Name: KEVIN MESQUITA SILVA
Publication date: 14/12/2023
Examining board:
Name |
Role |
|---|---|
| ALESSANDRA SIMAO PADILHA | Advisor |
Summary: INTRODUCTION: Fructose excessive consumption, mainly with the introduction of
high fructose corn syrup by the food industry, has been associated with vascular
alterations. The absorption and metabolism of fructose differs from glucose and is not
subject to the same regulatory mechanisms, so fructose can be used as a substrate
for de novo lipogenesis, a factor that contributes to the increase in lipid fractions that
is associated with the development of cardiovascular diseases (CVD). CVD affects
men and women differently and ovarian hormones are thought to have a protective
effect on cardiovascular dysfunction. Although studies of chronic fructose
consumption are well studied, the short-term effects of high fructose consumption
have not yet been fully clarified.
OBJECTIVE: To determine the effects of acute fructose overload on the vascular
function of female rats submitted to ovariectomy or not. To describe the role of
perivascular adipose tissue and endothelium in the contractile responses of rat aorta
after 4 days of fructose overload.
MATERIAL AND METHODS: Female Wistar rats (n=52) underwent ovariectomy
(OVX) or sham surgery (SHAM). After recovery, they received a 10% (w/v) fructose
solution (Fr) or water (Ct) for 4 days. Body weight, chow consumption and plasmatic
glycaemia were measured. Afterwards, the thoracic aorta was dissected and cut into
rings segments that were mounted in an organ bath to detect changes in arterial wall
tension induced by increasing concentrations of the alpha1-adrenergic agonist,
phenylephrine (Phe). Maximum responses (Rmax) and pD2 (-logEC50) to Phe were
expressed as mean ± standard error of mean and compared using Student's t test
and two-way ANOVA between groups, with p<0.05 considered statistically significant.
RESULTS: Ovariectomy induced increase in chow consumption on Ct group.
Fructose overload induced increase in weight gain in OVX group (Weight:
12,10±1,99g) when compare to both SHAM Fr (Weight: 7,13±1,01g) and OVX Ct
(Weight: 4,42±0,57g), also both ovariectomy and fructose treatment, alone,
promoted increase in plasmatic glycaemia. Fructose overload reduced Rmax of OVX
group (Rmax PVAT+/E+: OVX Ct 96,47±7,07 OVX Fr 65,44±3,00) in intact aorta
segments. Without PVAT, fructose treatment resulted in a decrease in Rmax in both
groups (Rmax PVAT-/E+: SHAM Ct 97,23±4,05 SHAM Fr 69,23±3,33 and OVX Ct
86,54±2,71 OVX Fr 72,51±2,61). These difference in the contractile responses of
aortic rings without PVAT, were eliminated in the absence of endothelium (Rmax
PVAT-/E-: SHAM Ct 141,53±4,63 SHAM Fr 135,81±7,03 and OVX Ct 138,04± 4,28
OVX Fr 146,16±7,70). Incubation with catalase revealed that hydrogen peroxide
contraction modulation was exacerbated by fructose overload in both SHAM and OVX
groups with intact aortic rings. In all groups, removal of the endothelium induced an
increase in the contractile response, also incubation with L-NAME increase contractile
response in all groups, but Fr groups showed no alteration in sensitivity.
CONCLUSION: The results found indicate that fructose influences the anti-contractile
modulation exerted by the PVAT and the endothelial layer in the contraction induced
by Phe in isolated rings of the aorta of rats and ovarian hormones appear to have no
influence over these alterations in vascular function promoted by 4 days of fructose
overload. Furthermore, fructose consumption, even for short-time, was sufficient to
increase weight gain and plasmatic glycaemia.
