute effects of chrysin (2 mg/kg) were investigated in female cycling Wistar rats in the elevated plus maze, locomotor activity test, and light/dark test. Diazepam (2 mg/kg) was used as reference anxiolytic drug. The participation of GABA receptor in the anxiolytic actions of chrysin was explored by pretreating the rats with the noncompetitive GABA chloride ion channel antagonist picrotoxin (1 mg/kg). Chrysin and diazepam prevented anxiety-like behavior that was associated with the metestrus-diestrus phase in both the elevated plus maze and light/dark test, and these effects were reversed by picrotoxin, with no significant changes in spontaneous locomotor activity. No significant motor effects of chrysin were detected in either behavioral test during proestrus-estrus or metestrus-diestrus phases, whereas diazepam produced motor hypoactivity in the locomotor activity test during proestrus-estrus phase. These results indicate that the flavonoid chrysin prevents anxiety-like behavior that naturally occurs during metestrus-diestrus in two unconditioned models that are used to evaluate anxiety-like behavior, and these effects were mediated by actions on GABA receptors.
Topics: Animals; Anti-Anxiety Agents; Anxiety; Behavior, Animal; Diazepam; Diestrus; Estrous Cycle; Estrus; Female; Flavonoids; GABA-A Receptor Antagonists; Metestrus; Picrotoxin; Proestrus; Rats; Rats, Wistar
PubMed: 33017640
DOI: 10.1016/j.bbr.2020.112952 -
Behavioural Brain Research Feb 2018Females are an under-represented research model and the mechanisms through which sleep loss impairs cognition are not clear. Since levels of reproductive hormones and...
Females are an under-represented research model and the mechanisms through which sleep loss impairs cognition are not clear. Since levels of reproductive hormones and the estrous cycle are sensitive to sleep loss and necessary for learning and memory, we hypothesized that sleep deprivation impacts learning and memory in female mice by interfering with the estrous cycle. We used the object recognition task to assess learning and memory in female mice during separate phases of the estrous cycle and after sleep loss. Mice in metestrus/diestrus attended to sample objects less than mice in proestrus/estrus during object acquisition, the first phase of the object recognition task. Subsequently, during the recognition phase of the task, only mice in proestrus/estrus displayed a preference for the novel object. Sleep deprivation for 12h immediately before the object recognition task reduced time attending to sample objects and novel object preference for mice in proestrus/estrus, without changing length of the estrous cycle. These results show that sleep deprived mice in proestrus/estrus had learning deficits and memory impairments, like mice in metestrus/diestrus. Since sleep deprivation did not disrupt the estrous cycle, however, results did not support the hypothesis. Cognitive impairments due to acute sleep loss were not due to alterations to the estrous cycle.
Topics: Animals; Behavior, Animal; Estrous Cycle; Female; Learning; Memory; Metestrus; Mice, Inbred C57BL; Proestrus; Sleep Deprivation
PubMed: 29180134
DOI: 10.1016/j.bbr.2017.11.033 -
Biochimica Et Biophysica Acta Aug 2007Early and late metestrus in the rat differ by progesterone levels. As it is known that progesterone shows a potential negative effect on cognitive performances and can... (Comparative Study)
Comparative Study
Early and late metestrus in the rat differ by progesterone levels. As it is known that progesterone shows a potential negative effect on cognitive performances and can counteract the estradiol-induced neural effects, we intended to study signaling proteins in the hippocampus, a structure representing a main brain area of cognitive function. Female OFA Sprague-Dawley rats were used in the studies and estrous phases were determined using vaginal smears. Hippocampal tissue was taken, proteins extracted, run on two-dimensional gel electrophoresis and proteins were identified by mass spectrometry methods (MALDI-TOF-TOF and nano-LC-ESI-MS/MS). Individual signaling protein levels quantified by specific software were shown to vary between the two phases, including NG,NG-dimethylarginine dimethylaminohydrolase 1 for nitric oxide signaling, guanine nucleotide-binding proteins, septin 6, septin 11, G-septin alpha, and 14-3-3 protein gamma. Results from this study indicate that early and late metestrus show differences in signaling pathways, that may help to design further investigations at the protein level and may assist to interpret literature on protein expression and brain protein levels in female rats. Moreover, signaling differences in hippocampus are challenging cognitive studies during these two metestrus phases probably revealing cognitive differences between early and late metestrus.
Topics: Animals; Brain Chemistry; Cognition; Electrophoresis, Gel, Two-Dimensional; Female; Hippocampus; Intracellular Signaling Peptides and Proteins; Mass Spectrometry; Metestrus; Nerve Tissue Proteins; Rats; Rats, Sprague-Dawley; Signal Transduction
PubMed: 17569602
DOI: 10.1016/j.bbapap.2007.05.002 -
Brain Research Mar 2018Studies have shown that changes in ovarian hormone concentrations promote natural fluctuations in the density of dendritic spines of hippocampal neurons in female...
Studies have shown that changes in ovarian hormone concentrations promote natural fluctuations in the density of dendritic spines of hippocampal neurons in female Sprague-Dawley rats, without changes in dendritic length, throughout the estrous cycle. However, it is still unknown whether these fluctuations are present in other rat strains. Due to our interest in Wistar rats, the objective of the present study was to determine if there is natural dendritic remodeling in the female Wistar rat throughout the estrous cycle. This study analyzed the dendritic arborization of pyramidal neurons CA1 and CA3 of the dorsal hippocampus in each phase of the estrous cycle. We used the Golgi-Cox staining method and Sholl analysis to evaluate the dendritic length and density of dendritic spines. Our results showed that the dendritic length of the basilar and apical trees of CA1 neurons was longer in the metestrus phase. In CA3 neurons, only the apical dendritic trees showed longer dendritic length during metestrus. There was no variation in the density of dendritic spines in relation to any of the phases of the estrous cycle. Taken together, these results indicated that pyramidal neurons of the CA1 and CA3 regions of the dorsal hippocampus in the Wistar rat exhibited changes in dendritic length in the metestrus phase of the estrous cycle. Together, these data are important when considering the use of these organisms in behavioral studies.
Topics: Analysis of Variance; Animals; CA1 Region, Hippocampal; CA3 Region, Hippocampal; Dendritic Spines; Female; Metestrus; Neurons; Rats; Rats, Wistar; Silver Staining
PubMed: 29337045
DOI: 10.1016/j.brainres.2018.01.008 -
BioMed Research International 2014In previous studies, the anxiolytic-like effects of Montanoa tomentosa and Montanoa frutescens were reported in male rats, but the potential anxiolytic-like effects of...
In previous studies, the anxiolytic-like effects of Montanoa tomentosa and Montanoa frutescens were reported in male rats, but the potential anxiolytic-like effects of Montanoa plants during the different phases of the ovarian cycle in rats remain to be explored. The anxiolytic-like effects of the aqueous crude extracts of M. frutescens (25 and 50 mg/kg) and M. grandiflora (25 and 50 mg/kg) in the elevated plus maze were investigated in Wistar rats during the estrous cycle and compared with 2 mg/kg diazepam as a reference anxiolytic drug. To investigate any motor effect (i.e., hyperactivity, no changes, or hypoactivity) associated with the treatments, the rats were evaluated in the open field test. The M. frutescens (25 and 50 mg/kg) and M. grandiflora (50 mg/kg) extracts exerted anxiolytic-like effects during the metestrus-diestrus phase, similar to diazepam, without disrupting spontaneous motor activity. No significant effects of the extracts were detected in either behavioral test during the proestrus-estrus phase, whereas diazepam produced motor hypoactivity in the open field test. These results indicate that the M. frutescens and M. grandiflora extracts possess anxiolytic-like effects that depend on the ovarian cycle phase, supporting the Mexican ancient medicinal use of these plants to ameliorate anxiety disorders.
Topics: Animals; Anti-Anxiety Agents; Anxiety; Behavior, Animal; Diestrus; Female; Maze Learning; Metestrus; Montanoa; Plant Extracts; Rats; Rats, Wistar
PubMed: 24800255
DOI: 10.1155/2014/938060 -
Journal of Animal Science Sep 1997A study was conducted with 360 gilts and sows from four herds to determine whether fertility was affected when the final of multiple inseminations was performed in late... (Comparative Study)
Comparative Study
A study was conducted with 360 gilts and sows from four herds to determine whether fertility was affected when the final of multiple inseminations was performed in late estrus or metestrus (late insemination). Sows and gilts were inseminated at 24-h intervals immediately after the detection of estrus. After receiving a first insemination, females were paired according to parity and estrus status on d 2 of estrus. Each pair set was inseminated with extended semen from the same semen collection(s). Control females were inseminated once on d 1 if they were not in estrus on d 2 (n = 31) or on both days if they were in estrus on d 2 (n = 149). Late inseminated females in each pair were managed and inseminated in the same manner as control females and then inseminated again 24 h later regardless of estrus status. Overall reproductive performance was similar among the four herds. Late insemination caused a drop in farrowing rate in parity 1 and 2 females (23 and 22%; P < .05 and P < .01, respectively) and average litter size decreased by 1.1 pigs per litter (P < .05) regardless of parity. There were no differences in either litter size or farrowing rate between late inseminated females in estrus and those that were in metestrus at the time of their last insemination.
