Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 15 de 15
Filtrar
2.
Arch Toxicol ; 94(2): 589-607, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31894354

RESUMO

Anabolic-androgenic steroids are testosterone derivatives, used by body-builders to increase muscle mass. Epistane (EPI) is an orally administered 17α-alkylated testosterone derivative with 2a-3a epithio ring. We identified four individuals who, after EPI consumption, developed long-lasting cholestasis. The bile acid (BA) profile of three patients was characterized, as well the molecular mechanisms involved in this pathology. The serum BA pool was increased from 14 to 61-fold, basically on account of primary conjugated BA (cholic acid (CA) conjugates), whereas secondary BA were very low. In in vitro experiments with cultured human hepatocytes, EPI caused the accumulation of glycoCA in the medium. Moreover, as low as 0.01 µM EPI upregulated the expression of key BA synthesis genes (CYP7A1, by 65% and CYP8B1, by 67%) and BA transporters (NTCP, OSTA and BSEP), and downregulated FGF19. EPI increased the uptake/accumulation of a fluorescent BA analogue in hepatocytes by 50-70%. Results also evidenced, that 40 µM EPI trans-activated the nuclear receptors LXR and PXR. More importantly, 0.01 µM EPI activated AR in hepatocytes, leading to an increase in the expression of CYP8B1. In samples from a human liver bank, we proved that the expression of AR was positively correlated with that of CYP8B1 in men. Taken together, we conclude that EPI could cause cholestasis by inducing BA synthesis and favouring BA accumulation in hepatocytes, at least in part by AR activation. We anticipate that the large phenotypic variability of BA synthesis enzymes and transport genes in man provide a putative explanation for the idiosyncratic nature of EPI-induced cholestasis.


Assuntos
Ácidos e Sais Biliares/sangue , Colestase/induzido quimicamente , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Congêneres da Testosterona/toxicidade , Adulto , Ácidos e Sais Biliares/biossíntese , Ácidos e Sais Biliares/metabolismo , Doença Hepática Induzida por Substâncias e Drogas/etiologia , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Colestase/metabolismo , Ácido Cólico/metabolismo , Feminino , Fatores de Crescimento de Fibroblastos/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Células Hep G2 , Humanos , Transportador 1 de Ânion Orgânico Específico do Fígado/genética , Masculino , Receptores Androgênicos/genética , Receptores Citoplasmáticos e Nucleares/genética , Receptores Citoplasmáticos e Nucleares/metabolismo , Membro 1B3 da Família de Transportadores de Ânion Orgânico Carreador de Soluto/genética , Esteroide 12-alfa-Hidroxilase/genética , Esteroide 12-alfa-Hidroxilase/metabolismo , Regulação para Cima/efeitos dos fármacos , Adulto Jovem
3.
Food Chem Toxicol ; 116(Pt B): 360-368, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29704577

RESUMO

Remains unknown if dietary lipids and anabolic steroids (AS) can interact to modify energy metabolism, hepatic structure and function. We investigated the impact of AS on gene expression, lipid profile, redox status and the development of nonalcoholic fatty liver disease (NAFLD) in mice treated with a diet rich in trans fatty acids. Seventy-two C57BL/6 mice were equally randomized into six groups and treated with a standard diet (SD) or high-fat diet (HFD) alone or combined with testosterone cypionate (10 or 20 mg/kg) for 12 weeks. When combined with a HFD, AS reduced plasma HDL cholesterol levels. It also upregulated SREBP-1, PPARα, SCD-1 and ACOX1 gene expression; plasma and hepatic triglyceride levels; oxidative stress; circulating hepatic transaminase levels and NAFLD severity. Our finding indicated that the activity of antioxidant enzymes such as catalase, glutathione-s-transferase and superoxide dismutase was attenuated by HFD, an effect whose implications for AS-induced hepatotoxicity requires further investigation. Increased lipid, protein and DNA oxidative damage as well as worsening NAFLD in response to the interaction of HFD and AS were also potentially associated with the ability of AS to amplify the activation of regulatory lipid metabolism genes that are also involved in the control of cellular redox balance.


Assuntos
Interações Alimento-Droga , Fígado/efeitos dos fármacos , Hepatopatia Gordurosa não Alcoólica/induzido quimicamente , Hepatopatia Gordurosa não Alcoólica/fisiopatologia , Congêneres da Testosterona/toxicidade , Ácidos Graxos trans/toxicidade , Triglicerídeos/metabolismo , Acil-CoA Oxidase/genética , Alanina Transaminase/sangue , Animais , Antioxidantes/metabolismo , Aspartato Aminotransferases/sangue , Composição Corporal , Catalase/sangue , Dieta Hiperlipídica , Regulação da Expressão Gênica , Glutationa Transferase/sangue , Fígado/metabolismo , Camundongos Endogâmicos C57BL , Hepatopatia Gordurosa não Alcoólica/genética , Hepatopatia Gordurosa não Alcoólica/metabolismo , Estresse Oxidativo/efeitos dos fármacos , PPAR alfa/genética , Estearoil-CoA Dessaturase/genética , Proteína de Ligação a Elemento Regulador de Esterol 1/genética , Superóxido Dismutase/sangue , Triglicerídeos/sangue , Regulação para Cima
4.
Int J Mol Sci ; 17(4): 537, 2016 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-27070596

RESUMO

Dietary supplements (DS) are extensively consumed worldwide despite unproven efficacy. The true incidence of DS-induced liver injury (DSILI) is unknown but is probably under-diagnosed due to the general belief of safety of these products. Reported cases of herbals and DS-induced liver injury are increasing worldwide. The aim of this manuscript is to report a tabular listing with a description of DS associated with hepatotoxicity as well as review the phenotype and severity of DSILI. Natural remedies related to hepatotoxicity can be divided into herbal product-induced liver injury and DS-induced liver injury. In this article, we describe different DS associated with liver injury, some of them manufactured DS containing several ingredients (Herbalife™ products, Hydroxycut™, LipoKinetix™, UCP-1 and OxyELITE™) while others have a single ingredient (green tea extract, linoleic acid, usnic acid, 1,3-Dimethylamylamine, vitamin A, Garcinia cambogia and ma huang). Additional DS containing some of the aforementioned ingredients implicated in liver injury are also covered. We have also included illicit androgenic anabolic steroids for bodybuilding in this work, as they are frequently sold under the denomination of DS despite being conventional drugs.


Assuntos
Doença Hepática Induzida por Substâncias e Drogas/etiologia , Suplementos Nutricionais/toxicidade , Doença Hepática Induzida por Substâncias e Drogas/epidemiologia , Ensaios Clínicos como Assunto , Suplementos Nutricionais/análise , Feminino , Humanos , Masculino , Preparações de Plantas/química , Preparações de Plantas/toxicidade , Plantas Medicinais/química , Plantas Medicinais/toxicidade , Congêneres da Testosterona/química , Congêneres da Testosterona/toxicidade
5.
Curr Neuropharmacol ; 13(1): 146-59, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26074749

RESUMO

Anabolic androgenic steroids (AASs) represent a large group of synthetic derivatives of testosterone, produced to maximize anabolic effects and minimize the androgenic ones. AAS can be administered orally, parenterally by intramuscular injection and transdermally. Androgens act by binding to the nuclear androgen receptor (AR) in the cytoplasm and then translocate into the nucleus. This binding results in sequential conformational changes of the receptor affecting the interaction between receptor and protein, and receptor and DNA. Skeletal muscle can be considered as the main target tissue for the anabolic effects of AAS, which are mediated by ARs which after exposure to AASs are up-regulated and their number increases with body building. Therefore, AASs determine an increase in muscle size as a consequence of a dose-dependent hypertrophy resulting in an increase of the cross-sectional areas of both type I and type II muscle fibers and myonuclear domains. Moreover, it has been reported that AASs can increase tolerance to exercise by making the muscles more capable to overload therefore shielding them from muscle fiber damage and improving the level of protein synthesis during recovery. Despite some therapeutic use of AASs, there is also wide abuse among athletes especially bodybuilders in order to improve their performances and to increase muscle growth and lean body mass, taking into account the significant anabolic effects of these drugs. The prolonged misuse and abuse of AASs can determine several adverse effects, some of which may be even fatal especially on the cardiovascular system because they may increase the risk of sudden cardiac death (SCD), myocardial infarction, altered serum lipoproteins, and cardiac hypertrophy. The aim of this review is to focus on deaths related to AAS abuse, trying to evaluate the autoptic, histopathological and toxicological findings in order to investigate the pathophysiological mechanism that underlines this type of death, which is still obscure in several aspects. The review of the literature allowed us to identify 19 fatal cases between 1990 and 2012, in which the autopsy excluded in all cases, extracardiac causes of death.


