Statement of the problem: The epithelial sodium channels (ENaC) play an important role in regulation of blood pressure (BP). Although the genes are identical in Dahl salt sensitive (S) and Dahl salt resistant (R) rats, expression of ENaC subunits is increased in kidneys of S rats on high salt diet. Intracerebroventricular (icv) infusion of ENaC blocker benzamil prevents Na+ induced hypertension. It was not known whether ENaC subunits are expressed in the brain and whether or not brain ENaC plays a role in regulation of [Na+] in CNS. Hypothesis: 1. Epithelial sodium channels are expressed in the brain. 2. Expression of ENaC is increased in the kidneys and brain of Dahl S rats on high salt diet. 3. ENaC in the brain contributes to regulation of [Na+] in the CSF and brain interstitium. Methods of investigation: We studied expression and distribution of the ENaC subunits and assessed the effects of icv infusion of Na+-rich aCSF in Wistar rats or high salt diet in Dahl S rats in different areas of the brain. Function of ENaC in the choroid plexus was evaluated by studying the effects of benzamil and ouabain on Na+ transport. Major findings: In Wistar rats, both mRNA and protein of all three ENaC subunits are expressed in brain epithelia and magnocellular neurons in the supraoptic (SON) and paraventricular (PVN) nucleus. ENaC abundance is higher on the apical versus basolateral membrane of choroid cells. Benzamil decreases Na+ influx into choroid cells by 20-30% and increases CSF [Na+] by ~8 mmol/L. Na+ rich aCSF increases apical membrane expression of βENaC in the choroid cells and of α and βENaC in basolateral membrane of ependymal cells, but has no effect on neuronal ENaC. Expression of ENaC is higher in choroid cells and SON of Dahl S versus R rats and the higher expression persists on a high salt diet. High salt attenuates the ouabain blockable efflux of Na+ from choroid cells and has no effect on CSF [Na+] in Dahl R rats. In contrast, high salt does not attenuate ouabain blockable efflux of 22Na+ and CSF [Na+] increases in Dahl S. Main Conclusion: ENaC in the brain contributes to Na+ transport into the choroid cells and appear to be involved in reabsorption of Na+ from the CSF. Aberrant regulation of Na+ transport and of Na+K+ATPase activity, might contribute to increases in CSF [Na+] in Dahl S rats on high-salt diet. ENaC in magnocellular neurons may contribute to enhanced secretion of mediators such as ‘ouabain’ leading to sympathetic hyperactivity in Dahl S rats.

Central mechanisms involving aldosterone - mineralocorticoid receptor (MR) activation mediate the increase in sympathetic tone after myocardial infarction (MI). We hypothesized that an increase in cardiac sympathetic activity (CSA) post MI facilitates cardiac sympathetic axonal sprouting, and that central MR blockade attenuates CSA and reduces cardiac sympathetic hyperinnervation post MI. Western blotting and qRT-PCR were used to assess protein and gene expression, and fluorescent immunohistochemistry was used to study changes in sympathetic innervation. Tyrosine hydroxylase (TH) and Norepinephrine transporter protein content in the non-infarcted base of the heart remained unaltered. In contrast, protein gene product (PGP 9.5) protein was significantly increased 2 fold in the base of the heart, and 6 fold in the peri-infarct area at 1 wk post MI, and associated with increased ubiquitin expression. Cardiac myocytes rather than sympathetic axons were identified as the main source of elevated PGP 9.5 expression. At the infarct border sympathetic hyperinnervation was observed with a 4 fold increase in growth associated protein 43 (GAP 43), a 2 fold increase in TH and a 50% increase in PGP 9.5 positive fibers when compared to the epicardial side of the left ventricle in sham rats. Central infusion of the MR blocker eplerenone at 5 ug/day for 9 days post MI markedly attenuated the increase in TH, GAP 43 and PGP 9.5 nerve densities at the infarct border. Central MR blockade may attenuate sympathetic hyperinnervation by several mechanisms, including decreasing CSA post MI, or affecting expression or function of nerve growth factor protein. Marked PGP 9.5 expression occurs in cardiomyocytes early post MI, which may contribute to the increase in ubiquitin and the early cardiac remodeling post MI.

