Influence of saturated high-fat diet on cardiac morphology in obesity-prone and resistant animals
Name: VINÍCIUS VALOIS PEREIRA MARTINS
Publication date: 28/04/2022
Advisor:
Name |
Role |
|---|---|
| ANA PAULA LIMA LEOPOLDO | Co-advisor * |
| ANDRÉ SOARES LEOPOLDO | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| ANA PAULA LIMA LEOPOLDO | Co advisor * |
| ANDRÉ SOARES LEOPOLDO | Advisor * |
| ÉRICA AGUIAR MORAES | Internal Alternate * |
| FABIANO KENJI HARAGUCHI | Internal Examiner * |
Summary: The prevalence of obesity has grown rapidly and represents one of the main
challenges to public health. Excess body mass contributes to the
establishment of comorbidities such as diabetes, arterial hypertension and
dyslipidemia. These morbidities associated with obesity, induce cardiac
hypertrophy and accumulation of interstitial collagen, being harmful to
cardiac physiology. However, some animals and humans, even consuming
hypercaloric and hyperlipidic diets, have the ability to resist the
phenomenon of hyperphagia and body fat gain, a condition that we call Obesity
Resistance. Few studies have investigated the cardiac morphological effects
of high fat diets saturated at the expense of lard, in the face of Obesity
Resistance condition. Thus, the purpose of the study was to investigate the
influence of a saturated high-fat diet on cardiac morphology in obesity-prone
and resistant animals. The hypothesis of our study is that Obesity-Resistant
(ROb) animals present cardioprotection against pathological cardiac
remodeling due to greater sensitivity to insulin and the hormone leptin.
Wistar rats (n =71), aged 30 days, were initially randomized into two groups:
a) DP: fed a standard diet (n = 35) and b) DHS: fed a saturated high-fat diet
(n = 36). The experimental protocol consisted of 2 two moments: induction (4
weeks) and maintenance of obesity (10 weeks), totaling 14 consecutive weeks.
Using the tertile criterion, using body mass (after the onset of obesity),
the animals were redistributed into 3 groups: Control (C), Obese (Ob) and
ROb. The food intake variables evaluated were: food consumption, caloric
intake and feed efficiency. Body composition was measured through body mass
and fat, in addition to the adiposity index. Metabolic alterations were
investigated by the glucose tolerance test, measurements of serum insulin and
leptina levels, and the insulin resistance index (HOMA-IR). The total mass of
the heart, right and left ventricles, atrium and their respective
relationships with the tibia length, as well as the cross-sectional area
(AST) and myocardial collagen, were determined to identify the absence or
presence of cardiac hypertrophy. The pathophysiological damage was measured
from the quantification of the enzymes creatine kinases (CK) and its subunit
MB and lactate dehydrogenase (LDH). The results were statistically evaluated
using ANOVA (one- and two-way) and complemented with Tukey`s multiple
comparison test, with a significance level of 5%. Caloric intake, feed
efficiency, final body mass, visceral, retroperitoneal and epididymal fat
pads, as well as the adiposity index were higher in the Ob and Rob groups in
relation to C; however, ROb showed a statistical difference in relation to
the Ob for food consumption and caloric intake (ROb < Ob), as well as for
body adiposity parameters (ROb < Ob). These findings demonstrate that ROb
rats presented an intermediate characteristic between the Ob and C groups.
The area under the glycemic curve, HOMA-IR, serum insulin and leptin, total
cholesterol and HOMA-IR and HDL were higher in the groups exposed to DHS,
regardless of the condition resistance or propensity to obesity. However,
there was no significant difference in triglycerides in the Ob and ROb groups
in relation to the C group. The Ob and ROb groups presented higher
statistically values of total heart mass, LV, RV and their respective
relationships with the tibia length, as well as AST and myocardial collagen
in relation to C, characterizing a process of cardiac hypertrophy in both
groups undergoing DHS. The cardiac damage biomarker CK-MB was significantly greater in the two experimental groups undergoing DHS. In conclusion, the results indicate that both obesity-prone and resistant animals present cardiac hypertrophy combined with the accumulation of interstitial collagen, in addition to changes in glucose sensitivity and elevation of biomarkers of cardiac damage.