Assuntos
Anabolizantes/efeitos adversos , Morte Súbita Cardíaca/epidemiologia , Morte Súbita Cardíaca/etiologia , Esteroides/efeitos adversos , Congêneres da Testosterona/efeitos adversos , Anabolizantes/intoxicação , Anabolizantes/toxicidade , Autopsia , Humanos , Esteroides/intoxicação , Esteroides/toxicidade , Congêneres da Testosterona/intoxicação , Congêneres da Testosterona/toxicidade
6.
Acta Pharm ; 56(2): 203-18, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16613726

RESUMO

Condensation of 3beta-hydroxy-16-[(4-chlorophenyl)methylene]androst-5-en-17-one (1) with hydrazine hydrate in acetic acid afforded N-acetyl pyrazoline derivative 2, while condensation of 1 with semicarbazide afforded compound 3. Also, compound 1 was treated with hydrazine hydrate in absolute methanol or ethanol to afford the corresponding alpha-methoxy (4) and alpha-ethoxy (5) derivatives, which were cyclized with etherated boron trifluoride to the pyrazoline derivative 6. The latter could be prepared directly by refluxing 1 with hydrazine hydrate in dioxane. Oxidation of compound 6 with Oppenour or Moffat oxidizing agents yielded 3-oxo-derivatives 7 and 8, respectively. On the other hand, condensation of compound 1 with substituted hydrazines, gave the corresponding 3beta-hydroxyandrostenopyrazolines 9a,b, which were oxidized using the Moffat method to give 3-oxo-androstenopyrazolines 10a,b, which were condensed with ethylene triphenyl-phosphorane in DMSO to yield 3-ethylene androstenopyrazolines 11a,b. Dehydrogenation of 9a,b with Wettestein oxidation afforded Delta4,6-diene-3-one analogues 12a,b, which were treated with chloranil to yield Delta(4,6,8(14))-tri-ene-3-one analogues 13a,b. Oppenour oxidation of 9a,b afforded Delta4-ene-3-one analogues 14a,b, which were treated with dichlorodicyanoquinone (DDQ) in dioxane to give Delta1,4,6-triene-3-one analogues 15a,b. Pharmacological screening showed that many of these compounds inhibit 5alpha-reductase activity.


Assuntos
Colestenona 5 alfa-Redutase/antagonistas & inibidores , Pirazóis/síntese química , Congêneres da Testosterona/síntese química , Animais , Colestenona 5 alfa-Redutase/metabolismo , Di-Hidrotestosterona/sangue , Inibidores Enzimáticos/administração & dosagem , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/toxicidade , Injeções Subcutâneas , Dose Letal Mediana , Masculino , Próstata/efeitos dos fármacos , Próstata/metabolismo , Pirazóis/administração & dosagem , Pirazóis/toxicidade , Ratos , Ratos Sprague-Dawley , Relação Estrutura-Atividade , Testosterona/sangue , Congêneres da Testosterona/administração & dosagem , Congêneres da Testosterona/toxicidade
7.
Toxicol Appl Pharmacol ; 196(2): 235-46, 2004 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-15081270

