Recently, oxidative stress has been highlighted as a potential mediator underlying life-history trade-offs in animals. However, despite growing interest in the role of oxidative stress as a mechanistic explanation of trade-offs, the importance of oxidative stress in wild populations remain poorly understood. In this thesis, I use four commonly applied markers of oxidative stress. I apply two markers of oxidative damage, protein carbonyls and malondialdehyde, and two markers of antioxidant protection, superoxide dismutase activity and total antioxidant capacity. These were applied to samples collected in 2010-2013 and 2015 from the wild population of Soay sheep (Ovis aries), St Kilda, Scotland. I investigate correlations among different markers of oxidative stress, and their within individual repeatability over time. In addition, I examine the role played by oxidative stress in mediating life-history traits at different life-stages; specifically, I test for associations between oxidative stress, growth and survival in Soay sheep lambs. I also investigate the oxidative costs of reproduction in adult Soay sheep females and I test whether any such costs vary with age. My findings reveal, firstly, that plasma markers of oxidative stress vary dramatically among years, and that the different markers of oxidative damage and antioxidant protection applied throughout this thesis, are uncorrelated with each other (Chapter 2). This indicates that oxidative stress is a multifaceted process, where each oxidative stress marker may reflect different and potentially uncoupled biochemical processes (Chapter 2). Second, faster lamb growth shows a weak, positive association with malondialdehyde. However, growth is not associated with variation in the other three markers (Chapter 3). In addition, lamb survival also shows marker dependent associations; lambs with higher superoxide dismutase activity are more likely to survive their first winter, as are male but not female lambs with lower protein carbonyl content. Survival does not vary with malondialdehyde or antioxidant capacity. Thus, different markers of oxidative stress capture different aspects of the complex relationships between individual oxidative state, physiology and fitness (Chapter 3). Third, protein carbonyl content and superoxide dismutase activity measured at birth and at four month old in the lambs, show no within individual repeatability, although there is a significant difference in mean marker values over time (Chapter 4). This indicates that these markers of oxidative stress might reflect transient, rather than general, physiological states. Finally, I find some evidence for an oxidative cost of reproduction and for age-related variation in oxidative stress (Chapter 5). However, once again, effect are highly marker and year dependent, and I find no consistent patterns of variation across the two oxidative damage markers or across the two antioxidant protection markers, as they all show different responses to both breeding and age (Chapter 5). Together, my results provide some support for the association between oxidative stress and life-histories, but the effects are both marker and year dependent. Furthermore, the lack of correlation among different markers and the lack of within individual repeatability of oxidative stress markers highlight the need for careful selection and interpretation of plasma oxidative stress markers in the wild.

Made available in DSpace on 2014-06-11T19:29:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-20Bitstream added on 2014-06-13T18:39:58Z : No. of bitstreams: 1 spada_apm_me_botfm.pdf: 214670 bytes, checksum: 608905a90c46918e2a91642487aaed16 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Objetivo: avaliar o estresse oxidativo no sangue e na placenta de ratas com diabete de intensidade moderada. Métodos: O diabete foi induzido em ratas Wistar recém-nascidas (grupo diabete moderado) no dia do nascimento (dia 0) por streptozotocin (100 mg/kg, via subcutênea). As ratas do grupo nãodiabético (controle) receberam somente tampão citrato. Na vida adulta, as ratas (diabéticas e controle) foram submetidas ao acasalamento