In vivo implants of beta-sitosterol cause reductions of reactive cholesterol pools in mitochondria isolated from gonads of male goldfish (Carassius auratus)

β-sitosterol isolated from the leaves of Trema orientalis (Cannabaceae) promotes viability and proliferation of BF-2 cells

Trema orientalis is a pioneer species in the cannabis family (Cannabaceae) that is widely distributed in Thai community forests and forest edges. The mature leaves are predominantly used as an anti-parasite treatment and feed for local freshwater fish, inspiring investigation of their phytochemical composition and bioactivity. The purpose of this work was to investigate the bioactive compounds in T. orientalis leaf extract and their cytotoxicity in the BF-2 fish cell line (ATCC CCL-91). Flash column chromatography was used to produce 25 mL fractions with a mixture solvent system comprised of hexane, diethyl ether, methanol, and acetone. All fractions were profiled with HPLC-DAD (mobile phase methanol:aqueous buffer, 60:40 v/v) and UV detection (wavelengths 256 and 365 nm). After drying, a yellowish powder was isolated from lipophilic leaf extract with a yield of 280 µg/g dry weight. Structure elucidation by nuclear magnetic resonance (NMR) indicated it to consist of pure β-sitosterol. The lipophilic extract and pure compound were evaluated for cytotoxicity using BF-2 cells. MTT assays showed both leaf extract and pure compound at 1 µg/mL to increase cell viability after 24 h treatment. The respective half maximal inhibitory concentration (IC50) values of leaf extract and β-sitosterol were 7,027.13 and 86.42 µg/ml, indicating a lack of toxicity in the BF-2 cell line. Hence, T. orientalis can serve as a source of non-toxic natural lipophilic compounds that can be useful as bioactive ingredients in supplement feed development.

Intraperitoneal injection of genistein affects the distribution and metabolism of cholesterol in female yellow catfish Tachysurus fulvidraco

Genistein is an abundant phytoestrogen in soybean. This study aimed to determine the effects of genistein on cholesterol distribution and metabolism in female yellow catfish. Three hundred fish (49.2 ± 1.4 g) were randomly divided into five treatments and received intraperitoneal injections as follows: (1) blank, no injection; (2) control, vehicle only; (3) E2, 17β-estradiol at 10 μg·g^-1 body weight; (4) low genistein doses, genistein at 10 μg·g^-1 body weight; (5) high genistein doses, genistein at 100 μg·g^-1 body weight. Both high and low genistein doses significantly reduced (p < 0.05) serum TC and LDL-C 24 h after injection. Moreover, the high genistein doses significantly reduced (p < 0.05) serum HDL-C. Both high and low doses of genistein significantly increased (p < 0.05) hepatic TC. Only high genistein doses significantly increased (p < 0.05) ovary TC. In the liver, both high and low genistein doses significantly increased (p < 0.05) protein and mRNA expression of ldlr. Meanwhile, high genistein doses significantly decreased (p < 0.05) mRNA expression of hmgcr. In ovary tissue, high genistein doses significantly decreased (p < 0.05) mRNA expression of cyp11a1. These results suggested that genistein affected the cholesterol distribution in female yellow catfish. Both high and low doses of genistein reduced cholesterol content in blood and increased its content in the liver by increasing the uptake of blood cholesterol. Meanwhile, high genistein doses may inhibit hepatic cholesterol synthesis. Additionally, high genistein doses could increase cholesterol transfer from serum into the ovary and disturb cholesterol conversion to pregnenolone.

Phytosterols: Targeting Neuroinflammation in Neurodegeneration

Plant-derived sterols, phytosterols, are well known for their cholesterol-lowering activity in serum and their anti-inflammatory activities. Recently, phytosterols have received considerable attention due to their beneficial effects on various non-communicable diseases, and recommended use as daily dietary components. The signaling pathways mediated in the brain by phytosterols have been evaluated, but little is known about their effects on neuroinflammation, and no clinical studies have been undertaken on phytosterols of interest. In this review, we discuss the beneficial roles of phytosterols, including their attenuating effects on inflammation, blood cholesterol levels, and hallmarks of the disease, and their regulatory effects on neuroinflammatory disease pathways. Despite recent advancements made in phytosterol pharmacology, some critical questions remain unanswered. Therefore, we have tried to highlight the potential of phytosterols as viable therapeutics against neuroinflammation and to direct future research with respect to clinical applications.

Terminalia arjuna induced testicular assault through Leydig cell derangement: an in vitro approach

OBJECTIVES

Terminalia arjuna (TA) has been widely used as folk medicine since ancient times. Apart from its therapeutic properties it also has anti-spermatogenic activity, but its effectiveness and mode of action on male gonadal activity remains to be revealed.

METHODS

TA bark extract was dissolved in 1% dimethyl sulfoxide and applied in primary Leydig cell culture from rat testis in dose dependent manner. After 24 h of treatment cellular toxicity marker, cytokines, steroid 5-alpha-reductase 1 (SRD5A1) and androgen receptor (AR) were measured.

RESULTS

Present study first proposed the cytotoxic impacts of TA on Leydig cells via leakage of lactate dehydrogenase and inflammatory responses by altering the pro- and anti-inflammatory cytokines in dose-dependent-manner. Furthermore, down regulation of SRD5A1 and AR indicated inhibition of normal steroidogenesis which well corroborated with cytotoxity and inflammation related parameters to promote damage of Leydig cell function. Nevertheless, it can be speculated that the inhibition of normal steroidogenesis and thereby spermatogenesis induced by TA is possibly due to the presence of β-sitosterol.

CONCLUSIONS

Therefore, the dose and duration of treatment should be carefully monitored in cases of its medicinal uses and longer duration should be avoided to protect reproductive health and fertility.

