The plasma carnitine concentration regulates renal OCTN2 expression and carnitine transport in rats

Previous findings in rats and in human vegetarians suggest that the plasma carnitine concentration and/or carnitine ingestion may influence the renal reabsorption of carnitine. We tested this hypothesis in rats with secondary carnitine deficiency following treatment with N-trimethyl-hydrazine-3-propionate (THP) for 2 weeks and rats treated with excess L-carnitine for 2 weeks. Compared to untreated control rats, treatment with THP was associated with an approximately 70% decrease in plasma carnitine and with a 74% decrease in the skeletal muscle carnitine content. In contrast, treatment with L-carnitine increased plasma carnitine levels by 80% and the skeletal muscle carnitine content by 50%. Treatment with L-carnitine affected neither the activity of carnitine transport into isolated renal brush border membrane vesicles, nor renal mRNA expression of the carnitine transporter OCTN2. In contrast, in carnitine deficient rats, carnitine transport into isolated brush border membrane vesicles was increased 1.9-fold compared to untreated control rats. Similarly, renal mRNA expression of OCTN2 increased by a factor of 1.7 in carnitine deficient rats, whereas OCTN2 mRNA expression remained unchanged in gut, liver or skeletal muscle. Our study supports the hypothesis that a decrease in the carnitine plasma and/or glomerular filtrate concentration increases renal expression and activity of OCTN2.

Evaluation des effets de l’extrait aqueux des fleurs de Nymphaea lotus Linn. (Nymphéacées) sur la fonction de reproduction des rats normoglycémique et diabétique de type 1

In traditional medicine of Cameroon, Nymphaea lotus Linn. (Nympheaceae) is used for treatment of male sexual disorders. The aim of this study was to evaluate the effects of the N. lotus flowers aqueous extracts on general mating behavior, fertility and some androgenic parameters of normoglycemic and diabetic adult male rats. Mating behavior assessment was carried out with primiparous and with oestrus female rats. Male rats were divided into 5 groups and subjected once in a day to the following treatment: distilled water (10 mL/kg), Sildenafil citrate (5mg/kg), Testosterone enanthate (5mg/kg) and plant extract (75 mg/kg and 150 mg/kg). Treatment lasted for 8 and 55 days before sacrifice. Organ weight, epididymal sperm counts, motility, viability, histomorphometric analysis, muscular strength, seminal fructose, cholesterol level, epididymal and serum proteins testicular were determined. Results showed a dose- dependant influence of the treatment in sperm count and motility which significantly increases compared to the distilled water-administered control. An increase in some sexual performance parameters (mount and intromission frequencies) was observed in both diabetic and normal rats compared to respective controls. The latencies of mount and intromission were significantly reduced. Computed frequencies of penile licking, index of libido and sexual motivation were higher in normal and diabetic extract-treated animals; which suggest an enhancement of motivational parameters. The treatment also caused significant increases in the weight of the testis, prostate, epididymis, in serum cholesterol and epididymal protein level in normal rats compared to the distilled water-administered control. These results indicate an androgenic pro-sexual potential of N. lotus in male rats and justify the empirical use of N. lotus in the management of erectile dysfunction and fertility disorders in males. Key-words: Nymphaea lotus, prosexual, androgenic, fertility, diabetic, male rat. //Selon les tradipraticiens de l’Ouest-Cameroun, Nymphaea lotus Linn. (N. lotus), de la famille des Nymphéacées, est utilisé pour le traitement des dysfonctionnements sexuels chez les hommes. Dans cette étude, l’effet de l’extrait aqueux des fleurs de N. lotus sur la fonction de reproduction des rats mâles adultes normaux et diabétiques a été évalué. Dans le but d’évaluer les effets de l’extrait aqueux des fleurs de N. lotus sur les paramètres généraux de copulation, d’androgénicité et de fertilité, les rats normoglycémiques et diabétiques ont été divisé en 3 groupes contrôle [Groupe I- recevant de l’eau distillée, Groupe II et III recevant respectivement du citrate de sildénafil (5 mg/kg) et l’énanthate de testostérone (5 mg/kg)] et deux groupes expérimentaux traités à l’extrait aux doses 75 mg/kg (Groupe IV) et 150 mg/kg (Groupe V). L’eau distillée, l’extrait et la substance de référence était administré per os une fois par jour. Pour analyser le comportement sexuel et la fertilité, des femelles primipares et en oestrus étaient utilisées. Le traitement a duré 8 et 55 jours avant le sacrifice. Le poids relatif des organes, le nombre de spermatozoïde, la motilité, les analyses morphométriques, la force musculaire, le taux de cholestérol, le taux de protéines sériques et épididymaires étaient déterminé. Le temps de latence de monte et d’intromission a diminué significativement alors que la fréquence d’éjaculation a augmenté. L’index de libido, la fréquence de monte, d’intromission, d’éjaculation, d’orientation des mâles vis-à-vis d’eux même et l’index de motivation sexuelle a augmenté chez les animaux traités l’extrait comparés à ceux ayant reçu de l’eau distillée aussi bien chez les normaux que chez le diabétiques qui n’enregistrent d’ailleurs aucune éjaculation. Le traitement a augmenté significativement (P < 0,01) le poids des testicules, de la prostate et de l’épididyme. Il est observé une augmentation dose-dépendante du nombre et de la motilité des spermatozoïdes (P < 0,05), ainsi qu’une augmentation significative (P < 0,001) temps-dépendant du taux de cholestérol sérique et de protéines épididymaires. Ces résultats indiquent un potentiel androgénique pro-érectile de N. lotus chez les rats mâles et justifient l’utilisation empirique des fleurs de N. lotus dans le traitement des dysfonctions érectiles et des problèmes de fertilité chez les hommes. Mots-clés: Nymphaea lotus, pro-érectile, androgénique, fertilité, diabétiques, rat male