L’hormone minéralocorticoïde aldostérone en se fixant à son récepteur, le récepteur minéralocorticoïde (RM), module la réabsorption de sodium au niveau du rein. De nombreuses étude sont rapporté l’implication du complexe aldostérone/RM dans les pathologies cardiovasculaires, sans que les voies de signalisation activées soient encore entièrement élucidées à ce jour. Ce travail de thèse se propose d’approfondir les connaissances sur les mécanismes de la signalisation cardiaque du RM à travers deux objectifs principaux i) l’identification de nouvelles cibles moléculaires du RM dans lecoeur et ii) la compréhension des effets physiopathologiques de son activation. Par une approche pharmacologique, nous avons montré que le diurétique torasémide n’est pas capable de bloquer la voie de signalisation minéralocorticoïde dans la lignée cellulaire de cardiomyocyte transfectée avec le RM,H9C2-RM+. L’étude de l’activité transcriptionnelle du RM cardiaque a concerné la majeure partie de ce travail de thèse. Par une approche gène candidat, nous avons mis en évidence que l’expression dugène codant pour le facteur de croissance du tissu conjonctif (CTGF, pour connective tissue growthfactor) est augmentée par le RM et que l’aldostérone potentialise cet effet in vivo. Nous avons pu localiser CTGF spécifiquement dans les cardiomyocytes, et une étude in vitro nous a permis d’identifier que le RM se lie au niveau d’éléments de réponse hormonale dans le promoteur du gène codant pour CTGF. Des souris surexprimant le RM humain spécifiquement dans les cardiomyocytes et traitées avec de l’aldostérone ou de la corticostérone ont permis une exploration plus large des gènesdifférentiellement exprimés par les deux ligands du RM dans le coeur. L’analyse des transcriptomes cardiaques de ces souris et de leurs contrôles montre qu’une augmentation modeste de la concentration plasmatique en aldostérone induit dans le coeur l’expression de gènes impliqués dans le cycle cellulaire comme la Cycline B1 ou sa kinase associée Cdk1 (pour Cyclin-dependent kinase 1). Nous avons montré également que l’aldostérone active la prolifération des cellules endothéliales cardiaques. / The mineralocorticoid hormone aldosterone binding its receptor, the mineralocorticoid receptor (MR),regulates the renal reabsorption of sodium. Several studies showed the involvement of the aldosterone/MR complex in cardiovascular diseases, even if the activated signalling pathways are still unclear. This thesis work has been established to increase the knowledge on the mechanisms of thecardiac signalling of MR using two main purposes i) the identification of new molecular targets of the MR in the heart and ii) the understanding of the pathophysiological effects of its activation. Apharmacological approach showed that the diuretic torasemide cannot block the mineralocorticoid signalling in the cell line cardiomyocytes transfected with MR, H9C2-MR+. The study of the MR’s cardiac transactivation activity formed the most important part of this thesis work. We demonstrated with a candidate gene approach that the MR increases the expression of the gene coding the connective tissue growth factor (CTGF) and the aldosterone increases even more this effect in vivo. We foundCTGF specifically expressed in cardiomyocytes and we identified in vitro that the MR binds tohormonal responsive elements on the promoter of the gene coding CTGF. In order to investigate the whole genes differentially expressed by the two ligands of MR in the heart, we treated mice with cardiomyocyte-targeted human MR over expression and their controls with aldosterone or corticosterone. The cardiac transcriptomic analyses show that the majority of aldosterone-regulatedgenes is involved in cell division as Cyclin B1 or Cyclin-dependent kinase 1 (Cdk1). Also, we identified that aldosterone promotes cardiac endothelial cells proliferation.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第22042号 / 医博第4527号 / 新制||医||1039(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 佐藤 俊哉, 教授 湊谷 謙司, 教授 稲垣 暢也 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Binding parameters of soluble Type I and Type II receptors were assessed in hippocampus of adult, adrenalectomized, male and female rats. No sex differences in the number of either Type I or Type II receptors could be demonstrated between gonadally intact animals. When females treated with 17β-estradiol benzoate (10 μg/day) were compared with males, a statistically significant reduction in Type II receptors was observed in the females; progesterone produced no further decrease in receptor numbers. The amount of tissue-associated corticosteroid-binding globulin in gonadally intact animals (perfused with dextran-saline) was twice as great in females as males. Sex-dependent differences in these gonadally intact rats were found in the affinity, measured as the dissociation constant (Kd), of both the Type I and Type II receptors. For both receptors, affinity in cytosols from females was reduced. The difference for the Type II receptor was slight, but the Kd value of the type I receptor was several-fold higher in females. The difference in affinity was evident with both natural and synthetic steroid ligands. There appears to be little, if any, difference in affinity between the hippocampal Type I and the Type II receptors in females. This suggests that the occupancy of Type I receptors in females is substantially less than that of males at low circulating concentrations of corticosteroids.

