Cysteine-Cysteine Motif Chemokine Receptor 5 Expression in Letrozole-Induced Polycystic Ovary Syndrome Mice.

Polycystic ovary syndrome (PCOS), which affects 5-10% of women of reproductive age, is associated with reproductive and metabolic disorders, such as chronic anovulation, infertility, insulin resistance, and type 2 diabetes. However, the mechanism of PCOS is still unknown. Therefore, this study used a letrozole-exposed mouse model in which mice were orally fed letrozole for 20 weeks to investigate the effects of letrozole on the severity of reproductive and metabolic consequences and the expression of cysteine-cysteine motif chemokine receptor 5 (CCR5) in letrozole-induced PCOS mice. The letrozole-treated mice showed a disrupted estrous cycle and were arrested in the diestrus phase. Letrozole treatment also increased plasma testosterone levels, decreased estradiol levels, and caused multicystic follicle formation. Furthermore, histological analysis of the perigonadal white adipose tissue (pgWAT) showed no significant difference in the size and number of adipocytes between the letrozole-treated mice and the control group. Further, the letrozole-treated mice demonstrated glucose intolerance and insulin resistance during oral glucose and insulin tolerance testing. Additionally, the expression of CCR5 and cysteine-cysteine motif ligand 5 (CCL5) were significantly higher in the pgWAT of the letrozole-treated mice compared with the control group. CCR5 and CCL5 were also significantly correlated with the homeostasis model assessment of insulin resistance (HOMA-IR). Finally, the mechanisms of insulin resistance in PCOS may be caused by an increase in serine phosphorylation and a decrease in Akt phosphorylation.

Analysis of the uterine flush fluid proteome of healthy mares and mares with endometritis or fibrotic endometrial degeneration.

The objective of this study was to evaluate the differences in the uterine flush fluid proteome between healthy mares and mares with endometritis or fibrotic endometrial degeneration (FED). Uterine flush fluid samples were collected from healthy mares (n=8; oestrus n=5 and dioestrus n=3) and mares with endometritis (n=23; oestrus n=14 and dioestrus n=9) or FED (n=7; oestrus n=6 and dioestrus n=1). Proteomic analysis was performed using label-free liquid chromatography-tandem mass spectrometry. Of 216 proteins identified during oestrus, 127 were common to all three groups, one protein was exclusively detected in healthy mares, 47 proteins were exclusively detected in mares with endometritis and four proteins were exclusively detected in mares with FED. Of 188 proteins identified during dioestrus, 113 proteins were common between healthy mares and mares with endometritis, eight proteins were exclusively detected in healthy mares and 67 proteins were exclusively detected in mares with endometritis. Quantitative analysis revealed a subset of proteins differing in abundance between the three groups during oestrus and between healthy mares and mares with endometritis during dioestrus. These results provide a springboard for evaluation of specific proteins as biomarkers of uterine health and disease and for investigation of their roles in the establishment and maintenance of pregnancy.

Qualitative analysis and functional classification of the uterine proteome of mares in oestrus and dioestrus.

Quantitative analysis of the uterine flush fluid proteome of mares in oestrus and dioestrus has been previously reported. The objectives of this study were to: a) evaluate qualitative differences in the uterine flush fluid proteome between mares in oestrus and mares in dioestrus and b) perform a functional classification of proteins either unique to each stage or common between the two stages. Uterine flush fluid samples were collected from 8 light breed mares in either oestrus (n = 5) or dioestrus (n = 3). Proteomic analysis of the samples was conducted using liquid chromatography-tandem mass spectrometry. Proteins exclusively detected in oestrus or dioestrus and those common to both stages were identified using the Scaffold software (version 4.4.8, Proteome Software Inc., Portland, OR). The identified proteins were classified into gene ontology (GO) categories (cellular component [CC], molecular function [MF] and biological process [BP]) using the PANTHER (www.pantherdb.org) classification system version 14.0. Of 172 proteins identified, 51 and 28 were exclusively detected in mares in oestrus and dioestrus, respectively, and 93 proteins were common to both stages. The most represented terms in various GO categories were similar among the three subsets of proteins. The most represented CC terms were extracellular region and cell, the most represented MF terms were catalytic activity and binding, and the most represented BP terms were metabolic process and cellular process. In conclusion, proteomic analysis of the uterine flush fluid enabled the identification of subsets of proteins unique to oestrus or dioestrus, or common to both stages. The results of this study can serve as a baseline for future research focused on finding stage-specific protein markers or evaluating differences in the uterine flush fluid proteome between normal mares and those with uterine disease.

Hexokinase 2 drives glycogen accumulation in equine endometrium at day 12 of diestrus and pregnancy.

BACKGROUND: Secretion of histotroph during the prolonged pre-implantation phase in mares is crucial to pregnancy maintenance, manifested as increased embryonic loss in mares with age-related endometrial degeneration. Glycogen content of uterine histotroph is higher during the progesterone-dominated phase of the estrous cycle in mares, but regulatory mechanisms are not well understood. METHODS: mRNA expression of glycogen-metabolizing enzymes (HK1, HK2, GSK3B, GYS1, PEPCK, PKM, PYGM) in endometrial samples were compared among mares in anestrus, estrus, and at Day 12 of diestrus and pregnancy. In addition, hexokinase 2 (HK2) activity was assessed using a colorimetric assay. RESULTS: HK2 was the key regulator of glycogen accumulation during diestrus and pregnancy; hexokinase transcript abundance and enzyme activity were significantly higher during diestrus and pregnancy than estrus and anestrus. In addition, despite similar relative transcript abundance, hexokinase activity was significantly greater in the pregnant versus diestrous endometrium. Therefore, we inferred there was regulation of hexokinase activity through phosphorylation, in addition to its regulation at the transcriptional level during early pregnancy. Based on immunohistochemistry, HK2 was localized primarily in luminal and glandular epithelial cells, with weaker staining in stromal cells. CONCLUSION: Among glycogen metabolizing enzymes identified, expression of HK2 was significantly greater during the progesterone-dominated phase of the cycle.

Peri-ovulatory endocrine regulation of the prostanoid pathways in the bovine uterus at early dioestrus.

We hypothesised that different endocrine profiles associated with pre-ovulatory follicle (POF) size would impact on uterine prostanoid pathways and thereby modulate the histotroph composition. Beef cows (n=15 per group) were hormonally manipulated to have small (SF-SCL group) or large (LF-LCL group) pre-ovulatory follicles (POF) and corpora lutea (CL). Seven days after induction of ovulation, animals were slaughtered and uterine tissues and flushings were collected for quantification of prostanoids. The POF and CL size and the circulating progesterone concentrations at Day 7 were greater (P<0.05) in the LF-LCL cows than in the SF-SCL group, as expected. The abundance of 5 out of 19 genes involved in prostanoid regulation was different between groups. Transcript abundance of prostaglandin F2α, E2 and I2 synthases was upregulated (P<0.05) and phospholipase A2 was downregulated (P<0.05) in endometrium of the LF-LCL group. No difference (P>0.1) in prostanoid concentrations in the endometrium or in uterine flushings was detected between groups. However, prostaglandin F2α and E2 concentrations in the uterine flushings were positively correlated with the abundance of transcripts for prostaglandin endoperoxide synthase 2 (0.779 and 0.865, respectively; P<0.002). We conclude that endometrial gene expression related to prostanoid synthesis is modulated by the peri-ovulatory endocrine profile associated with POF size, but at early dioestrus differences in transcript abundance were not reflected in changes in prostanoid concentrations in the uterine tissue and fluid.

Neuromodulatory effect of oestradiol in the metabolism of ovarian progesterone and oestradiol during dioestrus II: participation of the superior mesenteric ganglion.

The aims of the present study were to determine: (1) whether oestradiol (E2) in the superior mesenteric ganglion (SMG) modifies the release of ovarian progesterone (P4), androstenedione (A2) and E2, the activity and gene expression of 3ß-hydroxysteroid dehydrogenase (3ß-HSD) and 20α-HSD and the expression of P450 aromatase (Cyp19a1) and (2) whether any such modifications are related to changes in ovarian nitric oxide (NO) and noradrenaline (NA) levels during dioestrus II. Using an ex vivo SMG-ovarian nervous plexus-ovary system, ovarian P4 release was measured following the addition E2 plus tamoxifen (Txf) (10-6M) to the ganglion, whereas A2, E2, NA and NO were measured following the addition of E2 alone. Steroids were measured by radioimmunoassay, NA concentrations were determined by HPLC and gene expression was evaluated using reverse transcription-polymerase chain reaction. Oestradiol in the ganglion decreased ovarian P4, E2 and NA release, as well as 3ß-HSD activity, but increased the release of A2 and nitrites, as well as the 20α-HSD expression and its activity. No changes were observed in Cyp19a1 gene expression. The addition of E2 plus Txf to the ganglion reversed the effects of E2 alone. The action of oestradiol in SMG favours the beginning of functional luteolysis, due to an increase in NO release and a decrease in NA in the ovary. These results may help elucidate the role of E2 in hormone-dependent pathologies in women.

Evaluation of cell proliferation and endometrial thickness of bitches in different periods of diestrus.

This study aimed to determine the histological features of the endometrium of bitches, as well as the cell proliferation at specific moments of diestrus, 10, 20, 30, 40, 50 and 60 days post ovulation, correlating the endometrial thickness with the uterine cell proliferation and the metabolic state (weight, blood glucose and plasma cholesterol) of the animals. Therefore, the right and left uterine horns of 26 clinically healthy bitches submitted to ovariohysterectomy were histologically analyzed 10, 20, 30, 40, 50 and 60 days post ovulation. The hematoxylin-eosin and AgNOR staining techniques were performed. All parameters were evaluated by ANOVA and post-hoc Tukey test (p<0.05). The correlation between endometrial thickness and uterine cell proliferation, weight, blood glucose and plasma cholesterol of animals was observed using the Pearson method (p<0.05). In the present study, it is concluded that endometrial thickness does not differ at any of the moments analyzed in diestrus. The endometrial thickness is not influenced by hormones, weight, blood glucose or serum cholesterol of bitches in this phase of the estrous cycle. However, there is greater cell proliferation in the endometrium at day 40 compared to day 60 post ovulation under the influence of the endocrine profile.

Phospholipid Profile and Distribution in the Receptive Oviduct and Uterus During Early Diestrus in Cattle.

Phospholipid metabolism and signaling influences on early pregnancy events in cattle are unknown. This study aimed to characterize global phospholipid composition of oviduct and uterus during early diestrus in a model of contrasting embryo receptivity. Beef cows were treated to ovulate a larger (LF-LCL group, associated with greater receptivity) or smaller (SF-SCL group) follicle and, consequently, to present greater or smaller plasma concentrations of estradiol during proestrus-estrus, as well as progesterone during early diestrus. Oviduct and uterus (4 days after gonadotropin-releasing hormone-induced ovulation; D4) as well as the uterus (D7) were collected, and lipid profiles were monitored by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). This technique allowed the identification and tissue localization of sphingomyelins (SM), phosphatidylcholines (PC), ceramides (Cer), and phosphatidylethanolamines (PE). Multivariate statistics were used to separate samples into groups with distinctly different phospholipid profiles in the uterus at D4 and D7. Different abundance of ions corresponding to specific lipids were detected on D4 (Cer [42:1], PC [31:0], PC [32:1], PC [34:4], and PC [36:4] greater for LF-LCL group; and PC [38:7], PC [38:5], PC [38:4], PC [40:7], and PC [40:6] greater for SF-SCL group) and D7 (SM [34:2], SM [34:1], PC [32:1], and PC [35:2] greater for LF-LCL group). The MALDI-MS imaging showed the spatial distributions of major phospholipids. In conclusion, distinct phospholipid profiles were associated with animals treated to show contrasting receptivity to the embryo. Functional roles of the identified phospholipids on uterine function and preimplantation embryo development deserve further studies.

The participation of the muscarinic receptors in the preoptic-anterior hypothalamic areas in the regulation of ovulation depends on the ovary.

BACKGROUND: Muscarinic receptors (mAChRs) of the preoptic and anterior hypothalamus areas (POA-AHA) regulate ovulation in an asymmetric manner during the estrous cycle. The aims of the present study were to analyze the effects of a temporal blockade of mAChRs on either side of the POA-AHA performed in diestrus-2 rats on ovulation, the levels of estradiol, follicle stimulating hormone (FSH) and luteinizing hormone (LH) and the mechanisms involved in changes in ovulation. METHODS: Cyclic rats on diestrus-2 day were anesthetized and randomly assigned to the following groups: 1) microinjection of 1 µl of saline or atropine solution (62.5 ng) in the left or right POA-AHA; 2) removal (unilateral ovariectomty, ULO) of the left (L-ULO) or right (R-ULO) ovary, and 3) rats microinjected with atropine into the left or right POA-AHA plus L-ULO or R-ULO. The ovulation rate and the number of ova shed were measured during the predicted estrus, as well as the levels of estradiol, FSH and LH during the predicted proestrus and the effects of injecting synthetic LH-releasing hormone (LHRH) or estradiol benzoate (EB). RESULTS: Atropine in the left POA-AHA decreased both the ovulation rate and estradiol and LH levels on the afternoon of proestrus, also LHRH or EB injection restored ovulation. L- or R-ULO resulted in a lower ovulation rate and smaller number of ova shed, and only injection of LHRH restored ovulation. EB injection at diestrus-2 restored ovulation in animals with L-ULO only. The levels of estradiol, FSH and LH in rats with L-ULO were higher than in animals with unilateral laparotomy. In the group microinjected with atropine in the left POA-AHA, ovulation was similar to that in ULO rats. In contrast, atropine in the right POA-AHA of ULO rats blocked ovulation, an action that was restored by either LHRH or EB injection. CONCLUSIONS: These results indicated that the removal of a single ovary at noon on diestrus-2 day perturbed the neuronal pathways regulating LH secretion, which was mediated by the muscarinic system connecting the right POA-AHA and the ovaries.

A Novel Letrozole Model Recapitulates Both the Reproductive and Metabolic Phenotypes of Polycystic Ovary Syndrome in Female Mice.

Polycystic ovary syndrome (PCOS) pathophysiology is poorly understood, due partly to lack of PCOS animal models fully recapitulating this complex disorder. Recently, a PCOS rat model using letrozole (LET), a nonsteroidal aromatase inhibitor, mimicked multiple PCOS phenotypes, including metabolic features absent in other models. Given the advantages of using genetic and transgenic mouse models, we investigated whether LET produces a similar PCOS phenotype in mice. Pubertal female C57BL/6N mice were treated for 5 wk with LET, which resulted in increased serum testosterone and normal diestrus levels of estradiol, similar to the hyperandrogenemia and follicular phase estrogen levels of PCOS women. As in PCOS, ovaries from LET mice were larger, polycystic, and lacked corpora lutea versus controls. Most LET females were acyclic, and all were infertile. LET females displayed elevated serum LH levels and higher Lhb mRNA in the pituitary. In contrast, serum FSH and Fshb were significantly reduced in LET females, demonstrating differential effects on gonadotropins, as in PCOS. Within the ovary, LET females had higher Cyp17, Cyp19, and Fsh receptor mRNA expression. In the hypothalamus, LET females had higher kisspeptin receptor mRNA expression but lower progesterone receptor mRNA levels. LET females also gained more weight than controls, had increased abdominal adiposity and adipocyte size, elevated adipose inflammatory mRNA levels, and impaired glucose tolerance, mirroring the metabolic phenotype in PCOS women. This is the first report of a LET paradigm in mice that recapitulates both reproductive and metabolic PCOS phenotypes and will be useful to genetically probe the PCOS condition.

The periovulatory endocrine milieu affects the uterine redox environment in beef cows.

BACKGROUND: In cattle, recent studies have shown positive associations between pre-ovulatory concentrations of estradiol (E2), progesterone (P4) at early diestrus and fertility. However, information on cellular and molecular mechanisms through which sex steroids regulate uterine function to support early pregnancy is lacking. Based on endometrial transcriptome data, objective was to compare function of the redox system in the bovine uterus in response to different periovulatory endocrine milieus. METHODS: We employed an animal model to control growth of the pre-ovulatory follicle and subsequent corpus luteum (CL). The large follicle-large CL group (LF-LCL, N=42) presented greater levels of E2 on the day of GnRH treatment (D0; 2.94 vs. 1.27 pg/mL; P=0.0007) and P4 at slaughter on D7 (3.71 vs. 2.62 ng/mL, P=0.01), compared with the small follicle-small CL group (SF-SCL, N=41). Endometrium and uterine washings (N=9, per group) were collected for analyses of variables associated with the uterine redox system. RESULTS: The SF-SCL group had lower endometrial catalase (0.5 vs. 0.79 U/mg protein, P<0.001) and glutathione peroxidase (GPx; 2.0 vs. 2.43 nmol ß-nicotinamide adenine dinucleotide phosphate reduced/min/mg protein, P=0.04) activity, as well as higher lipid peroxidation (28.5 vs. 17.43 nmol malondialdehyde/mg of protein, P<0.001) and superoxide dismutase (SOD) activity (44.77 vs. 37.76 U; P=0.04). There were no differences in the endometrial reactive species (RS) or glutathione (GSH) concentrations between the groups. The uterine washing samples showed no differences in the concentrations of RS or GSH or in total SOD activity (P>0.1). Additionally, catalase, GPx4, SOD1 and SOD2 gene expression was lower in the SF-SCL group than in the LF-LCL group. CONCLUSIONS: We concluded that the intrauterine environment of cows from the LF-LCL group exhibited higher antioxidant activity than that of the cows from the SF-SCL group. We speculate that uterine receptivity and fertility are associated with an optimal redox environment, such as that present in the animals in the LF-LCL group.

