Progesterone-Related Diabetes Mellitus in the Bitch: Current Knowledge, the Role of Pyometra, and Relevance in Practice.

Progesterone-related diabetes mellitus (PRDM) in dogs is known for its particular potential for diabetes remission. This narrative review aims to provide relevant detailed information on (1) the canine estrus cycle and its impact on canine diabetes mellitus (CDM) etiology and management, (2) the role of pyometra as a further cause of insulin resistance, and (3) useful individual therapeutic and preventive strategies. PRDM is recognized due to diestrus, exogenous progestogen exposure, pregnancy, and P4-production ovarian dysfunction. Pyometra represents additional inflammatory and septic negative influence on insulin sensitivity, and its diagnosis associated with CDM is therapeutically challenging. The estrus cycle's hormone fluctuations seem to modulate peripheric insulin sensibility by influencing insulin receptor (IR) affinity and its binding capacity, as well as modulating tyrosine kinase activity. Pyometra was shown to negatively influence IR compensatory mechanisms to insulin resistance causing glucose intolerance. Spaying and pregnancy termination may cause diabetes remission in PRDM cases in a median time of 10 days (1-51). Pharmacological annulment of progesterone effects may benefit patients unable to undergo surgery; however, remission chances are virtually null. The ALIVE (Agreeing Language in Veterinary Endocrinology) project proposed new criteria for CDM diagnoses and subclinical diabetes recognition. These new concepts may increase the frequency of a PRDM diagnosis and, even more, its relevance. Spaying represents a preventive measure against pyometra and PRDM that should be individually assessed in light of its recognized benefits and harms.

Antinociceptive action of cannabidiol on thermal sensitivity and post-operative pain in male and female rats.

This study investigated the antinociceptive potential of cannabidiol (CBD) in male and female Wistar rats. The assessment and analysis included tail withdrawal to thermal stimulation (tail flick test) and mechanical allodynia induced by plantar incision injury (von Frey test). CBD reduced acute thermal sensitivity in uninjured animals and post-operative mechanical allodynia in males and females. In the tail flick test, CBD 30 mg/kg i.p. was required to induce antinociception in males. During the proestrus phase, females did not show a statistically significant antinociceptive response to CBD treatment despite a noticeable trend. In contrast, in a separate group of rats tested during the late diestrus phase, antinociception varied with CBD dosage and time. In the post-operative pain model, CBD at 3 mg/kg decreased mechanical allodynia in males. Similarly, this dose reduced allodynia in females during proestrus. However, in females during late diestrus, the lower dose of CBD (0.3 mg/kg) reduced mechanical allodynia, although the latency to onset of the effect was slower (90 min). The effectiveness of a 10-fold lower dose of CBD during the late diestrus stage in females suggests that ovarian hormones can influence the action of CBD. While CBD has potential for alleviating pain in humans, personalized dosing regimens may need to be developed to treat pain in women.

Isoallopregnanolone Inhibits Estrus Cycle-Dependent Aggressive Behavior.

Among female rats, some individuals show estrus cycle-dependent irritability/aggressive behaviors, and these individual rats may be used as a model for premenstrual dysphoric disorder (PMDD). We wanted to investigate if these behaviors are related to the estrus cycle phase containing moderately increased levels of positive GABA-A receptor-modulating steroids (steroid-PAM), especially allopregnanolone (ALLO), and if the adverse behavior can be antagonized. The electrophysiology studies in this paper show that isoallopregnanolone (ISO) is a GABA-A-modulating steroid antagonist (GAMSA), meaning that ISO can antagonize the agonistic effects of positive GABA-A receptor-modulating steroids in both α1ß2γ2L and α4ß3δ GABA-A receptor subtypes. In this study, we also investigated whether ISO could antagonize the estrus cycle-dependent aggressive behaviors in female Wistar rats using a resident-intruder test. Our results confirmed previous reports of estrus cycle-dependent behaviors in that 42% of the tested rats showed higher levels of irritability/aggression at diestrus compared to those at estrus. Furthermore, we found that, during the treatment with ISO, the aggressive behavior at diestrus was alleviated to a level comparable to that of estrus. We noticed an 89% reduction in the increase in aggressive behavior at diestrus compared to that at estrus. Vehicle treatment in the same animals showed a minimal effect on the diestrus-related aggressive behavior. In conclusion, we showed that ISO can antagonize Steroid-PAM both in α1ß2γ2L and α4ß3δ GABA-A receptor subtypes and inhibit estrus cycle-dependent aggressive behavior.

Cushing's Syndrome and Other Causes of Insulin Resistance in Dogs.

The most common causes of insulin resistance in diabetic dogs are Cushing syndrome, diestrus, and obesity. Cushing-associated effects include insulin resistance, excessive postprandial hyperglycemia, perceived short duration of insulin action, and/or substantial within-day and/or day-to-day glycemic variability. Successful strategies to manage excessive glycemic variability include basal insulin monotherapy and combined basal-bolus insulin treatment. Ovariohysterectomy and insulin treatment can achieve diabetic remission in about 10% of cases of diestrus diabetes. Different causes of insulin resistance have an additive effect on insulin requirements and the risk of progression to clinical diabetes in dogs.

Involvement of D2-like dopaminergic receptors in contextual fear conditioning in female rats: influence of estrous cycle.

Introduction: Dopamine has been increasingly recognized as a key neurotransmitter regulating fear/anxiety states. Nevertheless, the influence of sex and estrous cycle differences on the role of dopamine in fear responses needs further investigation. We aimed to evaluate the effects of sulpiride (a dopaminergic D2-like receptor antagonist) on contextual fear conditioning in females while exploring the influence of the estrous cycle. Methods: First, using a contextual fear conditioning paradigm, we assessed potential differences in acquisition, expression, and extinction of the conditioned freezing response in male and female (split in proestrus/estrus and metestrus/diestrus) Wistar rats. In a second cohort, we evaluated the effects of sulpiride (20 and 40 mg/kg) on contextual conditioned fear in females during proestrus/estrus and metestrus/diestrus. Potential nonspecific effects were assessed in motor activity assays (catalepsy and open-field tests). Results: No sex differences nor estrous cycle effects on freezing behavior were observed during the fear conditioning phases. Sulpiride reduced freezing expression in female rats. Moreover, females during the proestrus/estrus phases of the estrous cycle were more sensitive to the effects of sulpiride than females in metestrus/diestrus. Sulpiride did not cause motor impairments. Discussion: Although no sex or estrous cycle differences were observed in basal conditioned fear expression and extinction, the estrous cycle seems to influence the effects of D2-like antagonists on contextual fear conditioning.

Sex-dependent differences in the anxiolytic-like effect of cannabidiol in the elevated plus-maze.

RATIONALE: Cannabidiol (CBD), the major non-psychoactive constituent of cannabis, has therapeutic potential for the treatment of anxiety. Most preclinical studies investigate only acute effects of CBD and only in males, yet the drug is most likely to be used over a sustained period in clinical practice. OBJECTIVES: The objectives of this study were to investigate the anxiolytic-like effect of CBD in female rats compared to males and to determine whether the responsiveness of females was influenced by the stage of the estrous cycle. METHODS: We carried out experiments to compare the effect of CBD in male and female rats in the elevated plus maze (EPM) in response to acute and short-term (4 days) administration through a complete cycle in females. RESULTS: Male and female rats behaved in a similar manner in the EPM, but females in the late diestrus (LD) phase exhibited more anxiety-like behavior than at other stages, the difference reaching statistical significance compared to proestrus stages. CBD produced anxiolytic-like effects in both sexes, but female rats were responsive only in LD and 10-fold lower dose than males. After sub-chronic (4 days) treatment, responsiveness to CBD was maintained in females in LD, but females in proestrus remained unresponsive to CBD treatment. CONCLUSIONS: We suggest that there are sex differences in the anxiolytic-like effects of CBD in rats that reflect different underlying mechanisms: based on literature data, gonadal hormone status linked to GABAA receptor expression in females, and 5-HT1A receptor activation in males.