RESUMO

Many persistent organochlorine pesticides (OCs) have been implicated in adverse effects, that is, reproductive and developmental effects, in man and in wildlife alike. It has been hypothesized that these so-called xeno-hormones could be responsible for the increased incidence in various male sexual differentiation disorders such as hypospadias, cryptorchidism, low sperm counts and quality. In this report, OCs, called endocrine disrupters, were tested for their interaction with the androgen receptor. The stable prostatic cell line PALM, which contains a human androgen receptor (hAR) expression vector and the reporter MMTV-luciferase, was used to characterize the response of hAR to OC and was compared with synthetic androgen compound R1881. We found that all the OC pesticides tested were able to shift the agonist [(3)H]-R1881 from its binding site to the AR in competitive binding assays. In addition, these compounds antagonize-in a dose-dependent manner-the AR-mediated transcription by synthetic AR ligand R1881. None of the pesticides reacted as agonists. These results demonstrate that OC endocrine activities in vivo probably result from direct and specific binding to the AR ligand-binding domain. Although the antagonistic potential of OC pesticides is lower than that of hydroxyflutamide, they are capable of disrupting the male hormone signaling pathway. Because these chemicals are extremely persistent and tend to bioaccumulate, these results support the hypothesis that the recent increase in the incidence of male sexual disorders could be due to long exposure to ubiquitous OC pesticides found in the environment.


Assuntos
Antagonistas de Androgênios/toxicidade , Flutamida/análogos & derivados , Inseticidas/toxicidade , Metribolona/toxicidade , Receptores Androgênicos/metabolismo , Congêneres da Testosterona/toxicidade , Antagonistas de Androgênios/metabolismo , Ligação Competitiva , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Flutamida/metabolismo , Flutamida/toxicidade , Humanos , Concentração Inibidora 50 , Inseticidas/metabolismo , Masculino , Metribolona/metabolismo , Congêneres da Testosterona/metabolismo
8.
Nihon Rinsho ; 62(2): 379-84, 2004 Feb.
Artigo em Japonês | MEDLINE | ID: mdl-14968549

RESUMO

Transplacental and lactogenic exposure of fetus and neonate to exogenous hormones and endocrine disrupters can cause a range of abnormalities of the reproductive system including sex differentiation and sex maturation. Sex differentiation is critically dependent on the normal action of androgens and can be disturbed by unbalanced androgen/estrogen ratios. Androgenic substances masculinize female fetus. Progestogens act both as androgen antagonists, demasculinizing males, and as androgen agonists, masculinizing females. Transplacental exposure of male fetus to synthetic estrogen diethylstilbestrol is recognized to have led to increases in the incidence of cryptorchidism, hypospadia and decreased sperm counts. A growing number of endocrine disrupters have been found to possess either weak estrogenic, anti-androgenic or other hormonal activities. Increased exposure to environmental endocrine disrupters can cause male pseudohermaphroditism.


Assuntos
Transtornos do Desenvolvimento Sexual/etiologia , Xenobióticos/toxicidade , Animais , Dioxinas/toxicidade , Poluentes Ambientais/toxicidade , Congêneres do Estradiol/toxicidade , Estrogênios não Esteroides/toxicidade , Feminino , Genitália/efeitos dos fármacos , Genitália/embriologia , Humanos , Recém-Nascido , Masculino , Exposição Materna/efeitos adversos , Troca Materno-Fetal , Gravidez , Congêneres da Progesterona/toxicidade , Congêneres da Testosterona/toxicidade
10.
Toxicol Lett ; 131(1-2): 51-63, 2002 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-11988358