Of marsupials and men: "Backdoor" dihydrotestosterone synthesis in male sexual differentiation

Following development of the fetal bipotential gonad into a testis, male genital differentiation requires testicular androgens. Fetal Leydig cells produce testosterone that is converted to dihydrotestosterone in genital skin, resulting in labio-scrotal fusion. An alternative 'backdoor' pathway of dihydrotestosterone synthesis that bypasses testosterone has been described in marsupials, but its relevance to human biology has been uncertain. The classic and backdoor pathways share many enzymes, but a 3α-reductase, AKR1C2, is unique to the backdoor pathway. Human AKR1C2 mutations cause disordered sexual differentiation, lending weight to the idea that both pathways are required for normal human male genital development. These observations indicate that fetal dihydrotestosterone acts both as a hormone and as a paracrine factor, substantially revising the classic paradigm for fetal male sexual development.

Steroid hormone related male biased parasitism in chamois, Rupicapra rupicapra rupicapra

Parasites are linked with their host in a trophic interaction with implications for both hosts and parasites. Interaction stretches from the host's immune response to the structuring of communities and the evolution of biodiversity. As in many species sex determines life history strategy, response to parasites may be sex-specific. Males of vertebrate species tend to exhibit higher rates of parasites than females. Sex-associated hormones may influence immunocompetence and are hypothesised to lead to this bias. In a field study, we tested the prediction of male biased parasitism (MBP) in free ranging chamois (Rupicapra rupicapra rupicapra), which are infested intensely by gastrointestinal and lung helminths. We further investigated sex differences in faecal androgen (testosterone and epiandrosterone), cortisol and oestrogen metabolites using enzyme immunoassays (EIA) to evaluate the impact of these hormones on sex dependent parasite susceptibility. Non-invasive methods were used and the study was conducted throughout a year to detect seasonal patterns. Hormone levels and parasite counts varied significantly throughout the year. Male chamois had a higher output of gastrointestinal eggs and lungworm larvae when compared to females. The hypothesis of MBP originating in sex related hormone levels was confirmed for the elevated output of lungworm larvae, but not for the gastrointestinal nematodes. The faecal output of lungworm larvae was significantly correlated with androgen and cortisol metabolite levels. Our study shows that sex differences in steroid levels play an important role to explain MBP, although they alone cannot fully explain the phenomenon.

