The effect of a high sucrose diet on ovarian morphology : an age-matched generational study

Foiret, Jaudon Ron (2019-03)

Thesis (MSc)--Stellenbosch University, 2019.

Thesis

ENGLISH ABSTRACT: Metabolic syndrome (MetS) is rapidly becoming an epidemic in society, affecting between 10% and 40% of Western populations. High-fat and refined sugar diets have been implicated in the increased prevalence of insulin resistance, obesity and dyslipidaemia, the hallmarks of MetS. Risk factors of MetS have been correlated with decreased reproductive potential and suboptimal pregnancy outcomes, while predisposing offspring to a MetS state in adulthood. Therefore, this study aimed to assess the effects of a high-sucrose diet on the reproductive potential and mating outcomes of albino Wistar rats, and their offspring using a foetal programming model. Female nulliparous albino Wistar rats (n=28) were randomly divided into a high-sucrose feed group (HSF) (n=19) and a control-feed group (CF) (n=9). All animals in this study were housed in standard rat cages in a temperature and humidity-controlled environment on a reverse 12-hour dark/light cycle with free access to water and respective feeds. Diets consisted of 68% carbohydrate consisting of either sucrose (HSF) or corn starch (CF). Maternal feeding commenced four weeks prior to mating with unexposed males. Maternal metabolic profile and mating outcomes were recorded. Maternal animals were euthanised and the ovaries harvested immediately after their offspring were weaned. The offspring were randomly divided into three groups; HSF/HSF (pups from HSF dam maintained on high-sucrose feed) (n=6), CF/CF (pups from CF dam maintained on control-feed) (n=6) and HSF/CF (pups from HSF dam and maintained on control-feed) (n=4). Pups were maintained on their respective feed for 10 weeks to achieve an age match comparison with dams. All animal’s ovaries were harvested, formalin-fixed and paraffin-embedded, routinely stained and histologically evaluated for follicle type and numbers, follicle development, and morphological changes. Results indicated no overt hyperglycaemia or obesity in any group, however a significant (p<0.01) decrease in mean body mass (MBM) was observed in the HSF and HSF/HSF groups when compared to their respective controls. Mating was deleteriously affected, with HSF dams birthing fewer and significantly lighter offspring. End point metabolic profiles of pups, indicated no significant differences in fasting blood glucose level, however the HSF/HSF MBM was found to be significantly decreased. An intermediate metabolic profile was observed in the HSF/CF group. Histological examination indicated a significant decrease in numbers of functional follicles in any sucrose feed group, with varying degrees of indicative morphological changes. Metabolic profiles of all animals, although not overtly pathological, displayed dysregulation in energy balance. This is hypothesised to be a result of adaptations in hepatic fructose metabolism and the protective effects of oestrogen. Effects on reproductive potential and ovarian morphology in this study appear to be as result of gonadotropic hormone dysregulation mediated by metabolic status. Foetal programming by means of highsucrose diet was confirmed in this study with HSF/CF being deleteriously affected despite control feed postnatal diet. This study demonstrated the deleterious effects of a high-sucrose diet on maternal reproductive health and its compounding effects on their offspring. Deductions from this research emphasise the importance of maternal diet beyond overt MetS risk factors and can be applied in family planning.