RESUMO

Indications of effects on fish endocrine system have been noted when exposed to effluents of sewage treatment plants and subsequently in the receiving surface waters. For screening purposes, the concentration of vitellogenin (VTG) in plasma is employed to detect potential exposure of fish, to (anti-)estrogenic substances. However, little is known about the variability of VTG determinations and morphological endpoints (secondary sexual characteristics) in fish under exposure conditions employing compounds with hormonal activity other than estrogens. An in vivo test system was established to study the effects of methyltestosterone (MT, a potential model androgen) and fadrozole (F, an aromatase inhibitor) as well as the combination of MT and F on juvenile, sexually undifferentiated fathead minnows (Pimephales promelas). Fish were exposed to those compounds continuously in the (nominal) microg/l range (MT, 10, 50 and 100 microg/l; F, 25, 50, 100 microg/l; MT+F, 10 microg MT per l +50 microg F per l), for 14 days (MT+F) or 21 days (MT and F) using a flow-through system. The concentration of VTG and the expression of VTG mRNA was determined using whole body homogenates in an enzyme linked immunosorbant assay (ELISA) or reverse transcription-polymerase chain reaction (RT-PCR), respectively. Exposure to MT alone led to de novo mRNA expression as well as up to a four-fold increase of VTG. F had no effect on the VTG mRNA expression and VTG protein synthesis. The combination of MT and F had no effect on VTG concentrations, however, this produced a strong masculinisation of the juvenile fish, e.g. after 13 days of exposure 100% of the fish showed typical male sex characteristics, e.g. formation of nose tubercles and pigmentation of the dorsal fin. The above findings suggest that in fish MT may be aromatised to an estrogen. F, on the other hand, inhibits testosterone aromatisation. Consequently, the combination of MT and F strongly morphologically masculinised the juvenile fathead minnows. VTG detection at the mRNA and protein level is a sensitive parameter, however, it does not provide for any information regarding the baseline "estrogenicity" of a given parent compound.


Assuntos
Antagonistas de Estrogênios/toxicidade , Fadrozol/toxicidade , Metiltestosterona/toxicidade , Diferenciação Sexual/efeitos dos fármacos , Congêneres da Testosterona/toxicidade , Animais , Bioensaio , Cyprinidae/fisiologia , Transtornos do Desenvolvimento Sexual , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Ensaio de Imunoadsorção Enzimática , Antagonistas de Estrogênios/metabolismo , Fadrozol/metabolismo , Feminino , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Masculino , Metiltestosterona/metabolismo , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Diferenciação Sexual/fisiologia , Congêneres da Testosterona/metabolismo , Vitelogeninas/genética , Vitelogeninas/metabolismo
11.
Toxicol Appl Pharmacol ; 179(1): 1-12, 2002 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-11884232

RESUMO

Twenty-four pesticides were tested for interactions with the estrogen receptor (ER) and the androgen receptor (AR) in transactivation assays. Estrogen-like effects on MCF-7 cell proliferation and effects on CYP19 aromatase activity in human placental microsomes were also investigated. Pesticides (endosulfan, methiocarb, methomyl, pirimicarb, propamocarb, deltamethrin, fenpropathrin, dimethoate, chlorpyriphos, dichlorvos, tolchlofos-methyl, vinclozolin, iprodion, fenarimol, prochloraz, fosetyl-aluminum, chlorothalonil, daminozid, paclobutrazol, chlormequat chlorid, and ethephon) were selected according to their frequent use in Danish greenhouses. In addition, the metabolite mercaptodimethur sulfoxide, the herbicide tribenuron-methyl, and the organochlorine dieldrin, were included. Several of the pesticides, dieldrin, endosulfan, methiocarb, and fenarimol, acted both as estrogen agonists and androgen antagonists. Prochloraz reacted as both an estrogen and an androgen antagonist. Furthermore, fenarimol and prochloraz were potent aromatase inhibitors while endosulfan was a weak inhibitor. Hence, these three pesticides possess at least three different ways to potentially disturb sex hormone actions. In addition, chlorpyrifos, deltamethrin, tolclofos-methyl, and tribenuron-methyl induced weak responses in one or both estrogenicity assays. Upon cotreatment with 17beta-estradiol, the response was potentiated by endosulfan in the proliferation assay and by pirimicarb, propamocarb, and daminozid in the ER transactivation assay. Vinclozolin reacted as a potent AR antagonist and dichlorvos as a very weak one. Methomyl, pirimicarb, propamocarb, and iprodion weakly stimulated aromatase activity. Although the potencies of the pesticides to react as hormone agonists or antagonists are low compared to the natural ligands, the integrated response in the organism might be amplified by the ability of the pesticides to act via several mechanism and the frequent simultaneous exposure to several pesticides.


