Plasma Levels Of 11-KT Research Articles

Development of gonad and brood pouch and expression profiles of cgα, fshβ and lhβ transcripts and plasma 17β-E2 and 11-KT during the first reproductive cycle of farmed big-belly seahorse (Hippocampus abdominalis)

Limited data are available regarding the gonadal development of farmed seahorse along with the physiological role of gonadotropins and sex steroids during gonadal maturation. In the present study, we conducted an examination of the developmental stages of gonad and brood pouch during the initial reproductive cycle of the farmed big-belly seahorse (Hippocampus abdominalis), and our results showed that males sexually matured half of a month later than females, and the brood pouch emerged at 3.5-month old and then reached the late-stage at 5.5-month old. Meanwhile, the open reading frame (ORF) of gonadotropin subunits (cgα, fshβ and lhβ) of the big-belly seahorse were cloned and characterized, and tissue distribution profiles of their transcripts were analyzed, revealing their detectability across various tissues, with a notable presence observed in the brain tissues. Furthermore, expression profiles of cgα, fshβ and lhβ transcripts and the plasma levels of 17β-estradiol (E2) and 11-ketotestosterone (KT) in farmed big-belly seahorse during the first reproductive cycle were also investigated. The findings indicated that cgα, fshβ and lhβ transcripts exhibited low expressions at the initial development of ovary or testis, raised continuously and reached their peak levels at the period of spawning or spermation, and they kept gradually increasing accompany with brood pouch growth. It is noteworthy that variation of mRNA levels of fshβ were slightly higher than those of lhβ. Besides, the results showed that plasma 11-KT levels presented an increasing trend during testicular development, peaking in fish with III and IV-stage testis and early-stage brood pouch, and plasma 17β-E2 levels were higher in vitellogenic stage of fish with II-stage ovary and early III-stage ovary. Taken together, these data reveal that gonadotropins and sex steroids likely play a role in the regulation of gonad and brood pouch growth in seahorse. These observations not only contribute to clarifying function of reproductive hormones on growth of gonad and brood pouch of seahorse, but also providing an important theoretical foundation for the artificial breeding of seahorses.

Steroid profile and ovarian gene expression in Genyatremus luteus (Teleostei, Perciformes: Haemulidae) during sexual maturation

The aim of the present study was to assess histological features, sex steroid profile, and ovarian gene expression throughout the ovarian maturation of Genyatremus luteus in Brazilian Coastal Equatorial Amazon. Specimens were categorized into different gonadal maturation stages–immature (n = 7), maturing (n = 7), mature (n = 7), and spawned (n = 7)–based on histological features of ovarian follicles and on oocyte development. Plasma E2, 11-KT and 17α-OHP levels were measured through enzyme-linked immunosorbent assays. The gene expression of estrogen (er) and LH (lhr) receptors in the ovary was analyzed through real-time polymerase chain reaction. The highest plasma E2 concentration was found in mature specimens (P< 0.05). Plasma 17α-OHP concentrations have significantly increased from the immature to the final maturation stage (P< 0.05). Maturational reproductive stage did not have any effect on plasma 11-KT concentrations. Er expression in ovaries has significantly increased throughout ovarian maturation (P < 0.05), and it remained high at mature and spawned stages. Lhr expression showed similar trend throughout the maturation process, although its peak was observed at spawned stage (P< 0.05). In conclusion, the gene expression profile of er and lhr and plasma E2 and 17α-OHP concentrations are proportional to oocyte development; they play important role in regulating ovarian development and ovulation in G. luteus.

Embryonic benzophenone-3 exposure inhibited fertility in later-life female zebrafish and altered developmental morphology in offspring embryos.