An approach to uncover the relationship between 17b-estradiol and ESR1/ESR2 ratio in the regulation of canine corpus luteum.

The canine corpus luteum (CL) is able to synthetise, activate and deactivate 17b-estradiol (E2) and also expresses nuclear estrogen receptors in a time-dependent manner during diestrus. Nevertheless, we are still missing a better comprehension of E2 functions in the canine CL, especially regarding the specific roles of estrogen receptor alpha (ERa) and ERb, encoded by ESR1 and 2, respectively. For that purpose, we analyzed transcriptomic data of canine non-pregnant CL collected on days 10, 20, 30, 40, 50 and 60 of diestrus and searched for differentially expressed genes (DEG) containing predicted transcription factor binding sites (TFBS) for ESR1 or ESR2. Based on biological functions of DEG presenting TFBS, expression of select transcripts and corresponding proteins was assessed. Additionally, luteal cells were collected across specific time points during diestrus and specificity of E2 responses was tested using ERa and/or ERb inhibitors. Bioinformatic analyses revealed 517 DEGs containing TFBS, from which 67 for both receptors. In general, abundance of predicted ESR1 targets was greater in the beginning, while abundance of ESR2 targets was greater in the end of diestrus. ESR1/ESR2 ratio shifted from an increasing to a decreasing pattern from day 30 to 40 post ovulation. Specific receptor inhibition suggested an ERa-mediated positive regulation of CL function at the beginning of diestrus and an ERb-mediated effect contributing to luteal regression. In conclusion, our data points toward a broad spectrum of action of E2 and its nuclear receptors, which can also act as transcription factors for other genes regulating canine CL function.

Effects of Different Energy Diets on FSHR mRNA Expression and DNA Methylation in Promoter Region of Duolang Sheep During Diestrus.

The aim of this study was to study the relationship between the methylation level of the promoter region of follicle-stimulating hormone receptor (FSHR) gene and the mRNA expression of Duolang sheep fed different energy diets. In this experiment, three groups of diets with different energy levels (dietary nutrient level reference (NY/T816 - 2004)) were designed to obtain medium energy level diets with metabolic energy of 10.88 MJ/d. The treatments with high and low energy levels increased and decreased by 15%, 12.51, and 9.25 MJ/d, respectively, on the basis of medium energy level. Total RNA and genomic DNA were extracted from the ovaries of Duolang sheep, and qPCR was performed. Bisulfite genomic sequencing PCR and sequence alignment were used to detect the relationship between the relative expression level of FSHR and methylation. The results showed that the expression of FSHR in high-energy group and medium-energy group was significantly higher than that in low-energy group (p < 0.01), and there was no significant difference between high-energy group and medium-energy group (p > 0.05). The methylation rate of the target fragment in the promoter region of FSHR gene was 41.67% in the high-energy group, 75.00% in the medium-energy group, and 83.33% in the low-energy group. This study revealed that different dietary energy levels had certain effects on DNA methylation level of FSHR gene and then affected gene expression, and the expression level was negatively correlated with methylation level.

Analysis of Gut Microbiota and Metabolites in Diannan Small Ear Sows at Diestrus and Metestrus.

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 Spirochaetes, Spirochaetia, Spirochaetales, Spirochaetaceae, Deltaproteobacteria, unidentified_Alphaproteobacteria, Ruminococcus_sp_YE281, and Treponema_berlinense 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 unidentified_Alphaproteobacteria, Intestinimonas, Peptococcus, Terrisporobacter, and differential metabolites of piperidine, propionic acid, and benzyl butyrate, sucrose, 4-methyl catechol, and AICAR exist a certain degree of correlation. Therefore, unidentified_Alphaproteobacteria, Ruminococcus_sp_YE281, and Treponema_berlinense 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.

Estrous cycle contributes to state-dependent contextual fear in female rats.

