Investigating the cardiovascular effects of antiretroviral drugs in a lean and high fat/sucrose diet rat model of obesity : an in vivo and ex vivo approach

Everson, Frans Pieter (2016-03)

Thesis (MSc)--Stellenbosch University, 2016.

Thesis

ENGLISH ABSTRACT: Introduction: An interaction exists between cardiovascular risk factors (e.g. obesity) and antiretroviral treatment (ART) in the pathogenesis of cardiovascular disease. While ART reverses HIV- related weight loss, studies investigating ART effects in the context of obesity are lacking. Objective: To investigate the effects of Odumine® (first-line fixed ART-drug combination) on several cardio-metabolic parameters in a high fat/sucrose diet (HFD) rat model of obesity. Methods: Groups: Lean, untreated (C/-ART); HFD, untreated (HFD/-ART); Lean, treated (C/+ART); HFD, treated (HF/+ART). Sample size: n = 28 - 34 / group; male Wistar rats. The HFD feeding programme followed for 16 weeks and ART treatment programme for the last 6 weeks of HFD feeding programme. The Endpoints measured included: Food and water consumption for the first 31 days during the drug treatment programme; Biometric measurements: Total body mass (TBM), intra-peritoneal (IP) fat mass, heart mass and liver mass; Blood and serum: Glucose, insulin, total cholesterol (TC), triglycerides (TGs); Thiobarbituric acid reactive substance (TBARS) and conjugated dienes (CD); Isolated heart perfusion: Functional recovery (Global ischaemia-reperfusion) and infarct sizes (Regional ishcaemia-reperfusion); Western blot (Pre- and post-ischaemia-reperfusion): Nitric oxide synthase (NOS) signalling (eNOS, PKB/Akt and AMPK), indicators of reactive oxygen species (ROS) (Nitrotyrosine and p22 phox) and an indicator of pro-inflammatory NF-κB signalling (IκBα) in heart tissue. Results: The HFD was validated by increases in TBM, IP fat mass and heart mass. The HFD was further validated by increased TG and TBARS levels (lipid peroxidation). Pre-ischaemia-reperfusion, the HFD was associated with reduced oxidative stress (nitrotyrosine and p22 phox) vs. C/-ART. Reduced oxidative stress was associated with increased activation of the pro-inflammatory NF-κB pathway. The HFD upregulated eNOS post-ischaemia- reperfusion, downregulated PKB/Akt and increased NF-κB activation. Lastly, the HFD was associated with reduced functional recovery vs. C/-ART and HF/+ART, and increased infarct size vs. C/-ART and HF/+ART. ART treatment did not affect the food and water consumption, was associated with reduced insulin levels vs. C/-ART and HF/+ART, increased TC levels vs. C/-ART and elevated levels of oxidative stress (increased TBARS) vs. C/-ART. Pre-ischaemia- reperfusion, ART improved oxidative stress in heart tissue (reduced p22 phox) vs. C/-ART and reduced inflammation (downregulated IκBα). Post-ichaemia-reperfusion, ART upregulated eNOS in the heart tissue, downregulated PKB/Akt and increased oxidative stress (nitrotyrosine) vs. C/-ART. ART per se did not affect functional recovery or infarct size. The HFD combined with ART increased liver mass vs. HF/-ART. Pre-ischaemia- reperfusion, HFD/+ART improved oxidative stress (decreased nitrotyrosine and p22 phox) vs. HF/-ART, but decreased NF-κB activation vs. HF/-ART. Post-ischaemia-reperfusion, ART combined with HFD upregulated eNOS, downregulated PKB/Akt and increased oxidative stress (p22 phox) vs. HF/-ART and C/+ART. Post-ischaemia-reperfusion, ART with HFD seemed to improved functional recovery vs. HF/-ART and ameliorated the increased infarct size vs. HF/-ART. Discussion and Conclusion: Our study demonstrates the detrimental effect of HFD/obesity on cardiovascular health. Interestingly, when combined with ART, cardiovascular function seem to be improved vs. HFD/-ART. ART alone, affected cardiovascular health to a lesser extent in our study vs. HF/-ART and HF/+ART, and did not affect functional recovery and infarct size vs. C/-ART at all.

