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Characterisation of high fat, high sugar diet-induced epigenetic changes in skeletal muscle of wistar rats and metabolic effects of an aspalathin-rich rooibos extract
Thesis (PhD)--Stellenbosch University, 2021.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2021
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| _version_ | 1867613940381384704 |
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| access_status_str | Open Access |
| author | Myataza, Asive |
| author2 | Pheiffer, Carmen |
| author_browse | Myataza, Asive Pheiffer, Carmen |
| author_facet | Pheiffer, Carmen Myataza, Asive |
| author_sort | Myataza, Asive |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2021. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/123580 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:44:07.837Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2021 |
| publishDateRange | 2021 |
| publishDateSort | 2021 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/123580 Characterisation of high fat, high sugar diet-induced epigenetic changes in skeletal muscle of wistar rats and metabolic effects of an aspalathin-rich rooibos extract Myataza, Asive Pheiffer, Carmen Willmer, Tarryn Windvogel, Shantal Johnson, Rabia Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences: Medical Physiology. UCTD Epigenetics Obesity -- Diet therapy Aspalathus Rooibos tea DNA Thesis (PhD)--Stellenbosch University, 2021. Background Animal models are widely used to elucidate the pathophysiological mechanisms that underlie obesity and to test the efficacy of anti-obesity therapeutics. However, these models have been largely biased towards males, partly due to the complexity of hormonal fluctuations in females. The primary aim of this study was to elucidate DNA methylation profiles and gene regulatory networks that are altered in the skeletal muscle during the development of obesity in female and male Wistar rats, and to explore whether Afriplex-GRT™ could prevent aberrant DNA methylation patterns and the progression of metabolic disease. Methods Different animal models were employed where female and/or male Wistar rats were fed a standard or a high fat, high sugar (HFHS) diet for 12, 3 or 9 months. The effect of rooibos was investigated in the latter model, where 60 mg/kg of bodyweight Afriplex-GRTTM was co-administered with the diets. Parameters measured included food and water intake, bodyweight, and glucose, insulin, lipid and cytokine concentrations. Skeletal muscle was harvested for histology, gene expression measured using RT2 Profiler™ PCR arrays and Taqman® assays and global and gene-specific DNA methylation were quantified using pyrosequencing. To further explore the effects of DNA methylation, high glucose and fatty acids on skeletal muscle, C2C12 myocytes were differentiated with 7 μM 5-azacytidine, a global DNA methylation inhibitor, 33 mM glucose and 0.5 mM palmitate. Mitochondrial activity and oxidative stress were measured using appropriate assays. Myoblast differentiation and the expression of myoblast determination protein 1 (MyoD), myosin heavy chain 1 (Myh1), insulin growth factor 2 (Igf2), sterol regulatory element binding transcription factor 1 (Srebf1) and DNA methyltransferase 1 (Dnmt1) were assessed. Results The HFHS diet induced visceral adiposity and hypertriglyceridaemia in both male and female rats, while hyperinsulinaemia and significant bodyweight gain was observed in male rats, and systemic inflammation in females only. These changes were accompanied by increased expression of Igf2 and decreased expression of Srebfb1 and Dnmt1 in skeletal muscle of male, but not female rats. No differences in DNA methylation patterns were observed. Treatment with Afriplex-GRT™ did not ameliorate HFHS diet-induced metabolic dysregulation. In C2C12 cells, treatment with 5-azacytidine induced myoblast differentiation and MyoD and Myh1 expression, while palmitate inhibited differentiation and decreased the expression of MyoD, Myh1, Igf2 and Srebf1, which was restored by 5-azacytidine. High glucose increased Igf2 expression but did not affect Srebf1 expression, while a combination of high glucose and 5- azacytidine decreased Srebf1 and Dnmt1 expression. Conclusion The HFHS diet induced different metabolic responses and gene expression patterns in females and males. In general, females exhibited a dampened metabolic response, which we presume may be due to the intrinsic protective effects of female reproductive hormones. Afriplex-GRTTM did not prevent HFHS diet-induced weight gain, which contrasts previous findings where treatment with 60 mg/kg Afriplex-GRTTM decreased bodyweight in obese male rats, suggesting that Afriplex-GRTTM may be better targeted as a therapeutic than a preventative nutraceutical. This study provides novel information on how molecular differences in skeletal muscle may contribute to sex differences in response to HFHS feeding and may have important implications for the identification of therapeutic targets. Agtergrond Dieremodelle word wyd gebruik om die patofisiologiese meganismes wat onder vetsug lê, toe te lig en om die doeltreffendheid van terapie teen vetsug te toets. Hierdie modelle was egter grotendeels bevooroordeeld teenoor mans, deels as gevolg van die kompleksiteit van hormonale fluktuasie in wyfies. Die primêre doel van hierdie studie was om DNA-metileringsprofiele en genetiese reguleringsnetwerke wat in die skeletspier verander word, toe te lig tydens die ontwikkeling van vetsug by wyfies en mannetjie Wistar-rotte, en om te ondersoek of Afriplex-GRT ™ afwykende DNA- metileringspatrone en die vordering van metaboliese siektes kan voorkom. Metodes Verskillende diermodelle is gebruik waar vroulike en / of manlike Wistar-rotte 'n standaard- of 'n hoë vet, hoë suiker (HFHS) dieet vir 12, 3 of 9 maande gevoer het. Die effek van rooibos is in laasgenoemde model ondersoek, waar 60 mg / kg liggaamsgewig Afriplex-GRTTM saam met die diëte toegedien is. Parameters wat gemeet is, het voedsel- en waterinname, liggaamsgewig en glukose-, insulien-, lipied- en sitokienkonsentrasies ingesluit. Skeletspiere is geoes vir histologie, geenuitdrukking met behulp van RT2 Profiler™ PCR-skikkings en Taqman®-toetse en globale en geen-spesifieke DNA-metilering is gekwantifiseer met behulp van pirosekvensering. Om die effekte van DNA-metilering, hoë glukose en vetsure op die skeletspier verder te ondersoek, is C2C12 miosiete gedifferensieer met 7 μM 5- azacytidine, 'n globale DNA-metileringsremmer, 33 mM glukose en 0.5 mM palmitaat. Mitochondriale aktiwiteit en oksidatiewe stres is gemeet met behulp van toepaslike toetse. Mioblast differensiasie en die uitdrukking van mioblast bepaling proteïen 1 (MyoD), miosien swaar ketting 1 (Myh1), insulien groeifaktor 2 (Igf2), sterol regulatoriese element bindende transkripsiefaktor 1 (Srebf1) en DNA metieltransferase 1 (Dnmt1) is assesseer. Resultate Die HFHS-dieet het visserale adipositeit en hipertrigliseridemie by rotte geïnduseer, terwyl hiperinsulinemie en 'n beduidende toename in liggaamsgewig by manlike rotte waargeneem is, en slegs sistemiese ontsteking by wyfies. Hierdie veranderinge het gepaard gegaan met verhoogde uitdrukking van Igf2 en verminderde uitdrukking van Srebfb1 en Dnmt1 in skeletspiere van manlike, maar nie vroulike rotte nie. Geen verskille in DNA-metilering is waargeneem nie. Behandeling met Afriplex- GRT ™ het nie die HFHS dieet-geïnduseerde metaboliese wanregulasie verbeter nie. In C2C12-selle het behandeling met 5-azasytidien mioblastdifferensiasie en MyoD en Myh1-uitdrukking veroorsaak, terwyl palmitaat differensiasie inhibeer het, sowel as die uitdrukking van MyoD, Myh1, Igf2 en Srebf1 verminder het, wat herstel is deur 5-azacytidine. Hoë glukose het die Igf2-uitdrukking verhoog, maar het nie die Srebf1-uitdrukking beïnvloed nie, terwyl 'n kombinasie van hoë glukose en 5-azasitidien die Srebf1- en Dnmt1-uitdrukking verminder het. Afsluiting Die HFHS-dieet het verskillende metaboliese reaksies en geenuitdrukkingspatrone by wyfies en mannetjies veroorsaak. Oor die algemeen het wyfies 'n gedempte metaboliese reaksie vertoon, wat ons vermoed die gevolg is van die intrinsieke beskermende effekte van vroulike voortplantingshormone. Afriplex-GRTTM het nie die gewigstoename wat deur HFHS-dieet veroorsaak word, verhoed nie, wat die vorige bevindings kontrasteer waar behandeling met 60 mg/kg Afriplex-GRTTM die liggaamsgewig verlaag het by vetsugtige manlike rotte, wat daarop dui dat Afriplex-GRTTM beter geteiken kan word as terapeuties as 'n voorkomende voedingsmiddel. Hierdie studie bied nuwe inligting oor hoe molekulêre verskille in skeletspiere kan bydra tot geslagsverskille in reaksie op HFHS-voeding en dat dit belangrike implikasies kan hê vir die identifisering van terapeutiese teikens. Doctoral 2021-05-28T10:45:12Z 2021-12-22T14:10:39Z 2021-05-28T10:45:12Z 2021-12-22T14:10:39Z 2021-12 Thesis http://hdl.handle.net/10019.1/123580 en_ZA Stellenbosch University 167 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | UCTD Epigenetics Obesity -- Diet therapy Aspalathus Rooibos tea DNA Myataza, Asive Characterisation of high fat, high sugar diet-induced epigenetic changes in skeletal muscle of wistar rats and metabolic effects of an aspalathin-rich rooibos extract |
| title | Characterisation of high fat, high sugar diet-induced epigenetic changes in skeletal muscle of wistar rats and metabolic effects of an aspalathin-rich rooibos extract |
| title_full | Characterisation of high fat, high sugar diet-induced epigenetic changes in skeletal muscle of wistar rats and metabolic effects of an aspalathin-rich rooibos extract |
| title_fullStr | Characterisation of high fat, high sugar diet-induced epigenetic changes in skeletal muscle of wistar rats and metabolic effects of an aspalathin-rich rooibos extract |
| title_full_unstemmed | Characterisation of high fat, high sugar diet-induced epigenetic changes in skeletal muscle of wistar rats and metabolic effects of an aspalathin-rich rooibos extract |
| title_short | Characterisation of high fat, high sugar diet-induced epigenetic changes in skeletal muscle of wistar rats and metabolic effects of an aspalathin-rich rooibos extract |
| title_sort | characterisation of high fat high sugar diet induced epigenetic changes in skeletal muscle of wistar rats and metabolic effects of an aspalathin rich rooibos extract |
| topic | UCTD Epigenetics Obesity -- Diet therapy Aspalathus Rooibos tea DNA |
| url | http://hdl.handle.net/10019.1/123580 |
| work_keys_str_mv | AT myatazaasive characterisationofhighfathighsugardietinducedepigeneticchangesinskeletalmuscleofwistarratsandmetaboliceffectsofanaspalathinrichrooibosextract |