β-Sitosterol: An Antibacterial Agent in Aquaculture Management of Vibrio Infections

This study aims at investigation of antibacterial property of Parthenium hysterophorous against aquatic bacterial pathogens and to identify the key bioactive compound of the same. Antibacterial activity of the crude extracts confirmed that chloroform extract PHC has strong antibacterial activity against aquatic pathogens V.anguillarum and V.harveyi with 16mm and 15mm ZOI at 1mg/well concentration. The crude extracts were subjected for GC-MS analysis to identify the secondary metabolites. PHC was subjected to silica-gel column chromatography to separate the individual phytochemicals. PHC was separated into 9 fractions, among which Fraction No.2 demonstrated significant antibacterial activity against V.anguillarum and V.harveyi with 19mm and 17mm ZOI at 10µg/well concentration. Fraction No.2 was identified to be β-sitosterol based on mass spectrometry analysis and fragmentation analysis. In-silico protein ligand docking demonstrated that β-sitosterol has highest affinity to inhibit dihydrofolate reductase (DHFR) enzyme with -10.10Kcal/mol binding energy. This prediction was further validated using molecular dynamic simulation for 20ns. Based on these computational analyses, it was proposed that β-sitosterol exhibits antibacterial activity via inhibition of DHFR enzyme. β-sitosterol is a well known nutritionally valuable compound that reduces cholesterol levels in humans. It is also been used as supplement feed to increase the nutritional value of cultured fishes. β-sitosterol has also been proven to have positive effect in growth and reproduction of cultivated fishes. Findings of this study strongly suggest the usage of β-sitosterol in aquaculture, as nutritional supplement and also as disease control agent to prevent and control fish diseases caused by Vibrio species.

Comparison of steroidogenic gene expression in mummichog (Fundulus heteroclitus) testis tissue following exposure to aromatizable or non-aromatizable androgens

Androgens are a recognized class of endocrine disrupting compounds with the ability to impact reproductive status in aquatic organisms. The current study utilized in vitro exposure of mummichog (Fundulus heteroclitus) testis tissue to either the aromatizable androgen 17α-methyltestosterone (MT) or the non-aromatizable androgen 5α-dihydrotestosterone (DHT) over the course of 24 h to determine if there were differential effects on steroidogenic gene expression. Testis tissue was exposed to androgen concentrations of 10^-12 M, 10^-9 M and 10^-6 M for 6, 12, 18 or 24 h, after which a suite of steroidogenic genes, including steroidogenic acute regulatory protein, 3β-hydroxysteroid dehydrogenase (3βhsd) and cytochrome P450 17A1 (cyp17a1), were quantified using real-time polymerase chain reaction. Both androgens affected steroidogenic gene expression, with most alterations occurring at the 24-hour time point. The gene with the highest fold-change, and shortest interval to expression alteration, was 3βhsd for both androgens. Potential differences between the two model androgens were observed in increased expression of cyp17a1 and 11β-hydroxysteroid dehydrogenase (11βhsd), which were only altered after exposure to DHT and in expression levels of cytochrome P450 11A1 (cyp11a1), which was upregulated by MT but not altered by DHT. Results from this study show both androgens interact at the gonadal level of the hypothalamus-pituitary-gonadal axis and may possess some distinct gene expression impacts. These data strengthen the current research initiatives of establishing in vitro test systems that allow toxic potential of untested chemicals to be predicted from molecular perturbations.

Effects of Phytosterols as Food Additives on Adrenal and Reproductive Endocrine Function during Sexual Maturation in Male Japanese Quail (Coturnix coturnix japonica)

Varying amounts of phytosterols (PS) occur naturally in several foods of plant origin. PS, which are structurally and functionally similar to cholesterol, have been shown to reduce plasma total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) levels. Moreover, PS disrupts endocrine function in certain animals. In the present study, we investigated the effects of high doses of PS on adrenal and reproductive endocrine function during sexual maturation in Japanese male quails. Two experiments were conducted; in the first experiment, quail chicks were subjected to long-term chronic feeding of PS (8, 80, and 800 mg/kg body weight [BW]) and the chemicals were gavaged into the crop sac from 7-50 days post-hatching. From the forty-fourth day, half of the animals in each group were subjected to a 6-day adrenocorticotropic hormone (ACTH) challenge for artificial stimulation of the adrenal gland and evaluation of long-term PS effects; in the second experiment, single doses of PS were subcutaneously injected (SC) into adult males (10-weeks-old) to assess the acute direct effect. Results indicated that chronically PS-fed animals showed a better adrenal response to ACTH challenge, and the corticosterone levels were higher (P<0.05) than those of the controls. Moreover, corticosterone levels were also high (P<0.05) 3 h after SC injection of PS. In contrast, testosterone levels and the testes weights were significantly lower (P<0.05) in the groups chronically administered with PS. No differences were observed in the testosterone levels in the acute experiment or luteinizing hormone (LH) levels in either experiment. In conclusion, the differential effects of PS on the adrenal gland and testis might be due to preferential use of different lipoprotein-cholesterol forms for steroid production. In addition, PS might locally perturb testosterone production by its accumulation or delay in testicular maturation.

Critical Analysis on Characterization, Systemic Effect, and Therapeutic Potential of Beta-Sitosterol: A Plant-Derived Orphan Phytosterol

Beta-sitosterol (BS) is a phytosterol, widely distributed throughout the plant kingdom and known to be involved in the stabilization of cell membranes. To compile the sources, physical and chemical properties, spectral and chromatographic analytical methods, synthesis, systemic effects, pharmacokinetics, therapeutic potentials, toxicity, drug delivery and finally, to suggest future research with BS, classical as well as on-line literature were studied. Classical literature includes classical books on ethnomedicine and phytochemistry, and the electronic search included Pubmed, SciFinder, Scopus, the Web of Science, Google Scholar, and others. BS could be obtained from different plants, but the total biosynthetic pathway, as well as its exact physiological and structural function in plants, have not been fully understood. Different pharmacological effects have been studied, but most of the mechanisms of action have not been studied in detail. Clinical trials with BS have shown beneficial effects in different diseases, but long-term study results are not available. These have contributed to its current status as an "orphan phytosterol". Therefore, extensive research regarding its effect at cellular and molecular level in humans as well as addressing the claims made by commercial manufacturers such as the cholesterol lowering ability, immunological activity etc. are highly recommended.

Pollution by oestrogenic endocrine disruptors and β-sitosterol in a south-western European river (Mira, Portugal)

The Mira River is a Portuguese water body widely known for its wilderness and is advertised as one of the less polluted European rivers. On this presumption, the levels of endocrine-disrupting compounds (EDCs) in Mira waters were never measured. However, because environmentalists have claimed that the Mira could be moderately polluted, a range of 17 EDCs were measured not only at the estuary but also along the river. The targeted EDCs included natural and pharmaceutical oestrogens (17β-oestradiol, oestrone and 17α-ethynylestradiol), industrial/household pollutants (octylphenols, nonylphenols and their monoethoxylates and diethoxylates and bisphenol A), phytoestrogens (formononetin, biochanin A, daidzein, genistein) and the phytosterol sitosterol (SITO). For this propose, waters from six sampling sites were taken every 2 months, over a 1-year period (2011), and analysed by gas chromatography-mass spectrometry. Unexpectedly high levels of oestrogens and of industrial/household pollutants were measured at all sampling sites, including those located inside natural protected areas. Indeed, the annual average sum of EDCs was ≈57 ng/L for oestrogens and ≈1.3 μg/L for industrial/household chemicals. In contrast, the global average levels of phytoestrogens (≈140 ng/L) and of SITO (≈295 ng/L) were lower than those reported worldwide. The EDC concentrations were normalised for ethynylestradiol equivalents (EE2eq). In view of these, the oestrogenic load of the Mira River attained ≈47 ng/L EE2eq. In addition, phosphates were above legal limits at both spring and summer (>1 mg/L). Overall, data show EDCs at toxicant relevant levels in the Mira and stress the need to monitor rivers that are allegedly less polluted.

Pollution by endocrine disruptors in a southwest European temperate coastal lagoon (Ria de Aveiro, Portugal)

Ria de Aveiro is a Portuguese lagoon renowned for its ecological and economic importance. Nonetheless, in literature, few data exist about its organic pollution. Accordingly, this study chemically monitored for the first time a series of 17 endocrine disruptor compounds (EDCs). The target EDCs include natural (17β-oestradiol, oestrone) and pharmaceutical (17α-ethynylestradiol) oestrogens, industrial/household xenoestrogenic pollutants (octylphenols, nonylphenols and their mono and diethoxylates and bisphenol A), phytoestrogens (formononetin, biochanin A, daidzein, genistein) and the phytosterol sitosterol (SITO). For the investigation of these EDCs, water samples were taken from eight sampling sites widely spread along the lagoon, at three different occasions in 2011, and analysed by gas chromatography-mass spectrometry. Results not only proved the ubiquitous distribution of all analysed EDCs but revealed that their amounts were extremely high at all sampling sites. The annual average concentrations were ≈ 46 ng/L for oestrogens, ≈ 3962 ng/L for industrial/household chemicals, ≈ 1740 ng/L for phytoestrogens and ≈ 908 ng/L for SITO. Normalising these values in ethynylestradiol equivalents (EE2eq), the oestrogenic load in this lagoon attained ≈ 50 ng/L EE2eq, which is a value well above that known to produce oestrogenic-induced disorders in aquatic fauna. Additionally, phosphate concentrations were also above the legal limits (>1 mg/L). Overall, data show EDCs at toxic relevant levels in the Ria de Aveiro and stress the need to enforce depollution measures in this habitat.

Phytoestrogens and mycoestrogens in surface waters--Their sources, occurrence, and potential contribution to estrogenic activity

This review discusses the potential contribution of phytoestrogens and mycoestrogens to in vitro estrogenic activities occurring in surface waters and in vivo estrogenic effects in fish. Main types, sources, and pathways of entry into aquatic environment of these detected compounds were summarized. Reviewed concentrations of phyto/mycoestrogens in surface waters were mostly undetectable or in low ng/L ranges, but exceeded tens of μg/L for the flavonoids biochanin A, daidzein and genistein at some sites. While a few phytosterols were reported to occur at relatively high concentrations in surface waters, information about their potencies in in vitro systems is very limited, and contradictory in some cases. The relative estrogenic activities of compounds (compared to standard estrogen 17β-estradiol) by various in vitro assays were included, and found to differ by orders of magnitude. These potencies were used to estimate total potential estrogenic activities based on chemical analyses of phyto/mycoestrogens. In vivo effective concentrations of waterborne phyto/mycoestrogens were available only for biochanin A, daidzein, formononetin, genistein, equol, sitosterol, and zearalenone. The lowest observable effect concentrations in vivo were reported for the mycoestrogen zearalenone. This compound and especially its metabolites also elicited the highest in vitro estrogenic potencies. Despite the limited information available, the review documents low contribution of phyto/mycoestrogens to estrogenic activity in vast majority of surface waters, but significant contribution to in vitro responses and potentially also to in vivo effects in areas with high concentrations.

Toxicological relevance of endocrine disruptors in the Tagus River estuary (Lisbon, Portugal)

The Tagus is the longest Iberian river, notwithstanding, the levels of natural and xenoestrogenic endocrine-disrupting compounds (EDCs) were never measured in its estuary. Suspecting for their presence, we made a major survey of 17 EDCs that include: (i) natural (17β-oestradiol and estrone) and pharmaceutical oestrogens (17α-ethynylestradiol); (ii) industrial and household pollutants (octylphenols, nonylphenols and their mono and diethoxylates, and bisphenol A); (iii) phytoestrogens (biochanin A, daidzein, formononetin, genistein); and (iv) the phytosterol (sitosterol). Water samples from the Tagus estuary were taken from nine locations every 2 months over a 1-year period and analysed by gas chromatography. Oestrogens, industrial/household pollutants were consistently higher at two sites-at Tagus River mouth and close to the Trancão tributary, both at Lisbon region. The overall oestrogenic load, in ethynylestradiol equivalents, was 13 ng/L for oestrogens, 2.3 ng/L for industrial/household pollutants and 43 ng/L for phytoestrogens; well in the range of toxicological significance. Water physicochemical parameters also indicated anthropogenic pollution, mainly at the two above-referred sampling sites.

