Influence of Unsaturations on the Organization and Air Reactivity of Triglyceride Monolayers.

The behavior of Langmuir monolayers of saturated and unsaturated C18 triglycerides (TAGs) was studied as two-dimensional (2D) models for paint systems at the air-water interface or transferred onto solid films. The organization of saturated tristearin (C18:0) monolayer was probed thanks to grazing incidence X-ray diffraction: one observes a hexagonal packing of the chains perpendicular to the air-water interface, in contrast to what is described in the literature. Conversely, the mono- and polyunsaturated TAGs (triolein C18:1, trilinolein C18:2, and trilinolenin C18:3) monolayers do not present any organization at the air-water interface but do exhibit peculiar reactivity regarding the air atmosphere. The obtained results derived from the evolution of surface pressure-molecular area isotherms and monolayer compressibility under different atmospheres over time, combined with ultrahigh-vacuum infrared (UHV-FTIR) spectroscopy, showed the adsorption of O2 molecules in the monolayer together with chemical reactions with hydrocarbon chains. The kinetic effect of lead ions, known to be efficient siccative agents in oil paints, was also assessed: the addition of Pb2+ in the subphase induces an increase of the O2 adsorption.

FORTE - a multipurpose high-vacuum diffractometer for tender X-ray diffraction and spectroscopy at the SIRIUS beamline of Synchrotron SOLEIL.

A new high-vacuum multipurpose diffractometer (called FORTE from the French acronyms of the project) has recently been installed at the tender/hard X-ray SIRIUS beamline of Synchrotron SOLEIL, France. The geometry chosen allows one to work either in the classical Eulerian four-circle geometry for bulk X-ray diffraction (XRD) or in the z-axis geometry for surface XRD. The diffractometer nicely fits the characteristics of the SIRIUS beamline, optimized to work in the 1.1-4.5 keV range, and allows one to perform unprecedented diffraction anomalous fine structure (DAFS) experiments in the tender X-ray region, also around non-specular reflections, covering a large reciprocal-space volume. Installation of an X-ray fluorescence detector on a dedicated flange allows simultaneous DAFS and X-ray absorption (XAS) measurements. The access to the tender X-ray region paves the way to resonant investigations around the L-edges of second-row transition elements which are constituents of functional oxide materials. It also enables access to several edges of interest for semiconductors. Finally, the control architecture based on synchronized Delta Tau units opens up exciting perspectives for improvement of the mechanical sphere of confusion.

Direct Measurement of Lateral Correlations under Controlled Nanoconfinement.

Lateral correlations along hydrophobic surfaces whose separation can be varied continuously are measured by x-ray scattering using a modified surface force apparatus coupled with synchrotron radiation, named SFAX. A weak isotropic diffuse scattering along the equatorial plane is revealed for mica surfaces rendered hydrophobic and charge neutral by immersion in cationic surfactant solutions at low concentrations. The peak corresponds to a lateral surface correlation length ξ≈12 nm, without long-range order. These findings are compatible with the atomic force microscopy imaging of a single surface, where adsorbed surfactant stripes appear surrounded by bare mica zones. Remarkably, the scattering patterns remain stable for gap widths D larger than the lateral period but change in intensity and shape (to a lesser extent) as soon as D<ξ. This evolution codes for a redistribution of counterions (counterion release from antagonistic patches) and the associated new x-ray labeling of the patterns. The redistribution of counterions is also the key mechanism to the long-range electrostatic attraction between similar, overall charge-neutral walls, reported earlier.

Does constant photoperiod inhibit the onset of the reproductive cycle in northern pike (Esox lucius) males?

