Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Although antiretroviral treatment decreases HIV-AIDS morbidity/mortality, long-term effects include onset of insulin resistance and cardiovascular diseases. Increased oxidative stress and dysregulation of the ubiquitin-proteasome system (UPS) are implicated in protease-inhibitor (PI)-mediated cardio-metabolic pathophysiology. We hypothesized that PI treatment (Lopinavir/Ritonavir) elevates myocardial oxidative stress and concomitantly inhibits the UPS, thereby attenuating cardiac function. Lopinavir/Ritonavir was dissolved in 1% ethanol (vehicle) and injected into mini-osmotic pumps that were surgically implanted into Wistar rats for eight weeks vs. vehicle and sham controls. Subsequently, we evaluated metabolic parameters and heart function (ex vivo and in vivo methods) at baseline and following ischemia-reperfusion. PI-treated rats exhibited weight gain, increased serum LDL-cholesterol, higher tissue triglycerides (heart, liver), but no evidence of insulin resistance. It also upregulated hepatic gene expression of acetyl-CoA carboxylase β and 3-hydroxy-3-methylglutaryl-CoA-reductase, key regulators of fatty acid oxidation and cholesterol synthesis, respectively. Further, PI-treated hearts displayed impaired UPS, increased superoxide dismutase (SOD) activity and unaltered superoxide levels, and elevated peroxisome proliferator-activated receptor-γ coactivator 1-α (PGC-1α) peptide levels. Perfusion data revealed contractile dysfunction at baseline and following ischemia-reperfusion, while post-ischemic hearts exhibited decreased ATPase specific activity vs. matched controls. Early changes initiated by PI treatment resemble the metabolic syndrome and reflect a pre-atherogenic profile. Moreover, the effects of PIs on cardiac contractile function may in part be triggered by impaired UPS activity together with strain on the mitochondrial energetic system. Our study alerts to cardio-metabolic side effects of PI treatment and raises the question of the most appropriate co-therapies for patients on chronic antiretroviral treatment. / AFRIKAANSE OPSOMMING: Alhoewel anti-retrovirale behandeling MIV-VIGS morbiditeit/mortaliteit verlaag, bestaan daar langtermyn effekte soos die aanvang van insulienweerstandigheid en kardiovaskulêre siektes. Verhoogde oksidatiewe stres en wanregulering van die ubikwitien-proteosoomsisteem (UPS) word geïmpliseer met protease-inhibeerder (PI) gemediëerde kardio-metaboliese patofisiologie. Ons hipotetiseer dat PI behandeling (Lopinavir/Ritonavir) miokardiale oksidatiewe stres verhoog, en gevolglik die UPS inhibeer waardeur dit kardiale funksie verander. Lopinavir/Ritonavir is in 1% etanol (draer) opgelos en in ‘n mini-osmotiese pomp ingespuit wat chirurgies in Wistar rottes ingeplant is vir agt weke vs. draer en valskontroles. Gevolglik het ons die metabolise parameters en hartfunksie (ex vivo en in vivo metodes) op basislyn en na afloop van ischemie-reperfusie ondersoek. PI-behandelde rotte het ‘n toename in massa getoon asook verhoogde serum LDL-cholesterol, hoër weefseltrigliseriede (hart, lewer), maar geen bewys van insulienweerstandigheid nie. Dit het ook hepatiese asetielko-ensiem A karboksilase β en 3-hidrokise-3-metielglutariel KoA reduktase geenuidrukking opwaarts gereguleer, wat sleutel reguleerders van vetsuuroksidasie en cholesterolsintese onderskeidelik is. Verder, het PI-behandelde harte ingeperkte UPS, verhoogde SOD aktiwiteit en onveranderde superoksiedvlakke vertoon, asook verhoogde peroksisoomproliferator-geaktiveerde reseptor-γ ko-aktiveerder 1-α (PGC-1α) peptiedvlakke. Perfusie data toon kontraktiele wanfunskionering gedurende basislyn en na afloop van ischemie-reperfussie, terwyl post-ischemiese harte verlaagde ATPase spesifieke aktiwiteit vs gepaarde kontrole vertoon. Vroeë veranderinge wat deur PI behandeling veroorsaak word, kom ooreen met die metabolise sindroom en reflekteer op ‘n pre-aterogeniese profiel. Bowendien kan die effekte van PIs op kardiale kontraktiele funksie deels veroorsaak word deur die ingeperkte UPS aktiwiteit tesame met die las op die mitochondriale energie sisteem. Ons studie waarsku teen kardio-metaboliese newe effekte met PI behandeling en rig die vraag; wat die mees gepaste ko-behandeling vir pasiënte op chroniese anti-retrovirale behandeling is.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/85782 |
| Date | 12 1900 |
| Creators | Reyskens, Kathleen Maria Simone Elise |
| Contributors | Essop, M. Faadiel, Stellenbosch University. Faculty of Science. Dept. of Physiological Sciences. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Format | 203 p. : ill. |
| Rights | Stellenbosch University |
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