O diabetes é uma doença crônica que afeta mais de 8% da população mundial. As alterações vasculares estão relacionadas às principais complicações do diabetes. A aldosterona contribui para a disfunção endotelial após a ativação do receptor mineralocorticóide (MR). Recentemente, foi demonstrado que a aldosterona ativa o receptor de estrógeno acoplado à proteína G (GPER). A ativação de GPER está relacionada a efeitos benéficos na vasculatura. Entretanto, ainda não existem estudos em artérias de resistência relacionando aldosterona e GPER e essa interação no diabetes. Dessa forma, o presente estudo testou a hipótese de que a aldosterona ativando receptores GPER promove efeitos benéficos na vasculatura, mas esses efeitos estão diminuídos no diabetes. Os objetivos foram investigar os níveis de expressão de GPER nos animais controle e db/db [camundongos com mutação no receptor de leptina que desenvolvem obesidade e diabetes tipo 2], quais efeitos da aldosterona são mediados por ativação de GPER e quais mecanismos envolvidos nessa ativação e verificar se estão alterados no diabetes. O grupo diabético apresentou maior expressão de GPER, mas não de MR. A aldosterona promoveu aumento da resposta máxima contrátil à fenilefrina (PE) somente no grupo controle, que foi revertido pelo uso do antagonista de GPER, G15. No grupo diabético, a resposta à PE já é aumentada, o uso dos antagonistas de MR e GPER reduziram a resposta da PE. A aldosterona ainda reduziu a potência de relaxamento da acetilcolina (ACh) em ambos os grupos, por ativação de MR. O antagonismo de GPER por G15 promoveu um redução adicional na potência do relaxamento no grupo controle, mas não afetou a resposta do grupo diabético. Esses achados confirmam a hipótese de que GPER exerce um papel benéfico na vasculatura e esse efeito é perdido no diabetes. Nossos resultados contribuem para a compreensão dos mecanismos que a aldosterona influencia os danos vasculares no diabetes através da ativação de receptores MR e GPER. / Diabetes is a chronic disease that affects more than 8 % of the world population. Vascular changes are related to the major complications of diabetes. Aldosterone contributes to endothelial dysfunction after activation of the mineralocorticoid receptor (MR). It was recently shown that aldosterone also activates the G protein-coupled estrogen receptor (GPER) and induces non genomic effects. The activation of GPER by estrogen or G1 is related to beneficial effects on the vasculature. However, there are no studies demonstrating the relationship between aldosterone and GPER in diabetes mellitus. Therefore, we hypothesized that the beneficial effects of aldosterone mediated by the activation of GPER receptors on vascular reactivity are decreased in diabetes mellitus. Female control and diabetic (db/db) mice [leptin receptor knockout mice that develop obesity and type 2 diabetes] were used. We determined the expression of GPER and the effect of aldosterone in the presence of MR and GPER antagonists in arteries from control and db/db mice and the major signaling pathways involved. The diabetic group showed increased GPER expression, but not MR. In the presence of aldosterone the control increased the maximal contractile response to phenylephrine (PE), and this increase was reversed by the use of GPER antagonist, G15. The response to PE is already increased in the diabetic group. Although aldosterone did not cause further increase the use of MR and GPER antagonists reduced the maximum response to PE at the same level of control. Aldosterone also reduced the potency of acetylcholine (ACh)-induced relaxation in both groups by the activation of MR. GPER antagonism caused further decrease in the potency of ACh-induced relaxation in the control group, while not affecting the response of the diabetic group. These findings confirm the hypothesis that the beneficial effects of aldosterone mediated by the activation of GPER receptors are decreased in diabetes mellitus. Our results contribute to understanding the mechanisms that aldosterone influences the vascular damage in diabetes through activation of MR and GPER receptors.