Topics: Analysis of Variance; Animals; Estrus; Female; Insemination, Artificial; Litter Size; Male; Parity; Pregnancy; Pregnancy Rate; Reproduction; Swine; Time Factors
PubMed: 9303448
DOI: 10.2527/1997.7592323x -
Pharmacology Research & Perspectives Jun 2022Sexual dimorphisms are observed in cannabinoid pharmacology. It is widely reported that female animals are more sensitive to the cataleptic, hypothermic,... (Review)
Review
Sexual dimorphisms are observed in cannabinoid pharmacology. It is widely reported that female animals are more sensitive to the cataleptic, hypothermic, antinociceptive, and anti-locomotive effects of cannabinoid receptor agonists such as CP55,940. Despite awareness of these sex differences, there is little consideration for the pharmacodynamic differences within females. The mouse estrus cycle spans 4-5 days and consists of four sex hormone-mediated phases: proestrus, estrus, metestrus, and diestrus. The endocannabinoid system interacts with female sex hormones including β-estradiol, which may influence receptor expression throughout the estrus cycle. In the current study, sexually mature female C57BL/6 mice in either proestrus or metestrus were administered either 1 mg/kg i.p. of the cannabinoid receptor agonist CP55,940 or vehicle. Mice then underwent the tetrad battery of behavioral assays measuring catalepsy, internal body temperature, thermal nociception, and locomotion. Compared with female mice in metestrus, those in proestrus were more sensitive to the anti-nociceptive effects of CP55,940. A similar trend was observed in CP55,940-induced catalepsy; however, this difference was not significant. As for cannabinoid receptor expression in brain regions underlying antinociception, the spine tissue of proestrus mice that received CP55,940 exhibited increased expression of cannabinoid receptor type 1 relative to treatment-matched mice in metestrus. These results affirm the importance of testing cannabinoid effects in the context of the female estrus cycle.
Topics: Animals; Cannabinoid Receptor Agonists; Cannabinoids; Catalepsy; Estrus; Female; Male; Mice; Mice, Inbred C57BL; Receptors, Cannabinoid
PubMed: 35466560
DOI: 10.1002/prp2.950 -
Journal of Leukocyte Biology Oct 2006We hypothesized that administration of androgen receptors antagonist flutamide following trauma-hemorrhage (T-H) in metestrus females will maintain immune function and...
We hypothesized that administration of androgen receptors antagonist flutamide following trauma-hemorrhage (T-H) in metestrus females will maintain immune function and reduce remote organ damage under those conditions. Female B57BL/J6 mice (metestrus state, 8-12 weeks old) underwent laparotomy and hemorrhagic shock (35.0+/-5.0 mmHg for 90 min) and then received 17beta-estradiol (E2; 50 microg/25 g), flutamide (625 microg/25 g), or E2 + flutamide. Four hours after resuscitation, plasma cytokine and chemokine (TNF-alpha, IL-6, IL-10, IFN-gamma, and MCP-1) concentrations and their release in vitro by hepatic and pulmonary tissue macrophages (M Phi) were determined by flow cytometry. Organ damage was assessed by edema formation (wet-to-dry weight ratio) and neutrophil infiltration [myeloperoxidase (MPO) activity]. Administration of E2, flutamide, or E2 + flutamide following T-H resulted in a significant decrease in systemic TNF-alpha, IL-6, and MCP-1 concentrations under those conditions. This was accompanied by significantly decreased in vitro TNF-alpha release by Kupffer cells after administration of E2, flutamide, or E2 + flutamide. The in vitro release of proinflammatory cytokines by alveolar M Phi, however, was reduced significantly only by the addition of E2 or E2 + flutamide but not by the addition of flutamide. A significant decrease in pulmonary and hepatic edema formation as well as neutrophil infiltration in the lung was observed after E2, flutamide and E2 + flutamide administration. In contrast, hepatic neutrophil infiltration was only significantly reduced following E2 and E2 + flutamide administration. Thus, although flutamide does not produce synergistic, salutary effects with E2, its administration in females following T-H also produces salutary effects on the immune and organ function, similar to E2 administration under those conditions.
Topics: Animals; Chemokine CCL2; Cytokines; Enzyme Activation; Estradiol; Female; Flow Cytometry; Flutamide; Hemorrhage; Inflammation; Injections, Subcutaneous; Kupffer Cells; Liver; Lung; Macrophages; Metestrus; Mice; Mice, Inbred C57BL; Organ Size; Peroxidase; Sensitivity and Specificity
PubMed: 16895975
DOI: 10.1189/jlb.0406254