e o dia de diagnóstico positivo de prenhez foi considerado dia 0. A glicemia foi determinada nos dias 0, 7, 14 e 21 de prenhez. No 21º dia de prenhez, as ratas foram anestesiadas e dessangradas para determinação das atividades enzimáticas de superóxido dismutase (SOD), glutationa peroxidase (GSH-Px) e glutationa redutase (GSH-Rd) e das concentrações de grupos tiólicos (SH) e de espécies reativas ao ácido tiobarbitúrico (TBARS). Em seguida, as placentas foram retiradas e processadas para determinação das atividades de SOD e catalase e concentração de TBARS, gluationa reduzida e grupos tiólicos. Resultados: Ratas com diabete induzido no período neonatal (grupo diabético) apresentaram glicemia superior a 120mg/dl no dia 0 de prenhez e foi observada hiperglicemia no 14º dia de prenhez. A análise do estresse oxidativo em hemáceas lavadas mostrou que no grupo diabético houve aumento significativo na atividade da GSH-Px. No tecido placentário a atividade da catalase foi significativamente maior em ratas com diabete moderado. Conclusão: Frente às condições experimentais analisadas, o aumento dos biomarcadores do sistema antioxidante em ratas com diabete de intensidade moderada foram suficientes para conter o estresse oxidativo. / Objective: To evaluate the oxidative stress in blood sample and placental of female rats that received streptozotocin in the neonatal period. Methods: The diabetes was induced in female offspring (diabetic group) in the day of the birth (day 0) for streptozotocin (100 mg/kg, subcutaneous route). Female control rat (control group) received only citrate buffer. In the adult life, the female rats were submitted to the mating and the day the positive diagnosis, was considered day 0 of pregnancy. The glycemia was measured in the 0, 7, 14 and 21 of pregnancy. At day 21 of pregnancy, the female rats were anesthetized and died by decapitation for collection of the blood for determination of the enzymatic activity of the superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione reductase (GSH-Rd) and of the concentrations of thiols group and thiobarbituric acid reactive substances (TBARS). Afterwards, placental were removed and processed for determinations of the enzymatic activity of the SOD and catalase and of the concentrations of the TBARS, glutathione reduced (GSH) and thiols group (SH). Results: Diabetic rats presented blood glucose concentration greater than 120 mg/dL in the day 0 of pregnancy and hyperglycemia in 14 º day of pregnancy. The analysis of the oxidative stress in maternal blood sample showed increased in GSH-Px activity. In placental tissue catalase activity of diabetic group is found to be increase in homogenate tissue in diabetic group. Conclusion: The hyperglycemia in diabetic rats increased antioxidant system biomarkers, however, these alterations were enough to control oxidative stress.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / O transtorno afetivo bipolar (TAB) à um transtorno psiquiÃtrico multifatorial, progressivo, que se caracteriza por uma oscilaÃÃo entre episÃdios manÃacos ou hipomanÃacos e depressivos. Estima-se que o transtorno afete cerca de 1 â 2 % da populaÃÃo mundial. O diagnÃstico definitivo e o tratamento adequado podem demorar 10 anos para se concretizar. Leva a grande prejuÃzo à qualidade de vida dos pacientes, gerando altas taxas de incapacidade funcional, comorbidades clÃnicas, como hipertensÃo e alta prevalÃncia de suicÃdio. A fisiopatologia do transtorno ainda permanece obscura, porÃm muitos esforÃos sÃo empregados em pesquisas para tentar elucidar os possÃveis mecanismos envolvidos no TAB, bem como para melhorar seu tratamento. As hipÃteses para explicar a fisiopatologia do TAB incluem: desregulaÃÃo da dopamina, alteraÃÃes mitocondriais, aumento do estresse oxidativo, reduÃÃo dos nÃveis de neurotrofinas, dentre outras. Diante deste cenÃrio, buscou-se investigar os possÃveis efeitos antimanÃacos do carvedilol (CVD), um beta-bloqueador nÃo seletivo usado amplamente no tratamento da hipertensÃo arterial com comprovada aÃÃo antioxidante e neuroprotetora. Para tanto, se utilizou um modelo animal de mania induzido por dimesilado de lisdexanfetamina (LDX), recentemente validado por nosso grupo de pesquisa. O LDX à um prÃ-fÃrmaco que se converte a D-anfetamina, a qual possui efeito psicoestimulante. O CVD foi avaliado em dois protocolos de tratamento, prevenÃÃo (simulando a fase de manutenÃÃo do TAB) e reversÃo (simulando a fase de crise do TAB), em ambos o valproato (VAL) foi utilizado como estabilizante do humor padrÃo. Foram avaliadas no presente estudo alteraÃÃes comportamentais e de estresse oxidativo. Os animais submetidos aos protocolos de prevenÃÃo (animais prÃ-tratados durante 7 dias com CVD, VAL e Salina e por mais 7 dias com LDX 10 mg/kg) e reversÃo (prÃ-tratados durante 7 dias com LDX e posteriormente tratados com CVD, VAL e Salina) tiveram os nÃveis de glutationa reduzida (GSH) e de peroxidaÃÃo lipÃdica (TBARS) determinados nas Ãreas cerebrais do cÃrtex prÃ-frontal (PFC) e corpo estriado (CE) e o fator neurotrÃfico derivado do cÃrebro (BDNF) no hipocampo (HC). Os resultados indicaram que o CVD preveniu e reverteu a hiperlocomoÃÃo e comprometimento da interaÃÃo social induzidas por LDX. Na avaliaÃÃo neuroquÃmica o CVD foi capaz de aumentar prevenir e reverter as alteraÃÃes nos nÃveis de GSH, BDNF e peroxidaÃÃo lipÃdica dos animais submetidos ao modelo de mania com resultados comparÃveis aos dos animais tratados com VAL e controles. Em conclusÃo, os resultados deste estudo revelaram que o CVD à um fÃrmaco em potencial para o tratamento da mania, sendo indicados, portanto, estudos clÃnicos que comprovem a aÃÃo deste fÃrmaco. / Bipolar disorder (BD) is a psychiatric disorder with multifactorial development and neuroprogressive characterized by oscillation between periods of manic and depressive episodes. It is estimated that the disease affects about 1 - 2% of the worldwide population and it takes about 10 years to a definitive diagnosis and appropriate treatment. BD brings many impairment of quality of life of patients, generating high rates of functional disability, comorbidities such as hypertension during the clinical course of the disease and presenting a high prevalence of suicide. The pathophysiology of the disease remains unclear, but many efforts are employed in research to try to elucidate the possible mechanisms involved in BD. The pathways hypothesized to take part of BD pathophysiology includes: dopamine deregulation, increased oxidative stress, decreased levels of neurotrophins such as BDNF, mitochondrial dysfunction among others. Based on the described above we sought to investigate the effects of carvedilol, (CVD), a nonseletive beta-blocker widely used in the treatment of hypertension with antioxidant properties, in a model of mania induced by dimesilate of lisdexamfetamine (LDX) a prodrug metabolized to D-amphetamine, in rats. The experimental design of the study consisted evaluation of CVD against behavioral changes and oxidative stress alterations in two protocols of treatment, prevention and reversal using valproate (VAL) a humor stabilizer as standard drug to assess the effectiveness of CVD. In the prevention protocol the animals were pre-treated for 7 days with CVD, saline or VAL). In the reversal protocol the animals were pre-treated for 7 days with LDX and for further 7 days received CVD, saline or VAL plus LDX. The behavioral determinations of locomotor activity and social interaction were conducted 2 h after the last administration of LDX. Reduced glutathione (GSH) and lipid peroxidation (TBARS) levels were determined in brain areas of the prefrontal cortex (PFC) and striatum (EC) and brain-derived neurotrophic factor (BDNF) in the hippocampus (HC) rats. The results indicated that CVD prevented and reversed the hyperlocomotion and deficit in social contacts induced by LDX. In the neurochemical determinations CVD significantly prevented and reversed the alterations in BDNF, GSH and MDA levels induced by LDX presenting results comparable to those of saline and VAL groups. Therefore, the results of the present study indicates that CVD prevents reverts the behavioral and neurochemical alterations induced by LDX used as an animal model of mania being, thus, a potential drug for the treatment of BD.

A doenÃa de Parkinson (DP) à caracterizada pela degeneraÃÃo nigroestriatal, com depleÃÃo dopaminÃrgica, alteraÃÃes inflamatÃrias e oxidativas cerebrais levando a prejuÃzo no controle do movimento e coordenaÃÃo. Trabalhos recentes mostram que a atividade fÃsica em esteira pode ser benÃfica para estes pacientes, mas hà poucas evidÃncias avaliando os parÃmetros sanguÃneos relacionados, como estresse oxidativo e nÃveis de neurotrofinas. Assim, o presente estudo objetivou avaliar o impacto do treinamento da marcha atravÃs da esteira ergomÃtrica na capacidade funcional e marcadores de estresse oxidativo bem como os nÃveis de neurotrofinas em pacientes com DP. Tratou-se de ensaio clÃnico controlado, aberto e aleatorizado, de agosto de 2013 a fevereiro de 2014. IncluÃdos 22 indivÃduos com DP estÃgio II e/ou III, na escala de Hoehn e Yahr, acima de 40 anos, e que nÃo apresentaram quadro de demÃncia pelo Mini Teste do Estado Mental (escore> 21). ExcluÃdos os que apresentaram sinais de piora clÃnica apÃs o inicio do estudo com aumento no tremor Ãs atividades e com duas faltas consecutivas ao tratamento proposto ou trÃs no tempo total deste. Os pacientes foram aleatorizados em dois grupos: Grupo Controle (GC) e Grupo de IntervenÃÃo (GI). As avaliaÃÃes relacionadas à capacidade funcional (qualidade de vida, anÃlise estÃtica e dinÃmica da marcha) e parÃmetros sanguÃneos como peroxidaÃÃo lipÃdica (TBARS), glutationa reduzida (GSH) e fator neurotrÃfico derivado do cÃrebro (BDNF) foram realizadas antes e apÃs as oito semanas de intervenÃÃo. O GI iniciou o protocolo individualmente, com duas intervenÃÃes semanais na esteira ergomÃtrica, utilizando 80% da velocidade mÃxima encontrada no protocolo de Harbor, num total de 16 atendimentos. Jà o GC manteve-se somente com o tratamento medicamento previsto. Resultados foram avaliados pelo programa estatÃstico SPSS versÃo 17.0 e expressos como mÃdia  desvio padrÃo, sendo estatisticamente significante valores de p< 0,05. Os dados demogrÃficos dos grupos foram homogÃneos quanto Ãs variÃveis idade, gÃnero, altura, peso, tempo de doenÃa, teste mini mental e teste da escala de depressÃo. A qualidade de vida nÃo mostrou diferenÃas no coeficiente fÃsico sumarizado, entretanto no coeficiente mental sumarizado foi observado diferenÃa entre os grupos no perÃodo pÃs-intervenÃÃo (p=0,03), o SF-36 considera QV acima de 50 pontos. NÃo foram encontradas diferenÃas na superfÃcie do pà (P) direito (D) e esquerdo (E), nem na distÃncia dos pÃs em relaÃÃo ao barocentro, tambÃm nÃo houve diferenÃa na pressÃo mÃdia e mÃxima dos PD e PE, em ambos os grupos. Com relaÃÃo a variÃvel superfÃcie, viu-se diferenÃa no perÃodo prÃ-intervenÃÃo no PE (p=0,001). No perÃodo pÃs-intervenÃÃo houve diferenÃa na superfÃcie do PD (p=0,001), na oscilaÃÃo Ãntero-posterior do PE (0,01) e na oscilaÃÃo lÃtero-lateral do PD (p=0,01). Na velocidade da marcha foi encontrado, antes da intervenÃÃo, diferenÃa na velocidade mÃdia do PD (p=0,04). No GI, viu-se associaÃÃo forte entre BDNF e GSH com valores de significÃncia estatÃstica (r= 0,8; p=0,001), assim como entre BDNF e prÃtica de atividade fÃsica (r= 0,7; p=0,03). Conclui-se que a caminhada controlada na esteira melhora o equilÃbrio estÃtico, qualidade de vida e os nÃveis plasmÃticos de GSH em pacientes com DP. / Parkinson disease (PD) is characterized by nigrostriatal degeneration with consequent depletion of dopamine content in the striatum as well as brain inflammatory and oxidative alterations leading to movement and coordination impairment. Recent studies showed that physical exercise in the treadmill is benefic for PD patients although there is a lack in the literature of plasma alterations in oxidative stress parameters and neurotrophins in PD patients submitted to physical exercise. Based on this, the present study had the goal to evaluate the impact of controlled treadmill walking in the functional capacity and plasma levels of oxidative stress parameters and brain derived neurotrophic factor (BDNF) of PD patients. To do this, participants from both sexes were submitted to an open and randomized trial from august 2013 to February 2014. The participants were randomized in two groups control (CG) and intervention group (IG). The IG comprised PD patients in stage II and/or III, based on the Hoehn and Yahr scale. These patients were 40 years old or above and did not present dementia as evaluated by Mini-mental state examination (score> 21). Patients who presented signals of clinical worsening, such as increased tremor during activities, or presented two consecutive absences during the treatment or a total of three absences were excluded from the study. The evaluation related to the functional capacity (e.g. quality of life, static analyses and dynamic gait) and plasma parameters (lipid peroxidation, reduced glutathione (GSH) and BDNF were performed before and immediately after eight weeks of intervention. The IG group started the protocol individually with two weekly interventions in the treadmill with 80 % of maximum velocity based on the Harbor protocol in a total of 16 interventions. The CG was maintained only in drug treatment. The results were evaluated using the SPSS software version 17.0 considering differences when p<005. The demographic data were homogeneous based on the variables age, sex, weight, time of disease, mini-mental and depression tests. Quality of life did not present significant differences in the physical coefficient summarized, however in the mental coefficient summarized there was a difference between groups in the post intervention period (p= 0.03). There were no differences in the surface of right (RF) and left feet (LF) neither in the distance of the feet in relation to the barocenter. There was no alteration in the medium and maximal pressure of RF and LF. In relation to the variable surface, a significant difference in the period pre-intervention in the LF was observed (p= 0.001). In the period post-intervention there as a difference in the surface of RF (p= 0.001), in the antero-posterior oscillation of the LF (p= 0.01) and in the latero-lateral oscillation of the RF (p= 0.01). Regarding the gait velocity we observed before intervention a difference in the mean velocity of RF (p= 0.04). In the IG we observed a strong association before intervention between BDNF and GSH (r= 0,8; p=0,001), as well as between BDNF and physical activity (r= 0,7; p=0,03). We can conclude that controlled treadmill walking improves functional capacity of PD patients, accompanied by increased levels of antioxidant defenses.

MinistÃre de l'Enseignement SupÃrieur et de la Recherche / Pancreatite aguda (PA) à uma doenÃa inflamatÃria em que mediadores prÃ-inflamatÃrios, estresse oxidativo e sinalizaÃÃo de NF- kB desempenham um papel fundamental. O 1,8-cineol, um monoterpeno presente em diversas espÃcies vegetais, à conhecido por seu potencial antioxidante e anti-inflamatÃrio. Para verificar a sua eficÃcia na prevenÃÃo da PA, este estudo avaliou o 1,8-cineol (100, 200 e 400 mg / kg, v.o) na PA induzida por ceruleÃna (50 Âg / kg / h à 5, i.p.) em camundongos Swiss. O 1,8-cineol foi administrado uma hora antes da primeira injeÃÃo de ceruleÃna. Grupos tratados com veÃculo ou talidomida foram incluÃdos como controles. Seis horas depois, as amostras de sangue foram coletadas para determinar os nÃveis sÃricos de amilase, lipase e citocinas. O pÃncreas foi removido para exame morfolÃgico, ensaios de mieloperoxidase (MPO) e malondialdeÃdo (MDA), alteraÃÃes na glutationa reduzida (GSH) e para a imunocoloraÃÃo do fator nuclear NF-&#954;B. O pulmÃo direito foi removido para ensaio de MPO. O 1,8-cineol reduziu o dano histolÃgico e a expressÃo de NF-&#954;B induzidos por ceruleÃna. CeruleÃna aumentou significativamente a amilase, lipase, TNF-&#945;, IL1-&#946; e IL-6 e reduziu IL-10. O 1,8-cineol 100, 200 e 400 mg/kg reverteu significativamente os danos causados pela ceruleÃna, atravÃs da reduÃÃo da amilase (14; 16; 21%), lipase (49; 48; 42%), TNF-&#945; (46; 66; 44%), IL1-&#946; (53; 45 e 67%) e IL-6 (49; 40; 41%) e aumento da IL-10 (34; 29 e 46%), respectivamente. CeruleÃna produziu edema pancreÃtico, aumentou MDA, MPO pancreÃtica, MPO pulmonar e reduziu GSH em comparaÃÃo com o grupo veÃculo (p &#706; 0,05). O 1,8-cineol 100, 200 e 400 mg/kg reduziu o edema pancreÃtico (6; 27; 17 %), MDA (34; 29; 46 %), MPO pancreÃtica (40; 55 e 78 %), MPO pulmonar (42; 45 e 22 %) e preservou GSH (62; 63 e 65 %). Estes achados sugerem que o 1,8-cineol pode prevenir a severidade da pancreatite aguda induzida por ceruleÃna em camundongos por meio de um mecanismo anti-inflamatÃrio e antioxidante. / Acute pancreatitis (AP) is an inflammatory condition in which pro-inflammatory mediators, oxidative stress and NF-kB signaling have a fundamental role. The 1,8-cineole, a monoterpene present in several plants species, is known for its antioxidant and anti-inflammatory potential. In order to verify its efficacy preventing AP, this study evaluated 1,8-cineole (100, 200 and 400 mg/kg, oral) on AP induced by cerulein (50 Âg / kg / h à 5, i.p.) in Swiss mice. The 1,8-cineole was administrated one hour before the first injection of cerulein. Groups treated with vehicle or thalidomide were included as controls. Six hours later, blood samples were collected to determine blood levels of amylase, lipase and cytokines. The pancreas was removed for morphological examination, myeloperoxidase (MPO) and malondialdehyde (MDA) trials, changes in reduced glutathione (GSH) and for immunostaining of nuclear factor NF-&#954;B. The right lung was removed for MPO trial. The 1,8-cineole reduced the histological damage and the expression of NF-&#954;B induced by cerulein. Cerulein increased significantly amylase, lipase, TNF- &#945;, IL1- &#946; and IL-6, reducing IL-10. The 1,8-cineole 100, 200 and 400 mg/kg reversed significantly the damages caused by cerulein by reducing amylase (14; 16; 21 %), lipase (49; 48; 42 %), TNF-&#945; (46; 66; 44 %), IL1-&#946; (53; 45 e 67 %) e IL-6 (49; 40; 41 %) and enhanced IL-10 (34; 29 e 46 %), respectively. Cerulein produced pancreatic edema, increased MDA, pancreatic MPO, pulmonary MPO and decreased GSH comparing to the vehicle group (p < 0,05). The 1,8 cineole 100, 200 and 400 mg/kg reduced pancreatic edema (6; 27; 17%), MDA (34; 29; 46%), pancreatic MPO (40; 55 and 78 %), pulmonary MPO (42; 45 and 22 %) and preserved GSH (62; 63 and 65 %). These findings suggest that 1,8-cineol can prevent the severity of cerulein-induced acute pancreatitis in mice through an anti-inflammatory and antioxidant mechanisms.

No description available.

Parkinson's disease (PD) is a chronic, progressive disorder of the central nervous system that affects approximately 1.5 million Americans. One of the principal pathological features of PD is dopamine deficiency in the substantia nigra of the brain. A key enzyme that has been associated with the neurodegeneration seen in PD is monoamine oxidase-B (MAO-B). Several inhibitors of this enzyme have resulted in neuroprotection in the mouse model of PD. One such compound is 7-nitroindazole (1). This thesis describes the synthesis and MAO activity of several indazolyl and benzimidazolyl prodrugs that are designed to release an enzyme inhibitor in the affected brain area. These studies have provided information regarding the nucleophilic aromatic substitutions of the ambident nucleophiles under consideration. We have also discovered a compound that releases the enzyme inhibitor upon bioactivation by MAO. These results as well as a MPTP mouse study with the aforementioned compound are detailed within. / Master of Science

During peak lactation female mammals reach a limit in their maximal sustained energy intake (SusEI). The causes of such limits is disputed. In this thesis, I examined the causes of the limits on SusEI at peak lactation, and then explored the consequences of such limits for reproductive performance. Finally I tested a possible physiological mechanism that may underpin the trade-off between reproduction and somatic protection (the oxidative stress theory). To answer these questions, I studied reproductive performance and oxidative stress in two lines of mice previously selected for high and low food intake (MH and ML, respectively). I found that these mice reached a plateau in their food intake around day 13 of lactation. In support of the heat dissipation limits theory, reproductive performance in the MH mice was significantly higher than that of the ML mice. Oxidative damage is expected to be higher among lactating individuals. Moreover, lactating mice with greater reproductive performance are also predicted to experience more oxidative damage. By measuring multiple-markers of oxidative damage and protection in different tissues, I found that lactation resulted in reduced oxidative damage in both brain and serum. Additionally, it did not increase oxidative damage to proteins and DNA in liver. Moreover, multiple measures of oxidative stress in the mammary gland were not significantly different between mice with different reproductive effort. Furthermore, I found that lactating mice with greater reproductive performance (litter size and litter mass) had reduced protein damage in their livers and upregulated protection (HSP70) in their brains. These results were inconsistent with the oxidative stress theory. Finally, I employed a novel approach to assess oxidative stress differences with metabolomics analysis. I found that lactation resulted in significant differences in the metabolome. By focusing on the metabolites that are related to vi oxidative stress, I found that most of these metabolites measured in livers and brains were not affected by lactation which provides more evidence against the oxidative stress theory. My results provide support for the heat dissipation theory as a mechanism explaining the limits on reproductive performance. Moreover it provides comprehensive information against oxidative stress as a mediator of life history trade-offs.

Background: Myocardial infarction (MI) results in severe biochemical, physiological, and cellular changes that lead to alterations in the structure and function of the myocardium. Oxidative stress potentiates this remodeling response and is associated with progressive worsening of cardiac function. Accordingly, we used a powerful antioxidant-based therapeutic strategy to improve cardiac health and study redox-dependent signaling. Methods: MI was surgically induced in rats by ligating the left anterior descending coronary artery. Subgroups of MI rats received resveratrol (i.p., 10 mg/kg/day for 28 days beginning immediately post-MI). Cardiac histology and biochemical analyses of genes and proteins implicated in cardiac fibrosis, hypertrophy, and apoptosis, and redox-dependent signaling were analyzed. Results: As expected, MI resulted in profound structural changes to the myocardium. Further, we observed a sharp reduction in nuclear factor-erythroid 2-related factor 2 (Nrf2) and Krüppel-like factor 15 (KLF15), factors that are responsible for maintaining the endogenous antioxidant capacity and regulating cardiac gene expression, respectively. It is likely that disruption of normal KLF15 signaling permitted the expression of several cardiac genes associated with progressive cardiac remodeling. Importantly, daily treatment with resveratrol ameliorated cardiac remodeling, improved redox state, restored Nrf2 expression, and up-regulated KLF15 expression. Further, induction of KLF15 signaling following resveratrol treatment is associated with attenuated expression of several genes implicated in cardiac remodeling. Conclusions: Chronic oxidative stress potentiates cardiac remodeling post-infarct, in part, by suppressing Nrf2 and KLF15 expression. Importantly, we demonstrate that normal KLF15 signaling may be rescued with an antioxidant-based therapy, which may be an attractive therapeutic target to support cardiac health post-MI.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Previous studies in yeast in this laboratory have found carnitine to be both protective against oxidative stress induced by hydrogen peroxide and to increase the detrimental effect of dithiothreitol. These phenotypes were found to be independent of the role of carnitine within the carnitine shuttle. A screen for suppressor mutations for these carnitine-dependent phenotypes identified, among others, Δcho2 and Δopi3. Cho2p and Opi3p catalyse the sequential methylation reactions in the formation of phosphatidylcholine from phosphatidylethanolamine. Therefore, this study aimed to investigate the relationship between choline, phosphatidylcholine and the carnitine phenotypes. Liquid growth assays of Δcho2 and Δopi3 cultures revealed that addition of choline can restore the protective effects of carnitine against hydrogen peroxide. The connection between the cellular phospholipid composition and the carnitine-dependent shuttleindependent phenotypes was also investigated. Analysis of the lipid composition of cells by LCMS showed that Δcho2 and Δopi3 had a largely different lipid composition compared with the wild type, most notably, a reduction in phosphatidylcholine and an increase in triacylglycerol content were observed for both mutants. These changes were reversed by supplementation with choline. However, no effects on the lipid composition of cells in response to carnitine treatment were observed, either when supplemented alone or in combination with DTT and hydrogen peroxide. Carnitine has also been investigated in mammalian systems for its potential to protect cells from oxidative stress, an effect which would be of benefit in various neurodegenerative disorders. Several studies have documented the positive effects of carnitine against oxidative stress in mammalian cells however the mechanism behind this action remains unknown. It is therefore thought that, provided similar effects for carnitine can be shown in mammalian cells as was observed in yeast, it would be beneficial to use yeast as a model system for the study of the molecular changes induced by carnitine. In view of this, the effects of carnitine on toxicity induced by oxidative stress in mammalian neural cells were compared to that which has been observed in yeast. For this purpose the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, a measure of reductive capacity of cells, was used. However, no effects for carnitine were observed in the MTT assay in combination with either dithiothreitol or paraquat. / AFRIKAANSE OPSOMMING: Vorige studies op gis in hierdie laboratorium het bevind dat karnitien beskermend is teenoor oksidatiewe stres wat deur waterstofperoksied geïnduseer word en ook die nadelige effek van ditiotreitol verhoog. Hierdie fenotipes is gevind om onafhanklik te wees van die rol van karnitien binne die karnitien-pendel. Die sifting vir onderdrukker-mutasies van hierdie karnitienafhanklike fenotipes het onder andere Δcho2 en Δopi3 geïdentifiseer. Cho2p en Opi3p kataliseer die opvolgende metileringsreaksies tydens die vorming van fosfatidielcholien vanaf fosfatidieletanolamien. Hierdie studie het dus gepoog om die verhouding tussen cholien, fosfatidielcholien en die karnitienfenotipes te ondersoek. Vloeistofanalises van Δcho2- en Δopi3-kulture het aangedui dat die byvoeging van cholien die beskermende effekte van karnitien teenoor waterstofperoksied kan herstel. Die verband tussen die sellulêre fosfolipiedsamestelling en die karnitienafhanklike pendel-onafhanklike fenotipes is ook ondersoek. Die analise van die lipiedsamestelling van selle deur middel van LCMS het getoon dat Δcho2 en Δopi3 ‘n grootliks verskillende samestelling het in vergelyking met die wilde tipe, en daar is veral ‘n afname in fosfatidielcholien en ‘n verhoging in triasielgliserol-inhoud vir beide mutante waargeneem. Hierdie veranderinge is omgekeer deur aanvulling met cholien. Geen effekte op die lipiedsamestelling van die selle is egter in reaksie op die karnitienbehandelings waargeneem nie, hetsy toe dit alleen aangevul is of in kombinasie met ditiotreitol en waterstofperoksied. Karnitien is ook in soogdierstelsels ondersoek vir sy potensiaal om selle teen oksidatiewe stres te beskerm, ‘n effek wat groot voordeel sal inhou vir verskeie neurodegeneratiewe steurings. Verskeie studies het reeds die positiewe effekte van karnitien teen oksidatiewe stres in soogdierselle opgeteken, hoewel die meganisme agter hierdie werking nog onbekend is. Daar word dus vermoed dat, gegewe dat soortgelyke effekte vir karnitien in soogdierselle getoon kan word as wat in gis waargeneem is, dit voordelig sou wees om gis as ‘n modelsisteem vir die studie van die molekulêre veranderinge wat deur karnitien geïnduseer word, te gebruik. In die lig hiervan is die effekte van karnitien op giftigheid wat deur oksidatiewe stres in soogdiersenuselle geïnduseer is, vergelyk met dít wat in gis waargeneem is. Om hierdie rede is die 3-[4,5-dimetieltiasool-2-iel]-2,5-difeniel tetrasoliumbromied (MTT) essaiëring, ‘n meting van die verminderende kapasiteit van selle, gebruik. Geen effekte vir karnitien is egter met die MTT essaiëring in kombinasie met óf ditiotreitol óf parakwat waargeneem nie.