Assuntos
Inibidores da Aromatase , Bioensaio , Inibidores Enzimáticos/toxicidade , Congêneres do Estradiol/toxicidade , Praguicidas/toxicidade , Congêneres da Testosterona/toxicidade , Animais , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Células CHO , Divisão Celular/efeitos dos fármacos , Cricetinae , Feminino , Humanos , Microssomos/efeitos dos fármacos , Microssomos/enzimologia , Placenta/efeitos dos fármacos , Placenta/enzimologia , Gravidez , Receptores Androgênicos/efeitos dos fármacos , Receptores de Estrogênio/efeitos dos fármacos , Ativação Transcricional/efeitos dos fármacos , Células Tumorais Cultivadas
12.
Arch Toxicol ; 75(11-12): 635-42, 2002 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11876496

RESUMO

As part of the international validation project to establish the Enhanced OECD Test Guideline 407, we performed a 28-day repeated-dose toxicity study of 17alpha-methyltestosterone, an exogenous androgen agonist. Special attention was paid to the sensitivity of additional parameters for detecting endocrine-related effects of endocrine-disrupting chemicals, based on the existing Test Guideline 407. Seven-week-old Crj:CD(SD)IGS rats were allocated to one of four groups, each consisting of ten males and ten females, and 17alpha-methyltestosterone was administered daily by gavage at doses of 0 (control), 5, 20 and 80 mg/kg body weight per day. Male rats were killed on the day after the 28th administration and females on the day of the diestrus stage during the 4 day period after the 28th administration. Male rats receiving 80 mg/kg 17alpha-methyltestosterone demonstrated decreases in testis and epididymis weights, atrophy of seminiferous tubules and Leydig cells, and degenerated pachytene spermatocytes in the testes and degenerated germ cells in the epididymides as major alterations. Female rats showed abnormal estrous cycles, decreases in ovary and adrenal weights, increase in immature follicles with decreased corpus lutea in the ovaries at doses of 5 mg/kg and higher, as well as atrophy of zona reticularis in the adrenals and increase in mammary gland secretion at 20 mg/kg and above. Dilatation of the lumina and apoptosis of endometrial cells in the uterus, mucinification in the vagina and increase in serum follicle-stimulating hormone were seen with 80 mg/kg. Among the parameters examined in the present experimental system, effects of 17alpha-methyltestosterone on endocrine-related organs were detected in organ weights and histopathological examination of both sexes, and in serum hormones and estrous cycle of females. Based on these results, the no-observed-adverse-effect level (NOAEL) in the present study was estimated to be below 5 mg/kg per day. In particular, effects were most sensitively detected by organ weights and histopathological examination of sexual organs.


Assuntos
Antagonistas de Hormônios/toxicidade , Metiltestosterona/toxicidade , Congêneres da Testosterona/toxicidade , Administração Oral , Animais , Relação Dose-Resposta a Droga , Ciclo Estral/efeitos dos fármacos , Feminino , Hormônio Foliculoestimulante/sangue , Genitália Feminina/efeitos dos fármacos , Genitália Feminina/patologia , Genitália Masculina/efeitos dos fármacos , Genitália Masculina/patologia , Antagonistas de Hormônios/administração & dosagem , Masculino , Metiltestosterona/administração & dosagem , Nível de Efeito Adverso não Observado , Tamanho do Órgão/efeitos dos fármacos , Ratos , Ratos Endogâmicos , Congêneres da Testosterona/administração & dosagem
13.
Environ Toxicol Chem ; 20(6): 1276-90, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11392137