Benzophenone-3 (BP3), an organic UV filter widely used in personal care products, is ubiquitous in aquatic environments. Previous studies have shown that BP3 can interfere with oocytes development in the ovary. The current study was conducted to evaluate the effects of embryonic BP3 exposure on reproductive outcomes in later life. Zebrafish embryos were exposed to different concentrations of BP3 (0, 1, 10, 100 μg/L) for 5 days in the developmental stage and subsequently fed for 4 months without any toxins. The body length, body weight, and ovary weight in F0 female adult zebrafish and morphology indices in F1 offspring embryos were measured. The reproductive behaviors of adult zebrafish were recorded by a digital camera. HE staining was used to estimate the development of oocytes and the proportion of different phases was calculated. qPCR was used to detect the expression levels of reproduction-related genes of the hypothalamic-pituitary-gonadal (HPG) axis. Our findings revealed that the body length and body weight were not changed with embryonic BP3 exposure, but BP3 exposure inhibited the development and maturation of ovaries in later-life female zebrafish, accompanied by an increased proportion of follicles in the primary growth and early vitellogenic stages, and a decline in the full-growth stage in ovaries. Meanwhile, reduced egg production, delayed hatching rate, altered somite count and increased mortality rate were observed at 100 μg/L in offspring embryos. Behavioral results showed that BP3 exposure reduced the frequency of chasing, touching, entering the spawning area, and the duration of fish entering the spawning area later in life, qPCR analysis showed that the expression levels of reproduction-related genes of the HPG axis were downregulated in females, following a decreasing trend in plasma E2 and 11-KT levels. These results suggested that embryonic BP3 exposure negatively affected the fertility of fish and the development of their offspring embryos, which may cause potential risks to aquatic ecosystems and human health.

Mechanisms involved in tributyltin-enhanced aggressive behaviors and fear responses in male zebrafish

Tributyltin (TBT), an aromatase inhibitor, has been found to disrupt gametogenesis and reproductive behavior in several fish species. However, whether TBT is capable of affecting other behaviors such as aggressive behavior and fear response in fish and the underlying mode(s) of action remain unclear. To study aggressive behavior, adult zebrafish (Danio rerio) males were continuously exposed to two nominal concentrations of TBT (TBT-low, 100 ng/L and TBT-high, 500 ng/L) for 28 days. To study the fear response, the fish were divided into four groups (Blank and Control, 0 ng/L TBT; TBT-low, 100 ng/L; and TBT-high, 500 ng/L). The fish were then treated with DW (Blank) or with alarm substance (AS) (Control, TBT-low and TBT-high). After exposure, the aggressive behavior of the fish was tested using the mirror test (mirror-biting frequency, approaches to the mirror and duration in approach zone).and fighting test (fish-biting frequency) The mirror-biting frequency, approaches to the mirror, duration in approach zone and fish-biting frequency of the TBT-exposed fish increased significantly compared to those of the control fish, indicating enhanced aggressive behavior. The fear response parameters tested using the novel tank dive test (onset time to the higher half, total duration in the lower half and the frequency of turning) of the TBT-exposed fish were also significantly increased after AS administration, suggesting an enhanced fear response. Further investigation revealed that TBT treatment elevated the plasma level of 11-ketotestosterone (11-KT) and decreased the plasma level of estradiol (E2) in a concentration-dependent manner. Moreover, TBT up-regulated the mRNA levels of ar, c-fos and bdnf1, and suppressed the expression of btg-2 in fish. In addition, exposure to AS increased the plasma level of cortisol and down-regulated the mRNA expression levels of genes involved in 5-HT synthesis (such as tph1b and pet1) in both control and TBT-treated fish. AS significantly suppressed the mRNA level of tph1b, tph2, pet1 and npy in the TBT-high group compared to the control fish. The present study demonstrates that TBT enhances aggressive behavior and fear responses in male zebrafish probably through altering plasma levels of 11-KT, E2 and cortisol and altering the expression of genes involved in the regulation of aggressive behavior (ar, c-fos, bdnf1 and btg-2) and fear responses (tph1b, tph2, pet1 and npy). The present study greatly extends our understanding of the behavioral toxicity of TBT to fish.

Advanced puberty triggered by bi-weekly changes in reproductive factors during the photolabile period in a male teleost fish, Dicentrarchus labrax L.

This study evaluated the impact of continuous light (LL) within the photolabile period on advanced puberty in juvenile male European sea bass. The exposure to an LL regime for 1 month, from August 15 to September 15 (LLa/s), was compared to a constant simulated natural photoperiod (NP) and constant continuous light conditions year-round (LLy). Somatic growth, hormone plasma levels, rates of testicular maturation and spermiation, as well as the mRNA levels of some reproductive genes were analyzed. Our results demonstrated that both LLa/s and LLy treatments, which include LL exposure during the photolabile period, were highly effective in inhibiting the gametogenesis process that affects testicular development, and clearly reduced the early sexual maturation of males. Exposure to an LL photoperiod affected body weight and length of juvenile fish during early gametogenesis and throughout the first year of life. Interestingly, LL induced bi-weekly changes in some reproductive factors affecting Gnrh1 and Gnrh2 content in the brain, and also reduced pituitary fshβ expression and plasmatic levels of 11-KT, E2, Fsh throughout early gametogenesis. We suggest that low levels of E2 in early September in the LL groups, which would be concomitant with the reduced number of spermatogonial mitoses in these groups, might indicate a putative role for estrogens in spermatogonial proliferation during the early gonadal development of this species. Furthermore, a significant decrease in amh expression was observed, coinciding with low plasma levels of 11-KT under LL regimes, which is consistent with the idea that this growth factor may be crucial for the progress of spermatogenesis in male sea bass.

