Estrus cyclicity of spinogenesis: underlying mechanisms

Hippocampal spine density varies with the estrus cycle. The cyclic change in estradiol levels in serum was hypothesized to underlie this phenomenon, since treatment of ovariectomized animals with estradiol induced an increase in spine density in hippocampal dendrites of rats, as compared to ovariectomized controls. In contrast, application of estradiol to hippocampal slice cultures did not promote spinogenesis. In addressing this discrepancy, we found that hippocampal neurons themselves are capable of synthesizing estradiol de novo. Estradiol synthesis can be suppressed by aromatase inhibitors and by knock-down of Steroid Acute Regulatory Protein (StAR) and enhanced by substrates of steroidogenesis. Expression of estrogen receptors (ERs) and synaptic proteins, synaptogenesis, and long-term potentiation (LTP) correlated positively with aromatase activity in hippocampal cultures without any difference between genders. All effects due to inhibition of aromatase activity were rescued by application of estradiol to the cultures. Most importantly, gonadotropin-releasing hormone (GnRH) increased estradiol synthesis dose-dependently via an aromatase-mediated mechanism and consistently increased spine synapse density and spinophilin expression. As a consequence, our data suggest that cyclic fluctuations in spine synapse density result from pulsative release of GnRH from the hypothalamus and its effect on hippocampal estradiol synthesis, rather than from varying levels of serum estradiol. This hypothesis is further supported by higher GnRH receptor (GnRH-R) density in the hippocampus than in the cortex and hypothalamus and the specificity of estrus cyclicity of spinogenesis in the hippocampus, as compared to the cortex

Semen molecular and cellular features: these parameters can reliably predict subsequent ART outcome in a goat model

Currently, the assessment of sperm function in a raw or processed semen sample is not able to reliably predict sperm ability to withstand freezing and thawing procedures and in vivo fertility and/or assisted reproductive biotechnologies (ART) outcome. The aim of the present study was to investigate which parameters among a battery of analyses could predict subsequent spermatozoa in vitro fertilization ability and hence blastocyst output in a goat model. Ejaculates were obtained by artificial vagina from 3 adult goats (Capra hircus) aged 2 years (A, B and C). In order to assess the predictive value of viability, computer assisted sperm analyzer (CASA) motility parameters and ATP intracellular concentration before and after thawing and of DNA integrity after thawing on subsequent embryo output after an in vitro fertility test, a logistic regression analysis was used. Individual differences in semen parameters were evident for semen viability after thawing and DNA integrity. Results of IVF test showed that spermatozoa collected from A and B lead to higher cleavage rates (0 < 0.01) and blastocysts output (p < 0.05) compared with C. Logistic regression analysis model explained a deviance of 72% (p < 0.0001), directly related with the mean percentage of rapid spermatozoa in fresh semen (p < 0.01), semen viability after thawing (p < 0.01), and with two of the three comet parameters considered, i.e tail DNA percentage and comet length (p < 0.0001). DNA integrity alone had a high predictive value on IVF outcome with frozen/thawed semen (deviance explained: 57%). The model proposed here represents one of the many possible ways to explain differences found in embryo output following IVF with different semen donors and may represent a useful tool to select the most suitable donors for semen cryopreservation

Appareil destiné à l'étude des intensités lumineuse et chromatique des couleurs spectrales et de leurs mélanges

Pas de Résumé disponibl

Impact of the polycarbonate strippers used in assisted reproduction techniques on embryonic development