RESUMO

Due to the time and expense associated with full life-cycle testing, most current toxicity tests with fish do not explicitly consider reproductive output as an endpoint but, rather, focus on early life-stage survival and development. However, some classes of chemicals could adversely impact reproduction at concentrations below those that affect development. Further, estimates of the effects of toxic compounds on reproductive output can be critical to the ecological risk assessment process. In this manuscript, we describe a short-term reproduction test with the fathead minnow (Pimephales promelas) and evaluate the test using two model reproductive toxicants, methoxychlor (an estrogenic compound) and methyltestosterone (an androgenic chemical). The test is initiated with reproductively mature animals and is comprised of a pre-exposure phase of 14 to 21 d, followed by a chemical exposure of up to 21 d. During and at completion of the test, several endpoints related to reproductive fitness and endocrine function are assessed. Both chemicals evaluated in our study caused a significant decrease in fecundity of the fish at nominal concentrations of 5.0 micrograms/L (methoxychlor) and 0.2 mg/L (methyltestosterone). Methoxychlor decreased plasma concentrations of one or more steroids (testosterone, 11-ketotestosterone, beta-estradiol) in both sexes and caused a significant induction of plasma vitellogenin in males, a response consistent with activation of the estrogen receptor by the pesticide (or its metabolites). Methyltestosterone decreased plasma concentrations of sex steroids and adversely affected gonadal status (as evaluated by relative weight and histopathology) in both sexes. The androgenic nature of methyltestosterone was clearly expressed as masculinization of exposed females via formation of nuptial tubercles, structures normally present only in reproductively active males. The chemical also caused a significant induction of plasma vitellogenin in both males and females; this unexpected estrogenic response was most likely due to aromatization of the androgen to a form capable of binding to the estrogen receptor. These studies demonstrate the utility of this short-term assay for identifying chemicals that exert reproductive toxicity through alterations in endocrine systems controlled by estrogens and androgens.


Assuntos
Cyprinidae/fisiologia , Reprodução/efeitos dos fármacos , Animais , Comportamento Animal/efeitos dos fármacos , Embrião não Mamífero , Feminino , Fertilização/efeitos dos fármacos , Inseticidas/toxicidade , Larva , Masculino , Metoxicloro/toxicidade , Metiltestosterona/toxicidade , Caracteres Sexuais , Análise de Sobrevida , Congêneres da Testosterona/toxicidade , Vitelogeninas/metabolismo
14.
Life Sci ; 60(11): 839-48, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-9076323

RESUMO

This study investigates the effect of orally administered testosterone on serum testosterone levels and immune responses including outcome of Plasmodium chabaudi malaria. Female C57BL/10 mice were fed on a diet impregnated with 17 alpha-methyl-testosterone for 3 weeks. This raised the circulating testosterone levels from 0.28 ng/ml to 2.69 ng/ml on the average. In these mice, blood-stage infections of P. chabaudi resulted in a lethal outcome, whereas protective immunity developed in about 80% of mice fed on control diet without testosterone. Dietary 17 alpha-methyl-testosterone reduced the capacity of peritoneal cells to generate reactive oxygen intermediates after stimulation with C3b-coated zymosan and phorbol-myristate-acetate. Also, mice fed on dietary 17 alpha-methyl-testosterone responded to heat-killed Salmonella typhimurium with a higher increase in serum TNF, whereas the induced increase in the production of IL-10 by spleen cells was largely suppressed and no effect was found with respect to the production of IFN-gamma and IL-4. Our data indicate that the method of oral administration of 17 alpha-methyl-testosterone raises circulating testosterone to levels that impair protective immune responses to P. chabaudi malaria.


Assuntos
Malária/imunologia , Metiltestosterona/toxicidade , Plasmodium chabaudi , Congêneres da Testosterona/toxicidade , Testosterona/sangue , Animais , Doença Hepática Induzida por Substâncias e Drogas , Citocinas/sangue , Dieta , Suscetibilidade a Doenças , Feminino , Imunidade Inata/efeitos dos fármacos , Hepatopatias/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Cavidade Peritoneal/citologia , Baço/citologia , Baço/efeitos dos fármacos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA