Vascular effects of cocoa shell extract supplementation in a rat model of fetal programming of hypertension

• Autores: Santiago Ruvira Hernando
• Directores de la Tesis: Silvia Magdalena Arribas Rodríguez (dir. tes.), David Ramiro Cortijo (dir. tes.)
• Lectura: En la Universidad Autónoma de Madrid ( España ) en 2024
• Idioma: inglés
• Número de páginas: 196
• Tribunal Calificador de la Tesis: M Ángeles Martín Cabrejas (presid.), Ana Belén García Redondo (secret.), Beatriz Somoza Hernández (voc.), José Fernando Magalhaes Pinto Pereira (voc.), José María González Granado (voc.)
• Programa de doctorado: Programa de Doctorado en Farmacología y Fisiología por la Universidad Autónoma de Madrid
• Calificación: Sobresaliente Cum Laude
• Materias:
  • Ciencias de la vida
    • Fisiología humana
      • Fisiología cardiovascular
  • Ciencias tecnológicas
    • Tecnología de los alimentos
      • Antioxidantes en los alimentos
• Enlaces
  • Tesis en acceso abierto en: Biblos-e Archivo
• Resumen

  • Introduction. Cardiovascular diseases (CVD) are the leading cause of morbidity and mortality in the world, with a high socio-health impact. Their development is associated with several risk factors, with hypertension standing out for its high prevalence worldwide. In addition, intrauterine quality of life has an important influence on the development of CVD and hypertension in the offspring, supported by epidemiological and experimental studies showing that an adverse intrauterine environment due to malnutrition, hypoxia or obstetric complications increases the susceptibility, a phenomenon known as fetal programming. The aetiology of arterial hypertension is largely unknown, although it is multifactorial in the majority of cases. However, there are common pathophysiological denominators, such as functional and structural alterations of resistance arteries, being oxidative stress a central mechanism. Management strategies for hypertension include lifestyle changes and pharmacological treatments, in many cases requiring more than one type of drug for effective blood pressure reduction. Therefore, supplementation with food- or plant-derived nutraceuticals with bioactive compounds is emerging as a non-pharmacological strategy. Cocoa has been shown to contain bioactive compounds such as methylxanthines (caffeine and theobromine) and flavonoids (catechin, epicatechin) that have beneficial cardiovascular and blood pressure-lowering effects. The cocoa industry generates large quantities of by-products, such as cocoa shell, which are usually discarded despite containing valuable bioactive compounds. Previous research on a cocoa shell extract (CSE) has shown that it possesses antioxidant, anti-inflammatory and vasodilatory effects in vitro. Hypothesis and aims. This thesis hypothesises that CSE supplementation in rats has antihypertensive effects. The main objectives are to evaluate the effect of CSE supplementation in an animal model of programmed hypertension, exploring the structural and functional changes in resistance mesenteric arteries (MRA) and its possible antioxidant mechanism of action. Materials and methods. The study used male and female Sprague Dawley rats of 8-10 months of age, which were offspring from control rats or rats with 50% reduced intake during the second half of gestation (maternal undernutrition, MUN). A voluntary supplementation protocol based on gelatine cubes was developed, establishing which parameters influenced acceptance, 12 latency to ingestion and recall to training. Subsequently, supplementation groups were formed with vehicle gelatine (control-VEH; MUN-VEH), or with CSE at a dose of 250 mg/kg/day (control-CSE; MUN-CSE), administered for 3 weeks. Systolic blood pressure was measured before and after supplementation; vascular function (wire myography) and vascular structure and mechanics (pressure myography) were studied in vitro in the MRA; redox status was assessed in plasma and arteries (confocal microscopy, spectrophotometry and western blotting). Results. Fasting for 4 hours significantly reduced latency to gelatine ingestion and rats were able to recall the training after 1 month, establishing the supplementation protocol. Male MUN rats: 1) developed hypertension, 2) MRA showed reduced AMPK-dependent and soluble guanylate cyclase vasodilator responses, evidencing a vasoconstrictor prostanoid, 3) MRA developed hypotrophic inward remodelling with increased stiffness, related to an elevation of collagen, 4) plasma oxidative damage, increased O2.- in MRA and reduced expression of Nrf2 in aorta. CSE supplementation in males: 1) had an antihypertensive effect, 2) normalised vascular dysfunction, 3) reversed structural alterations inducing hypertrophic outward remodelling with normal wall/lumen ratio and reduced fibrosis, 4) decreased O2.- production and increased Nrf2 expression, without elevation in antioxidant enzyme expression. MUN females showed inward eutrophic remodelling without functional, mechanical or oxidative alterations and CSE had similar effects as males on remodelling and reduced O2.- production. Conclusions. Supplementation with CSE reverses programmed hypertension in male rats, through an improvement of several endothelium-dependent and endothelium-independent pathways, and reduction of stiffness in resistance arteries, effects mediated, at least in part, by the reactive oxygen species-scavenging capacity of its bioactive components and inhibition of superoxide anion production. Cocoa shell could be used for the development of nutraceuticals as a strategy to reduce hypertension and contributing to the circular economy.