International audienceStudy question: Do daily manipulations of preimplantation embryos with polycarbonate (PC)-made bisphenol A (BPA)-releasing strippers influence embryo development?Summary answer: Compared to glass strippers, PC strippers enhance the blastocyst development rate but this does not seem to be BPA-related.What is known already: PC strippers have been shown to release tiny amounts (around 0.5 ng/ml BPA) of BPA in routine human IVF procedures. A chronic exposure to BPA either in vivo or in vitro during the preimplantation period can impact post-implantation and post-natal development. BPA can act rapidly by binding to membrane receptors and inducing rapid non-genomic effects.Study design, size, duration: This experimental study using mouse embryos had a balanced design and blinded evaluations of the endpoints.Participants/materials, setting, methods: In vivo fertilized zygotes were obtained from outbred Swiss CD1 mice crossings after an ovarian stimulation. The zygotes were allocated to three daily handling conditions (HCs) and cultured until Day 4 in a single human commercial medium. Each day, the embryos were handled for 20 s either in a PC stripper (HC1) or in a glass stripper (HC2). In HC3, the embryos were pre-exposed to 0.5 ng/ml BPA before being handled for 20 s in a glass stripper. Handling operations were repeated on Days 1, 2 and 3. Embryo development was assessed blindly on Day 4. Expanded blastocysts were selected for a transcriptomic analysis using Agilent Sureprint G3 Mouse GE v2 microarrays and the retrotransposon LINE1-Orf2 expression was analysed using qRT-PCR, as a proxy for a global evaluation of the epigenetic status.Main results and the role of chance: Compared to the embryos manipulated in HC2 (n = 243), those in HC1 (n = 228) developed significantly more often to the blastocyst stage (55 vs 46%; P < 0.05). It appears the effect of these PC strippers was not BPA-related because embryos pre-exposed to BPA (HC3, n = 230) showed no difference in the blastocyst rate when compared to HC2 (43 vs 46%). When analysing same-stage blastocysts, we noticed no difference in the embryo gene expression between the three HC groups.Large scale data: https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE148868.Limitations, reasons for caution: Our results using a mouse model designed to mimic human conditions (outbred strain, human commercial IVF dishes and a unique commercial human embryonic culture media) are reassuring since no gene was found to be differentially expressed, including LINE-1 genes, as a proxy for a global evaluation of the epigenetic status. However, no global epigenetic analysis of the genome has been performed. Furthermore, we did not evaluate post-implantation events, although BPA exposure during peri-conception could affect foeto-placental and post-natal development.Wider implications of the findings: Based on the precautionary principle, several European countries banned the use of BPA in baby bottles and food packaging several years before European Agencies took an official position. The question of applying this principle to plastics in closed contact with human embryos is raised. Further studies are needed for a decision to be made

Hum Reprod

STUDY QUESTION: Does endometrial scratch in women undergoing a first or second IVF/ICSI attempt improve the clinical pregnancy rate (CPR)? SUMMARY ANSWER: Endometrial scratch (ES) in women undergoing their first or second IVF/ICSI attempt does not enhance the CPR under the technical conditions of our study. WHAT IS KNOWN ALREADY: Several studies have suggested that physical scratch of the endometrium before an IVF attempt could improve embryo implantation. STUDY DESIGN, SIZE, DURATION: This was a randomized controlled multi-center, two-arm, parallel trial. Inclusions started in February 2010 and stopped prematurely in July 2014 after an unplanned interim analysis. At the time of study closure, 191 of the planned 358 patients had been included. PARTICIPANTS/MATERIALS, SETTING, METHODS: Patients included in the study were randomly assigned to either the ES arm or the non-ES arm. Local ES was performed between Day 20 and Day 24 of the cycle preceding ovarian stimulation using a device for endometrial biopsy. Ovarian stimulation used a combination of recombinant FSH and either an GnRH agonist protocol or a GnRH antagonist protocol without any estrogen pre-treatment. CPR was analyzed on an intent-to-treat basis. All comparisons between the two groups were done using a logistic regression model adjusted for age, BMI and infertility etiology. Differences between the two arms were considered statistically significant at P value of less than 0.0446 for the primary outcome only. MAIN RESULTS AND THE ROLE OF CHANCE: Sixty-eight embryo transfers were performed in the ES arm and sixty-four in the non-ES arm. CPR was 23.5% (16/68) in the ES arm and 35.9% (23/64) in the non-ES arm (hazard ratio (HR) = 0.43; 95% CI, 0.18-1.02; P = 0.0568). The implantation rate was 19.1% and 24.0% in the ES arm and in the non-ES arm, respectively. Two miscarriages and one ectopic pregnancy were reported in each arm. The multiple pregnancy rate was higher in the scratch arm (50.0% vs 20.0%), but the difference was not statistically significant (odds ratio (OR) = 4.54; 95% CI, 0.50-40.93; P = 0.1349). The endometrial biopsy procedure was well tolerated in most women. Of 50 patients in the ES arm having received the embryo transfer, 40 (80.0%) patients reported having felt pain during the procedure, the pain resolving quickly for 31 of them. LIMITATIONS, REASONS FOR CAUTION: An interim analysis of the primary endpoint was conducted and an independent data monitoring committee agreed on stopping the inclusions. This analysis was prompted by the tendency towards lower pregnancy rates observed in the ES arm. Consequently, the study suffered from a lower inclusion rate and failed to reach the planned sample size. WIDER IMPLICATIONS OF THE FINDINGS: Under the technical condition employed in this study, ES in the luteal phase of the cycle preceding the ovarian stimulation does not improve CPR in patients undergoing a first or second IVF/ICSI attempt. STUDY FUNDING/COMPETING INTERESTS: This study was supported by a grant from Ministere de la Sante Francais (Programme Hospitalier de Recherche Clinique 2009). There are no conflicts of interest. TRIAL REGISTRATION NUMBER: NCT01064193. TRIAL REGISTRATION DATE: 08-Feb-2010. DATE OF FIRST PATIENT'S ENROLMENT: 08-Feb-2010