Gonadal steroids and energy availability during ovarian maturation stages of the Amazonian pirarucu Arapaima gigas (Teleostei: Osteoglossidae) in the wild

The Amazonian pirarucu, Arapaima gigas, belongs to a phylogenetically basal group of teleosts (family Osteoglossidae). The commercial importance and the overexploited status of natural stocks of A. gigas brought the interest to rear it in the Amazon region, but rearing techniques are not fully understood to obtain reproduction success. Gonadal steroids (plasma and cephalic liquid), lipids and proteins (muscles, liver and ovary) of wild A. gigas females were analyzed during one year on Mexiana Island (Amazon Basin, Brazil) and ovarian maturation stages were described. The sexual gender determination method based on 11-ketostestosterone (11KT) and estradiol (E2) ratio was applied to check if the value is in agreement of the sex previously determined by direct observation. Adult females were classified into four reproductive stages according to ovary development stage: previtellogenic, maturation, mature, and regression/spawning. Immature females were also analyzed. All mature females were sampled during the rainy season. Lipids stored in the ventrecha (belly) are a possible source of this substrate for the developing ovary. Plasma steroid profile throughout A. gigas female reproductive stages is similar to that found in most teleosts, but plasma 11KT levels peaked at the mature stage, suggesting an important role of this androgen in female ovulation. The 11KT/E2 method was 100% efficient when sexing juveniles and adults at the beginning of their reproductive cycle and can successfully be applied to identify the sexual gender of animals. The steroid profile of the cephalic liquid suggests a possible role of this fluid as a pheromone, due to the high level of 17α-hydroxyprogesterone at the final stages of the reproductive cycle.

Photo-thermal manipulations induce captive maturation and spawning in endangered golden mahseer (Tor putitora): A silver-lining in the strangled conservation efforts of decades

Present study was undertaken to explore the possibilities of inducing maturity and spawning of T. putitora under captivity through manipulation of environmental cues i.e. photoperiod and temperature. In experiment I, adult T. putitora were subjected to three photoperiod (8L:16D, 12L:12D and 16L:12D) regimes for 100 days. In females, darker photoperiod (8L:16D) significantly decreased the plasma estradiol levels compared to 12L:12D and 16L:8D photoperiods. Plasma 17α, 20β-diOH-P was significantly (p < .05) changed both in females as well as males due to different photoperiods. Highest level was observed at 12L:12D in females and 16L:8D in males whereas the lowest level was found in 8L:16D. There was no significant effect of photoperiod on plasma 11-ketotestosterone (11-KT) levels and gonado-somatic index (GSI) of both males and females. In experiment II, effect of temperature (ambient, 21.2 ± 1.4 °C and elevated, 23.7 ± 1.3 °C; Mean ± SD) on inducing maturity under captive conditions was explored. The level of 17β-estradiol and 17α, 20β-diOH-P was significantly increased in females kept at elevated temperature compared to its ambient counterpart. Correspondingly, GSI of females increased 6-fold at elevated temperature. In fact in the ovary of females reared at elevated temperature, oocytes were in vitellogenic and maturing stage, whereas it was only in cortical alveolar stages in the fishes kept at ambient temperature. On the other hand, there was no marked change found in testicular histology. However, there was presence of some macrophage aggregations on the efferent duct region of testes at elevated temperature. No significant (p > .05) effect of temperature was observed on plasma levels of 11-KT of both sexes. Experiment III was meant to explore the possibility of achieving captive spawning by simulating natural spawning ground using a gravel bed bio-filter. Natural spawning occurred after four months of rearing in the simulated facility. Subsequently, fishes further spawned seven times in a period of 4 months on an interval of 15–20 days. Overall, our results suggested that captive maturity and spawning of golden mahseer can be achieved by manipulating the environmental cues. The results solved the prevailing decadal issue of captive maturation of golden mahseer which otherwise has been a major bottleneck for its wide spread rehabilitation and conservation programmes.

Involvement of Membrane Progestin Receptor Beta (mPRβ/Paqr8) in Sex Pheromone Progestin-Induced Expression of Luteinizing Hormone in the Pituitary of Male Chinese Black Sleeper (Bostrychus Sinensis).

Our previous studies showed that 17α, 20β-dihydroxy-4-pregnen-3-one (DHP) acted as a sex pheromone to induce reproductive success in Chinese black sleeper (Bostrychus sinensis), but its functional mechanism remains unclear. In the present study, we cloned the cDNAs of the gonadotropin subunits (cgα, fshβ, and lhβ), and found that, in exposure to 5 nM DHP, transcript levels of lhβ significantly increased in the pituitary at 6 h post exposure; plasma 11-KT levels increased at 24 h post exposure in mature male fish. In contrast, DHP exposure failed to increase the transcript levels of lhβ in the pituitary of immature male fish, suggesting that the responsiveness to DHP depends on reproductive status. Interestingly, expression of progestin and adipoQ receptor 8 (paqr8, also known as mPRβ) and progesterone receptor membrane component 2 significantly increased in the olfactory rosette of male fish at late meiosis stage following a co-injection of human chorionic gonadotropin (HCG) and luteinizing hormone releasing hormone-A3 (LHRH-A3), while no increases of other progestin receptors were observed. Moreover, Paqr8 protein was localized in the dendritic knobs of the olfactory sensory neurons, which were activated following the in vivo exposure to DHP. The DHP-induced expression of lhβ in pituitary was not inhibited by RU486, an antagonist of nuclear progesterone receptor. Taken together, our results suggested that sex pheromone DHP increased the expression of lhβ transcript in the pituitary and plasma 11-KT levels of mature male, important for reproduction; and Paqr8 might be involved in responding to sex pheromone DHP in the olfactory rosette of male B. sinensis.

Reproductive cycle of leopard grouper Mycteroperca rosacea (Streets, 1877) held in captivity: relation ship between gonad development and sex steroid concentration

In this study, sex steroids (E2, T, and 11-KT) concentrations in blood of captive leopard grouper ( Mycteroperca rosacea ) and their relation togonad development were determined during a reproductive cycle. Each month, gonad samples from 24 fish were obtained to analyze gonadal maturation and blood was extracted to determine steroid levels. Throughout the year, ovaries showed a higher percentageof primary oocytes. In January, oocytes at early and late vitellogenesis stages increased progressively; from March to June, ovulation rates were high. In females, estradiol levels increased from March and decreased after the spawning season. Lower levels of testosterone were found during the spawning season and 11-KT remained without significant changes throughout the year. Males exhibit a significant increase in E2 from March until July; testosterone remained without significant variation throughout theyear, and 11-KT plasma levels increased from March until July and decreased after the spawning season. In this study, we verified the sex change of an organism and the concentrations of sexual steroids were determined and discussed.

Natural endocrine profiles of the group-living skunk anemonefish Amphiprion akallopisos in relation to their size-based dominance hierarchy.

Group-living animals commonly display differences in behaviour, physiology and endocrine profiles between conspecifics within the group, which are tightly linked to reproduction. Teleosts exhibit a variety of social systems, where social status, as well as sex, has been linked to different androgen and oestrogen profiles. Levels of gonadal androgen and oestrogen were investigated as a function of sex and position in a social hierarchy in free-living individuals of the skunk anemonefish Amphiprion akallopisos, a protandrous pomacentrid fish with a size-based dominance hierarchical social system. Plasma levels of 11-ketotestosterone (11-KT), testosterone (T) and 17β-oestradiol (E2 ), as well as conversion ratios from T, were measured by ELISA from 111 individuals along a linear hierarchy from 38 social groups in the wild. Blood plasma levels of 11-KT and E2 showed sex differences, being higher in males and females respectively as expected based on their role as the major androgen and oestrogen in fish reproduction. However, no sex differences were found for T, which may represent its role in territorial defence or simply as a precursor for the synthesis of 11-KT and E2 . In terms of the hierarchical social system within males, 11-KT levels decline as the hierarchy is descended, which may represent their decreasing reproductive opportunity, as well as the decreasing levels of aggression towards males lower in the hierarchy. In summary, the size-based dominance hierarchy is associated with distinct steroid levels of 11-KT and E2 between individual free-living A. akallopisos that closely resemble those of species in which breeding individuals suppress reproduction of conspecifics lower in the hierarchy.

Identification of conserved genes triggering puberty in European sea bass males (Dicentrarchus labrax) by microarray expression profiling

BackgroundSpermatogenesis is a complex process characterized by the activation and/or repression of a number of genes in a spatio-temporal manner. Pubertal development in males starts with the onset of the first spermatogenesis and implies the division of primary spermatogonia and their subsequent entry into meiosis. This study is aimed at the characterization of genes involved in the onset of puberty in European sea bass, and constitutes the first transcriptomic approach focused on meiosis in this species.ResultsEuropean sea bass testes collected at the onset of puberty (first successful reproduction) were grouped in stage I (resting stage), and stage II (proliferative stage). Transition from stage I to stage II was marked by an increase of 11ketotestosterone (11KT), the main fish androgen, whereas the transcriptomic study resulted in 315 genes differentially expressed between the two stages. The onset of puberty induced 1) an up-regulation of genes involved in cell proliferation, cell cycle and meiosis progression, 2) changes in genes related with reproduction and growth, and 3) a down-regulation of genes included in the retinoic acid (RA) signalling pathway. The analysis of GO-terms and biological pathways showed that cell cycle, cell division, cellular metabolic processes, and reproduction were affected, consistent with the early events that occur during the onset of puberty. Furthermore, changes in the expression of three RA nuclear receptors point at the importance of the RA-signalling pathway during this period, in agreement with its role in meiosis.ConclusionThe results contribute to boost our knowledge of the early molecular and endocrine events that trigger pubertal development and the onset of spermatogenesis in fish. These include an increase in 11KT plasma levels and changes in the expression of several genes involved in cell proliferation, cell cycle progression, meiosis or RA-signalling pathway. Moreover, the results can be applied to study meiosis in this economically important fish species for Mediterranean countries, and may help to develop tools for its sustainable aquaculture.

Reproductive dysfunction in females of endangered golden mahseer (Tor putitora) in captivity

The present study was undertaken to gain insight on the physiological basis underlying the constraints in attaining maturity of endangered golden mahseer (Tor putitora) in captivity. Selected hormone levels and stress biomarkers were analysed in wild and captive reared brooders to address the above objectives. As compared to their captive counterparts, plasma 17β-estradiol was significantly (p<0.05) higher in wild caught females. A concurrent trend was observed for plasma vitellogenin, aromatase, 17α, 20β-dihydroxy progesterone (17α, 20β DHP), luteinizing hormone (LH) and11-ketotestosterone (11-KT) indicating a weak hormone response in captive females that potentially hindered maturity. To the contrary, the plasma11-KT levels were not significantly different between wild and captive males. Plasma 17α, 20β DHP level was found significantly (p<0.05) higher in wild caught females compared to females reared in captivity. However, both males of wild and captivity registered significantly higher 17α, 20β DHP than captive females. Plasma 11-KT level was significantly higher in males compared to females. However, the captive females had higher level of 11-KT than captive males. Stress biomarkers viz., cortisol, superoxide dismutase (SOD) and glutathione peroxidase (GPx) were also estimated both in wild and captive brooders. There was no significant difference in plasma cortisol levels of wild and captive reared brooders. However, plasma GPx and SOD activity were significantly higher in captive reared T. putitora as compared to wild brooders counterpart manifesting prevailing oxidative stress in captivity. Overall results showed endocrine and stress differences between wild and captive reared brood fishes during early spawning period which highlighted the endocrine failure of female reproductive maturity in captivity.