AFRIKAANSE OPSOMMING: Metaboliese sindroom (MetS) is vinnig besig om ʼn epidemie in die samelewing te word, en affekteer tussen 10% en 40% van Westerse populasies. Diëte met ʼn hoë vet en verfynde suikerinhoud word geïmpliseer by die kenmerke van MetS, naamlik ʼn toename in insulien weerstandigheid, vetsug en dislipidemie. Daar is verder ook ʼn korrelasie tussen die risikofaktore van MetS, ʼn afname in reproduktiewe potensiaal en ʼn sub-optimale uitkoms met swangerskap gevind, terwyl dit ook die nakomelinge predisponeer tot MetS as volwassenes. Die doelwit van die studie was om die effek van ʼn hoë sukrose dieet op die voortplantingspotensiaal en die uitkomste van paring in albino Wistar rotte, te bepaal, sowel as die effek op die nakomelinge met behulp van ʼn fetale programmeringsmodel. Vroulike, nullipareuse albino Wistar rotte (N=28) is lukraak ingedeel in ʼn hoë sukrose voedingsgroep (HSF) (n=19) en ʼn kontrole voedingsgroep (CF) (n=9). Alle diere in die studie is in standaard rothokke gehuisves, in ʼn temperatuur en humiditeit gekontroleerde omgewing met ʼn 12-uur donker/lig siklus, en met vrye toegang tot water en die onderskeie voere. Diëte het 68% koolhidrate bevat, wat bestaan het uit sukrose (HSF) of mieliestysel (CF). Voeding van vroulike diere het vier weke voor paring met manlike diere wat nie blootgestel is nie, begin. Vroulike diere se metaboliese profiele en die resultate van paring is aangeteken. Onmiddellik nadat die kleintjies gespeen is, is die vroulike diere getermineer en die ovaria geoes. Die kleintjies is lukraak in drie groepe verdeel; HSF/HSF (kleintjies vanaf HSF moeders is op hoë sukrose voedings behou) (n=6), CF/CF (kleintjies vanaf CF moeders het voortgegaan met kontrole voedings) (n=6), en HSF/CF (kleintjies vanaf HSF moeders het voortgegaan met kontrole voedings) (n=4). Kleintjies is vir 10 weke op die onderskeie voere gehou totdat ‘n ouderdom soortgelyk aan dié van die moederlike diere bereik is. Alle diere se ovaria is geoes, in formalien gefikseer en in paraffien ingebed, het roetine kleuring ondergaan, en is histologies geëvalueer vir tipe en aantal follikels, follikel ontwikkeling en morfologiese veranderinge. Resultate het geen uitgesproke hiperglisemie of obesiteit in enige groep getoon nie, maar ʼn betekenisvolle (p<0.01) afname in gemiddelde liggaamsmassa (MBM) is in die HSF en HSF/HSF groepe waargeneem, in vergelyking met die onderskeie kontroles. Paring is nadelig beïnvloed, met HSF moeders wat geboorte gegee het aan kleiner getalle kleintjies, met ʼn betekenisvolle laer geboortegewig. Eindpunt metaboliese profiele van die kleintjies het geen betekenisvolle verskille in vastende bloedglukosevlakke getoon nie, maar die HSF/HSF MBM was betekenisvol laer. ʼn Intermediêre metaboliese profiel is waargeneem in die HSF/CF groep. Histologiese ondersoek het ʼn betekenisvolle afname in die getal funksionele follikels in die groepe wat met sukrose gevoer is, getoon, met aanduidings van variërende grade van beduidende morfologiese veranderinge. Metaboliese profiele van alle diere het ʼn wangereguleerde energiebalans getoon, alhoewel nie uitermatig patologies nie. Die hipotese is dat dit die resultaat van aanpassings in fruktose metabolisme in die lewer, asook die beskermende effekte van estrogeen, is. Dit blyk uit die studie dat die effekte op die voortplantingspotensiaal en ovariale morfologie die gevolge van wanregulasie van die gonadotropiese hormone is, wat deur die metaboliese status bewerkstellig is. Fetale programmering deur middel van ʼn hoë sukrose dieet is in die studie bevestig, met HSF/CF wat nadelig geaffekteer is ten spyte van ʼn gekontroleerde postnatale dieet. Die studie toon die nadelige effekte van ʼn hoë sukrose dieet op die moederlike voortplantingsgesondheid, asook die saamgestelde effekte op die nakomelinge. Bo en behalwe uitgesproke MetS risiko faktore, beklemtoon gevolgtrekkings vanuit die navorsing die belang van die dieet wat deur die moeder gevolg word, en kan in gesinsbeplanning toegepas word.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/105682
This item appears in the following collections: