Avaliação dos efeitos da associação entre nitrato de sódio e lactobacillus plantarum wjl para o tratamento da aterosclerose em camundongos fêmeas knockout para apolipoproteína E

Abstract

Atherosclerosis is a pathology that is associated with increased cholesterol levels and is considered one of the main causes that lead to the development of cardiovascular diseases. Its pathogenesis is characterized by the formation of plaques (atheromas) along the arteries, stimulated by an inflammatory process. Inflammation occurs due to damage to arterial walls caused by several risk factors such as diabetes, hypertension and hypercholesterolemia. The inorganic nitrate is widely available in the diet and can be found in green leafy vegetables and beets. In the nitrate-nitrite-NO pathway, nitrate is reduced to nitrite by bacteria present in the oral cavity. When it reaches the stomach, the nitrite is reduced to nitric oxide. The nitric oxide is important for vascular homeostasis, since it induces the relaxation of vessels, thus preventing the adhesion of cellular elements and decreasing inflammation. Through this action, nitric oxide acts as an anti-atherogen, being fundamental in the genesis of atherosclerosis. Probiotics are living organisms that bring health benefits to their host and are present in the intestines of healthy people. Recent studies demonstrate its possible ability to prevent atherosclerosis by reducing total cholesterol, LDL and triglycerides. The present study evaluated the effects of the association between inorganic nitrate and orally administered probiotic for the treatment of atherosclerosis in female apolipoprotein E knockout mice. Mice of the C57BL/6 and apoE-/- strain were used, where the apoE-/- ones received an atherogenic diet from 8 weeks of age. The treatments lasted 12 weeks and consisted of inorganic nitrate (NaNO3) diluted in water (10mM) and probiotic (Lactobacillus plantarum WJL) administered by gavage (109 CFU/mL). Thus, the animals were divided into five groups: C57BL/6, control apolipoprotein E knockout (apoE-/- CT), apolipoprotein E knockout treated with inorganic nitrate (apoE-/- NT), apolipoprotein E knockout treated with probiotic (apoE-/- PB) and apolipoprotein E knockout treated with inorganic nitrate and probiotic (apoE-/- NT+PB). Serum was used to measure total cholesterol. The aorta was collected to assess the deposition of atherosclerotic plaques. To perform glucose tolerance test (GTT) and insulin tolerance test (ITT), a drop of blood was collected from the tip of the animals’ tail through an incision. The apoE-/- CT (n = 7) mice showed a 9-fold increase in total cholesterol level compared to C57BL/6 (n = 9) (816 ± 3.1 mg/dL vs. 90 ± 7.2 mg/dL) and nitrate had a hypocholesterolemic effect (619 ± 92 mg/dL vs. 619 ± 92 mg/dL, (n = 4)). In addition, the association of nitrate + probiotic was able to reduce the deposition of atherosclerotic plaques (13 ± 0.98% (n = 6) vs. 5.2 ± 0.72% (n = 9)). The groups C57BL/6 and apoE-/- CT showed similar glycemic profiles but the groups treated with probiotic and with the association peaked at 15 minutes of the glucose tolerance test curve, returning to baseline values over time. However, none of the treatments changed the insulin tolerance test. Thus, it is concluded that treatment with nitrate is sufficient to reduce cholesterol in atherosclerosis, however the association of nitrate and probiotic is necessary for an efficient reduction of atherosclerotic plaques.