AFRIKAANSE OPSOMMING: Inleiding: ‘n Interaksie bestaan tussen kardiovaskulêre risikofaktore (bv. vetsug) en antiretrovirale behandeling (ART) in die ontwikkeling van kardiovaskulêre siekte. Terwyl ART HIV- verwante gewigsverlies kan omkeer, is daar min bekend oor ART-effekte in die konteks van vetsug. Doelstelling: Om die effekte van Odumine® (eerste-linie ART-middel kombinasie) op verskeie kardio- metaboliese parameters in ‘n hoë vet/sukrose dieet (HFD) rotmodel van vetsug te bepaal. Metodes: Groepe: Kontrole/geen ART (C/-ART); HFD/geen ART (HFD/-ART); Kontrole/met ART (C/+ART); HVD/met ART (HF/+ART). Aantal proefdiere: n = 28-34/groep; manlike Wistar rotte. Die HFD voedingsprogram was 16 weke lank en ART was gedurende die laaste 6 weke van die voedingsprogram daagliks toegedien. Die Eindpunte was: Voedsel- en waterinname vir die eerste 31 dae van die middeltoedieningsprogram; Biometriese metings: Totale liggaamsmassa (TLM), intra- peritoneale (IP) vetmassa, hart- en lewermassa; Bloed and serum: Glukose, insulien, totale cholesterol (TC), triglisseriede (TGs); “Thiobarbituric acid reactive substance” (TBARS) and gekonjugeerde diëne (CD); Geisoleerde hartperfusies: Funksionele herstel (Globale isgemie-herperfusie) and infarkgrootte (Regionale isgemie-herpurfusie); Western blot (Voor- na na-isgemie-herperfusie): Stikstofoksied sintase (NOS) seintransduksie (eNOS, PKB/Akt en AMPK), merkers van reaktiewe suurstofspesies (ROS) (Nitrotirosien en p22 phox) en ‘n merker van pro-inflammatoriese NF-κB seintransduksie (IκBα). Resultate: Die HFD is bevestig deur ‘n betekenisvolle toename in die TLM, IP vetmassa en hartmassa. Die HVD was verder bevestig deur die toename in die TG en TBARS vlakke (lipiedperoksidasie). Die HFD was geassosieer met verlaagde eindpunte van oksidatiewe stres in die hartweefsel (nitrotirosien and p22 phox) versus C/-ART. Verlaagde oksidatiewe stres was met verhoogde NF- κB aktivering geassosieer. Isgemie-herperfusie het eNOS in die HFD hartweefsel opgereguleer, PKB/Akt afgereguleer en NF- κB aktivering verhoog in die HFD groep. Laastens was die HFD was geassosieer met verlaage funksionele herstel versus C/-ART en HF/+ART, en verhoogde infark grootte versus C/-ART en HF/+ART. ART toediening het geen effek op die voedsel- en waterinname gehad nie, was geassosieer met verlaagde insulienvlakke versus C/-ART en HF/+ART, verhogde TC vlakke versus C/-ART, en verhoogde oksidatiewe stres (verhoogde TBARS) versus C/- ART. Voor blootstelling aan isgemie-herperfusie, het ART-toediening oksidatiewe stres in hartweefsel verlaag (verlaagde p22 phox) versus C/-ART en pro-inflammatoriese NF- κB aktivering verhoog (afgereguleerde IκBα). Na blootstelling aan isgemie-herperfusie het ART-toediening eNOS opgereguleer, PKB/Akt afgeruguleer en oksidatiewe stres verhoog (nitrotirosien) versus C/-ART. ART het geen effek op funksionele herstel of infark grootte gehad nie. ART-toediening aan HFD diere het die lewermassa verhoog versus HF/-ART. Voor isgemie-herperfusie blootstelling, het ART-toediening in HFD diere oksidatiewe stres verbeter (verlaagde nitrotirosien and p22 phox) versus HF/-ART, maar NF-κB aktivering verlaag versus HF/-ART. Na isgemie-herperfusie-blootstelling, het ART-toedining in HFD diere eNOS opgereguleer, PKB/Akt afgereguleer en oksidatiewe stres verhoog (p22 phox) versus HF/-ART en C/+ART. Verder was die funksionele herstel beter en die infark-grootte kleiner na isgemie-herperfusie in die HFD-groep. Bespreking en Gevolgtrekking: Ons studie het die skadelike effekte van HFD/vetsug op kardiovaskulêre gesondheid gedemonstreer. ‘n Interessante waarneming was dat die kombinasie van vetsug met ART tot n mate kardiovaskulêre funksie verbeter het versus HFD/-ART. ARV self het kardiovaskulêre gesondheid tot ‘n mindere mate geaffekteer versus HF/-ART en HF/+ART, en het nie funksionele herstel en infarkt grootte in kontrole diere geaffekteer nie.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/98532
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