Changes in plasma steroid levels and gene expression of pituitary gonadotropins, testicular steroidogenesis-related proteins and insulin-like growth factors during spermatogenesis of the yellowtail Seriola quinqueradiata

We have examined the annual cycle of spermatogenesis in captive yellowtail Seriola quinqueradiata, including the associated changes in both plasma 11-ketotestosterone (11-KT) level and gene expression of key endocrine factors, such as the pituitary gonadotropin subunits, testicular steroidogenesis-related proteins and insulin-like growth factors (IGFs), at different testicular developmental stages. Spermatogenesis was initiated in January, and all males had progressed to the spermiation stage in April. Plasma 11-KT levels and gene expression profiles were analyzed in relation to changes in histological findings. Plasma 11-KT levels increased during early to late spermatogenesis and were positively correlated with early mitotic divisions of spermatogonia leading to meiosis. The genes encoding the follicle stimulating hormone (FSH) beta subunit (fshb) and the luteinizing hormone (LH) beta subunit (lhb) both showed parallel expression patterns during spermatogenesis. A previous study revealed that FSH receptor mRNA in yellowtail testes is strongly expressed from early to late spermatogenesis, whereas levels of LH receptor mRNA peak during spermiation; only cyp17a1 [encoding cytochrome P450 17α-hydroxylase/C17-C20 lyase (P450c17)] transcript levels increased during early spermatogenesis. The expression patterns of the genes encoding testicular IGF-1 and -2 (igf-1 and igf-2) differed from each other. Altogether, early spermatogenesis was associated with the regulation of 11-KT, which was probably induced by FSH through stimulation of specific steroidogenic enzymes, such as P450c17, and spermiation was considered to be triggered by LH. In addition, IGF-1 and IGF-2 are individually involved in spermatogenesis via autocrine/paracrine mechanisms.

11-Ketotestosterone Is a Major Androgen Produced in Human Gonads

11-ketotestosterone (11-KT) is a novel class of active androgen. However, the detail of its synthesis remains unknown for humans. The objective of this study was to clarify the production and properties of 11-KT in human. Design, Participants, and Methods: Expression of cytochrome P450 and 11β-hydroxysteroid dehydrogenase types 1 and 2 (key enzymes involved in the synthesis of 11-KT) were investigated in human gonads. The production of 11-KT was investigated in Leydig cells. Plasma concentrations of testosterone and 11-KT were measured in 10 women and 10 men of reproductive age. Investigation of its properties was performed using breast cancer-derived MCF-7 cells. Cytochrome P450 and 11β-hydroxysteroid dehydrogenase types 1 and 2 were detected in Leydig cells and theca cells. Leydig cells produced 11-KT, and relatively high levels of plasma 11-KT were measured in both men and women. There was no sexual dimorphism in the plasma levels of 11-KT, even though testosterone levels were more than 20 times higher in men than in women. It is noteworthy that the levels of testosterone and 11-KT were similar in women. In a luciferase reporter system, 11-KT activated human androgen receptor-mediated transactivation. Conversely, 11-KT did not activate estrogen receptor-mediated transactivation in aromatase-expressed MCF-7 cells, whereas testosterone did following conversion to estrogen. 11-KT did not affect the estrogen/estrogen receptor -mediated cell proliferation of MCF-7 cells. Furthermore, it significantly inhibited cell proliferation when androgen receptor was transfected into MCF-7 cells. The current study indicates that 11-KT is produced in the gonads and represents a major androgen in human. It can potentially serve as a nonaromatizable androgen.

Differential modulation of neuro- and interrenal steroidogenesis of juvenile salmon by the organophosphates - tris(2-butoxyethyl)- and tris(2-cloroethyl) phosphate

Following the ban of polybrominated diphenyl ether (PBDEs) flame retardants under well-documented toxicity issues, organophosphate such as tris(2-butoxyethyl) phosphate (TBOEP) and tris(2-cloroethyl) phosphate (TCEP) were considered as potential substitutes. Although TBOEP and TCEP are consistently detected in the aquatic environment, there are few data about the possible toxicological effects of these compounds on aquatic organisms, including fish. In the present study, we have investigated the influence of TBOEP and TCEP on neuro- and interrenal steroidogenesis of juvenile Atlantic salmon (Salmo salar), after a seven-day exposure to four different concentrations (0 (control), 0.04, 0.2 and 1mg/L) of each compound. TBOEP and TCEP were diluted in Milli-Q water. The expression of genes involved in steroidogenesis (StAR, cyp19a, cyp19b, cholesterol side-chain cleavage enzyme (P450scc), 3β-hydroxysteroid dehydrogenase (3β-hsd), and 11β-hydroxylase (cyp11β)), were analyzed in the brain and head kidney using real-time PCR. Plasma 11-ketotestosterone (11-KT) analysis was performed using enzyme immunoassay (EIA). Our results showed that TBOEP accumulated more rapidly than TCEP in fish muscle tissue. Surprisingly, TBOEP produced less pronounced effects than TCEP on neural and interrenal steroidogenic responses, despite the observed rapid uptake and bioaccumulation pattern. Specifically, TBOEP produced significant and consistent concentration-specific alterations on neural- and interrenal steroidogenesis. Plasma levels of 11-KT were not significantly altered by any of the exposures. The increased expression of steroidogenic genes demonstrated in the present study could produce time-specific alterations in the production of glucocorticoids and steroid hormones that play integral roles in fish metabolism, stress responses and adaptation, sexual maturation, reproduction and migration with overt consequences on reproductive success and survival.

In-vitro and in-vivo biological activity of recombinant yellowtail kingfish (Seriola lalandi) follicle stimulating hormone

Biologically active recombinant yellowtail kingfish follicle stimulating hormone (rytkFsh) was produced in yeast Pichia pastoris and its biological activity was demonstrated by both in-vitro and in-vivo bioassays. Incubation of ovarian and testicular fragments with the recombinant hormone stimulated E2 and 11-KT secretion, respectively. In-vivo trial in immature female YTK resulted in a significant increase of plasma E2 levels and development of oocytes. In males at the early stages of puberty, advancement of spermatogenesis was observed, however plasma 11-KT levels were reduced when administered with rytkFsh.

Extra-gonadal steroids modulate non-breeding territorial aggression in weakly electric fish

The neuroendocrine control of intraspecific aggression is a matter of current debate. Although aggression in a reproductive context has been associated with high levels of circulating androgens in a broad range of species, it has also been shown to occur during the non-breeding season when gonads are regressed and plasma steroid hormone levels are low. In mammals and birds the aromatization of androgens into estrogens plays a key role in the regulation of aggression in both the breeding and non-breeding seasons. This is the first study in a teleost fish to explore the role of steroids in the modulation of non-breeding aggression. Gymnotus omarorum is a highly aggressive teleost fish that exhibits aggression all year-round. We analyzed male–male non-breeding agonistic behavior, compared circulating 11-Ketotestosterone (11-KT) levels between dominants and isolated males, assessed the regulatory role of aromatization of androgens into estrogens, and evaluated the gonads as a source of these sex steroids. We found that high levels of aggression occurred in the non-breeding season despite low plasma 11-KT levels, and that there was no difference in 11-KT levels between dominant and isolated males. We demonstrated that acute aromatase inhibition decreased aggression, distorted contest dynamics, and affected expected outcome. We also found that castrated individuals displayed aggressive behavior indistinguishable from non-castrated males. Our results show, for the first time in teleost fish, that territorial aggression of G. omarorum during the non-breeding season depends on a non-gonadal estrogenic pathway.

A multidisciplinary study on social status and the relationship between inter-individual variation in hormone levels and agonistic behavior in a Neotropical cichlid fish

Social animals with hierarchal dominance systems are particularly susceptible to their social environment. There, interactions with conspecifics and hierarchal position can greatly affect an individual's behavior, physiology and reproductive success. Our experimental model, Cichlasoma dimerus, is a serially-monogamous Neotropical cichlid fish with a hierarchical social system, established and sustained through agonistic interactions. In this work, we aimed to describe C. dimerus social structure and its association with hormonal profiles and testicular cellular composition. We recorded and quantified agonistic interactions from the territorial pair, i.e. the top ranked male and female, and the lowest ranked male of stable social groups. Plasma levels of 11-ketotestosterone (11-KT), testosterone, 17β-estradiol (E2) and cortisol were measured by ELISA. Results show that territorial pairs cooperatively guarded the territory, but rarely attacked in synchrony. Territorial males had higher testosterone and 11-KT plasma levels than non-territorial males, while E2 and an index of its metabolization from testosterone were higher in non-territorial males. No difference was observed in cortisol levels. Plasma 11-KT and an index of the conversion of testosterone to 11-KT, positively correlated with the frequency of aggressiveness, while E2 showed the opposite pattern. Territorial males had a higher gonadosomatic index than non-territorial males. The quantification of testicular cellular types revealed that the percentage of spermatocytes and spermatids was higher in non-territorial males, while territorial males showed a greater percentage of spermatozoa. Thus, C. dimerus male social position within a stable hierarchy is associated with distinct behaviors, steroid levels and testicular degree of development.

Seasonal changes and endocrine regulation of pejerrey (Odontesthes bonariensis) spermatogenesis in the wild

The endocrine mechanisms that regulate spermatogenesis and their interaction with environmental cues have been poorly studied compared with oogenesis in fish. The aim of this work was to study the spermatogenesis in pejerrey under the influence of photoperiod and water temperature fluctuation in the wild, evaluating the transcript levels of brain Gnrh variants and cyp19a1b, pituitary Gth subunits, gonadal Gth receptors, 11β-hsd, and 11-KT plasma levels. Males at spermiogenic stage were observed during spring and autumn, under a photoperiod above 11h of light and a water temperature below 23°C. Most arrested males were observed in summer when water temperatures increased above 23°C. Males at spermatogonial stage were mainly observed in autumn, while most males at spermatocytary stage were caught in winter. An increase of gnrh-I, cyp19a1b, fshb, gpha and 11β-hsd transcripts and 11-KT plasma levels was observed during spermatogonial and/or spermatocytary stage (early spermatogenesis). The spermiogenic stage was associated to the maximum gnrh-I gene expression level and a significant increase of Gth receptors transcripts, being this fact more evident for lhcgr. During this last gonadal stage, cyp19a1b transcript level remained high, while fshb mRNA and 11-KT plasma levels showed a significant decreased compared to that occurred at the spermatocytary stage. Also, gphα and 11β-hsd gene expression levels fell during spermiation up to similar values to those observed in arrested males. A significant correlation between 11-KT and gnrh-I, cyp19a1b, gphα, fshb, 11β-hsd transcripts, and the number of spermatocytes was observed during spermatogenesis. All these findings suggested that in pejerrey, the spermatocyte proliferation occurs mainly during winter under the stimulation of 11-KT induced by FSH through the stimulation of specific enzymes, including the 11β-hsd while spermiation occurs after photoperiod increase and with temperatures of the water below 23°C, through the stimulation of gnrh-I, cyp19a1b and lhcgr.

Assessment of the health status of wild fish inhabiting a cotton basin heavily impacted by pesticides in Benin (West Africa)

To determine the impact of agricultural pesticides used in cotton cultivation on the health status of fish living in a Beninese cotton basin, we compared the reproductive and hepatic systems of fish sampled from rivers located in both contaminated and pristine conditions. Different types of biomarkers, including biometric indices (a condition factor K, a gonadosomatic index GSI, and a hepatosomatic index HSI), plasma levels of sex steroids (11-ketotestosterone 11-KT, testosterone T and estradiol-17β E2) and the histopathology of the gonads and liver, were investigated for two different trophic levels of the following two fish species: the Guinean tilapia Tilapia guineensis and the African catfish Clarias gariepinus. The fish were captured during both the rainy season (when there is heavy use of pesticides on cotton fields) and the dry season from one site, in Pendjari River (reference site), which is located outside the cotton-producing basin, and from three other sites on the Alibori River within the cotton-producing basin. Comparing fish that were sampled from contaminated (high levels of endosulfan, heptachlor and DDT and metabolites) and reference sites, the results clearly indicated that agricultural pesticides significantly decreased K and GSI while they increased HSI, regardless of the season, species and sex of the fish. These pesticides also induced a decrease in the plasma levels of 11-KT and T and increased those of E2. The histopathology of the testes revealed, in both species, a high rate of testicular oocytes, up to 50% in the African catfish, downstream of the Alibori River, which indicated estrogenic effects from the pesticides. The disruption of male spermatogenesis primarily included necrosis, fibrosis and the presence of foam cells in the lobular lumen. The histopathology of the ovaries revealed high levels of pre-ovulatory follicular atresia, impaired oogenesis, a decrease in the oocyte vitellogenic diameter and other lesions, such as fibrosis, vacuolation and melano-macrophagic centers. The histopathology of the liver revealed the presence of necrosis, hypertrophic hepatocytes, foci of vacuolation, glycogen depletion and hemosiderin. An assessment of the general health of the fish indicated that all of the sampled fish from the polluted sites were in poorer health compared with those from the reference site but that the African catfish appeared much more affected than the Guinean tilapia, regardless of the sex and season. In conclusion, the overall results indicated that agricultural pesticides significantly impair the endocrine regulation of fish living in the Beninese cotton basin and that this would most likely be one of the causes of the severe damage observed in the liver and gonads and the reduced health condition.