Serum leptin and C-reactive protein levels in the physiological spontaneous menstrual cycle in reproductive age women

OBJECTIVE: Only a few studies have investigated variations of different markers for inflammatory processes during the physiological menstrual cycle. The results are conflicting, particularly concerning the correlation between the marker leptin and steroid hormones. The aim of the study was to investigate the inflammatory markers C-reactive protein (CRP) and leptin in the serum of healthy, normally ovulating women and to correlate these with each other and with the hormones of the gonadal axis. A cycle-dependence of the markers studied would imply an exact timing of the blood sampling for clinical needs. DESIGN: Observational study investigating the two inflammatory markers CRP and leptin in relation to the hormonal pattern of the gonadal axis during the normal cycle. METHODS: Ovulatory cycles of 36 healthy, young, normo-androgenic women, having a normal body mass index were evaluated. Serum concentrations of leptin and CRP, as well as of follicle-stimulating hormone, luteinising hormone, 17beta-oestradiol, progesterone, prolactin (PRL) and free testosterone were measured every 1-2 days during one full cycle. RESULTS: Serum levels of leptin and CRP behaved differently during ovulatory cycles, with higher concentrations for leptin only during certain phases. Significant correlations were found in the follicular phase between leptin and PRL and leptin and free testosterone. CONCLUSIONS: Leptin levels change during the menstrual cycle. Leptin levels are more stable on cycle days 1-5 than later in the cycle. For precise cycle-independent measurements, these fluctuations have to be taken into account. There is no similar cyclic pattern for CRP.

Observation and identification of metabolites emerging during postmortem decomposition of brain tissue by means of in situ 1H-magnetic resonance spectroscopy

Postmortem decomposition of brain tissue was investigated by (1)H-magnetic resonance spectroscopy (MRS) in a sheep head model and selected human cases. Aiming at the eventual estimation of postmortem intervals in forensic medicine, this study focuses on the characterization and identification of newly observed metabolites. In situ single-voxel (1)H-MRS at 1.5 T was complemented by multidimensional homo- and heteronuclear high-resolution NMR spectroscopy of an extract of sheep brain tissue. The inclusion of spectra of model solutions in the program LC Model confirmed the assignments in situ. The first postmortem phase was characterized mainly by changes in the concentrations of metabolites usually observed in vivo and by the appearance of previously reported decay products. About 3 days postmortem, new metabolites, including free trimethylammonium, propionate, butyrate, and iso-butyrate, started to appear in situ. Since the observed metabolites and the time course is comparable in sheep and human brain tissue, the model system seems to be appropriate.

Hypogonadism in HIV-1-infected men is common and does not resolve during antiretroviral therapy

OBJECTIVES: To assess the prevalence of abnormal testosterone and gonadotropin values in HIV-infected men before and after 2 years of combination antiretroviral therapy (cART). DESIGN: Multicentre cohort of HIV-infected adults. METHODS: We identified 139 Caucasian antiretroviral-naive male patients who started zidovudine/ lamivudine-based cART that was virologically successful over a 2 year period. Ninety-seven were randomly chosen and plasma hormone determinations of free testosterone (fT) and luteinizing hormone (LH) at baseline and after 2 years of cART were evaluated. RESULTS: At baseline 68 patients (70%) had subnormal fT levels. In these, LH levels were low in 44%, normal in 47% and high in 9%. There was a trend for an association between lower CD4+ T-cell counts and hypogonadism. Most participants had normal FSH levels. No significant changes of fT, LH and FSH levels were observed after 2 years of cART. CONCLUSIONS: Low fT levels, mainly with normal or low LH levels and thus indicating secondary hypogonadism, are found in the majority of HIV-infected men and do not resolve during 2 years of successful cART.

