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1.
Cardiovasc Endocrinol Metab ; 13(3): e0305, 2024 Sep.
Article in English | MEDLINE | ID: mdl-38846628

ABSTRACT

Blood pressure (BP) regulation is a complex process involving various hormones, including aldosterone and its mineralocorticoid receptor. Mineralocorticoid receptor is expressed in several tissues, including the kidney, and plays a crucial role in regulating BP by controlling the sodium and water balance. During different stages of life, hormonal changes can affect mineralocorticoid receptor activity and aldosterone levels, leading to changes in BP. Increasing evidence suggests that sex steroids modulate aldosterone levels. Estrogens, particularly estradiol, mediate aldosterone biosynthesis by activating classical estrogen receptors and the G protein-coupled receptor. Progesterone acts as an anti-mineralocorticoid by inhibiting the binding of aldosterone to the mineralocorticoid receptor. Moreover, progesterone inhibits aldosterone synthase enzymes. The effect of testosterone on aldosterone synthesis is still a subject of debate. However, certain studies show that testosterone downregulates the mRNA levels of aldosterone synthase, leading to decreased plasma aldosterone levels.

2.
Zoology (Jena) ; 164: 126171, 2024 May.
Article in English | MEDLINE | ID: mdl-38761613

ABSTRACT

Estrogens, acting through their receptors (ERα and ERß), regulate cell turnover in the pituitary gland, influencing cell proliferation and apoptosis across various species. However, their role in pituitary processes in seasonally reproducing animals remains poorly understood. This study aims to investigate the influence of estrogens, through the expression of their specific receptors, on the apoptosis of PD cells in relation to sexual maturity, the reproductive cycle, and pregnancy in a seasonal reproductive rodent (Lagostomus maximus maximus). ERα and caspase-3-cleaved (CASP3c) immunoreactive (-ir) cells were identified through immunohistochemistry. Apoptotic cells were detected using the TUNEL technique, with quantitative analysis facilitated by image analysis software, alongside measurement of serum estradiol levels using radioimmunoassay The immunostaining pattern for ERα included nuclear (ERαn) and cytoplasmic (ERαc) staining. In male viscachas, ERα expression significantly increases from immature to adult animals, correlating with the rise in serum estradiol levels and a decrease in the percentage of apoptotic cells. During the gonadal regression period in adult males, a decrease in the number of ER-ir cells and serum levels of estradiol corresponds with an increase in the number of apoptotic cells. In females, serum levels of estradiol peaked during mid-pregnancy, coinciding with a significant decrease in the number of apoptotic cells in the PD. Simultaneously, the percentage of ERαn-ir cells reaches its maximum value during late pregnancy, indicating the need to maintain the protective action of this gonadal hormone throughout the extensive pregnancy in these rodents. Regional ERα receptor expression and apoptotic cells appear to be associated with distinct PD cell populations and their hormonal responses. Finally, elevated estradiol levels coincide with diminished apoptotic cells in the male reproductive cycle and during pregnancy, suggesting an antiapoptotic role of estradiol in this species.


Subject(s)
Apoptosis , Estrogens , Pituitary Gland , Rodentia , Animals , Female , Male , Rodentia/physiology , Estrogens/metabolism , Estrogens/blood , Pituitary Gland/metabolism , Pregnancy , Gene Expression Regulation , Estradiol/blood , Estradiol/metabolism
3.
Adv Lab Med ; 4(1): 52-69, 2023 Apr.
Article in English, Spanish | MEDLINE | ID: mdl-37359897

ABSTRACT

The proper clinical approach to a wide range of disorders relies on the availability of accurate, reproducible laboratory results for sexual steroids measured using methods with a high specificity and sensitivity. The chemiluminescent immunoassays currently available have analytical limitations with significant clinical implications. This position statement reviews the current limitations of laboratory techniques for the measurement of estradiol and testosterone and their impact on diverse clinical scenarios. A set of recommendations are provided to incorporate steroid hormone analysis by mass spectrometry in national health systems. International societies have recommended this methodology for a decade.

4.
Front Vet Sci ; 10: 1050510, 2023.
Article in English | MEDLINE | ID: mdl-37168096

ABSTRACT

Animal welfare is a key issue not only for aquaculture industry and food production, but also for daily husbandry practices in research topics related to physiology in wild and farmed animals. In this context, teleost fish constitute interesting models to assess alternative welfare indicators because of their wide diversity in reproductive and social structures. Any framework for assessing teleost fish welfare needs to account for the physiological mechanisms involved in each species as a first step. A comprehensive approach should also take into account how these physiological and behavioral parameters can be altered by environmental enrichment considering the specific requirements in each case and identifying intrinsic biological characteristics of individual species. This review will show how cortisol and sex steroids regulate social behavior in teleost fish, and how different aspects of social behavior can be employed as welfare indicators according to specific characteristics in each case. This article will consider evidence in teleost fish, including cichlids, characids and cyprinids with different reproductive strategies and social structures (e.g., territorial social hierarchies or shoaling behavior). Neotropical species will be particularly emphasized. The main laboratory-based animal welfare indicators are cortisol, a classical stress hormone, together with sex steroids. Considering that the endocrine landscape is intrinsically related to social behavior, reproductive and agonistic behavioral traits such as aggression, anxiety and courtship are key elements to assess welfare under housing and culture conditions. This review highlights the importance of assessing physiological mechanisms and identifying behavioral characteristics in teleost fish, especially in Neotropical species, as a baseline to understand which environmental enrichment can improve animal welfare in each individual species.

5.
Environ Sci Pollut Res Int ; 27(23): 29341-29351, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32440876

ABSTRACT

The synthetic estrogen, 17-α-ethinylestradiol (EE2), present in contraceptive pills, is an endocrine-disrupting chemical (EDC) that can be found in the aquatic environment. We examined the impacts of EE2 on zebrafish behavioral and physiological responses through the novel tank test (NTT), which measures anxiety-like behavior; the mirror-induced aggression (MIA) test, which measures aggressiveness; and the social preference test (SPT), which measures social cohesion. The steroid hormone levels were also measured. Here, we show that exposure to EE2 impairs stress responses by regulating the levels of specific hormones and eliciting an anxiolytic response, increasing aggression, and reducing social preference in zebrafish. In nature, these changes in behavior compromise reproduction and anti-predator behaviors, which, in turn, affects species survival. The maintenance of an intact behavioral repertoire in zebrafish is essential for their survival. Thus, our results point to the danger of environmental contamination with EE2 as it may alter the dynamics of the prey-predator relationship.


Subject(s)
Water Pollutants, Chemical , Zebrafish , Animals , Ethinyl Estradiol , Reproduction
6.
Reprod Domest Anim ; 55(3): 283-292, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31885111

ABSTRACT

Benign prostatic hyperplasia (BPH) is an age-dependent primarily non-inflammatory enlargement of the accessory gland in the intact dog. The aim of the present study was to control a previously raised suspicion of a breed-related higher incidence of BPH in dogs of the Rhodesian Ridgeback breed. For this, 18 Labrador Retrievers/LR and 20 Rhodesian Ridgebacks/RR were assigned to the age groups 18-24 months (n = 12), 25-48 months (n = 13) and 49-72 months (n = 13). Prostate gland status was determined by rectal palpation, B-mode ultrasound, calculation of the prostate gland volume and semen analysis regarding haemospermia and was classified according to blood plasma concentrations of canine prostate-specific arginine esterase (CPSE) (normal ≤ 60 ng/ml, increased ≥ 61 ng/ml; Pinheiro et al., 2017). Concentrations of testosterone, 5α-dihydrotestosterone and estradiol were analysed in peripheral blood serum or plasma for detecting breed-specific conditions regarding the endocrine metabolism. Prostatic volume was significantly larger in RR irrespective of the CPSE status. In RR, BPH occurred more frequently and started at an earlier age compared with the LR. Breed-related specificities in steroid metabolism in the RR were indicated by correlations of 5α-dihydrotestosterone and estradiol with age and of testosterone with prostate gland volume. Although the incidence of sonographic signs of BPH and haemospermia did not fit with normal and increased CPSE concentrations, a breed-specific higher incidence of BPH in the RR breed could be clearly verified.


Subject(s)
Dog Diseases/epidemiology , Prostatic Hyperplasia/veterinary , Animals , Carboxylic Ester Hydrolases/blood , Dihydrotestosterone/blood , Dihydrotestosterone/metabolism , Dog Diseases/blood , Dog Diseases/diagnosis , Dogs , Estradiol/blood , Estradiol/metabolism , Hemospermia/veterinary , Male , Prostate/diagnostic imaging , Prostatic Hyperplasia/blood , Prostatic Hyperplasia/diagnosis , Prostatic Hyperplasia/epidemiology , Semen Analysis , Species Specificity , Testosterone/blood , Testosterone/metabolism , Ultrasonography/veterinary
7.
Clin Nutr ; 39(3): 876-885, 2020 03.
Article in English | MEDLINE | ID: mdl-30975555

ABSTRACT

BACKGROUND & AIMS: Most evidence linking the polycystic ovary syndrome (PCOS) with chronic low-grade inflammation has been obtained in the fasting state. We have studied the postprandial inflammatory response to oral glucose, lipid and protein challenges and the possible influences of obesity, sex and PCOS on these responses. METHODS: On alternate days, we submitted 17 women with PCOS (9 non-obese, 8 obese), 17 control women (9 non-obese, 8 obese) and 19 control men (10 non-obese, 9 obese) to isocaloric (300 Kcal) oral macronutrient loads. We assayed serum for TNF-α, IL-6, IL-18, IL-10, pentraxin-3 and galectin-3 concentrations and leukocytes for expression of TNF, IL6, IL10 and their receptors TNFRSF1B, IL6R and IL10RA. RESULTS: Circulating IL-6 levels decreased after glucose and protein ingestion but slightly increased after oral lipid intake. Leukocyte IL6 expression did not change after the ingestion of any macronutrient yet IL6R expression increased during all macronutrient challenges, the largest increase being observed after glucose ingestion. Serum TNF-α similarly decreased during either macronutrient load, whereas TNF expression increased after macronutrient ingestion, the highest increase observed after oral glucose. TNFRSF1B expression also increased after glucose intake but not after lipid or protein ingestion. No global effect of obesity or group on postprandial circulating IL-6, TNF-α, or IL6, IL6R, TNF and TNFRSF1B expression was found. Circulating IL-18 concentrations decreased during all oral challenges, whereas in case of galectin-3 and pentraxin-3 only the protein load caused a reduction in its concentrations. Of the genes studied here, IL10 showed the largest increase in expression throughout all the postprandial curves, particularly after glucose. Obesity blunted the increase in IL10 expression. IL10RA expression decreased after glucose ingestion but remained unchanged during lipid and protein loads. CONCLUSIONS: Glucose ingestion, as opposed to lipid and protein intake, results into the largest increase in leukocyte gene expression of inflammatory mediators. The expression of the anti-inflammatory cytokine IL10 was the largest observed here, suggesting a compensatory mechanisms against postprandial inflammation that may be blunted in obesity. However, these responses did not translate into the circulating concentrations of these inflammatory mediators during the immediate postprandial phase.


Subject(s)
Dietary Proteins/pharmacology , Glucose/pharmacology , Inflammation/blood , Lipids/pharmacology , Obesity/blood , Polycystic Ovary Syndrome/blood , Postprandial Period , Administration, Oral , Adult , Dietary Proteins/administration & dosage , Dietary Proteins/blood , Female , Glucose/administration & dosage , Glucose/metabolism , Humans , Lipids/administration & dosage , Lipids/blood , Male , Sex Factors , Young Adult
8.
Arch. endocrinol. metab. (Online) ; 63(3): 208-214, May-June 2019. tab
Article in English | LILACS | ID: biblio-1011163

ABSTRACT

ABSTRACT Objectives We aimed to measure the quality of life (QoL) of patients with Turner syndrome (PTS) and determine the extent to which their clinical or laboratory alterations influence QoL compared to reference women (RW) of the same age range. Subjects and methods From Dec-2013 to Dec-2014, 90 participants were recruited. They were 18 years and older: 48 with Turner syndrome (TS) (PTS) and 42 without (RW). Recruited subjects completed the Portuguese version of Short Form 36 (SF-36) questionnaire, and blood was drawn to measure LH, FSH, oestradiol (E2), progesterone (P4), SHBG, and SDHEA (by ECLIA) and testosterone (by LC MS/MS). Results Age and schooling were similar between groups. The most common occupations for PTS were health worker, administration and education, and health worker or cashier for RW. Most participants were Catholic or Evangelical. Eighty-one percent (39/48) of cases used Hormonal Replacement Therapy (HRT), mostly transdermal (23/39). RW and PTS scored similarly on the SF-36 questionnaire. RW had higher oestradiol (p = 0,01), lower FSH (p = 0,01) and higher testosterone (p = 0,01) than PTS. Concentrations of P4, LH, SHBG or SDHEA were similar. Significant associations were found among QoL and hormones (E2 with Vitality and LH with Physical Role) only in the PTS group. Conclusions PTS do not consider that TS affects their QoL as measured by domains on the SF-36. Oestradiol was related with QoL, emphasising the importance of HRT.


Subject(s)
Humans , Female , Adolescent , Adult , Middle Aged , Young Adult , Quality of Life , Turner Syndrome/psychology , Hormone Replacement Therapy/psychology , Testosterone/blood , Turner Syndrome/blood , Brazil , Case-Control Studies , Surveys and Questionnaires , Estradiol/blood
9.
Aquat Toxicol ; 197: 136-142, 2018 Apr.
Article in English | MEDLINE | ID: mdl-29482076

ABSTRACT

Atrazine, a widely use herbicide, has been classified as a potential endocrine disruptor, especially for freshwater species. In this study, we tested the hypothesis that atrazine can affect reproduction in crayfish through dysregulation of vitellogenin expression and hormone synthesis. Adult female crayfish (Procambarus clarkii) were exposed during one month to atrazine at concentrations of either 1 or 5 mg/L. At the end of the exposure, ovaries, hepatopancreas, and hemolymph samples were harvested for analysis of vitellogenin expression and steroid hormone levels. Ovarian tissue was also sampled for both biochemical and histological analyses. Our results show that atrazine-exposed crayfish had a lower expression of vitellogenin in the ovary and hepatopancreas, as well as smaller oocytes, and reduced vitellogenin content in the ovary. Despite these effects, circulating levels of estradiol increased in females exposed to 5 mg/L of atrazine, showing that the inhibiting effect of atrazine on vitellogenin production was not related to a lower secretion of sexual steroids. Instead, some early stimulating effects of estradiol on vitellogenesis could have occurred, particularly in the hepatopancreas. On the other hand, atrazine caused a higher metabolic effort, in terms of lactate production, presumably triggered to provide the energy needed to face the unspecific stress produced by the herbicide. Lipid peroxidation was not affected by atrazine, but glutathione levels were significantly increased.


Subject(s)
Astacoidea/metabolism , Atrazine/toxicity , Lipid Peroxidation/drug effects , Steroids/metabolism , Vitellogenesis/drug effects , Animals , Estradiol/metabolism , Female , Gene Expression Regulation/drug effects , Glucose/metabolism , Hemolymph/drug effects , Hemolymph/metabolism , Hepatopancreas/drug effects , Hepatopancreas/metabolism , Herbicides/toxicity , Lactic Acid/metabolism , Metabolome/drug effects , Oocytes/drug effects , Oocytes/metabolism , Ovary/drug effects , Ovary/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Reproducibility of Results , Reproduction , Survival Analysis , Testosterone/metabolism , Thiobarbituric Acid Reactive Substances/metabolism , Vitellogenins/genetics , Vitellogenins/metabolism , Water Pollutants, Chemical/toxicity
10.
Toxicol In Vitro ; 46: 86-93, 2018 Feb.
Article in English | MEDLINE | ID: mdl-28982594

ABSTRACT

Previous studies with perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) indicate that they act as endocrine disruptors, in addition to inducing alterations and damaging reproductive health; however, the biological mechanisms by which these disorders are produced are not yet understood. The aim of this study was to analyze the effect of PFOS and PFOA on in vitro steroidogenic secretion in porcine theca and granulosa cells, with or without gonadotropic stimulation. Granulosa and theca cells were isolated and cultured. Cell nature was performed by immunocytochemistry. PFOS and PFOA effect on steroid secretion was analyzed by chemiluminescence. In the present study, alterations in steroidogenic secretion were found when administering PFOS (0.12, 1.2, 12, 120 or 240µM) or PFOA (0.012, 0.12, 1.2, 12 or 24µM) to theca and granulosa cells. When theca and granulosa cells were stimulated with 500ng/mL LH or 500ng/mL FHS, respectively and immediately followed with 1.2µM of PFOS or PFOA, the perfluorinated compounds inhibited the secretion of steroid hormones in both stimulated cell types. The results indicate that PFOS and PFOA act on steroidogenic ovarian cells as endocrine disruptors, which could affect the dependent functions of sexual steroids.


Subject(s)
Alkanesulfonic Acids/toxicity , Caprylates/toxicity , Estradiol/metabolism , Fluorocarbons/toxicity , Granulosa Cells/drug effects , Progesterone/metabolism , Theca Cells/drug effects , Androstenedione/metabolism , Animals , Cell Survival , Dose-Response Relationship, Drug , Endocrine Disruptors/toxicity , Environmental Pollutants/toxicity , Female , Follicle Stimulating Hormone/pharmacology , Luteinizing Hormone/pharmacology , Swine
11.
Article in English | MEDLINE | ID: mdl-28602421

ABSTRACT

Among the chemicals found in the aquatic environment, some have been reported to interact with the endocrine system of organisms and have been identified as endocrine disrupting compounds. In this study, we have assessed the biological effects due to environmental estrogenic compounds in adult male roach (Rutilus rutilus). Wild fish were collected in the Seine River, and one of its affluent, the Epte River in Normandy, France and impacts on endocrine and reproductive functions have been assessed. This study provides innovative data on the intersex condition in wild fish that are crucial to understand estrogenic contamination impacts and maintenance of sustainable fish population. The biomarker responses found in fish from contaminated sites included high plasmatic vitellogenin concentrations, altered steroid levels, histopathological and up to 50% intersex fish among the male. However, the overall sex ratio of the roach population indicated sign of feminization with some sites showing only 20% of males. The chemical organic contamination at the different location sites has been characterized by the levels of PAHs, PCBs and phthalates and total estrogenic activity was measured by the YES in vitro assay.


Subject(s)
Cyprinidae/physiology , Disorders of Sex Development/chemically induced , Endocrine Disruptors/toxicity , Fertility/physiology , Gonadal Steroid Hormones/metabolism , Gonads/drug effects , Water Pollutants, Chemical/toxicity , Animals , Female , Fertility/drug effects , France , Male , Rivers , Subcellular Fractions
12.
Gen Comp Endocrinol ; 221: 193-200, 2015 Sep 15.
Article in English | MEDLINE | ID: mdl-25688482

ABSTRACT

The South American cichlid fish Cichlasoma dimerus presents a high breeding frequency and biparental care of the eggs and larvae. The male parental care period was divided in four different phases according to the developmental degree of the offspring: pre-spawning activity (MP, day 0), guarding eggs (ME, one day after fertilization (1 DAF)), guarding hatched larvae (MHL, 3 DAF), and guarding swimming larvae (MSL, 8 DAF). The aim of this study was to characterize male reproductive physiology by measuring steroid hormone plasma levels and analyzing testes cellular composition. Males exhibiting pre-spawning activity showed 8.4 times higher 11-ketotestosterone and 5.63 times higher testosterone levels than MHL. No differences were observed in estradiol and cortisol levels among the different phases. The cellular composition of the testes varied during the reproductive and parental care periods. Testes of MP were composed of 50% of spermatozoa, whereas spermatogonia type B and spermatocytes were predominant in the subsequent parental phases. A morphometric analysis of Leydig cells nuclear area revealed that MP and ME's Leydig cells averaged 1.27 times larger than that those of MHL and MSL and was positively correlated with circulating 11-KT and T levels. Hence, C. dimerus males showed important changes in its hormonal profiles and testicular cellular composition throughout the reproductive and parental care period.


Subject(s)
Androgens/metabolism , Behavior, Animal/physiology , Cichlids/physiology , Reproduction/physiology , Reproductive Physiological Phenomena , Spermatogenesis/physiology , Animals , Fertilization/physiology , Humans , Larva/growth & development , Larva/metabolism , Leydig Cells/metabolism , Male , Testis/cytology , Testis/metabolism
13.
Drug Des Devel Ther ; 8: 1381-90, 2014.
Article in English | MEDLINE | ID: mdl-25246776

ABSTRACT

Recognition of the two main pathologic mechanisms equally leading to breast cancer development may provide explanations for the apparently controversial results obtained by sexual hormone measurements in breast cancer cases. Either insulin resistance or estrogen receptor (ER) defect is the initiator of pathologic processes and both of them may lead to breast cancer development. Primary insulin resistance induces hyperandrogenism and estrogen deficiency, but during these ongoing pathologic processes, ER defect also develops. Conversely, when estrogen resistance is the onset of hormonal and metabolic disturbances, initial counteraction is hyperestrogenism. Compensatory mechanisms improve the damaged reactivity of ERs; however, their failure leads to secondary insulin resistance. The final stage of both pathologic pathways is the breakdown of estrogen surveillance, leading to breast cancer development. Among premenopausal breast cancer cases, insulin resistance is the preponderant initiator of alterations with hyperandrogenism, which is reflected by the majority of studies suggesting a causal role of hyperandrogenism in breast cancer development. In the majority of postmenopausal cases, tumor development may also be initiated by insulin resistance, while hyperandrogenism is typically coupled with elevated estrogen levels within the low postmenopausal hormone range. This mild hyperestrogenism is the remnant of reactive estrogen synthesis against refractory ERs that were successfully counteracted at a younger age. When refractoriness of ERs is the initiator of pathologic processes, reactively increased estrogen levels may be found in both young and older breast cancer cases, while they may exhibit clinical symptoms of estrogen deficiency. Studies justifying a causal correlation between hyperestrogenism and tumor development compile such breast cancer cases. In conclusion, the quantitative evaluation of ER refractoriness in breast cancer cases has great importance, since the stronger the estrogen resistance, the higher the promising dose of estrogen therapy.


Subject(s)
Breast Neoplasms/drug therapy , Breast Neoplasms/metabolism , Estrogens/metabolism , Breast Neoplasms/pathology , Estrogens/blood , Humans , Receptors, Estrogen/blood , Receptors, Estrogen/metabolism
14.
Rev. Assoc. Med. Bras. (1992, Impr.) ; Rev. Assoc. Med. Bras. (1992, Impr.);58(4): 493-497, July-Aug. 2012.
Article in Portuguese | LILACS | ID: lil-646894

ABSTRACT

No Brasil, o crescimento dos casos registrados de doenças degenerativas das cartilagens articulares por ano é de 20%, o que representa, anualmente, que mais de 200 mil brasileiros desenvolvem doenças degenerativas das articulações e, com repercussões negativas sobre a massa óssea. Este trabalho mostra evidências que a produção hormonal de esteroides sexuais (estrogênios, progestagênios e androgênios) têm influência na qualidade da cartilagem, bem como na massa óssea. Portanto, o objetivo dessa revisão foi o de analisar os dados da literatura sobre a ação molecular e gênica dos esteroides sexuais na fisiologia da cartilagem hialina e do osso, bem como a interferência da osteoartrite na qualidade dessas estruturas.


In Brazil, the increase in the reported cases of degenerative diseases of articular cartilage is 20% per year, meaning that 200,000 Brazilians develop degenerative joint diseases every year, which have a negative impact on bone mass. This study shows evidence that hormone production of sexual steroids (estrogens, progestogens, and androgens) have an influence on cartilage quality, as well as on bone mass. Therefore, this review aimed to analyze literature data on the molecular and genic action of sexual steroids on hyaline cartilage and bone physiology, as well as osteoarthritis interference on the quality of these structures.


Subject(s)
Female , Humans , Male , Androgens/physiology , Chondrogenesis/physiology , Estrogens/physiology , Osteogenesis/physiology , Progestins/physiology , Chondrocytes/physiology , Osteoarthritis/physiopathology , Osteoblasts/physiology , Osteoclasts/physiology , Postmenopause
15.
Acta amaz ; 40(3): 435-449, set. 2010. ilus, graf, tab
Article in Portuguese | LILACS, VETINDEX | ID: lil-560515

ABSTRACT

Esta pesquisa teve como objetivo caracterizar a reprodução e o perfil hormonal dos esteróides sexuais do pirarucu, Arapaima gigas, além de validar um aspecto do dimorfismo sexual secundário. O experimento foi realizado na Fazenda Santo Antônio II, em Presidente Figueredo-AM, no período de fevereiro de 2004 a fevereiro de 2005. Foram selecionados 24 exemplares e divididos em três grupos de oito peixes (grupo "A", "B" e "C" com pirarucus de mais de quatro anos de idade, com três anos e dois anos, respectivamente). Os pirarucus foram estocados em três tanques de 400m², um para cada grupo. Aspectos comportamentais, como o interesse por alimento, brigas, formação de casais e presença de ninhos, foram observados ao longo de todo o experimento. Amostras de sangue foram coletadas mensalmente, de todos os peixes, observou-se a presença de uma mancha alaranjada no macho como uma característica sexual secundária. Foram mensurados os níveis de testosterona (T), 17beta-estradiol (E2) e 17alfa-hidroxi-progesterona (17aOHP) através de radioimunoensaio (RIA) de fase sólida. Todos os machos dos grupos "A" e "B" puderam ser identificados pela mancha alaranjada na região inferior da cabeça, corroborada pela concentração de testosterona, comprovando o conhecimento empírico dos ribeirinhos. Os níveis de T e E2 nos peixes do grupo "A" e "B" tiveram maiores picos no início do período de chuva, enquanto que o 17aOHP teve oscilações constantes e pequenos picos no final do período chuvoso, os peixes do grupo "C" acompanharam essa tendência em concentrações menores.


The purpose of this study was to characterize the growth, reproduction and hormonal profile of pirarucu, Arapaima gigas, and validate one sexual dimorphism characteristic. The experiment was carried in the fish farm Santo Antonio II, Presidente Figueredo city in the state of Amazonas Brazil, from February 2004 to February 2005. In the experiment, 24 fishes were selected and divided in three groups, with eight fish in each one. The pirarucus from "A" group were older than four years. In "B" group the fishes were three years old and in "C" group these were two years old. The pirarucus were stocked in 400 m² excavated ponds, one pond for each group. Reproductive behavior like feeding interest, fights, pair formation and presence of nest were observed. Blood samples were taken monthly from all fishes during the experiment period, the sexual dimorphism characteristic was observed. Testosterone (T), 17b-estradiol (E2) and 17ahidroxi-progesterona (17aOHP) levels were measured by radioimunoassay (RIA) in solid phase. All males of group "A" and "B" could be identified by an orange mark under the head, and the levels of T validated this data, proving the empirical knowledge of river men. T and E2 levels of group "A" and "B" picked in the beginning of raining period and the 17áOHP levels were higher in the end of raining period. The levels of these hormones in "C" group fishes followed the tendency of "A" and "B" group hormonal levels, but in lower concentration.


Subject(s)
Reproduction/physiology , Gonadal Steroid Hormones/analysis , Fishes/physiology
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