O estresse provoca alterações significativas no metabolismo dos animais, provocando a liberação de hormônios glicocorticoides. Estas alterações do metabolismo têm efeito anabólico sobre o metabolismo proteico muscular, podendo afetar os processos bioquímicos de transformação do músculo em carne. O presente trabalho teve como objetivo geral (i) verificar as relações entre variáveis endócrinas e metabólicas associadas ao estresse e características indicadoras de qualidade da carne, em animais castrados e não-castrados; (ii) avaliar a expressão gênica dos receptores mineralocorticoide (MR) e glicocorticoide (GR) em variáveis endócrinas, metabólicas e relacionadas à qualidade da carne de bovinos Nelore castrados e não-castrados. Para tal, 130 animais foram abatidos entre os anos de 2009 e 2011. Amostras de sangue foram coletadas antes e depois do abate para mensuração das concentrações de ACTH e cortisol. Amostras do músculo Longissimus dorsi foram coletadas durante os abates para mensuração do glicogênio e lactato, bem como, para análises de expressão gênica (RT-qPCR). Para as análises de maciez, foram coletadas amostras maturadas por um, sete e 14 dias. Para expressão gênica foram determinados os genótipos dos animais para três marcadores relacionados ao MR (MR1_1, MR1_2 e MR1_3) e dois ao GR (GR2_1 e GR2_2), por meio de PCR em tempo real. Foi verificado que animais castrados apresentam pH 24 horas menores e carnes mais macias ao sétimo e 14º dias de maturação, bem como, concentrações de cortisol (in vivo e post mortem) e lactato significativamente superiores aos animais não-castrados. O marcador MR1_3 apresenta expressão gênica significativamente diferenciada. Os animais com genótipo GA apresentaram 57,27% mais transcritos quando comparados aos animais GG. A expressão gênica do MR e GR foi significativamente relacionada às concentrações de cortisol in vivo e post mortem, porém não influenciou as concentrações de ACTH (in vivo e post mortem), glicogênio e lactato. A expressão gênica do MR e GR não foi relacionada às características indicadoras da qualidade da carne. / The stress causes significant changes in the metabolism of the animals causing the release of glucocorticoid hormones. These metabolic changes have anabolic effect on muscle protein metabolism, affecting the biochemical processes of transformation of muscle on meat. This study aimed to (i) examine relationships between endocrine and metabolic variables associated with stress and meat quality characteristics in castrated and non-castrated animals, (ii) evaluate mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) gene expression in endocrine and metabolic characteristics and related this to meat quality of Nellore castrated and non-castrated animals. To this end, 130 animals were slaughtered between the years 2009 and 2011. Blood samples were collected before and after slaughter to measure concentrations of ACTH and cortisol. Longissimus dorsi muscle samples were collected during slaughter for measurement of glycogen and lactate, as well for gene expression analyzes (RT-qPCR). For the shear force analyzes, samples were aged for one, seven and 14 days. For gene expression analysis, genotypes of three markers related to MR (MR1_1, MR1_2 and MR1_3), and the two related to GR (GR2_1 and GR2_2) were determined via real-time PCR. It was observed that castrated have lower pH value at 24 hours than non-castrated animals, and tender meat on the seventh and 14th day of aging, such as cortisol (in vivo and post mortem) and lactate concentrations significantly superior to non-castrated animals. Gene expression of MR1_3 was significantly different. Animals with GA genotype had 57.27% more transcripts than GG genotype. The gene expression of MR and GR was significantly related to cortisol concentrations in vivo and post mortem, but did not influence the concentrations of ACTH (in vivo and post mortem), glycogen and lactate. The MR and GR gene expression was not related to the meat quality characteristics.