The increased susceptibility of women to stress and trauma-related disorders compared to men suggests a role for ovarian hormones in modulating fear and anxiety. In both humans and rodents, estrogen and progesterone have been shown to influence fear learning during acquisition, expression, and extinction. Recently, we showed that allopregnanolone (ALLO), a progesterone (PROG) metabolite and GABAA receptor potentiator, confers state-dependent contextual fear when infused into the bed nucleus of the stria terminalis of male rats. In order to determine whether estrous cycle-related fluctuations in circulating PROG confer state-dependent contextual fear in female rats, animals received Pavlovian fear conditioning during an estrous cycle phase when PROG was either low (late diestrus) or high (late proestrus). After conditioning, animals were tested for contextual fear in either the same or different estrous cycle phase. Subjects conditioned in diestrus and tested in proestrus showed lower levels of contextual fear compared to subjects conditioned and tested in the same estrous cycle phase (either diestrus or proestrus), suggesting a state-dependent effect of estrous cycle phase on fear learning. This state dependence was asymmetric, however, as animals trained in proestrus and tested in diestrus exhibited high levels of contextual fear. In ovariectomized (OVX) females treated acutely with either PROG or vehicle, state dependence was not observed. These results suggest that the hormonal state in diestrus may play a role in conferring state dependence to conditioned fear in naturally cycling female rats but not in an OVX model.

Early Pregnancy in Jennies in the Caribbean: Corpus Luteum Development and Progesterone Production, Uterine and Embryo Dynamics, Conceptus Growth and Maturation.

We aimed to characterize early embryo development and changes in corpus luteum (CL) development and progesterone profile in pregnant vs. non-pregnant jennies. Eight jennies were enrolled in the study. In the first two cycles, the jennies were monitored by transrectal ultrasonography and had blood harvested for hormone profile assay. In the third cycle, jennies were bred by a jack of proven fertility. Jennies were then monitored and sampled for up to 30 days of pregnancy. Data were evaluated by random-effects multiple linear regression, and correlations were expressed as Pearson's correlation coefficient. Progesterone concentration rose rapidly from ovulation (D0) until D7, plateaued until D12-14, then precipitously declined between D14 and 15, remaining low until the next ovulation in non-pregnant cycles. In the pregnant jennies, the progesterone concentration rose to maximal concentrations on D7-11, being higher at this stage than in non-pregnant cycles, then declined gradually up to D30. In all cycles, the volume of the CL increased steadily until D6, when it plateaued in pregnant jennies. For non-pregnant jennies, CL volume decreased slowly from D6 to D11 and then had a faster drop. Uterine tone increased following ovulation, becoming turgid around the day of embryo fixation (D15.0 ± 0.9). An embryonic vesicle (EV) was first detected on D9.3 ± 0.5 (2.4 ± 0.5 mm). The EV remained spherical until D18.6 ± 1.4. The embryo proper was first detected ventrally in the vesicle on D20.8 ± 1.1 and the embryonic heartbeat by D22.0 ± 0.9. The allantoic sac was identified at D24.0 ± 0.9, and at D30, the allantoic sac filled the ventral half of the EV. This study provides evidence that higher cumulative concentrations of progesterone are correlated to size of the EV, and there were changes in the luteal dynamics and progesterone profiles in pregnant vs. non-pregnant jennies.

Structural and Functional Dynamics of the Ovary and Uterus during the Estrous Cycle in Donkeys in the Eastern Caribbean.

