Proceedings of The Physiological Society

Physiology 2016 (Dublin, Ireland) (2016) Proc Physiol Soc 37, PCB174

Poster Communications

Role of high fat diets on AngII and oxytocin metabolism in hypothalamus

A. Segarra1, M. Martínez-Cañamero1, M. Ramírez-Sánchez1, I. Prieto1

1. Health Sciences, University of Jaén, Jaén, Spain.

Obesity is one of the most important nutritional problems in developed countries. Usually, it is associated with an increase in the prevalence of hypertension and cardiovascular diseases, the primary cause of worldwide mortality. Obesity and hypertension have been widely related to the intake of high fat diets, and both seem to be associated with changes in brain Renin Angiotensin System (RAS), specifically with an increase in hypothalamic Ang II levels (de Kloet et al, 2014), and changes in others related peptides, as oxytocin. However, not all fat sources seem to show the same effects on health, and Virgin Olive Oil (EVOO), the main fat source in the Mediterranean Diet, have demonstrated beneficial effects on cardiovascular disease and hypertension (Villarejo et al 2015). On the other hand, dietary fatty acids are able to change the brain fatty acid composition, and modulate the activity of different peptidase activities (Segarra et al., 2011). The main objective of this work was to analyse the possible effects of two high fat diets, with different fat source, on AngII and oxytocin metabolism, and their relationships with body adiposity and arterial blood pressure. Male Swiss Webster mice were divided in three groups (n=9). One group was fed with a standard chow diet (Control group), and the other two with a high fat diet, but supplemented with different sources at 20%: butter (Butter group) or Virgin Olive Oil (EVOO group). Animals were fed during three months in ad libitum conditions and, at the end of the experimental period, were sacrificed under anaesthesia, and samples of hypothalamus were taken out. Only Butter group showed high levels of BP and visceral adipose tissue amount. When the hypothalamus samples of these animals were analysed, the expression of Aminopeptidase A (1,71±0,279 relative RNA level; p<0,05) and IRAP (2,75±0,438 relative RNA level; p<0,01) were both increased, but the activity was lower for Aminopeptidase A(3256±207,5 vs 3579±159,8 pmol/mg prot/min; p<0,05). We did not find significant differences in AngII (31,6±3,36 vs 26,8 ± 2,84 pg/mL) and oxytocin levels (49,3±25,25 vs 9,9±3,91 pg/mL) compared with control, although the medium values were higher in Butter group. However, no significant changes were found in hypothalamic Aminopeptidase A (1,01±0,154 relative RNA level) and IRAP (2,03±0,350 relative RNA level) expression or activities (3256±207,5 and 6976±349,8 pmol/mgprot/min; respectively), or in AngII (28,1±3,80 pg/mL) and oxytocin (36,4±15,20 pg/mL) levels in EVOO group compared with Control. Taken together, these results support the role of hypothalamic RAS in the development of obesity and hypertension induced by diet, and the specific effects of different fat sources; showing the protective effect of Virgin Olive Oil, characterized by its elevated amount of monounsaturated fatty acids and polyphenols.

Where applicable, experiments conform with Society ethical requirements