Nuclear hormone receptors (NHRs) are ligand-activated transcriptions factors which transduce the effects of various hormones as well as nutritional and other environmental signals. They thus function to maintain physiological homeostasis by integrating the tissue expression of specific target genes to regulate a wealth of biological processes including reproduction, development, metabolism and environmental adaptation. Mounting evidence indicates NHRs are the target of endocrine disrupting compounds (EDCs), exogenous chemicals, often of anthropogenic origin, which disrupt NHRs and thus the processes under their control. EDCs can interfere with NHR signalling by activating receptors (agonists), by inhibiting the actions of the receptor (antagonists), or by disrupting endogenous hormone synthesis, secretion, transport or metabolism. Much of the focus to date has been on the risk of EDCs to reproductive functions, via estrogen and androgen NHRs in humans, and also in aquatic organisms. However environmental pollutants also have the potential to interact with other NHRs, particularly in aquatic environments, and cause dysregulation of other critical physiological processes, including energy homeostasis, immune functions and the stress response. To address this possibility a reporter gene assay was developed, allowing the high-throughput screening of pollutants for their interactions with piscine NHRs with critical roles in energy homeostasis, stress reponse and immune functions, namely the peroxisome proliferator-activated receptors (PPARs) and corticosteroid receptors (CRs) from European plaice (Pleuronectes platessa) and European flounder (Platichthys flesus), respectively. Complementary DNA (cDNA) sequences encoding the ligand-binding domains of PPARs and CRs, critical for receptor-ligand interactions and receptor activation, were ligated to the DNA-binding domain (DBD) of the yeast Gal4 transcription activator protein to create experimental expression plasmid constructs. Co-transfection of these expression plasmids into the fathead minnow (FHM) cell line with an upstream-activating sequence (UAS)-firefly luciferase reporter gene plasmid increased luciferase expression in the presence of known PPAR and CR ligands. Several aquatic pollutants including pharmaceuticals, industrial by-products and biocides were tested for their potential to disrupt PPAR and CR functions by interacting with these receptors in an agonistic or antagonistic manner. Several fibrates, a group of pharmaceutical compounds used to treat dyslipidemia in humans by targeting the PPARs, were able to activate plaice Gal4-PPARα and Gal4-PPARβ in the reporter gene assay, indicative of an interaction with PPAR receptors in non-target species. Fibrates which did not activate Gal4-PPARα were able to inhibit the activation of Gal4-PPARα by the PPARα-specific agonist, Wy14643, suggesting differential effects of fibrates on human and flounder PPARs. In addition some metabolites of widespread phthalate ester pollutants were also agonists of the Gal4-PPARα and Gal4-PPARβ constructs. The Gal4-PPARγ construct was unresponsive to almost all the compounds tested, including the mammalian PPARγ agonist, rosiglitazone. The exception to this was the phthalate metabolite monobenzylphthalate, which induced a small increase in firefly luciferase in Gal4-PPARγ transfected cells. All of the above effects required concentrations of at least 10 µM, which are unlikely to be encountered in the aquatic environment. In contrast bis(tributyltin) oxide (TBTO), a notorious environmental pollutant, inhibited Gal4-PPARα and Gal4-CR constructs at concentrations as low as 1 nM and 100 nM, respectively. These concentrations are lower than those reported in aquatic environments, or in fish tissues, making TBTO a candidate endocrine disruptor in fish by inhibiting PPARα and CR signalling. A European flounder cDNA microarray was used to investigate the trasnscriptional responses of flounder hepatocytes to TBTO (10 nM) exposure. Exposure to TBTO and Wy14643, both alone and in combination, indicated a TBTO-driven downregulation of several potential PPARα-target genes with functions in the immune system, the proteasome, and lipid metabolism, although, based on mammalian comparisons, some potential PPARα-target genes were also upregulated, indicating differences in mammalian and fish PPAR-target genes or reflecting the complexity of organisms at a higher organisational level than cell-based assay systems. However, the microarray-based approach was useful in formulating further hypotheses about the effects of TBTO on PPARα signalling. Overall, these results indicate that exogenous chemicals entering the aquatic environment can interfere with NHRs with functions in energy homeostasis, immune functions and stress, in non-target organisms. The cell-based reporter gene assay is a useful tool for identifying potential endocrine disruptors which target PPARs and CRs and would be a useful method in a first tier testing approach, limiting the use of live animal models and enabling investigation into specific receptors which are targets of endocrine disrupting compounds. Although more work is required to confirm the physiological consequences of TBTO inhibition of PPARα, the results presented here indicate that organisms inhabiting TBTO-polluted environments may experience suppression of the immune system, an increase in non-functional or misfolded proteins through suppression of genes involved in the ubiquitin/proteasome system and a disruption in lipid homeostasis.

