Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

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The response of frog sciatic nerve action potentials to x-irradiation and metabolic (carbon monoxide) or transport (ouabain) inhibition was determined in an attempt to further identify the nature of radiation insult to nervous tissue. Carbon monoxide, ouabain (2 X 10-5 M), and nitrogen anoxia were shown to produce a near linear decline in action potential amplitude. The carbon monoxide and nitrogen inhibitions of activity were reversible in air; the carbon monoxide inhibition was light reversible. Ouabain inhibition was partially reversible by soaking the nerve in aerated Ringer's. Application of 120 kv x-rays (75 Kr at 4.9 Kr/min) to nerves during the linear decline in spike amplitude brought about a marked enhancement (146%) of inhibition by 99% CO/l% 02, nitrogen (136%), and ouabain (265%). All bhanges were shown to be statistically significant by a regression analysis. However, x-irradiation did not appear to alter the air reversibility of carbon monoxide and nitrogen inhibitions nor the reversibility in Ringerts of the ouabain inhibition. Additionally x-irradiation completely blocked light reversal of 98% CO/2% 02 inhibition and produced a decline in activity. A possible interpretation of these results is a compensation for radiation action at this dosage requiring metabolism and ion pump activity.

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Na+ sensitive hypertension in Dahl salt sensitive rats (Dahl S) or spontaneously hypertensive rats (SHR) is linked to intrinsic changes in the brain that favour increased Na+ entry into the cerebrospinal fluid (CSF) followed by increases in sympathetic hyperactivity and hypertension (Huang et al 2004). Similar responses are observed in salt resistant and Wistar rats that receive an intracerebroventricular (icv) infusion of Na+ rich artificial cerebrospinal fluid (aCSF) (Huang et al 2001, 2006). Downstream to increased CSF[Na+], a pathway has been described involving mineralocorticoid receptors (MRs), benzamil sensitive Na+ channels, “ouabain”, and angiotensin II type 1 receptors (AT1-R) (Huang et al 1998, Zhao et al 2001, Wang and Leenen 2003, Huang et al 2008). Blood pressure (BP) responses to increased CSF[Na+] may involve activation of AT1-R in the subfornical organ (SFO) as the BP response to injection of NaCl into a lateral ventricle can be blocked by AT1-R blockade in the SFO (Rohmeiss et al 1995a). The role of aldosterone and AT1-R in the SFO was investigated in mediating the BP and heart rate (HR) response to increases in CSF[Na+] and local [Na+]. Results show that infusion of 0.45M and 0.6M Na+ rich aCSF into the SFO increases BP but not HR. The BP is unchanged by infusion of a mannitol solution osmotically equivalent to 0.6M Na+ rich aCSF indicating that the SFO is Na+ sensitive. The BP response to a lower concentration of Na+ (0.45M) is enhanced by prior infusion of aldosterone while BP response to 0.6M is not further enhanced suggesting that the SFO may have maximal responsiveness to acute increases in [Na+] at 0.6M. The BP responses to Na+ rich aCSF in the SFO and the enhancement of those responses by aldosterone can be blocked by infusion of the AT1-R blocker Candesartan in the SFO. This response appears therefore to be mediated in the SFO through AT1-R activation, likely through Ang II release in the SFO. ICV infusion of Na+ rich aCSF increases BP but not HR and this response is partially blocked by infusion of the AT1-R blocker Candesartan in the SFO. This indicates that nearly half the BP responses to icv infusion of Na+ rich aCSF is mediated through AT1-R activation in the SFO. Lastly, contrary to icv, PVN and MnPO studies (Huang and Leenen 1996, Budzikowski and Leenen 2001, Gabor and Leenen 2009) ouabain in the SFO does not increase BP or HR. In conclusion, these results show that the SFO is Na+ sensitive and mediates half the BP responses to changes in CSF[Na+] through a mechanism that involves AT1-R activation. The SFO is further sensitized to Na+ by aldosterone presumably through its genomic effects. Lastly, ouabain in the SFO does not increase BP or HR suggesting that endogenous ouabain in the SFO is not involved in modulating BP or HR responses.

A administração crônica de ouabaína (OUA) induz hipertensão arterial (HA) em ratos, alterações funcionais e remodelamento em artérias mesentéricas de resistência (AMR). A literatura sugere que a resposta pressórica da OUA pode ser bloqueada pelo antagonismo do receptor AT1 e pela inibição COX-2. No entanto, não se conhece a participação dessas vias no remodelamento arterial nesse modelo de HA. O presente estudo teve como objetivo investigar o papel do sistema renina-angiotensina (SRA) e da COX no remodelamento das AMR induzido pela OUA. Em AMR de ratos OUA, o SRA e a COX-2 participam da resposta pressórica, do remodelamento hipotrófico para dentro e da rigidez. Esses ajustes estão associados ao stress oxidativo e a deposição de colágeno na parede vascular estimulados pela capacidade da OUA em promover a ativação do receptor AT1 e da COX-2. / The chronic administration of ouabain (OUA) induces hypertension in rats, functional and structural alterations in mesenteric resistance arteries (MRA). It is well known that OUA-induced hypertension is blocked by AT1 receptor antagonism and the COX-2 inhibition. However, the participation of these pathways in MRA remodeling in this model of hypertension remains unknown. This study aimed to investigate the role of the renin angiotensin system (RAS) and COX pathways on MRA remodeling induced by OUA. In AMR from OUA rats, RAS and COX-2 participate in the pressor response, the inward hypotrophic remodeling and stiffness. These adjustments are the result of oxidative stressand increasing collagen deposition in the vascular wall stimulated by the OUA ability to stimulate the activation of AT1 receptor and COX-2.

Na+ sensitive hypertension in Dahl salt sensitive rats (Dahl S) or spontaneously hypertensive rats (SHR) is linked to intrinsic changes in the brain that favour increased Na+ entry into the cerebrospinal fluid (CSF) followed by increases in sympathetic hyperactivity and hypertension (Huang et al 2004). Similar responses are observed in salt resistant and Wistar rats that receive an intracerebroventricular (icv) infusion of Na+ rich artificial cerebrospinal fluid (aCSF) (Huang et al 2001, 2006). Downstream to increased CSF[Na+], a pathway has been described involving mineralocorticoid receptors (MRs), benzamil sensitive Na+ channels, “ouabain”, and angiotensin II type 1 receptors (AT1-R) (Huang et al 1998, Zhao et al 2001, Wang and Leenen 2003, Huang et al 2008). Blood pressure (BP) responses to increased CSF[Na+] may involve activation of AT1-R in the subfornical organ (SFO) as the BP response to injection of NaCl into a lateral ventricle can be blocked by AT1-R blockade in the SFO (Rohmeiss et al 1995a). The role of aldosterone and AT1-R in the SFO was investigated in mediating the BP and heart rate (HR) response to increases in CSF[Na+] and local [Na+]. Results show that infusion of 0.45M and 0.6M Na+ rich aCSF into the SFO increases BP but not HR. The BP is unchanged by infusion of a mannitol solution osmotically equivalent to 0.6M Na+ rich aCSF indicating that the SFO is Na+ sensitive. The BP response to a lower concentration of Na+ (0.45M) is enhanced by prior infusion of aldosterone while BP response to 0.6M is not further enhanced suggesting that the SFO may have maximal responsiveness to acute increases in [Na+] at 0.6M. The BP responses to Na+ rich aCSF in the SFO and the enhancement of those responses by aldosterone can be blocked by infusion of the AT1-R blocker Candesartan in the SFO. This response appears therefore to be mediated in the SFO through AT1-R activation, likely through Ang II release in the SFO. ICV infusion of Na+ rich aCSF increases BP but not HR and this response is partially blocked by infusion of the AT1-R blocker Candesartan in the SFO. This indicates that nearly half the BP responses to icv infusion of Na+ rich aCSF is mediated through AT1-R activation in the SFO. Lastly, contrary to icv, PVN and MnPO studies (Huang and Leenen 1996, Budzikowski and Leenen 2001, Gabor and Leenen 2009) ouabain in the SFO does not increase BP or HR. In conclusion, these results show that the SFO is Na+ sensitive and mediates half the BP responses to changes in CSF[Na+] through a mechanism that involves AT1-R activation. The SFO is further sensitized to Na+ by aldosterone presumably through its genomic effects. Lastly, ouabain in the SFO does not increase BP or HR suggesting that endogenous ouabain in the SFO is not involved in modulating BP or HR responses.

Epigenetics continues to be redefined and new discoveries are likely to revolutionise the field still further. This thesis explores different aspects of how epigenetic regulation of gene expression contributes to human disease. Paper I explores the function of the IKKα kinase in regulating gene expression through the nuclear retinoic acid receptor (RAR). We define a set of genes requiring IKKα for their expression and found recruitment of IKKα to the RAR dependent on structural motifs in its protein sequence. This interplay between the NFκB pathway and nuclear receptor regulated transcription is important to consider when designing therapeutic strategies. Papers II and III focus on the plasma cell malignancy multiple myeloma (MM) and define a gene regulatory circuit defining an underexpressed gene profile in MM dependent on the Polycomb proteins. We provide proof-of-principle that the use of small chemical inhibitors may be operational in reactivating genes silenced by H3K27me3 and that this leads to decreased tumour load and increased survival in the 5T33 in vivo model of MM. We explored the genome-wide distribution of H3K27me3 and H3K4me3, and defined their association with gene expression in freshly-isolated malignant plasma cells from MM patients. Importantly, H3K27me3-marked genes in MM associated with more aggressive stages of the disease and less favourable survival. We present evidence that gene targeting by H3K27me3 is likely to not only involve a small population of tumour cells, but rather represent a common MM profile and further provide a rationale for evaluating epigenetic therapeutics in MM. Paper IV shows that pro-inflammatory gene expression in monocytes of psychiatric patients can be induced in vitro by sodium pump inhibitors, as the steroid hormone ouabain. We suggest that the ouabain-induced gene expression is regulated by an intricate network involving microRNAs, Polycomb and the H3K27me3 demethylase JMJD3. Our data indicates that epigenetic regulators play a role in transmitting cues between intrinsic and/extrinsic stimuli and gene expression in psychiatric illness. This thesis provides novel insights on how seemingly unrelated pathways may converge on transcriptional regulation and evidence that epigenetic modifiers contribute to the pathogenesis of human complex diseases such as multiple myeloma and mood disorders.

Made available in DSpace on 2015-05-14T13:00:17Z (GMT). No. of bitstreams: 1 parte1.pdf: 1834339 bytes, checksum: 9a90c51efd47d1b0c436c6b761659ab0 (MD5) Previous issue date: 2011-02-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Initially known as a cardiotonic steroid capable to inhibit the Na+/K+ATPase, ouabain was identified as an endogenous substance present in human plasma, produced by the adrenal, pituitary and hypothalamus and can interfere with various aspects of immune response. In this study, which aimed to study the modulating effect of ouabain on the immune system in vivo and in vitro using mouse models, we demonstrated that treatment for three consecutive days using 0,56 mg/kg ouabain was able to reduce cell migration induced by mitogen Concanavalian A (Con A) to the peritoneum, and this fact reflects a decrease in the number of polymorphonuclear leukocytes, mainly neutrophils. In this same model, ouabain was also able to increase the number of mononuclear leukocytes in the peritoneal cavity. Evaluating the effect of treatment on lymphocytes in peripheral organs, we found that, in lymphocytes from mesenteric lymph nodes, this substance induces a decrease of 20% of T CD3+ lymphocytes, concomitant with an increase in same percentage of B lymphocytes, without, however, modulating the proportion of CD4+ and CD8+ among themselves, as well as the number of regulatory T cells (CD4+/CD25+). In the thymus, the same treatment, does not affect the proportion of lymphocyte subpopulations studied. The analysis qualitative and quantitatively of peripheral blood leukocytes, biometrics and cellularity of spleen, thymus and lymph nodes showed no change in response to ouabain treatment. Comparative studies using treatment for one or two days, with the same dose of 0,56 mg/kg did not trigger modulation, in vivo, in populations of T lymphocytes, B lymphocytes and subpopulations of CD4+ and CD8+ cells in mesenteric lymph nodes. In addition, ouabain was able to inhibit mitochondrial activity of lymphocytes stimulated with Con A, using MTT assay.These findings indicate an immunomodulatory role of ouabain. / Inicialmente, conhecida como um esteróide cardiotônico e por sua propriedade de inibir a Na+/K+ATPase, a ouabaína foi identificada como uma substância endógena presente no plasma humano, produzida pela adrenal, hipófise e hipotálamo e capaz de interferir em vários aspectos da resposta imune. Neste trabalho, que teve como objetivo estudar o efeito modulador da ouabaína no sistema imunológico in vivo e in vitro por meio de modelos murinos, demonstrou-se que o tratamento por três dias consecutivos com ouabaína utilizando a dose de 0,56 mg/kg foi capaz de reduzir a migração celular induzida pelo mitógeno Concanavaliana A (Con A) para o peritôneo, sendo este fato reflexo da redução do número de leucócitos polimorfonucleares, principalmente, neutrófilos. Neste mesmo modelo, a ouabaína também foi capaz de aumentar o número de leucócitos mononucleares no lavado peritoneal. Avaliando-se o efeito desse tratamento no perfil linfocitário de órgãos periféricos, encontrou-se que, em linfócitos de linfonodos mesentéricos, esta substância induz a uma diminuição de 20% de linfócitos T CD3+, concomitante a um aumento de mesmo percentual de linfócitos B, sem, no entanto, modular a proporção de linfócitos TCD4+ e CD8+ entre si, bem como o número de células T regulatórias (CD4+CD25+). No timo, o mesmo tratamento com a ouabaína não interfere na proporção das subpopulações linfocitárias estudadas. As análises qualitativas e quantitativas de leucócitos do sangue periférico, da biometria e celularidade do baço, timo e linfonodos mesentéricos não apresentaram alteração em resposta ao tratamento com a ouabaína. Estudos comparativos utilizando tratamentos de um ou dois dias, com a mesma dose de 0,56 mg/Kg não desencadearam modulação, in vivo, nas populações de linfócitos T, linfócitos B e das subpopulações de linfócitos TCD4+ e CD8+ nos linfonodos mesentéricos. Adicionalmente, a ouabaína foi capaz de inibir a atividade mitocondrial de linfócitos estimulados com Con A, por meio do ensaio de MTT. Estes resultados indicam um papel imunomodulador da ouabaína.