Regulation of the polyamine metabolic pathway in the endometrium of cows during early diestrus.

The timing and magnitude of exposure to preovulatory estradiol followed by post-ovulatory progesterone (periovulatory endocrine milieu) in cattle modulate endometrial gene expression, histotroph composition, and conceptus development, but the mechanisms underlying this regulation remain unknown. Using an experimental model based on the modulation of follicle growth, this work aimed to evaluate if the polyamine metabolic pathway is regulated by the periovulatory endocrine milieu. Nelore cows were manipulated to ovulate small (n = 15) or large (n = 15) follicles, then the profiles of polyamines and their synthetic enzymes were compared between groups. Transcripts for the enzymes of this pathway, ornithine decarboxylase 1 (ODC1; the rate-limiting enzyme in polyamine biosynthesis) protein quantification, adenosylmethionine decarboxylase 1 (AMD1) protein immunolocalization, and concentrations of the different polyamines (putrescine, spermidine, and spermine) were respectively quantified by quantitative reverse-transcriptase PCR, immunoblotting, immunohistochemistry, and gas chromatography-mass spectrometry in both the endometrium and uterine flushing. No differences in gene and protein expression or concentration of polyamines were observed between groups. There were significant correlations between the relative abundance of ODC1 and spermidine/spermine N1-acetyltransferase 1 (SAT1) transcripts as well as between antizyme inhibitor 1 (AZIN1) and adenosylmethionine decarboxylase 1 (AMD1) transcripts. In conclusion, our results show that the polyamine metabolic pathway is present and functional, but not regulated by the periovulatory endocrine milieu in the bovine endometrium.

LPS-challenged TNFα production, prostaglandin secretion, and TNFα/TNFRs expression in the endometrium of domestic cats in estrus or diestrus, and in cats with pyometra or receiving medroxyprogesterone acetate.

Progesterone (P4) derivatives which are commonly used to block the cyclicity of domestic cats disturb the endocrine balance in the endometrium. The aims of this study were (i) to examine whether lipopolysaccharide (LPS) is responsible for enhancement of tumor necrosis factor-α (TNFα) secretion by the feline endometrial epithelial and stromal cells in vitro, (ii) to know whether immunolocalization of TNFα/TNFR1 and TNFR2 differs in cats at estrus or diestrus, receiving medroxyprogesterone acetate and suffering from pyometra, and (iii) to determine if TNFα-challenged prostaglandin secretion is stopped by prostaglandin synthases inhibitors. A total of 37 domestic adult cats in estrus or diestrus, receiving octane medroxyprogesterone or having clinical symptoms of pyometra, were enrolled in this study. The results obtained showed a distinct increase in LPS-challenged TNFα secretion in endometrial epithelial, but not stromal cells. TNFα augmented PG secretion was blocked by phospholipase A2 (PLA2) and cyclooxygeanase-2 (COX-2), but not by mitogen-activated protein kinase (MAPK) inhibitor. TNFα/TNFR1 and 2 protein expressions were limited mostly to the surface and glandular epithelium. TNFα/TNFRs protein was upregulated in the inflammatory uterus and hence may be involved in development of pathologic changes in the endometrial glands in cats receiving exogenous P4 as a hormonal contraceptive.

Proteomic analysis of the follicular fluid of Tianzhu white yak during diestrus.