O diabetes é uma doença crônica que afeta mais de 8% da população mundial. As alterações vasculares estão relacionadas às principais complicações do diabetes. A aldosterona contribui para a disfunção endotelial após a ativação do receptor mineralocorticóide (MR). Recentemente, foi demonstrado que a aldosterona ativa o receptor de estrógeno acoplado à proteína G (GPER). A ativação de GPER está relacionada a efeitos benéficos na vasculatura. Entretanto, ainda não existem estudos em artérias de resistência relacionando aldosterona e GPER e essa interação no diabetes. Dessa forma, o presente estudo testou a hipótese de que a aldosterona ativando receptores GPER promove efeitos benéficos na vasculatura, mas esses efeitos estão diminuídos no diabetes. Os objetivos foram investigar os níveis de expressão de GPER nos animais controle e db/db [camundongos com mutação no receptor de leptina que desenvolvem obesidade e diabetes tipo 2], quais efeitos da aldosterona são mediados por ativação de GPER e quais mecanismos envolvidos nessa ativação e verificar se estão alterados no diabetes. O grupo diabético apresentou maior expressão de GPER, mas não de MR. A aldosterona promoveu aumento da resposta máxima contrátil à fenilefrina (PE) somente no grupo controle, que foi revertido pelo uso do antagonista de GPER, G15. No grupo diabético, a resposta à PE já é aumentada, o uso dos antagonistas de MR e GPER reduziram a resposta da PE. A aldosterona ainda reduziu a potência de relaxamento da acetilcolina (ACh) em ambos os grupos, por ativação de MR. O antagonismo de GPER por G15 promoveu um redução adicional na potência do relaxamento no grupo controle, mas não afetou a resposta do grupo diabético. Esses achados confirmam a hipótese de que GPER exerce um papel benéfico na vasculatura e esse efeito é perdido no diabetes. Nossos resultados contribuem para a compreensão dos mecanismos que a aldosterona influencia os danos vasculares no diabetes através da ativação de receptores MR e GPER. / Diabetes is a chronic disease that affects more than 8 % of the world population. Vascular changes are related to the major complications of diabetes. Aldosterone contributes to endothelial dysfunction after activation of the mineralocorticoid receptor (MR). It was recently shown that aldosterone also activates the G protein-coupled estrogen receptor (GPER) and induces non genomic effects. The activation of GPER by estrogen or G1 is related to beneficial effects on the vasculature. However, there are no studies demonstrating the relationship between aldosterone and GPER in diabetes mellitus. Therefore, we hypothesized that the beneficial effects of aldosterone mediated by the activation of GPER receptors on vascular reactivity are decreased in diabetes mellitus. Female control and diabetic (db/db) mice [leptin receptor knockout mice that develop obesity and type 2 diabetes] were used. We determined the expression of GPER and the effect of aldosterone in the presence of MR and GPER antagonists in arteries from control and db/db mice and the major signaling pathways involved. The diabetic group showed increased GPER expression, but not MR. In the presence of aldosterone the control increased the maximal contractile response to phenylephrine (PE), and this increase was reversed by the use of GPER antagonist, G15. The response to PE is already increased in the diabetic group. Although aldosterone did not cause further increase the use of MR and GPER antagonists reduced the maximum response to PE at the same level of control. Aldosterone also reduced the potency of acetylcholine (ACh)-induced relaxation in both groups by the activation of MR. GPER antagonism caused further decrease in the potency of ACh-induced relaxation in the control group, while not affecting the response of the diabetic group. These findings confirm the hypothesis that the beneficial effects of aldosterone mediated by the activation of GPER receptors are decreased in diabetes mellitus. Our results contribute to understanding the mechanisms that aldosterone influences the vascular damage in diabetes through activation of MR and GPER receptors.