For most temperate and arctic fish species, photoperiod is the key abiotic factor determining the onset of the reproductive cycle, and, for many species, constant long photoperiod seems to have an inhibitory effect. Yet, there is no knowledge about the effect of photoperiod on the onset of the reproductive cycle in northern pike males. The aim of this work was to investigate the potential inhibitory effect of constant long photoperiod on pike males. Batches of fish were reared in triplicate under natural simulated photoperiod (NSP) or constant long photoperiod (CP; 16L:8D) from 14 October 2013 to 14 March 2014. Fish were sampled three times (at the beginning of the photoperiod decrease, at the beginning of the temperature decrease and at the end of the temperature decrease). Morphological parameters, sexual steroid levels and spermatogenetic stages were investigated. Our results showed that CP partially inhibited gonadal development (gonado-somatic index or GSI, %; 2.5% under NSP and 1.2% under CP at day 152), spermatic development (96.2% of spermatozoa under NSP and 69.3% under CP at day 152) and the plasmatic levels of testosterone (7.20 ng/mL under NSP and 2.37 ng/mL under CP at day 152). In conclusion, photoperiod may be one of the determinant factors that control the onset of the reproductive cycle in pike males, but temperature and endogenous rhythms also need to be investigated.

Charge and aggregation pattern govern the interaction of plasticins with LPS monolayers mimicking the external leaflet of the outer membrane of Gram-negative bacteria.

Bacterial resistance to antibiotics has become today a major public health issue. In the development of new anti-infectious therapies, antimicrobial peptides appear as promising candidates. However, their mechanisms of action against bacterial membranes are still poorly understood. We describe for the first time the interaction and penetration of plasticins into lipid monolayers and bilayers modeling the two leaflets of the asymmetrical outer membrane of Gram-negative bacteria. The lipid composition of these monolayers mimics that of each leaflet: mixtures of LPS Re 595 mutant and wild type S-form from Salmonella enterica for the external leaflet, and SOPE/SOPG/cardiolipin (80/15/5) for the inner one. The analysis of the interfacial behavior of native (PTCDA1) and modified (PTCDA1-KF) antimicrobial plasticins showed that PTCDA1-KF exhibited better surface properties than its unmodified counterpart. Both peptides could penetrate into the model monolayers at concentrations higher than 0.1 µM. The penetration was particularly enhanced for PTCDA1-KF into the mixed LPS monolayer, due to attractive electrostatic interactions. Grazing X-ray diffraction and atomic force microscopy studies revealed the changes in LPS monolayers organization upon peptide insertion. The interaction of plasticins with liposomes was also monitored by light scattering and circular dichroism techniques. Only the cationic plasticin achieved full disaggregation and structuration in α helices, whereas the native one remained aggregated and unstructured. The main steps of the penetration mechanism of the two plasticins into lipid models of the external leaflet of the outer membrane of Gram-negative bacteria have been established.

Placental antiangiogenic prolactin fragments are increased in human and rat maternal diabetes.

INTRODUCTION/OBJECTIVES: The role of the placenta in diabetic mothers on fetal development and programming is unknown. Prolactin (PRL) produced by decidual endometrial cells may have an impact. Although full-length PRL is angiogenic, the processed form by bone morphogenetic protein-1 (BMP-1) and/or cathepsin D (CTSD) is antiangiogenic. The objectives were to investigate the involvement of decidual PRL and its antiangiogenic fragments in placentas from type-1 diabetic women (T1D) and from pregnant diabetic rats with lower offspring weights than controls. METHODS: PRL, BMP-1, and CTSD gene expressions and PRL protein level were assessed in T1D placentas (n=8) at delivery and compared to controls (n=5). Wistar rats received, at day 7 of pregnancy, streptozotocin (STZ) (n=5) or nicotinamide (NCT) plus STZ (n=9) or vehicle (n=9). Placental whole-genome gene expression and PRL western blots were performed at birth. RESULTS: In human placentas, PRL (p<0.05) and BMP-1 (p<0.01) gene expressions were increased with a higher amount of cleaved PRL (p<0.05) in T1D than controls. In rats, diabetes was more pronounced in STZ than in NCT-STZ group with intra-uterine growth restriction. Decidual prolactin-related protein (Dprp) (p<0.01) and Bmp-1 (p<0.001) genes were up-regulated in both diabetic groups, with an increased cleaved PRL amount in the STZ (p<0.05) and NCT-STZ (p<0.05) groups compared to controls. No difference in CTSD gene expression was observed in rats or women. CONCLUSIONS: Alterations in the levels of the PRL family are associated with maternal diabetes in both rats and T1D women suggesting that placental changes in these hormones impact on fetal development.

Continuous lighting inhibits the onset of reproductive cycle in pikeperch males and females.

The effect of a constant photoperiod on the inhibition of male and female reproductive cycles was studied in pikeperch Sander lucioperca. Over a 153-day period, batches of pikeperch (2 years, 950 g) breeders were kept under either under natural or artificial photoperiod conditions (24L:0D) (30-35 fish/tank, triplicate) and sampled in late June (start of the photoperiod decrease in natural conditions), late August (start of temperature decrease) and late November (exogenous vitellogenesis) (7-10 fish/tank/sampling date). Morphological parameters, sexual steroids, alkaline-labile phosphate (µg/mL) levels and gamete developmental stages were investigated. Gonado-somatic index (%), developmental stages and sexual steroid levels (17ß-estradiol, testosterone and 11-ketotestosterone, ng/mL) in both sexes and oocyte diameter (µm) and plasma alkaline-labile phosphate (µg/mL) in females were lower in response to a continuous lighting (24L:0D). In both sexes, continuous lighting applied in June for 153 days totally inhibited or delayed the onset of the reproductive cycle. In conclusion, photoperiod manipulation can be used to delay the pikeperch reproductive cycle, even if temperature decreases. This is the first report of the inhibitory effect of photoperiod on the onset of the reproductive cycle in pikeperch.

Design of a prospective, longitudinal cohort of people living with type 1 diabetes exploring factors associated with the residual cardiovascular risk and other diabetes-related complications: The SFDT1 study.

Type 1 diabetes mellitus (T1DM) is associated with a high risk of cardiovascular (CV) complications, even after controlling for traditional CV risk factors. Therefore, determinants of the residual increased CV morbidity and mortality remain to be discovered. This prospective cohort of people living with T1DM in France (SFDT1) will include adults and children aged over six years living with T1DM, recruited throughout metropolitan France and overseas French departments and territories. The primary objective is to better understand the parameters associated with CV complications in T1DM. Clinical data and biobank samples will be collected during routine visits every three years. Data from connected tools, including continuous glucose monitoring, will be available during the 10-year active follow-up. Patient-reported outcomes, psychological and socioeconomic information will also be collected either at visits or through web questionnaires accessible via the internet. Additionally, access to the national health data system (Health Data Hub) will provide information on healthcare and a passive 20-year medico-administrative follow-up. Using Health Data Hub, SFDT1 participants will be compared to non-diabetic individuals matched on age, gender, and residency area. The cohort is sponsored by the French-speaking Foundation for Diabetes Research (FFRD) and aims to include 15,000 participants.

Adoptive transfer of minor histocompatibility antigen-specific T lymphocytes eradicates leukemia cells without causing graft-versus-host disease.

Adoptive transfer of T cells reactive to minor histocompatibility antigens has the unmatched ability to eradicate malignant hematopoietic cells. Unfortunately, its use is hampered by the associated graft-versus-host disease. The critical issue of a possible dissociation of the antileukemic effect and graft-versus-host disease by targeting specific minor histocompatibility antigens remains unresolved because of the unknown nature and number of minor histocompatibility antigens necessary or sufficient to elicit anti-leukemic activity and graft-versus-host disease. We found that injection of T lymphocytes primed against a single major histocompatibility complex class I-restricted immunodominant minor histocompatibility antigen (B6dom1) caused no graft-versus-host disease but produced a curative anti-leukemic response. Avoidance of graft-versus-host disease required that no other host-reactive T cells be co-injected with T cells primed with B6dom1. Here we show that effective and non-toxic immunotherapy of hematologic malignancies can be achieved by targeting a single immunodominant minor histocompatibility antigen.

[A priori prediction of gentamicin peak concentrations: Use of a simple and practical tool]. / Prédiction a priori des concentrations en gentamicine au pic : utilisation d'un outil simple et pratique.

Aminoglycosides are concentration-dependent killing antibiotics, so that it is necessary to obtain elevated peak levels to reach the pharmacokinetic-pharmacodynamic objectives. Because of their nephrotoxicity, this class of antibiotics are frequently underprescribed and giving at an insufficient dosage when prescribed. That is why therapeutical drug monitoring (TDM) of aminoglycosides is recommanded to assess efficacy. Unfortunately, this TDM allows not a dosage adaptation on the first dose of aminoglycosides. The aim of the work was to elaborate a model using simple pharmacokinetics formulae to estimate gentamicin peak levels and so to propose an optimal a priori dosage on the first dose of gentamicin. The final model was tested out on 24 patients treated by gentamicin. The model was able to predict gentamicin peak levels in 62% of patients with a 10% precision and in 79% of patients with a 15% precision. Using this simple and practical tool might avoid under-dosage of gentamicin and clinical failure due to the selection of resistant bacteriae.

Solvent-exchange process in MOF ultrathin films and its effect on CO2 and methanol adsorption.

Metal-organic framework (MOF) activation is crucial for the use of MOFs in several applications and solvent-exchange process is a necessary step in many activation methods. In this contribution, we have explored in situ MOF monolayer film formation at the air-water interface. Nanoparticles (NPs) of the Al trimesate MIL-96(Al) retain chloroform into their micropores, which considerably diminishes the CO2 adsorption capacity of MOF films. However, a solvent-exchange process between chloroform and water increases CO2 film adsorption capacity by 30%. Total Reflection X-Ray Fluorescence (TRXF) allows studying the kinetics of this process at the air-water interface, that strongly depends on the NP size. The conclusions derived from in situ studies allow optimizing the ex situ activation procedure of MIL-96(Al) films deposited onto quartz crystal microbalance (QCM) substrates in order to maximize CO2 and methanol adsorption.

Constant darkness negatively affects the outcome of hormonally induced reproduction in cultured Eurasian perch females.

This study aimed to assess the effect of constant darkness applied to fish during controlled breeding on reproductive traits in domesticated females of Eurasian perch. Based on the assumption that keeping fish in constant darkness during the reproduction operation may reduce stress, suspected to be responsible for variable spawning effectiveness in this species. Two conditions were assessed (16 h light per day [group 16L] and constant darkness [group 0L], two tank replicates per condition). The reproductive protocol involved a 7-day-long adaptation period for group 0L where photoperiod was reduced by 2.3 h a day down to constant darkness. After the adaptation period, two hormone injections (salmon gonadoliberin analogue) were applied to both groups: priming (10 µg/kg) and resolving (25 µg/kg) with a 7-day interval between them. During the study, morphometric indices were recorded and blood, brain, and pituitary samples were collected to assess stress markers and determine hypothalamic-pituitary-gonadal axis functioning via measuring blood plasma hormones, as well as gonadoliberin and gonadotropins (luteinising hormone [LH] and follicle-stimulating hormone [FSH]) transcript abundance (n = 7 for each group at each sampling point). In addition, kinetics of the final oocyte maturation (FOM) process, ovulation rate, and egg quality of each group was monitored (n = 12 for each group). The results indicated that there were no differences in terms of morphometry, FOM kinetics, and most stress indices between groups throughout the experiment, except haematocrit, which increased immediately following the acclimation period in fish kept in darkness. Constant darkness negatively affected plasma levels of 17α,20ß-dihydroxy-4-pregnen-3-one (DHP) and LH transcript expression at the time of the second hormone injection. This indicated that exposure to constant darkness negatively affected priming of the hormonal dose applied, resulted in the disruption of ovulation, and reduced ovulation rates (50%) for group 0L, as compared to 16L (91%). The findings of this study clearly indicate that constant darkness may have significant deleterious effects on reproductive traits throughout out-of-season induced, hormonally supported, controlled reproduction. Therefore, we advise against the use of constant darkness when managing broodstock reproduction in domesticated Eurasian perch.

Long-term metabolic outcome and quality of life after laparoscopic adjustable gastric banding in obese patients with type 2 diabetes mellitus or impaired fasting glucose.

BACKGROUND: The long-term outcome of type 2 diabetes mellitus after laparoscopic adjustable gastric banding (LAGB) is unknown. METHODS: A longitudinal cohort study was undertaken of patients with grade 3 obesity and type 2 diabetes or impaired fasting glucose (IFG) undergoing LAGB. Metabolic outcomes and quality of life (QoL) were assessed before and 5 years after LAGB. RESULTS: At 5 years, data for 22 out of 23 patients with type 2 diabetes and 51 out of 53 with IFG were available. Mean(s.d.) excess weight loss was 41(25) and 41(27) per cent in patients with type 2 diabetes and IFG respectively, and was associated with a significant decrease in haemoglobin (Hb) A1c, fasting and postprandial blood glucose, insulin and triglyceride levels, and in liver steatosis. There were significant increases in insulin sensitivity, beta-cell function, disposition index, high-density lipoprotein-cholesterol and QoL (Nottingham Health Profile). Good metabolic control (HbA1c 7 per cent or less) was obtained in 13 diabetic patients, but complete diabetes remission was maintained in only four. Longer duration of diabetes, and poor preoperative glucose control and beta-cell function at baseline were associated with a less favourable outcome. CONCLUSION: LAGB improved metabolic outcomes and QoL in patients with grade 3 obesity with IFG or type 2 diabetes but rarely led to prolonged remission in long-standing diabetes.

Comparison of early life-stage strategies in temperate freshwater fish species: trade-offs are directed towards first feeding of larvae in spring and early summer.

Based on the analysis of 12 egg and larval variables and temperature of 65 temperate freshwater fish species, the possible relationships between oocyte diameter, larval size at hatch, time and temperature were reassessed and the main early life-stage strategies were described and compared. Time and degree-days required to reach hatching and mixed feeding were weakly related to oocyte diameter and strongly to temperature. These results are chiefly because oocyte diameter and yolk reserves are weakly related and temperature strongly increases tissue differentiation rate, activity of hatching glands and embryo motility. Strong positive relationships were found between larval size and oocyte diameter and degree-days for incubation. No relationship was found between larval size and degree-days from hatching to mixed feeding and between degree-days for incubation and degree-days from hatching to mixed feeding. These last two results are chiefly because the developmental stages at hatching and at the onset of exogenous feeding are not fixed in ontogeny and are not directly related to either larval size or degree-days for incubation, but more probably are species specific. Whatever the spawning season, which can occur almost all year long, the different trade-offs at the early life-stages ensure that most larvae are first feeding during spring, when food size and abundance are the most appropriate.

Prevalence of diagnosed type 2 diabetes mellitus in the French general population: the INSTANT study.

AIMS: To estimate the prevalence of diagnosed type 2 diabetes mellitus in the French general population. Secondary objectives were to evaluate treatments and diabetic complications. METHODS: In this cross-sectional epidemiological survey, a representative sample of the French adult population was selected using a stratified quota method: 10,038 individuals were evaluated by a standardized face-to-face interview. The diagnosis of type 2 diabetes was determined on the basis of replies to six questions using a specific algorithm. Data were collected on risk factors, diabetes history, familial antecedents and diabetic complications. These patients also identified their treatments from an exhaustive list. RESULTS: The prevalence of type 2 diabetes was 5.08% in men and 4.11% in women, and rose progressively after the age of 50. Of these, 79 patients (13.4%) received no pharmacological treatment, 477 (80.9%) were taking an oral antidiabetic drug and 134 (22.7%) were taking insulin. Renal and ocular complications were reported by 6.8% and 21.0%, respectively, of the patients. Also, 10.4% had been hospitalized at some time of that year for a diabetes-related problem. The most frequently reported treatments were metformin and sulphonylureas, used by more than 50% of the patients. In addition, 380 patients (65.9%) claimed to be following a diet and 228 (39.2%) were consulting a dietitian. CONCLUSION: The prevalence of treated and untreated type 2 diabetes mellitus in France was 4.57%.

The relationship of oocyte diameter and incubation temperature to incubation time in temperate freshwater fish species.

Based on the analysis of six egg variables and incubation temperature of 65 temperate freshwater fish species, the possible relationships between oocyte diameter, incubation time and incubation temperature were reassessed and compared to the results obtained from marine fishes. Most freshwater species have eggs (mean +/-s.d. 2.19 +/- 1.52 mm) larger than marine species, that are chiefly demersal and develop stuck to various substrata, such as plants or rocks. A strong negative relationship was found between incubation time (t, days) and incubation temperature (T, degrees C): t = 186.23e(-0.197T) (r(2)= 0.87). A strong dependence of incubation time on oocyte diameter (Ø, mm) and incubation temperature was also found and was defined as: log(10)t= 3.002 + 0.599 log(10)Ø - 1.91 log(10) (T + 2), which explained 92% of the variance of the data set. Five major groups of species were defined based on the principal component analysis (PCA) of four quantitative variables. There were two distinct groups of salmonids, displaying demersal and non-adhesive eggs with a long incubation time at low temperature, the eggs of which required a high number of degree-days. There was a large group of species possessing small, mostly demersal and adhesive eggs developing at high temperature during a short period of time, and requiring a low number of degree-days. Between these two extremes, there was a fourth group displaying intermediate values and a fifth group including three species with large, adhesive and demersal eggs incubating at high temperatures during a short period of time. The burbot Lota lota displayed an unusual combination of variables compared to the remaining species in the data set.

Increasing incidence of abnormal glucose tolerance in women with prior abnormal glucose tolerance during pregnancy: DIAGEST 2 study.

AIMS: Mild blood glucose abnormalities during pregnancy may be linked to later glucose tolerance abnormalities or diabetes mellitus. Our aim was to determine the prevalence of diabetes mellitus (DM), impaired glucose tolerance (IGT) or impaired fasting glucose (IFG) 6.75 years after delivery in women with differential blood glucose status during pregnancy. METHODS: We compared long-term outcomes among control women (n = 221), women with abnormal glucose tolerance during pregnancy (AGT; n = 322) and women with gestational diabetes (GDM; n = 466) who participated in DIAGEST 1. Women were recruited from 15 public maternity units in France. Clinical parameters could be determined in 155 control, 220 AGT and 338 GDM subjects. Rates of DM, IGT, IFG and 'Any Abnormality' were compared between the groups (American Diabetes Association criteria). RESULTS: Adherence to follow-up was 70.7%. Rates of DM, IGT and IFG were respectively 0.9% DM, 2.1% IGT and 3.6% IFG in the control group; rates in the AGT group were 6.3%, 11.3% and 6.3%. In GDM women, the rates of DM, IGT and IFG were, respectively, 18.0%, 13.4% and 8.5%. Predictors for DM were previous GDM, medical history of hypertension, age at delivery > or = 33 years, family history of diabetes, fasting glucose during pregnancy > or = 5.5 mmol/l and the severity of hyperglycaemia during pregnancy defined by the number of abnormal blood glucose values fasting, 1, 2 and 3 h during the glucose tolerance test at diagnosis of GDM. CONCLUSION: This study has identified a high prevalence of glucose tolerance abnormalities after AGT during pregnancy. Compared with GDM women, women with AGT have an intermediate risk of later diabetes.

Rearing conditions and life history influence the progress of gametogenesis and reproduction performances in pikeperch males and females.

Pikeperch (Sander lucioperca) is a highly valuable fish in Europe. However, development of aquaculture of pikeperch is highly limited due to seasonality of production. This can be overcome by the controlled reproduction of domesticated fish. The first steps of domestication process may induce changes at anatomical, physiological and molecular levels, thereby affecting a variety of biological functions. While there is abundant literature on their effects on stress and growth for example, these effects on reproduction received limited attention notably in pikeperch, a promising candidate for the development of aquaculture. To answer the question of this life-history effect on pikeperch's reproduction, we compared two groups (weight: 1 kg) originated from Czech Republic and with the same domestication level (F0). The first group was a recirculating aquatic system cultured one (2 years, previously fed with artificial diet, never exposed to natural changes in temperature/photoperiod conditions) and the second one was a pond cultured group (3 to 4 years, bred under natural feeding and temperature/photoperiod). The wild group successfully spawned, while the farmed one did not spawn at all. During the program, gonadosomatic indexes of both males and females were significantly higher for the wild fish, as well as the sexual steroids. Gene expression analysis revealed significantly lower LH transcript levels at the pituitary level for the farmed females and lower FSH transcript levels at the pituitary level for the males. In conclusion this study showed that the previous rearing conditions (e.g. culture system, age, diet, etc.) alter the further progress of gametogenesis and the reproductive performances in response to controlled photothermal program for both sexes in pikeperch.

D1, but not D2, dopamine receptor regulates steroid levels during the final stages of pikeperch gametogenesis.

In pikeperch, Sander lucioperca, aquaculture hormonal treatment is usually applied to synchronize ovulation. However, the effect of dopamine (DA) receptor antagonists, in particular those blocking the D1 DA receptors, remains unknown. Thus, the aim of the present study was to investigate and compare the effects of D1 and D2 DA receptor antagonists on the sex-steroid production and reproductive performance of the species. Two experiments were performed during which mature pikeperch females were injected with different molecules: NaCl 0.9% (negative control) or human chorionic gonadotropin 500 IU/kg (positive control) in both experiments, metoclopramide (a D2 receptor antagonist; 4 mg/kg or 20 mg/kg) or SCH23390 (a D1 receptor antagonist; 0.8 mg/kg or 4 mg/kg) alone (experiment 1) or in combination with a salmon gonadotropin-releasing hormone analogue (sGnRHa at 25 µg/kg; experiment 2). In experiment 2, fish were also injected with sGnRHa (25 µg/kg) as positive control. Samplings of oocytes and blood were performed on the day of injection and after 24 h (both experiments), after 48 h (experiment 2) and at the time of ovulation (both experiments). In non-ovulating fish, samplings were performed 7 days (experiment 1) or 14 days (experiment 2) after injection. In experiment 2, various zootechnical parameters of fertilized eggs were recorded (survival, hatching and malformation rates). The two antagonists alone were ineffective in inducing the final stages and regulating sex-steroid (testosterone, 11 ketotestosterone, 17ß estradiol and 17,20ß-dihydroxy-4-pregnen-3-one) production. When administered with sGnRHa, both SCH23390 and metoclopramide induced the final stages. However, only SCH23390 stimulated testosterone (4 mg/kg) and 17ß estradiol (0.8 mg/kg) production compared with sGnRHa alone. None of the treatments affected the survival, hatching or malformation rates. This is the first report suggesting that in pikeperch the D1, but not the D2, DA receptor antagonist would be involved in the testosterone and 17ß estradiol production as a potentiator of the sGnRHa effect.