Eight non-bred, non-pregnant, regularly cycling Caribbean jennies were examined daily via transrectal ultrasound to define the ovarian and uterine dynamics during four consecutive estrous cycles. Blood samples were collected every other day for progesterone analysis. The mean (±SD) overall inter-ovulatory interval across all donkeys and cycles was 22.93 ± 1.99 days. The maximum follicular diameter was 34.6 ± 2.9 mm. A two-wave pattern was evident in 97% (30/31) of the cycles. The emergence of the future dominant follicle and the largest subordinate follicle of the major primary wave coincided on Day 5.7 ± 3.6 post-ovulation, whereas the secondary wave emerged on Day 19.8 ± 2.9 during estrus of the previous cycle or early diestrus. The secondary wave was often minor (93%, 28/30 cycles). Follicular deviation occurred 8.2 ± 1.4 days before the subsequent ovulation. Luteal volume increased for the first four days after ovulation and reached a maximum volume of 8.5 ± 2.7 mm3 at Day 5.4 ± 0.4, before gradually regressing after Day 15. Serum progesterone concentration increased from Day 1 after ovulation, peaking at 27.0 ± 9.6 ng/mL between 7 and 10 days after ovulation. Progesterone concentration dropped precipitously around Day 15 after ovulation and was below 2 ng/mL around Day 17 ± 2. A day effect (p < 0.0001) was observed for corpus luteum's volume, progesterone concentration, and uterine tone, but not for endometrial edema (p > 0.05). This study helps to clarify and define normal estrous characteristics of jennies in the Eastern Caribbean.

Efficacy and Side Effects of Low Single Doses of Cloprostenol Sodium or Dinoprost Tromethamine to Induce Luteolysis in Donkeys.

Due to the limited literature available evaluating doses of Prostaglandin F2α in donkeys, doses for horses have been extrapolated and used as guidelines. This study aimed to assess the efficacy and side effects of four different cloprostenol sodium and dinoprost tromethamine doses to induce luteolysis in jennies. Sixty-three cycles of seven Jennies (nine cycles per jenny) were used in this study. Seven days after ovulation, jennies randomly received one of the treatments in a crossover design as follows: Control, no treatment was administered; C1, 250 µg of cloprostenol sodium (CS, Estrumate , Merck Animal Health, USA); C2, 125 µg of CS; C3, 65.5 µg of CS, C4, 37.5 µg of CS; DT1, 5 mg of dinoprost tromethamine (DT, Lutalyse, Zoetis, USA); DT2, 2.5 mg of DT; DT3, 1.25 mg of DT; DT4, 0.625 mg of DT. Jennies were monitored for 30 minutes following treatment, and adverse effects were recorded. The measurement of the corpus luteum (CL) and the length of the estrous cycle were recorded. All DT and CS treatment doses were effective (P < .0001) in reducing the estrous cycle length compared to jenny's Control cycle. The CL volume was decreased in all treated groups one day after treatment (P < .05). The adverse effects were reduced as the dose of both Prostaglandin F2α analogs were reduced. In conclusion, a single low dose of dinoprost tromethamine (0.625 mg) or cloprostenol sodium (37.5 µg) can induce luteolysis and shorten the estrous length in jennies producing fewer adverse effects.

Protocolo para la citología vaginal directa de ratas de laboratorio / Protocol for direct vaginal cytology of laboratory rats

Introducción: La citología vaginal directa es un método muy utilizado para la evaluación del ciclo estral de las ratas de laboratorio, pero la información acerca de los procedimientos e interpretación de los resultados aparece disgregada en la literatura, lo cual dificulta su empleo en los estudios de reproducción. Objetivo: Proponer un protocolo para la realización de la citología vaginal directa de ratas de laboratorio y la interpretación de los resultados. Material y métodos: Se combinó la información de la literatura y la experiencia de 10 años de estudios de reproducción, en los que se han empleado un total de 250 ratas Wistar hembras, siguiendo preceptos éticos establecidos. Se describen los procedimientos para la obtención de las muestras, mediante lavado vaginal, así como para su observación y análisis en estado húmedo, con microscopio óptico y cámara digital acoplada. Resultados: Se describen los tipos celulares principales presentes en el lavado vaginal y las características que permiten identificar cada fase o estado de transición del ciclo estral. Se discuten aspectos a considerar en la interpretación de los resultados, que incluye la relación con los cambios hormonales, los cuidados en la obtención de la muestra y la influencia de factores ambientales. Se muestran imágenes y figuras representativas para ilustrar el texto. Conclusiones: El trabajo constituye un protocolo para el estudio del ciclo estral de ratas de laboratorio, mediante la citología vaginal directa. Provee métodos no invasivos, sencillos y económicos, así como conocimientos esenciales para la interpretación de los resultados, que integran una guía de gran utilidad para los estudios experimentales de reproducción(AU)

Introduction: Direct vaginal cytology is a widely used method for the evaluation of the estrous cycle of laboratory rats, but the information about the procedures and interpretation of results is dispersed through literature, making its use difficult in investigations on reproduction. Objective: To propose a protocol for performing direct vaginal cytology of laboratory rats as well as for the interpretation of the results. Material and methods: The information obtained from literature and the experience of 10 years of investigation on reproduction in 250 female Wistar rats were combined following the established ethical principles. The procedures for obtaining samples by vaginal washing and by observation and analysis in humid state with light microscope equipped with digital camera were described. Results: The main types of cells present in the vaginal washing and the characteristics that allow us to identify each phase or transitional phases of the estrus cycle are described. Aspects to take into consideration in the interpretation of the results, which include the association between hormonal changes, the cares in the obtaining of the sample and the influence of environmental factors, are discussed. Representative images and figures are included to illustrate the text. Conclusions: The work consists of a study protocol of the estrus cycle of laboratory rats by direct vaginal cytology. It provides noninvasive, simple and cost-reducing procedures as well as essential knowledge for the interpretation of results which integrate a very useful guideline for experimental investigations on reproduction(AU)

Association between progesterone concentration and endometrial gene expression in dairy cows.

The objective of this study was to evaluate the association between progesterone concentration on Days 4 and 9 of the estrus cycle and endometrial transcriptome at Day 9 in lactating grazing dairy cows. Blood samples were obtained on Days 0, 4, and 9 for progesterone measurement by chemiluminescence. Cows were assigned to one of the following groups (n = 3 per group): cows with low physiological progesterone on Day 4, cows in anestrous, cows with high physiological progesterone on Day 4, and superovulated cows. Endometrial biopsy samples were obtained on Day 9 for RNA sequencing. Quality control and determination of differentially expressed genes (false discovery rate <0.05) were determined using the edgeR package for R software. We identified 3,042 differentially expressed genes among the 4 groups. Cows having high physiological progesterone and superovulated cows showed high similarities and clustered apart from those in anestrus or having low physiological progesterone. Functional analysis using Database for Annotation, Visualization, and Integrated Discovery revealed that endometrial genes upregulated by low progesterone concentration are enriched genes involved in the immune system and inflammatory response. Conversely, cows with high physiological progesterone concentration presented an endometrial transcriptome with similarities to cows with good genetic merit for fertility, showing upregulation of genes related to uterine relaxation-contraction, focal adhesion, GnRH signaling pathway, and epidermal growth factor-like related terms, suggesting a favorable embryo environment. In conclusion, our results support the concept that there is a threshold of progesterone concentration at the beginning of the luteal phase associated with endometrial expression of critical genes involved in the preparation of the uterine environment for embryo implantation.

Vaginal Microbiota Is Stable throughout the Estrous Cycle in Arabian Maress.

Lactic acid bacteria (LAB) dominate human vaginal microbiota and inhibit pathogen proliferation. In other mammals, LAB do not dominate vaginal microbiota, however shifts of dominant microorganisms occur during ovarian cycle. The study objectives were to characterize equine vaginal microbiota in mares by culture-dependent and independent methods and to describe its variation in estrus and diestrus. Vaginal swabs from 8 healthy adult Arabian mares were obtained in estrus and diestrus. For culture-dependent processing, bacteria were isolated on Columbia blood agar (BA) and Man Rogosa Sharpe (MRS) agar. LAB comprised only 2% of total bacterial isolates and were not related to ovarian phases. For culture-independent processing, V3/V4 variable regions of the 16S ribosomal RNA gene were amplified and sequenced using Illumina Miseq. The diversity and composition of the vaginal microbiota did not change during the estrous cycle. Core equine vaginal microbiome consisted of Firmicutes, Bacteroidetes, Proteobacteria and Actinobacteria at the phylum level. At the genus level it was defined by Porphyromonas, Campylobacter, Arcanobacterium, Corynebacterium, Streptococcus, Fusobacterium, uncultured Kiritimatiaellae and Akkermansia. Lactobacillus comprised only 0.18% of the taxonomic composition in estrus and 0.37% in diestrus. No differences in the relative abundance of the most abundant phylum or genera were observed between estrus and diestrus samples.