The aim of this study was to identify differentially expressed proteins in the follicular fluid of Tianzhu white yak during diestrus. Follicles obtained from female yak were divided into four groups according to their diameter: 0-2, 2-4, 4-6 mm, and greater than 6 mm. The follicular fluid was directly aspirated from the follicles and mixed according to follicular size, and two-dimensional gel electrophoresis was carried out on the crude follicular fluid samples. Thirty-four differentially expressed spots were generated from these four sizes of follicles. Fourteen of these spots were analyzed by MALDI-TOF/TOF-MS and identified as: AS3MT, VDP, ANKRD6, C10orf107 protein, MRP4, MAPKAP1, AGO3, profilin-ß-actin, SPT2 homolog, AGP, AR, RNF20, obscurin-like-1, and one unnamed protein. These proteins were first reported in follicular fluid, in addition to VDP and AGP. Based on existing knowledge of their function and patterns of expression, we hypothesize that most of these differentially expressed proteins play a role in ovarian follicular growth and development, dominant follicle selection, or follicular atresia and development of oocytes; however, the function of the other differentially expressed proteins in reproduction remains ambiguous.

Identification of potential differences in salivary proteomic profiles between estrus and diestrus stage of estrous cycle in dairy cows.

In the present study, a comparative global high-throughput proteomic analysis strategy was used to identify proteomic differences between estrus and diestrus stage of estrous cycle in dairy cows. Saliva was collected from cows during estrus and diestrus, and subjected to LC-MS/MS-based proteomic analysis. A total of 2842 proteins were detected in the saliva of cows, out of which, 2437 and 1428 non-redundant proteins were identified in estrous and diestrous saliva, respectively. Further, it was found that 1414 and 405 salivary proteins were specific to estrus and diestrus, respectively while 1023 proteins were common to both groups. Among the significantly dysregulated proteins, the expression of 56 proteins was down-regulated (abundance ratio <0.5) while 40 proteins were up-regulated (abundance ratio > 2) in estrous compared to diestrous saliva. The proteins, such as HSD17B12, INHBA, HSP70, ENO1, SRD5A1, MOS, AMH, ECE2, PDGFA, OPRK1, SYN1, CCNC, PLIN5, CETN1, AKR1C4, NMNAT1, CYP2E1, and CYP19A1 were detected only in the saliva samples derived from estrous cows. Considerable number of proteins detected in the saliva of estrous cows were found to be involved in metabolic pathway, PI3K-Akt signaling pathway, toll-like receptor signaling pathway, steroid biosynthesis pathway, insulin signaling pathway, calcium signaling pathway, estrogen signaling pathway, oxytocin signaling pathway, TGF-ß signaling pathway and oocyte meiosis. On the other hand, proteins detected in saliva of diestrous cows were involved mainly in metabolic pathway. Collectively, these data provide preliminary evidence of a potential difference in salivary proteins at different stages of estrous cycle in dairy cows.

Immunopresence and functional activity of prostaglandin-endoperoxide synthases and nitric oxide synthases in bovine corpora lutea during diestrus.

The aim of this study was to evaluate the occurrence and the activity of prostaglandin-endoperoxide synthase 1 (PTGS1), PTGS2, and endothelial, neuronal, and inducible nitric oxide synthase (e-, n-, and iNOS) in early, mid, late, and regressive corpora lutea (CL) of bovines during diestrus. PTGS1 immunoreactivity was localised mainly in the cytoplasm of small luteal cells, whereas PTGS2 was detected in the cytoplasm of large luteal cells during early, mid, and late stages. The immunoexpression of all NOS isoforms was observed in the nuclei of luteal cells in the CL stages examined. PTGS1 enzyme activity was higher in late CL and lower in regressive ones; PTGS2 increased from early to late CL and lowered in regressive ones. Constitutive NOS enzymatic activity (eNOS plus nNOS) was higher in late CL and lower in regressive ones; iNOS was lower in regressive CL. These results support the idea that PTGSs and NOSs regulate the bovine CL life span mainly during the transition from the luteotrophic to the luteolytic phase.

Tropisetron, a 5-HT(3) receptor antagonist, enhances object exploration in intact female rats.

The effects of a 5-HT(3) receptor antagonist, tropisetron, on cognitive functions were evaluated using the object-recognition test in estrous (postovulatory) and in diestrous female rats. Recognition was measured by the ability of rats to discriminate between a familiar and a new object in a T-maze after a 3-h delay. Rats from both stages spent equivalent amounts of time exploring the objects on trial 1. Three hours after trial 1, trial 2 (test trial) was initiated. Before the test trial, rats were injected with either saline or 1.5 or 2.5 mg/kg tropisetron. During the test trial, one arm of a T-maze contained an object from trial 1 (familiar) and a new object (novel) was introduced into the other arm. Rats from both stages responded to tropisetron by showing a greater percentage of time exploring the novel object. These findings indicate that tropisetron facilitates cognition in female rats by improving the recognition of familiar information.

Histomorphometric analysis of the effects of creatine on rat myometrium.

OBJECTIVE: To analyze the myometrial thickness of rats subjected to creatine (Cr) ingestion. STUDY DESIGN: A total of 14 rats was equally divided into the control group (ConGr) receiving 1 ml potable water and the creatine group (CrGr) subjected to the ingestion of 1.6 g/kg Cr diluted in 1 ml potable water. At the end of 8 weeks, the animals were anesthetized (xylazine and ketamine) and sacrificed, the uteri and ovaries stained with hematoxylin and eosin, the thickness of both the myometrium and the epithelium measured and the follicles counted. RESULTS: Analysis revealed a significant increase in thickness of the myometrium in the CrGr (272.26 ± 66.71µm) contrasted with that from the ConGr (160.76 ± 35.65µm), CrGr > ConGr (p < 0001). CONCLUSION: Our data suggest that Cr changed myometrial morphology in rats by enhancing myometrial thickness, but its action mechanism in the smooth muscle is still unclear.

Oxytocin receptor expression in the midbrain dorsal raphe is dynamic across female reproduction in rats.

Central oxytocin receptor (OTR) expression is extremely sensitive to circulating steroid hormones and OTRs influence many of the neurobehavioural adaptations associated with female reproduction (e.g., postpartum caregiving, aggression, cognition, affective responses). Changes in central OTR expression across female reproduction have often been studied, but almost all of such research has focused on the forebrain, ignoring hormone-sensitive midbrain sites such as the serotonergic dorsal raphe (DR) that are also critical for postpartum behaviours. To investigate the effects of female reproductive state on OTRs in the DR, we first used autoradiography to examine OTR binding across four female reproductive states in laboratory rats: dioestrous virgin, pregnancy day 10, the day of parturition and postpartum day 7. OTR binding in the rostral DR (but not other DR subregions) was approximately 250% higher in parturient rats compared to dioestrous virgins and dropped back down to virgin levels by postpartum day 7. Given the chemical heterogeneity of the DR, we then examined OTR expression in the three most abundant neuronal phenotypes of the DR (i.e., serotonin, GABA and dopamine) in dioestrous virgins and recently parturient females. Using dual-label immunohistochemistry and in situ hybridisation, we found that twice as many dopaminergic cells in the parturient rostral DR contained OTR immunoreactivity compared to that found in virgins. On the other hand, mothers had fewer rostral DR GABAergic cells expressing OTRs than did virgins. OTR expression in serotonin cells did not differ between the two groups. Overall, these results suggest that the rostral subregion of the midbrain DR is uniquely sensitive to oxytocin around the time of parturition, with subpopulations of cells that become more sensitive (i.e., dopamine), less sensitive (i.e., GABA) and show no change (i.e., serotonin) to this neuropeptide. This dynamic OTR signalling in the female DR may help drive the numerous behavioural changes across female reproduction that are necessary for successful motherhood.

Estrogens regulate the expression of NHERF1 in normal colon during the reproductive cycle of Wistar rats.

In breast cancer cell lines, the Na(+)/H(+) exchanger regulator factor 1 (NHERF1) gene is regulated at the transcriptional level by estrogens, the protein expression levels correlate with the presence of estrogen receptors and the effect is blocked by anti-estrogens. However, there is limited information regarding the regulation of NHERF1 by estrogens in normal colon tissue. The NHERF1 protein has an important role in the maintenance of the intestine ultrastructure. NHERF1-deficient mice showed defects in the intestinal microvilli as well as molecular alterations in brush border membrane proteins. Here, we have studied the expression of NHERF1 in normal rat colon and uterus during the reproductive cycle of Wistar rats. We found that NHERF1 expression in rat colon during the estral cycle is modified by estrogen levels: higher expression of NHERF1 was observed during the proestrous and estrous stages and lower expression in diestrous 1 when estrogen levels decreased. In uterus, NHERF1 was expressed in the apical region of the luminal epithelium and glands in all stages of the estral cycle, and in both colon and uterus, the expression was independent of the proliferation status. Our results show that NHERF1 expression is regulated by estrogens in colon during the rat estral cycle.