P450 oxidoreductase deficiency - a new form of congenital adrenal hyperplasia

Patients with adrenal insufficiency, genital anomalies and bony malformations resembling the Antley- Bixler syndrome (a craniosynostosis syndrome), are likely to have P450 oxidoreductase (POR) deficiency. Since our first report in 2004, about 26 recessive POR mutations have been identified in 50 patients. POR is the obligate electron donor to all microsomal (type II) P450 enzymes, including the steroidogenic enzymes CYP17A1, CYP21A2 and CYP19A1. POR deficiency may cause disordered sexual development manifested as genital undervirilization in 46,XY newborns as well as overvirilization in those who are 46,XX. This may be explained by impaired aromatization of fetal androgens which may also lead to maternal virilization and low urinary estriol levels during pregnancy. A role for the alternate 'backdoor' pathway of androgen biosynthesis, leading to dihydrotestosterone production bypassing androstenedione and testosterone, has been suggested in POR deficiency but remains unclear. POR variants may play an important role in drug metabolism, as most drugs are metabolized by hepatic microsomal P450 enzymes. However, functional assays studying the effects of specific POR mutations on steroidogenesis showed that several POR variants impaired CYP17A1, CYP21A2 and CYP19A1 activities to different degrees, indicating that each POR variant must be studied separately for each potential target P450 enzyme. Thus, the impact of POR mutations on drug metabolism by hepatic P450s requires further investigation.

Androgen and gonadotropin patterns differ in HIV-1-infected men who develop lipoatrophy during antiretroviral therapy: a case-control study

OBJECTIVES: We compared androgen and gonadotropin values in HIV-infected men who did and did not develop lipoatrophy on combination antiretroviral therapy (cART). METHODS: From a population of 136 treatment-naïve male Caucasians under successful zidovudine/lamivudine-based cART, the 10 patients developing lipoatrophy (cases) were compared with 87 randomly chosen controls. Plasma levels of free testosterone (fT), dehydroepiandrosterone (DHEA), follicle-stimulating hormone and luteinizing hormone (LH) were measured at baseline and after 2 years of cART. RESULTS: At baseline, 60% of the cases and 71% of the controls showed abnormally low fT values. LH levels were normal or low in 67 and 94% of the patients, respectively, indicating a disturbance of the hypothalamic-pituitary-gonadal axis. fT levels did not significantly change after 2 years of cART. Cases showed a significant increase in LH levels, while controls showed a significant increase in DHEA levels. In a multivariate logistic regression model, lipoatrophy was associated with higher baseline DHEA levels (P=0.04), an increase in LH levels during cART (P=0.001), a lower body mass index and greater age. CONCLUSIONS: Hypogonadism is present in the majority of HIV-infected patients. The development of cART-related lipoatrophy is associated with an increase in LH and a lack of increase in DHEA levels.

INFLUENCE OF 24-HOUR SLEEP DEPRIVATION ON CARDIOVASCULAR AND NEURAL CONTROL AT REST AND DURING ACUTE STRESS IN HUMANS

Recent epidemiological studies report a consistent association between short sleep and incidence of hypertension, as well as short sleep and cardiovascular disease-related mortality. While the association between short sleep and hypertension appears to be stronger in women than men, the mechanisms underlying the relations between sleep deprivation, stress, risks of cardiovascular diseases, and sex remain unclear. We conducted two studies to investigate the underlying neural mechanisms of these relations. In study 1, we examined sympathetic neural and blood pressure responses to experimentally-induced sleep deprivation in men and women. We further investigated the influence of sleep deprivation on cardiovascular reactivity to acute stress. In study 2, we examined the neural and cardiovascular function throughout the ovarian cycle in sleep deprived women. Twenty-eight young healthy subjects (14men and 14 women) were tested twice in study 1, once after normal sleep (NS) and once after 24-h total sleep deprivation (TSD). We measured the blood pressure, heart rate (HR), muscle sympathetic nerve activity (MSNA) and forearm blood flow (FBF) during 10min baseline, 5min of mental stress (MS) and 2 min cold pressor test (CPT). We demonstrated that TSD increased resting arterial blood pressure to a similar extent in both men and women, but MSNA decreased only in men following TSD. This MSNA response was associated with altered baroreflex function in women and divergent testosterone responses to TSD between men and women. Regarding TSD and cardiovascular reactivity, TSD elicited augmented HR reactivity and delayed recovery during both MS and CPT in men and women, and responses between sexes were not statistically different. Fourteen young healthy women participated in study 2. Subjects were tested twice, once during their early follicular (EF) phase after TSD, once during their mid-luteal (ML) phase after TSD. Blood pressure, HR, MSNA, and FBF were recorded during 10min baseline, 5 min MS, and 2 min CPT. We observed an augmented resting supine blood pressure during EF compared to ML in sleep deprived women. In contrast, resting MSNA, as well as cardiovascular responses to stressors, were similar between EF and ML after TSD. In conclusion, we observed sex differences in MSNA responses to TSD that demonstrate reductions of MSNA in men, but not women. TSD elicited augmented HR reactivity and delayed HR recovery to acute stressors similarly in men and women. We also reported an augmented supine blood pressure during EF compared to ML in sleep deprived women. These novel findings provide new and valuable mechanistic insight regarding the complex and poorly understood relations among sleep deprivation, sex, stress, and risk of cardiovascular disease.

INTERACTIVE CONTROLS OF WATER TABLE POSITION AND PLANT FUNCTIONAL TYPES ON PEAT POREWATER CHARACTER IN NORTHERN BOG ECOSYSTEMS: IMPLICATIONS FOR CARBON CYCLING DYNAMICS

Northern wetlands, and particularly peatlands, have been shown to store around 30% of the world's soil carbon and thus play a significant role in the carbon cycle of our planet. Changes in climate are altering peatland hydrology and vegetation communities. These changes are possibly resulting in declines in the ability of peatlands to sequester carbon because losses through carbon oxidation and mineralization are likely to increase relative to C inputs from net primary production in a warmer, drier climate. However, the consequences of interactive effects of altered hydrology and vegetation on carbon storage are not well understood. This research evaluated the importance of plant species, water table, and their interactive effects on porewater quality in a northern peatland with an average pH of 4.54, ranging from 4.15 to 4.8. We assessed the effects of plant functional group (ericaceous shrubs, sedges, and bryophytes) and water table position on biogeochemical processes. Specifically, we measured dissolved organic carbon (DOC), total dissolved nitrogen (TDN), potential enzyme activity, organic acids, anions and cations, spectral indexes of aromaticity, and phenolic content. Our results indicate that acetate and propionate concentrations in the sedge-dominated communities declined with depth and water table drawdown, relative to the control and ericaceous treatments. DOC increased in the lowered water table treatments in all vegetation community types, and the peat porewater C:N ratio declined in the sedge-dominated treatments when the water table was lowered. The relationship between DOC and ferrous iron showed significant responses to vegetation type; the exclusion of Ericaceae resulted in less ferrous iron per unit DOC compared to mixed species treatments and Ericaceae alone. This observation was corroborated with higher mean oxidation redox potential profiles (integrating 20, 40, and 70 cm) measured in the sedge treatments, compared with the mixed and Ericaceae species treatments over a growing season. Enzymatic activities did not show as strong of a response to treatments as expected; the oxidative enzyme peroxidase and the hydrolytic enzyme phosphatase were the only enzymes to respond to water table, where the potential activity of both enzymes increased with water table drawdown. Overall, there were significant interactive effects between changes in vegetation and water table position on peat porewater composition. These data suggest that vegetation effects on oxidation reduction potentials and peat porewater character can be as important as water table position in northern bog ecosystems.

[Hyperreactive luteomas during pregnancy--symptoms and complications: a case report]

A 27-year-old Caucasian (gravida 2 para 1) presented in week 16 of her twin pregnancy with worsening of hyperandrogenic symptoms. In week 17, she developed an acute abdomen due to a twisted, incarcerated right ovary, which was surgically removed. Histological analysis revealed a diffuse steroid cell hyperplasia. Postsurgery testosterone levels fell temporarily within normal limits, diminishing the hyperandrogenic symptoms. Over time androgen levels rose again slowly above normal values with clinical worsening of hirsutism. In the 32nd week of gestation, a cesarean section of two healthy female infants was necessary due to the development of preeclampsia. An ovarian biopsy revealed again the picture of hyperreactio luteinalis. Postpartum peripheral hormone levels fell within normal limits and the hyperandrogenic symptoms subsided.