Serum progesterone concentration, volume, and apoptosis of corpora lutea in early, middle and late diestrus in the bitch.

The aim was to study number, volume, apoptosis of corpora lutea (CL), and serum P4 concentrations in early, middle, and late diestrus of dogs. Thirty-six bitches were ovari-hysterectomized (OVX): Early Diestrus (Group [G]1; OVX 20 days after end of estrus [DEH]); Mid-diestrus (GII; OVX between 21 and 40 days after DEH), and Late-diestrus (GIII; OVX between 41 and 60 days after DEH). Before OVX a blood sample was collected to quantify P4. After OVX, the number of CL (NCL) was recorded, CL measured using both ultrasonography (US) and caliper (CAL), and the volume (mm3) was calculated. Based on abundances of caspase-3, apoptotic luteal cells were detected. Bitches in early-diestrus had greater P4 concentrations than bitches in mid- and late-diestrus (23.52 ±â€¯3.78 and 10.86 ±â€¯3.88 ng/mL; P < 0.05). The NCL, cumulative USCLV, and CALCLV were similar among diestrus stages (P > 0.30). Bitches with CL (≥5) had twice the serum P4 concentrations as bitches with CL1-2 and CL3-4 (22.71 ±â€¯3.70 and 10.97 ±â€¯4.06 ng/mL; P < 0.05). There were correlations between P4 concentrations with USCLV, CALCLV, and NCL (r = 0.64, r = 0.67, r = 0.44; P < 0.0001). When serum P4 concentrations were adjusted for stages of diestrus, however, there were only correlations during early diestrus. The percentage of apoptotic cells was greater in GIII compared with GI and GII (13.75 ±â€¯2.26 % compared with 4.5 ±â€¯0.68 % and 4.6 ±â€¯1.5 %, respectively; P < 0.05). As days of diestrus increased, number of apoptotic cells increased, and serum P4 concentrations decreased.

G Protein-Coupled Estrogen Receptor Immunoreactivity Fluctuates During the Estrous Cycle and Show Sex Differences in the Amygdala and Dorsal Hippocampus.

G protein-coupled estrogen receptor (GPER) in the amygdala and the dorsal hippocampus mediates actions of estradiol on anxiety, social recognition and spatial memory. In addition, GPER participates in the estrogenic regulation of synaptic function in the amygdala and in the process of adult neurogenesis in the dentate gyrus. While the distribution of the canonical estrogen receptors α and ß in the amygdala and dorsal hippocampus are well characterized, little is known about the regional distribution of GPER in these brain regions and whether this distribution is affected by sex or the stages of the estrous cycle. In this study we performed a morphometric analysis of GPER immunoreactivity in the posterodorsal medial, anteroventral medial, basolateral, basomedial and central subdivisions of the amygdala and in all the histological layers of CA1 and the dentate gyrus of the dorsal hippocampal formation. The number of GPER immunoreactive cells was estimated in these different structures. GPER immunoreactivity was detected in all the assessed subdivisions of the amygdaloid nucleus and dorsal hippocampal formation. The number of GPER immunoreactive cells was higher in males than in estrus females in the central (P = 0.001) and the posterodorsal medial amygdala (P < 0.05); higher in males than in diestrus females in the strata orients (P < 0.01) and radiatum-lacunosum-moleculare (P < 0.05) of CA1-CA3 and in the molecular layer of the dentate gyrus (P < 0.01); higher in diestrus females than in males in the basolateral amygdala (P < 0.05); higher in diestrus females than in estrus females in the central (P < 0.01), posterodorsal medial (P < 0.01) and basolateral amygdala (P < 0.01) and higher in estrus females than in diestrus females in the strata oriens (P < 0.05) and radiatum-lacunosum-moleculare (P < 0.05) of CA1-CA3 and in the molecular layer (P < 0.05) and the hilus of the dentate gyrus (P < 0.05). The findings suggest that estrogenic regulation of the amygdala and hippocampus through GPER may be different in males and in females and may fluctuate during the estrous cycle.

Vaginal Microbiota Changes During Estrous Cycle in Dairy Heifers.

The vaginal microbiota plays an important role in the health of dairy cattle, and it could be manipulated for the prevention and treatment of reproduction-related infections. The present study profiles and compares the vaginal microbiota of healthy dairy heifers during the estrous cycle focusing the results in follicular (estrus) and luteal (diestrus) phases using 16S rRNA sequencing of the V3-V4 hypervariable region. Twenty 13-16-months-old virgin dairy heifers from a single farm were included in this study. Vaginal swabs and blood samples were obtained during estrus (6-8 h before artificial insemination) and diestrus (14 days after insemination). Estrus was evaluated by an activity monitoring system and confirmed with plasma progesterone immunoassay. Results showed that the taxonomic composition of the vaginal microbiota was different during the follicular and luteal phases. At the phylum level, the most abundant bacterial phyla were Tenericutes, Firmicutes, and Bacteroidetes which comprised more than 75% of the vaginal microbiota composition. The next more abundant phyla, in order of decreasing abundance, were Proteobacteria, Actinobacteria, Fusobacteria, Epsilonbacteraeota, and Patescibacteria. Together with Tenericutes, Firmicutes, and Bacteroidetes represented more than 96% of the bacterial composition. Ureaplasma, Histophilus, f_Corynebacteriaceae, Porphyromonas, Mycoplasma, Ruminococcaceae UCG-005, were the most abundant genera or families. The results also showed that the vaginal microbiota of dairy heifers was non-lactobacillus dominant. The genus Lactobacillus was always found at a low relative abundance during the estrous cycle being more abundant in the follicular than in the luteal phase. Despite more research is needed to explore the potential use of native vaginal microbiota members as probiotics in dairy heifers, this study represents an important step forward. Understanding how the microbiota behaves in healthy heifers will help to identify vaginal dysbiosis related to disease.

Estrogen and progesterone priming induces lordosis in female rats by reversing the inhibitory influence of the infralimbic cortex on neuronal activity of the lateral septal nucleus.

The lateral septal nucleus (LSN) exerts inhibitory control over lordosis in female rats, but the influence of forebrain structures, such as prelimbic (PL) and infralimbic (IL) regions of the medial prefrontal cortex (mPFC), on LSN activity during sexual receptivity is unknown. We hypothesized that the neural responsivity of these connections may differ depending on sexual receptivity. Gonadally intact female Wistar rats received sequential priming injections of estradiol and progesterone (E2-P4). The presence of lordosis was then confirmed by exposing the female rats to a sexually experienced male rat. Intromission was not allowed. Vaginal smear analyses verified that the rats were in proestrus-estrus of the estrous cycle. The results were compared with a diestrus group, which was verified by vaginal smears and the absence of lordosis. Under ethyl-carbamate anesthesia, single-unit extracellular recordings of the LSN were performed during electrical stimulation of the PL and IL to evaluate possible changes in the responsivity of neural connections. Stimulation of the PL or IL produced a short-latency, brief-duration (paucisynaptic) excitatory response in the LSN, followed by a period of afterhyperpolarization. Responsivity of the PL-LSN pathway was unaffected by E2-P4 priming. The paucisynaptic response of the IL-LSN pathway was significantly greater in the E2-P4-primed group than in the diestrus group, and the afterhyperpolarization response decreased to nearly zero. These findings indicate that the IL exerts inhibitory control over the LSN during diestrus in rats, but this inhibitory control decreases under the action of gonadal steroids, seemingly favoring sexual receptivity.