Assessment of the sensitivity of three North American fish species to disruptors of steroidogenesis using in vitro tissue explants

There is concern regarding exposure of aquatic organisms to chemicals that interfere with the endocrine system. One critical mechanism of endocrine disruption is impairment of steroidogenesis that can lead to altered hormone levels, altered or delayed sexual development, and ultimately reproductive failure. With the current large gap in knowledge and a high degree of uncertainty regarding the sensitivity of fishes native to northern ecosystems to endocrine disrupting chemicals (EDCs), the aim of this study was to develop an in vitro gonadal explant assay enabling the assessment of EDCs on sex-steroid production in wild fish species native to North America. Northern pike (Esox lucius), walleye (Sander vitreus), and white sucker (Catostomus commeroni) were sampled from a reference location in Lake Diefenbaker, Saskatchewan, Canada, at spawn and multiple post-spawn time points. Gonads were excised and immediately exposed for 24h to a model inducer (forskolin) or inhibitor (prochloraz) of steroidogenesis in L-15 supplemented media. Furthermore, seasonal profiles of plasma 11-ketotestosterone (11-KT) and 17-β estradiol (E2) concentrations were characterized. Enzyme-linked immunosorbent assays were used to quantify hormone concentrations in plasma and media. The seasonal profile of plasma hormones was significantly correlated with basal in vitro hormone production. Gonad tissue exposed to forskolin showed a concentration-dependent increase in E2 and a general increase in 11-KT. Gonad tissue exposed to prochloraz resulted in a decrease of concentrations of 11-KT and E2. These results illustrated that gonadal tissue is undergoing steroidogenesis in an in vitro setting that is comparable to in vivo hormone profiles, and which is responsive to chemical exposure in a concentration-dependent manner. The seasonal time point during which gonad explants were excised and exposed had an impact on the potency and magnitude of responses, resulting in a seasonal effect on sensitivity. Male and female white sucker showed greatest sensitivity to forskolin, while male and female walleye showed greatest sensitivity to prochloraz. Also, gonad explants from these species were found to have greater sensitivity than responses previously reported for in vitro explants of other fish species such as the fathead minnow (Pimephales promelas), and stable cell lines currently used as screening applications to detect chemicals that might disrupt the endocrine system. Therefore, current approaches that use stable cell lines or tissue explants from standardized small bodied laboratory species might not be protective of some wild fish species. Future research is required that investigates whether this in vitro gonadal explant assay is predictive of in vivo effects in wild species of fishes.

Phytoestrogens β -sitosterol and genistein have limited effects on reproductive endpoints in a female fish, Betta splendens

Phytoestrogens are produced by plants and may cause endocrine disruption in vertebrates. The present study hypothesizes that phytoestrogen exposure of female Siamese fighting fish (Betta splendens) may disrupt endogenous steroid levels, change agonistic behavior expression, and potentially also disrupt oocyte development. However, only the pharmacologic dose of β-sitosterol had a significant effect on opercular flaring behavior, while we did not find significant effects of β-sitosterol or genistein on steroids or gonads. These findings are in direct contrast with previous studies on the effects of phytoestrogens in female fish. Results of the current study support previous work showing that the effects of phytoestrogen exposure may be less acute in mature female B. splendens than in other fish.

Fathead minnow response to broad-range exposure of β-sitosterol concentrations during life-cycle testing

The β-sitosterol concentration in pulp and paper mill effluents is typically greater than that of other phytosterols and has been shown to cause a variety of effects in fish. The authors exposed fathead minnow (Pimephales promelas) to low (22 ± 0.93 µg/L), medium-low (70 ± 2.1 µg/L), medium-high (237 ± 5.5 µg/L), and high (745 ± 16.2 µg/L) concentrations of β-sitosterol as well as negative (water), positive (ethynyl estradiol, 16 ± 0.58 ng/L), and carrier (0.6 mL/L acetone) controls. Fish were monitored over a full life cycle for population-level endpoints including growth and survival, reproductive endpoints (e.g. fecundity, sex steroids and vitellogenin, gonado-/hepatosomatic indices, and gonad histology). No significant differences were seen in fish growth, mortality, or reproduction with β-sitosterol exposure, although a trend for lower egg production in β-sitosterol exposures relative to the water control may be related to the acetone carrier. All ethynyl estradiol-exposed fish were smaller, showed female characteristics, and did not spawn. Sex steroid and vitellogenin were highly variable with no detectable treatment-related differences. Gonadal tissue showed no β-sitosterol-related differences in reproductive development and spawning capability, although most ethynyl estradiol-exposed males had ovarian tissue and were not spawning-capable. The results indicate that β-sitosterol exposure had little apparent impact on fathead minnow survival, growth, and reproduction even at concentrations >10 times that of typical effluents, although small sample size and variability precluded fully evaluating treatment responses on sex steroids and vitellogenin.

Dietary Aloe vera components' effects on cholesterol lowering and estrogenic responses in juvenile goldfish, Carassius auratus

Aloes are now considered a very interesting source of bioactive compounds among which phytosterols should play a major role. The present study is an attempt to investigate the hypocholesterolemic activity of Aloe vera associated with its impact on the reproductive status of juvenile goldfish. Therefore, the short- and long-term effects of feeding supplementary diet containing aloe components (20 mg aloe/g diet; 2%) on plasma lipids, plasma vitellogenin, and hepatic estrogen receptor α/β1 mRNA levels in goldfish were examined. Results of GC-MS for phytosterols show high abundance of β-sitosterol in freeze-dried powder of Aloe vera whole leaves. Moreover, a 2% aloe powder dietary supplement was not found estrogenic in juvenile goldfish after either 7- or 30-day treatment, but was consistent in plasma hypocholesterolemic effects following long-term exposure. The present data further support that plasma cholesterol modulation induced by phytosterols may not be related to estrogen-like activity.

Dietary xenosterols lead to infertility and loss of abdominal adipose tissue in sterolin-deficient mice

The investigation of the human disease sitosterolemia (MIM 210250) has shed light not only on the pathways by which dietary sterols may traffic but also on how the mammalian body rids itself of cholesterol and defends against xenosterols. Two genes, ABCG5 and ABCG8, located at the sitosterolemia locus, each encodes a membrane-bound ABC half-transporter and constitutes a functional unit whose activity has now been shown to account for biliary and intestinal sterol excretion. Knockout mice deficient in Abcg5 or Abcg8 recapitulate many of the phenotypic features of sitosterolemia. During the course of our studies to characterize these knockout mice, we noted that these mice, raised on normal rodent chow, exhibited infertility as well as loss of abdominal fat. We show that, although sitosterolemia does not lead to any structural defects or to any overt endocrine defects, fertility could be restored if xenosterols are specifically blocked from entry and that the loss of fat is also reversed by a variety of maneuvers that limit xenosterol accumulation. These studies show that xenosterols may have a significant biological impact on normal mammalian physiology and that the Abcg5 or Abcg8 knockout mouse model may prove useful in investigating the role of xenosterols on mammalian physiology.

Reproductive consequences of exposure to waterborne phytoestrogens in male fighting fish Betta splendens

Phytoestrogens are plant compounds that can act as endocrine disruptors in vertebrates. Biologically active levels of phytoestrogens have been found in aquatic habitats near wood pulp and paper mills, biofuel manufacturing plants, sewage-treatment plants, and agricultural fields. Phytoestrogens are known to cause hormonal and gonadal changes in male fish, but few studies have connected these effects to outcomes relevant to reproductive success. In one experiment, we exposed sexually mature male fighting fish Betta splendens to environmentally relevant (1 μg L(-1)) and pharmacological concentrations (1000 μg L(-1)) of the phytoestrogen genistein as well as to a positive control of waterborne 17β-estradiol (E2; 1 μg L(-1)), and a negative control of untreated water. In a second experiment, we exposed male B. splendens to environmentally relevant concentrations (1 μg L(-1)) of genistein and β-sitosterol singly and in combination as well as to the positive and negative controls. All exposures were 21 days in duration. We measured sex-steroid hormone levels, gonadosomatic index (GSI), sperm concentration and motility, and fertilization success in these fish. We found that exposure to genistein did not affect circulating levels of the androgen 11-ketotestosterone or the estrogen E2 relative to negative-control fish. We also found that neither of the compounds nor their mixture affected GSI, sperm concentration or motility, or fertilization success in exposed fish relative to negative-control fish. However, fish exposed to phytoestrogens showed some evidence of fewer but more motile sperm than fish exposed to the positive control E2. We conclude that sexually mature male B. splendens are relatively immune to reproductive impairments from short-term exposure to waterborne phytoestrogens.

Identification of mitochondrial cytochrome P450 induced in response to polycyclic aromatic hydrocarbons in the mummichog (Fundulus heteroclitus)

Increasing evidence suggests that polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene (BaP) are localized to the mitochondria. Because the toxic effects of many PAHs are the result of metabolism by cytochrome P4501A (CYP1A), it is important to investigate whether active forms of these enzymes can be identified in the mitochondria. In this study, we identified mitochondrial P450s with a monoclonal antibody against scup (Stenotomus chrysops) CYP1A in the isolated mitochondrial fraction of the liver from adult male mummichog (Fundulus heteroclitus) livers. The size of the protein in the mitochondria was similar to that of microsomal CYP1A. Fish dosed with 10mg/kg BaP had increased EROD activity in the mitochondrial fraction compared to controls. In mummichog larvae dosed with 100 microg/L BaP and 100 microg/L benzo[k]fluoranthene, CYP1A protein levels as well as enzyme activity were elevated. However, fish from a PAH-polluted Superfund site (Elizabeth River, Portsmouth VA) showed recalcitrant mitochondrial CYP1A protein levels and enzyme activity in a similar manner to microsomal CYP1A.

Cadmium chloride-induced disruption of testicular steroidogenesis in rainbow trout, Oncorhynchus mykiss

Cadmium (Cd) is a known endocrine disruptor with the ability to affect the production of hormones involved in the regulation of reproductive processes. In the present study, the effects of CdCl(2) on unstimulated and stimulated testicular steroidogenesis were examined with the intention of furthering the understanding of the potential site(s) of action in the signaling pathway for 11-KT synthesis in teleosts. In short-term (2-h) exposures, CdCl(2 )stimulated 11-KT production (29% and 28% over controls) in minced testicular tissues at concentrations of 10 and 100 microM, respectively. However, 11-KT production was significantly lower than in controls (54%, 62%, and 54%) when tissues were incubated for 18 h with 1, 10, and 100 microM Cd. Incubation of testicular tissues with 100 IU/ml human chorionic gonadotropin (hCG) and 5 mM dibutyryl-cAMP (dbcAMP), which activate rate-limiting steps in steroid synthesis, or 1.3 microM 25-hydroxycholesterol (25-OHC), which augments production, resulted in significant increases in steroidogenesis over controls. hCG-stimulated steroidogenesis was reduced to 54% and 62% that of stimulated controls when tissues were incubated with CdCl(2) at 1 and 10 microM, respectively. 11-KT production in dbcAMP-stimulated and 25-OHC-augmented tissues was not affected by Cd exposure. The results of this study indicate that one site of action of Cd in the signaling steroidogenic pathway is located prior to cAMP formation. This impairment could be overcome when higher concentrations of Cd were used in hCG-stimulated cells, suggesting the presence of a stimulatory site at, or following, hCG receptor binding.

Effects of the wood extractives dehydroabietic acid and betulinol on reproductive physiology of zebrafish (Danio rerio)-a two-generation study

Two wood extractives, dehydroabietic acid (DHAA) and betulinol (BET), present in wood industry effluents were evaluated for their potential effects on the reproductive physiology of zebrafish. Adult zebrafish (F0) were exposed in a continuous flow-through system to 50 microg/l DHAA, 5 microg/l BET and 0.27 microg/l (1 nM) 17beta-estradiol (E2) for 3 months. Eggs were collected from F0 fish and the following F1 generation was exposed for 6 months. Biomarkers analyzed in both F0 and F1 fish were plasma vitellogenin (Vtg), testosterone (T), E2 (only females) and gonadal histology. DHAA and BET affected growth in terms of increased condition factor, and spawning was stimulated in BET-exposed fish of the F0 generation. F0 males exposed to DHAA and F0 females exposed to BET showed lower plasma Vtg concentration, but F1 males exposed to BET showed an increase in Vtg. In fish exposed to E2, the positive control for estrogenic effects, a pronounced increase in Vtg concentration was observed. Plasma sex steroids were not significantly affected by the wood extractives. However, although not statistically significant, the T concentration tended to be lower in fish of all BET treatments. The histological study revealed alterations in spermatogenic stages of F0 males exposed to DHAA and BET, which were different from those caused by E2. In F1 females, the percentage of vitellogenic oocytes was decreased in DHAA, BET and E2 exposures. This study shows that DHAA and BET may contribute to growth alterations and reproductive disturbances reported in fish exposed to pulp and paper mill effluents. Further, these wood extractives may have different effects in F0 and F1 generation fish, which highlights the value of two-generation studies in investigations regarding endocrine disrupting compounds.

Screening of synthetic and plant-derived compounds for (anti)estrogenic and (anti)androgenic activities

Recently we constructed yeast cells that either express the human estrogen receptor alpha or the human androgen receptor in combination with a consensus ERE or ARE repeat in the promoter region of a green fluorescent protein (yEGFP) read-out system. These bioassays were proven to be highly specific for their cognate agonistic compounds. In this study the value of these yeast bioassays was assessed for analysis of compounds with antagonistic properties. Several pure antagonists, selective estrogen receptor modulators (SERMs) and plant-derived compounds were tested. The pure antiestrogens ICI 182,780 and RU 58668 were also classified as pure ER antagonists in the yeast estrogen bioassay and the pure antiandrogen flutamide was also a pure AR antagonist in the yeast androgen bioassay. The plant-derived compounds flavone and guggulsterone displayed both antiestrogenic and antiandrogenic activities, while 3,3'-diindolylmethane (DIM) and equol combined an estrogenic mode of action with an antiandrogenic activity. Indol-3-carbinol (I3C) only showed an antiandrogenic activity. Coumestrol, genistein, naringenin and 8-prenylnaringenin were estrogenic and acted additively, while the plant sterols failed to show any effect. Although hormonally inactive, in vitro and in vivo metabolism of the aforementioned plant sterols may still lead to the formation of active metabolites in other test systems.

Development of a yeast-based assay to determine the (anti)androgenic contaminants from pulp and paper mill effluents in India

We have constructed an efficient and reliable yeast-based detection system to evaluate the androgenic activity of endocrine disruptors from pulp and paper mill effluents (PPME). This system consists of human androgen receptor and androgen response elements driven β-galactosidase genes transformed in yeast, Saccharomyces cerevisiae. The transcriptional activation by known androgens, correlated with androgenic activities as measured by other assay systems. This assay system when applied to evaluate anti-androgenic activities, the known anti-androgens effectively inhibited reporter gene induction by testosterone. The specificity of the assay was tested by incubating the transformed cells with supraphysiological concentrations of non-androgenic steroids and none of them gave a significant response. The extracted PPME from five different mills demonstrated strong androgenic activities (about five- to eight-folds over control). These results suggest that PPME are rich in androgenic chemicals and the employed detection system could be applicable to primary screening for effectors on androgen receptor functions.

Endocrine modulating actions of a phytosterol mixture and its oxidation products in zebrafish (Danio rerio)

In this study, a phytosterol preparation ("ultrasitosterol"; 80% beta-sitosterol) and an oxidized ultrasitosterol preparation were evaluated for reproductive effects in zebrafish. Adults were exposed in a continuous flow to 10 microg/L and 100 microg/L ultrasitosterol and oxidized ultrasitosterol, and to 0.27 microg/L 17beta-estradiol and 0.28 microg/L testosterone for 3 weeks. Biomarkers analysed included plasma vitellogenin, testosterone, 11-ketotestosterone, 17beta-estradiol, and gonadal histopathology. Ovarian steroid production of testosterone and 17beta-estradiol was examined in isolated zebrafish follicles exposed in vitro to the compounds at the same concentrations as in vivo. Vtg was induced in males exposed to ultrasitosterol, and in males and females exposed to 17beta-estradiol. Males exposed to oxidized phytosterols showed increased levels of testosterone and 11-ketotestosterone, and accelerated spermatogenesis. Increased follicular atresia was observed in females exposed to oxidized phytosterols and 17beta-estradiol. Correlation analyses between biomarkers revealed more intercorrelated values for females than for males, and the strongest associations were found in females exposed to oxidized phytosterols. Testosterone production was significantly increased in follicles exposed to the oxidized phytosterol preparations. These findings indicate that the phytosterol mixture is weakly estrogenic in male fish, and that the oxidized phytosterol mixture contains substances that may interfere with spermatogenesis, oogenesis and gonadal steroidogenesis in zebrafish.

Effects of kraft pulp mill condensates on plasma testosterone levels in mummichog (Fundulus heteroclitus)

Past studies at a bleached kraft pulp mill located in Saint John, NB, Canada have shown that chemical recovery condensates significantly depress circulating and gonadal steroids in mummichog (Fundulus heteroclitus), an endemic fish species. In the present study, compounds were extracted from the condensates, and a toxicity identification evaluation (TIE) was conducted to characterize the hormonally active substances (HASs) in the condensates. Extracts were fractionated by high performance liquid chromatography (HPLC) and mummichog were exposed to the fractions in a 7-day bioassay. Plasma testosterone was measured for each sex following exposure. Responses in fish exposed to the whole extract at 1% v/v were not as pronounced as had been observed previously (female plasma testosterone was reduced by 16% in the current study compared to 75% previously). Dose-response experiments showed an exposure concentration of 4% v/v was required to elicit significant plasma steroid reductions. Despite these responses, individual condensate fractions actually increased steroid levels in mummichog, which suggests that multiple HASs may need to act synergistically or additively to elicit effects, and if separated, the compounds may have different hormonal activity. The HASs in question caused a reduction in male gonad size at 4% v/v, and have sex-dependent mechanisms of action (males were more responsive to exposure than females).

Lipid dynamics in goldfish (Carassius auratus) during a period of gonadal recrudescence: Effects of beta-sitosterol and 17beta-estradiol exposure

The potential for contaminants to alter lipid or cholesterol dynamics in fish is rarely investigated and may include critical physiological endpoints that are impacted by exposure to endocrine-active substances. The current study investigated plasma and tissue lipid dynamics over a period of recrudescence in goldfish, while also examining the potential for beta-sitosterol (beta-sit), a phytosterol and 17beta-estradiol (E(2)), an endogenous estrogen, to alter lipid homeostasis. Goldfish were exposed to 0 microg/g (no chemical; control), 200 microg/g beta-sit (72.3% sitosterol mixture) or 10 microg/g 17beta-estradiol (E2) via Silastic implants for a period of five months. Plasma lipids peaked in control fish coincident with maximum liver size, while gonadal cholesterol concentration was highest concomitant with maximum gonad size. Plasma lipid concentrations were highly affected by E2 but not beta-sit exposure; E2 elevated total cholesterol (p<0.001) and triglyceride (TG; p<0.001) and decreased high-density lipoprotein (HDL) concentration (p<0.001) in male fish. Tissue cholesterol concentrations were minimally affected by beta-sit exposure, while hepatic cholesterol concentrations were increased in E2 exposed females (p=0.041), indicating elevated liver lipogenesis in response to E2, but not beta-sit, exposure. The present study demonstrates differential effects by beta-sit and E2 on plasma lipoprotein profile and TG concentration and indicates estrogen-specific effects on hepatic lipid metabolism during gonadal development.

Beta-sitosterol and 17beta-estradiol alter gonadal steroidogenic acute regulatory protein (StAR) expression in goldfish, Carassius auratus

Fish exposed to the phytosterol beta-sitosterol (beta-sit) have decreased circulating hormone and cholesterol concentrations, and decreased gonadal intra-mitochondrial cholesterol pools. The current study examined the potential for beta-sit to alter abundance of the key cholesterol transport protein, steroidogenic acute regulatory (StAR) protein, which delivers cholesterol to the first and rate-limiting steroidogenic enzyme P450 side chain cleavage (P450(scc)) inside the mitochondria. Plasma testosterone (T) and lipids (cholesterol, lipoproteins and triglycerides) were also measured. Goldfish were exposed to 200 microg/g beta-sit (97% pure or as a 72.6% pure phytosterol mixture) and 10 microg/g 17beta-estradiol (E(2); estrogenic control) by intra-peritoneal Silastic implants for 21-days or for five-months. Plasma T was significantly decreased in male fish exposed to the phytosterol mixture following the long-term exposure (p<0.001). There were no differences in total cholesterol concentrations among treatments in the short- or long-term exposure, but male fish in the long-term exposure had significantly lower HDL as compared to control fish (p<0.025) with a corresponding increase in LDL. StAR transcript levels were unchanged following the short-term exposure, but were reduced after five months in male beta-sit fish (p=0.05) and E(2)-treated female fish (p=0.05). This reduction in StAR transcript abundance in conjunction with decreased plasma T and altered plasma lipoprotein fractions demonstrates a non-estrogenic effect of beta-sit. This is the first study to show that beta-sit has the capacity to alter gonadal StAR transcript abundance, offering a mechanism by which beta-sit disrupts reproductive endocrine endpoints.

Determination of the androgenic potency of whole effluents using mosquitofish and trout bioassays

This study combined bioassay-derived and direct chemical analysis of steroidal compounds in pulp and paper and municipal sewage effluent in order to determine the cause of masculinization of female mosquitofish. The bioassays used in this study consisted of androgen and estrogen receptor binding, and aromatase inhibition using tissues from rainbow trout. This study observed no masculinization of female mosquitofish from a pulp and paper mill effluent that was previously observed to cause this effect. Mosquitofish sampled from the receiving environment of the same mill verified that masculinization was not occurring in the wild. The municipal sewage effluent also had no masculinizing effect. In vitro bioassays indicated significant sources of both androgens and estrogens in the effluents tested with sewage effluent having both the highest estradiol (41 ng/L) and testosterone (182 ng/L) equivalent concentration. These results could not be attributed to any particular compounds measured in the effluents. Two compounds implicated in the masculinization of mosquitofish by pulp and paper effluent, androstenedione and androstadienedione required relatively large (10-100 microg/L) waterborne concentrations to elicit a masculinizing effect and neither of these compounds are likely to occur at levels this high in the natural environment. The potent aromatase inhibitor, 4-hydroxyandrostenedione also did not cause masculinization at 100 microg/L indicating that masculinization did not occur through this mechanism. The mammalian anti-androgen, cyproterone acetate was only partially effective in mosquitofish and reduced the severity of masculinization in the presence of methyl testosterone. While neither effluent masculinized mosquitofish, there was a significant reduction of in vitro ovarian steroid production with the most severe effects observed with the sewage effluent. Overall, this study found the disappearance of a masculinizing effect that had been previously observed; concluded that based on 21 days aqueous exposures androstenedione and androstadienedione are not likely candidates for mosquitofish masculinization, and showed that masculinization and in vitro steroid production are unrelated biological endpoints.

Behavioral changes in fish exposed to phytoestrogens

We investigated the behavioral effects of exposure to waterborne phytoestrogens in male fighting fish, Betta splendens. Adult fish were exposed to a range of concentrations of genistein, equol, beta-sitosterol, and the positive control 17beta-estradiol. The following behaviors were measured: spontaneous swimming activity, latency to respond to a perceived intruder (mirror reflection), intensity of aggressive response toward a perceived intruder, probability of constructing a nest in the presence of a female, and the size of the nest constructed. We found few changes in spontaneous swimming activity, the latency to respond to the mirror, and nest size, and modest changes in the probability of constructing a nest. There were significant decreases, however, in the intensity of aggressive behavior toward the mirror following exposure to several concentrations, including environmentally relevant ones, of 17beta-estradiol, genistein, and equol. This suggests that phytoestrogen contamination has the potential to significantly affect the behavior of free-living fishes.

Investigation of de novo cholesterol synthetic capacity in the gonads of goldfish (Carassius auratus) exposed to the phytosterol beta-sitosterol

Total and intra-mitochondrial gonadal cholesterol concentrations are decreased in fish exposed to the phytoestrogen beta-sitosterol (beta-sit). The present study examined the potential for beta-sit to disrupt de novo cholesterol synthesis in the gonads of goldfish exposed to 200 microgram/g beta-sit and 10 microgram/g 17beta-estradiol (E2; estrogenic control) by intra-peritoneal Silastic implants for 21 days. The de novo cholesterol synthetic capacity was estimated by incubating gonadal tissue with 14C-acetate for a period of 18 hours, followed by chloroform/methanol lipid extraction and thin layer chromatography (TLC) lipid separation. Lipid classes were confirmed using infrared spectroscopy. Plasma testosterone (T) and total cholesterol concentration were measured and gonadosomatic index (GSI) was calculated. Plasma T was significantly reduced in male beta-sit-treated fish compared to control and E2-treated fish (p < 0.001). 14C-Acetate incorporation into cholesterol and cholesterol esters was not significantly different among treatment groups for male and female fish, however, 14C-enrichment was higher than expected in both triglycerides (TG) and free fatty acids (FFA). FFA incorporation was significantly higher in male control fish than either beta-sit or E2 treatments (p = 0.005). Plasma cholesterol concentration was significantly increased in the male beta-sit treatment group compared to controls (p = 0.027). These results indicate gonadal de novo cholesterol biosynthetic capacity is not disrupted by beta-sit or E2 treatment in early recrudescing male or female goldfish, while plasma cholesterol and steroid concentrations are sensitive to beta-sit exposure.

A decade of research on the environmental impacts of pulp and paper mill effluents in Canada: sources and characteristics of bioactive substances

This article is a review of research efforts over the last decade on the sources and characteristics of substances in Canadian pulp mill effluents associated with two responses in fish: (1) induction of detoxification enzymes and (2) reproductive effects. The initial uncertainty regarding the role of chlorine bleaching and dioxins in these responses was resolved by the mid 1990s, when it was determined that effects were not correlated with effluent adsorbable organic halogen (AOX) levels and that releases of dioxins had decreased substantially. In the mid 1990s researchers were able to partially attribute enzyme activity induction in fish to wood components, while other studies showed individual wood extractives had the potential to affect fish reproduction. A lack of correlation between threshold reproductive responses and effluent concentrations indicated additional unidentified compounds and mechanisms were involved. In the late 1990s, source identification approaches in concert with the development of mechanistically linked in vitro and in vivo bioassays showed multiple compounds are affecting production and signaling of sex steroids in fish. These substances are bioavailable and accumulated rapidly, consistent with the body of evidence that has shown a sustained exposure is required to produce both elevated enzyme activity and depressions in sex steroid levels. The patterns of these substances in effluents and fish tissues are not correlated with production type or effluent treatment. Collectively, these findings show that bioactive substances originate from wood and are derived from lignin and/or terpenoids, they are liberated during pulp digestion, and in kraft mills they are present in black liquor and chemical recovery condensates. Additional bioactive substances are also present in bleachery effluents containing residual lignin. The lack of a definitive identification of the responsible compounds has prevented an evaluation of the effectiveness of industry-wide process changes. Continued research into the identities, origins, and environmental fate of these substances and the efficacy of effluent treatment is required to determine their significance and relationship to the existing impacts of effluents from pulp and paper mills in Canadian aquatic ecosystems.

A decade of research on the environmental impacts of pulp and paper mill effluents in Canada: development and application of fish bioassays

Laboratory tests have been used to assess the regulatory and research questions related to the effects of pulp mill effluents on aquatic biota. Acute, short-term laboratory tests have clearly shown the improvement in final effluent quality following installation of secondary treatment at Canadian pulp mills. In an effort to predict and investigate impacts on wild fish, laboratory bioassays were developed to examine sublethal endpoints: induction of hepatic mixed function oxygenase activity and reduction of sex steroid concentrations. These laboratory assays have been used to assess whole effluents, specific chemicals, and components of pulp mill processes, and to discriminate between historical and present-day effluent discharges. These tests have shown that induction of mixed-function oxygenase activity and reduction of sex steroid concentrations are produced by effluents from a variety of mill types, with and without chlorine bleaching, in hardwood and softwood pulping facilities, and before and after effluent treatment. These short-term bioassays have enabled reductions in sex steroid concentrations to be linked to mill process streams, and have provided information on effective waste stream treatment. Longer term, life-cycle fish bioassays have shown that chronic exposure to pulp mill effluents commonly results in growth enhancement, liver enlargement, and decreases in gonad size, secondary sex characteristics, and fecundity. These long-term laboratory exposures are able to mimic the most commonly observed alterations of wild fish exposed to pulp mill effluents: increases in condition factors, increases in liver-somatic indices, and decreases in gonadosomatic indices. This pattern of response is a combination of nutrient enrichment with metabolic disruption. The most sensitive and biologically meaningful endpoint is decreased reproduction in fish life-cycle exposures. As the laboratory tests move forward into the next decade, attention will focus on the reproductive endpoints and on the possibility of shortening the fish bioassays while still maintaining sensitivity and biological relevance.

Salicylate disrupts interrenal steroidogenesis and brain glucocorticoid receptor expression in rainbow trout

Varying levels of pharmaceuticals, including salicylate, ibuprofen, and acetaminophen, have been reported in the aquatic environment, but few studies have actually addressed the impact of these drugs on aquatic organisms. We tested the hypothesis that these pharmaceuticals are endocrine disruptors in fish by examining their impact on interrenal corticosteroidogenesis in rainbow trout. Indeed, acute adrenocorticotrophic hormone (ACTH)-mediated cortisol production in trout interrenal cells in vitro was significantly depressed (20-40%) by these pharmaceutical drugs. Furthermore, we investigated whether this interrenal dysfunction involved inhibition of the steroidogenic capacity in rainbow trout. To this end, we fed trout salicylate-laced feed (100 mg/kg body weight) for 3 days and assessed the transcript levels of key proteins involved in corticosteroidogenesis, including steroidogenic acute regulatory protein (StAR), peripheral-type benzodiazepine receptor (PBR), cytochrome P450 cholesterol side chain cleavage (P450scc), and 11beta-hydroxylase. Salicylate treatment did not affect the resting plasma cortisol or glucose levels, whereas the acute ACTH-stimulated cortisol production was significantly depressed in the interrenal tissue. This disruption of steroidogenesis by salicylate corresponded to a significant drop in the gene expression of StAR and PBR, but not P450scc or 11beta-hydroxylase, compared to the sham-treated fish. Also, brain glucocorticoid receptor (GR) protein content and not GR mRNA level was significantly reduced by salicylate. Taken together, salicylate is a corticosteroid disruptor in trout and the targets include the key rate-limiting step in interrenal steroidogenesis and brain glucocorticoid signaling.

Toxicity of a phytosterol mixture to grayling (Thymallus thymallus) during early developmental stages

The study concerns the toxicity of a phytosterol mixture, ultrasitosterol, consisting mainly of beta-sitosterol 75.7% and beta-sitostanol 13.0%, to grayling (Thymallus thymallus) embryos. Eyed eggs were exposed to three concentrations (1 microg/l, 10 microg/l, and 50 microg/l) of ultrasitosterol for 4 weeks. Embryos and later on hatched fry were taken for triiodothyronine (T3), thyroxine (T4), and histopathological analyses after 7, 14, 21, and 28 days of exposure. Most of the eggs (>95%) hatched during the first week of exposure, and ultrasitosterol treatment shortened hatching time significantly (p < or = 0.0001) at all exposure concentrations in comparison to the control. Ultrasitosterol did not have any significant effect on T3 or T4 levels in the embryo extracts. However, an interesting observation was that T3 levels increased in all treatments and in the control near the time of hatching. In conclusion, ultrasitosterol showed potential to affect the development of grayling embryos and fry, but further long-term exposure experiments are needed to verify these changes in more detail.