Cortical and trabecular bone mineral density in transsexuals after long-term cross-sex hormonal treatment: a cross-sectional study

The aim of this study was to explore the effect of long-term cross-sex hormonal treatment on cortical and trabecular bone mineral density and main biochemical parameters of bone metabolism in transsexuals. Twenty-four male-to-female (M-F) transsexuals and 15 female-to-male (F-M) transsexuals treated with either an antiandrogen in combination with an estrogen or parenteral testosterone were included in this cross-sectional study. BMD was measured by DXA at distal tibial diaphysis (TDIA) and epiphysis (TEPI), lumbar spine (LS), total hip (HIP) and subregions, and whole body (WB) and Z-scores determined for both the genetic and the phenotypic gender. Biochemical parameters of bone turnover, insulin-like growth factor-1 (IGF-1) and sex hormone levels were measured in all patients. M-F transsexuals were significantly older, taller and heavier than F-M transsexuals. They were treated by cross-sex hormones during a median of 12.5 years before inclusion. As compared with female age-matched controls, they showed a significantly higher median Z-score at TDIA and WB (1.7+/-1.0 and 1.8+/-1.1, P < 0.01) only. Based on the WHO definition, five (who did not comply with cross-sex hormone therapy) had osteoporosis. F-M transsexuals were treated by cross-sex hormones during a median of 7.6 years. They had significantly higher median Z-scores at TEPI, TDIA and WB compared with female age-matched controls (+0.9+/-0.2 SD, +1.0+/-0.4 SD and +1.4+/-0.3 SD, respectively, P < 0.0001 for all) and reached normal male levels except at TEPI. They had significantly higher testosterone and IGF-1 levels (p < 0.001) than M-F transsexuals. We conclude that in M-F transsexuals, BMD is preserved over a median of 12.5 years under antiandrogen and estrogen combination therapy, while in F-M transsexuals BMD is preserved or, at sites rich in cortical bone, is increased to normal male levels under a median of 7.6 years of androgen treatment in this cross sectional study. IGF-1 could play a role in the mediation of the effect of androgens on bone in F-M transsexuals.

Autonomic stress responses elicited by watching a live broadcast soccer game: a pilot study

Aim: Increased rates of hospitalization due to cardiovascular events have been reported during phases of World Soccer Championships (WSC). The purpose of this pilot study was to explore acute psychological and physiological effects of watching a live broadcast soccer game during the WSC 2006. Methods: Seven male supporters (age: M=24; SD=2.7) of the Swiss National Soccer Team watched a game of their team in a controlled laboratory setting. Heart rate (HR), heart rate variability (HRV), salivary cortisol, alpha-amylase (sAA), and testosterone concentrations, as well as several mood ratings were captured repeatedly before, during, and after the game. Results: Subjects reported feeling stressed, and HR and sAA activity showed an increase during the game. In contrast, HRV, cortisol and testosterone were unaffected. Conclusion: Watching a sports competition seems to specifically affect the sympathetic nervous system, which can be measured by sensitive electrocardiographic and salivary markers.

Gonadotrophin stimulation for in vitro fertilization significantly alters the hormone milieu in follicular fluid: a comparative study between natural cycle IVF and conventional IVF.

STUDY QUESTION Is the steroid hormone profile in follicular fluid (FF) at the time of oocyte retrieval different in naturally matured follicles, as in natural cycle IVF (NC-IVF), compared with follicles stimulated with conventional gonadotrophin stimulated IVF (cIVF)? SUMMARY ANSWER Anti-Mullerian hormone (AMH), testosterone (T) and estradiol (E2) concentrations are ∼3-fold higher, androstenedione (A2) is ∼1.5-fold higher and luteinizing hormone (LH) is ∼14-fold higher in NC-IVF than in cIVF follicles, suggesting an alteration of the follicular metabolism in conventional gonadotrophin stimulated IVF. WHAT IS KNOWN ALREADY In conventional IVF, the implantation rate of unselected embryos appears to be lower than in NC-IVF, which is possibly due to negative effects of the stimulation regimen on follicular metabolism. In NC-IVF, the intrafollicular concentration of AMH has been shown to be positively correlated with the oocyte fertilization and implantation rates. Furthermore, androgen treatment seems to improve the ovarian response in low responders. STUDY DESIGN, SIZE, DURATION This cross-sectional study involving 36 NC-IVF and 40 cIVF cycles was performed from 2011 to 2013. Within this population, 13 women each underwent 1 NC-IVF and 1 cIVF cycle. cIVF was performed by controlled ovarian stimulation with HMG and GnRH antagonists. PARTICIPANTS/MATERIALS, SETTING, METHODS Follicular fluid was collected from the leading follicles. AMH, T, A2, dehydroepiandrosterone (DHEA), E2, FSH, LH and progesterone (P) were determined by immunoassays in 76 women. Aromatase activity in follicular fluid cells was analysed by a tritiated water release assay in 33 different women. For statistical analysis, the non-parametric Mann-Whitney U or Wilcoxon tests were used. MAIN RESULTS AND ROLE OF CHANCE In follicular fluid from NC-IVF and from cIVF, median levels were 32.8 and 10.7 pmol/l for AMH (P < 0.0001), 47.2 and 18.8 µmol/l for T (P < 0.0001), 290 and 206 nmol/l for A2 (P = 0.0035), 6.7 and 5.6 pg/ml for DHEA (n.s.), 3292 and 1225 nmol/l for E2 (P < 0.0001), 4.9 and 7.2 mU/ml for FSH (P < 0.05), 14.4 and 0.9 mU/ml for LH (P < 0.0001) and 62 940 and 54 710 nmol/l for P (n.s.), respectively. Significant differences in follicular fluid concentrations for AMH, E2 and LH were also found in the 13 patients who underwent both NC-IVF and cIVF when they were analysed separately in pairs. Hormone analysis in serum excluded any relevant impact of AMH, T, A2, and E2 serum concentration on the follicular fluid hormone concentrations. Median serum concentrations were 29.4 and 0.9 mU/ml for LH (P < 0.0001) and 2.7 and 23.5 nmol/l for P (P < 0.0001) after NC-IVF and c-IVF, respectively. Positive correlations were seen for FF-AMH with FF-T (r = 0.35, P = 0.0002), FF-T with FF-LH (r = 0.48, P < 0.0001) and FF-E2 with FF-T (r = 0.75, P < 0.0001). The analysis of aromatase activity was not different in NC-IVF and cIVF follicular cells. LIMITATION, REASONS FOR CAUTION Any association between the hormone concentrations and the implantation potential of the oocytes could not be investigated as the oocytes in cIVF were not treated individually in the IVF laboratory. Since both c-IVF and NC-IVF follicles were stimulated by hCG before retrieval, the endocrine milieu in the natural cycle does not represent the pure physiological situation. WIDER IMPLICATIONS OF THE FINDINGS The endocrine follicular milieu and the concentration of putative markers of oocyte quality, such as AMH, are significantly different in gonadotrophin-stimulated conventional IVF compared with natural cycle IVF. This could be a cause for the suggested lower oocyte quality in cIVF compared with naturally matured oocytes. The reasons for the reduced AMH concentration might be low serum and follicular fluid LH concentrations due to LH suppression, leading initially to low follicular androgen concentrations and then to low follicular AMH production. STUDY FUNDING/COMPETING INTERESTS Funding for this study was obtained from public universities (for salaries) and private industry (for consumables). Additionally, the study was supported by an unrestricted grant from MSD Merck Sharp & Dohme GmbH and IBSA Institut Biochimique SA. The authors are clinically involved in low-dose monofollicular stimulation and IVF therapies, using gonadotrophins from all gonadotrophin distributors on the Swiss market, including Institut Biochimique SA and MSD Merck Sharp & Dohme GmbH. Otherwise, the authors have no competing interests. TRIAL REGISTRATION NUMBER Not applicable.