O estresse provoca alterações significativas no metabolismo dos animais, provocando a liberação de hormônios glicocorticoides. Estas alterações do metabolismo têm efeito anabólico sobre o metabolismo proteico muscular, podendo afetar os processos bioquímicos de transformação do músculo em carne. O presente trabalho teve como objetivo geral (i) verificar as relações entre variáveis endócrinas e metabólicas associadas ao estresse e características indicadoras de qualidade da carne, em animais castrados e não-castrados; (ii) avaliar a expressão gênica dos receptores mineralocorticoide (MR) e glicocorticoide (GR) em variáveis endócrinas, metabólicas e relacionadas à qualidade da carne de bovinos Nelore castrados e não-castrados. Para tal, 130 animais foram abatidos entre os anos de 2009 e 2011. Amostras de sangue foram coletadas antes e depois do abate para mensuração das concentrações de ACTH e cortisol. Amostras do músculo Longissimus dorsi foram coletadas durante os abates para mensuração do glicogênio e lactato, bem como, para análises de expressão gênica (RT-qPCR). Para as análises de maciez, foram coletadas amostras maturadas por um, sete e 14 dias. Para expressão gênica foram determinados os genótipos dos animais para três marcadores relacionados ao MR (MR1_1, MR1_2 e MR1_3) e dois ao GR (GR2_1 e GR2_2), por meio de PCR em tempo real. Foi verificado que animais castrados apresentam pH 24 horas menores e carnes mais macias ao sétimo e 14º dias de maturação, bem como, concentrações de cortisol (in vivo e post mortem) e lactato significativamente superiores aos animais não-castrados. O marcador MR1_3 apresenta expressão gênica significativamente diferenciada. Os animais com genótipo GA apresentaram 57,27% mais transcritos quando comparados aos animais GG. A expressão gênica do MR e GR foi significativamente relacionada às concentrações de cortisol in vivo e post mortem, porém não influenciou as concentrações de ACTH (in vivo e post mortem), glicogênio e lactato. A expressão gênica do MR e GR não foi relacionada às características indicadoras da qualidade da carne. / The stress causes significant changes in the metabolism of the animals causing the release of glucocorticoid hormones. These metabolic changes have anabolic effect on muscle protein metabolism, affecting the biochemical processes of transformation of muscle on meat. This study aimed to (i) examine relationships between endocrine and metabolic variables associated with stress and meat quality characteristics in castrated and non-castrated animals, (ii) evaluate mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) gene expression in endocrine and metabolic characteristics and related this to meat quality of Nellore castrated and non-castrated animals. To this end, 130 animals were slaughtered between the years 2009 and 2011. Blood samples were collected before and after slaughter to measure concentrations of ACTH and cortisol. Longissimus dorsi muscle samples were collected during slaughter for measurement of glycogen and lactate, as well for gene expression analyzes (RT-qPCR). For the shear force analyzes, samples were aged for one, seven and 14 days. For gene expression analysis, genotypes of three markers related to MR (MR1_1, MR1_2 and MR1_3), and the two related to GR (GR2_1 and GR2_2) were determined via real-time PCR. It was observed that castrated have lower pH value at 24 hours than non-castrated animals, and tender meat on the seventh and 14th day of aging, such as cortisol (in vivo and post mortem) and lactate concentrations significantly superior to non-castrated animals. Gene expression of MR1_3 was significantly different. Animals with GA genotype had 57.27% more transcripts than GG genotype. The gene expression of MR and GR was significantly related to cortisol concentrations in vivo and post mortem, but did not influence the concentrations of ACTH (in vivo and post mortem), glycogen and lactate. The MR and GR gene expression was not related to the meat quality characteristics.