Avaliação dos efeitos da suplementação com Lactobacillus acidophilus LA – 05 nos parâmetros cardiovasculares de animais hipertensos

Abstract

Intestinal dysbiosis is characterized by an imbalance in the intestinal microbiota and has been related to hypertension. Benefits in blood pressure modulation are observed after changes in dietary components aimed at modulating the microbiota with the use of probiotics. Probiotics are defined as “live microorganisms which, when administered in adequate amounts, benefit the congenital health of the host”. The genus Lactobacillus has important effects on the cardiovascular system by decreasing blood pressure in spontaneously hypertensive humans and animals, in addition to promoting an improvement in dysbiosis. Therefore, our objective was to evaluate the effects induced by supplementation with Lactobacillus acidophilus LA-5 on the cardiovascular system of spontaneously hypertensive rats (SHR). For this, spontaneously hypertensive and Wistar Kyoto (WKY) rats were used. The animals were divided into three groups: 1. Normotensive control (WKY), 2. Hypertensive (SHR), and 3. Hypertensive + LA5 (SHR+LA5). After the onset of hypertension, the animals received daily the suspension of Lactobacillus acidophilus (109 log CFU/animal) for a period of 8 weeks orally. The implantation of catheters towards the abdominal aorta and inferior vena cava was performed to record blood pressure and heart rate, baroreflex assessment and autonomic function of the animals. Then, the animals were euthanized and plasma was collected for assessment of oxidative stress. The superior mesenteric artery was collected for vascular reactivity assays. Values are expressed as mean ± standard error of mean (s.e.m). Differences were considered significant when p<0.05. The program used was GraphPad Prism version 8.00®. As a result, we could observe that oral supplementation with LA-5 for 8 weeks reduced the diastolic blood pressure of the SHR+LA5 group when compared to SHR group (122.0±4.3 versus 153.0±6.7 mmHg, p<0.05), but there was no difference in systolic blood pressure in mean blood pressure. LA-5 supplementation did not alter the heart rate of the animals. Regarding autonomic activity, the SHR+LA5 group showed a decrease in the LF (low-frequency oscillatory component of blood pressure related to sympathetic activity) component, indicative of sympathetic activity, when compared with the SHR group (7.38±0.22 versus 9.5±0.75%, p<0. 05). The HF (oscillatory component of highfrequency blood pressure related to parasympathetic activity) component and the LF/HF (sympathovagal balance) ratio did not change. The baroreflex was assessed in an induced manner, with the aid of vasoactive substances, and spontaneously. Oral supplementation with LA-5 for 8 weeks was effective in improving the sensitivity of the induced baroreflex when comparing the SHR+LA5 and SHR groups (-2.48±0.32 versus -0.94±0.09 bpm.mmHg-1, p<0.05), but also improved the sensitivity of the spontaneous baroreflex (0.77±0.1 versus 0.44±0.04 ms.mmHg-1, p<0.05). LA-5 supplementation was also able to reduce malondialdehyde levels when comparing the SHR+LA5 and SHR groups (33.78±161 versus 60.45±2.89 nmol/mL, p<0.05, respectively). With regard to vascular reactivity, the SHR group showed an impairment in the relaxation profile induced by acetylcholine with a reduction in the maximum effect compared to the WKY group (71.35±9.37 versus 94.18±3.32%, p<0.05) and LA-5 supplementation was able to improve relaxation (SHR+LA5: 111.23±6.45%, p<0.05). Interestingly, LA-5 improved the maximum relaxing effect induced by sodium nitroprusside when compared to the SHR and SHR+LA5 groups (134.40±4.02% versus 106.41±5.52, p<0.05). Supplementation had no impact on the contraction profile induced by phenylephrine (Emax - WKY: 100.28±9; SHR: 113.17±12.9; and SHR+LA5: 97.47±12.5%). Together, the findings point to L. acidophilus LA-5 as a potential adjuvant in the management of hypertension, since it promoted a reduction in diastolic blood pressure, combined with a reduction in sympathetic hyperactivity, an improvement in baroreflex sensitivity and endothelial dysfunction and the reduction of oxidative stress.