ABSTRACT
Hibiscus sabdariffa Linn. or also known as roselle which is rich in polyphenols, has been demonstrated to cause loweringof blood pressure in animal and clinical settings. However its exact mechanism of action particularly from polyphenoliccompounds is not clearly understood. Therefore, we aimed to determine the effects of H. sabdariffa polyphenol extract(HPE) towards vascular reactivity and its mechanism of action. The HPE was studied on isolated thoracic aortic ringsfrom normal Sprague-Dawley rats, suspended in a 15-ml organ chambers containing Krebs-Henseleit solution. Thechanges in tension were recorded by isometric transducer connected to data acquisition. HPE relaxed the contractioninduced by phenylephrine (PE, 1 μM) in similar pattern for both endothelium-intact and endothelium denuded aorticrings in dose-dependent manner 0.1 ~ 0.9 mg/ml. The pretreatment with atropine (1 μM), a competitive muscarinicantagonist, and propranolol (1 μM), a non-selective beta- blocker did not alter HPE vasorelaxation response. In addition,HPE did not inhibit the contraction induced by extracellular Ca2+ precontracted by PE (1 μM) or KCl (60 mM), in Ca2+-free solution, suggesting that the relaxation effect of HPE was not via inhibition of calcium channels. In conclusion,HPE demonstrated vasorelaxation effects on rat thoracic aorta although the underlying mechanism is still unknown.The vasorelaxation effect could be via angiotensin type 1 receptor inhibition in the vascular smooth muscle cells or theactivation of hyperpolarizing K+ chan
ABSTRACT
Nowadays, probiotics have been widely consumed as supplementary food for their health benefits. However, safetyevaluation for many probiotic bacteria is still lacking. Furthermore, health benefits conferred by probiotics depend onthe strains used in producing probiotic products. Therefore, it is important to examine oral toxicity of newly isolatedLactobacillus casei (Lb. casei) C1. A total of 32 Wistar (WIS) rats were divided into acute (single dose) and subacuteoral toxicity (28-days repeated dose) groups. Rats in each group were further divided into control group which receivedphosphate buffer saline (PBS) orally and treatment group that was administered orally with Lb. casei C1 (1011 CFU/ml).For acute oral toxicity, treatment was performed on day-1 and the effects were monitored subsequently for 14 days. Forsubacute oral toxicity, treatment was given daily for 28 days and the effects were observed throughout the experimentalperiod. Body weight, food and water intake of the rats were recorded. Rats in acute and subscute groups were sacrificedon day-15 and day-29, respectively. Serum was collected to determine the levels of total protein, malondialdehyde (MDA),alanine transaminase (ALT), aspartate transaminase (AST), lactate dehydrogenase (LDH) and creatinine. Organs were alsoharvested for histological examination. There were no significant differences (p > 0.05) in body weight, food and waterintake between the control and treated rats in acute oral toxicity group. There were also no significant differences in theblood cell count, levels of total protein, MDA, LDH and creatinine between the control and treated rats. Similar findingswere recorded for the subacute oral toxicity group, except that the levels of ALT and AST which were significantly different(p < 0.05). When observed under a light microscope, there were no morphological changes detected in the kidney, liverand ileum of treated rats as compared to control rats in both of the experimental groups. In conclusion, Lb. casei C1exhibited no toxic effects in Wistar rats hence safe to be consumed orally.
ABSTRACT
Hypertension can be caused by various factors while the predominant causes include increase in body fluid volume and resistance in the circulatory system that elevate the blood pressure. Consumption of probiotics has been proven to attenuate hypertension; however, the effect is much strain-dependent. In this study, a newly isolated Lactobacillus casei (Lb. casei) strain C1 was investigated for its antihypertensive properties in spontaneously hypertensive rats (SHR). Lactic acid bacteria (LAB) suspension of 11 log colony-forming unit (CFU) was given to SHR (SHR+LAB, n=8), and phosphate buffer saline (PBS) was given as a control in SHR (SHR, n=8) and in Wistar rats as sham (WIS, n=8). The treatment was given via oral gavage for 8 weeks. The results showed that the weekly systolic blood pressure (SBP), mean arterial pressure (MAP), diastolic blood pressure (DBP) and aortic reactivity function were remarkably improved after 8 weeks of bacterial administration in SHR+LAB. These effects were mostly attributed by restoration of wall tension and tensile stress following the bacterial treatment. Although not statistically significant, the level of malondialdehye (MDA) in SHR+LAB serum was found declining. Increased levels of glutathione (GSH) and nitric oxide (NO) in SHR+LAB serum suggested that the bacterium exerted vascular protection through antioxidative functions and relatively high NO level that induced vasodilation. Collectively, Lb. casei strain C1 is a promising alternative for hypertension improvement.
Subject(s)
Arterial Pressure , Bacteria , Blood Pressure , Body Fluids , Glutathione , Hypertension , Lactic Acid , Lacticaseibacillus casei , Lactobacillus , Nitric Oxide , Probiotics , Rats, Inbred SHR , Rats, Wistar , Stem Cells , VasodilationABSTRACT
Disturbances in immune system contribute to chronic infection among diabetic patients. Hibiscus sabdariffa L. (roselle) fruit extract has been scientifi cally proven to possess antioxidant, antidiabetic and antiinfl ammatory properties. The aim of this study was to investigate the effects of H. sabdariffa fruit extract against oxidative stress parameter and T lymphocyte population in spleen of streptozotocin (STZ) induced diabetic rats. Male Sprague-Dawley rats were injected with 45 mg/kg STZ to induce diabetic condition and further treated with 100 mg/kg H. sabdariffa fruit aquoeus extract daily for 28 days. Spleen was harvested to determine the oxidative stress indicators and quantifi cation of T lymphocytes. The results showed a signifi cant decreased in the number of spleen cells and spleen weight in the diabetic rats compared with control rats. However, there were no signifi cant changes in the level of malondialdehyde (MDA), protein carbonyl and superoxide dismutase (SOD) activity the percentage of spleen CD3+ CD4+ and CD3+ CD8+ T lymphocytes amongst groups of study. In addition, histology observation showed no pathological alteration in spleen histology of diabetic rats. The fi ndings suggested that aqueous extract of H. Sabdariffa fruit supplementation has no effect on the oxidative stress and the percentage of CD3+ CD4+ and CD3+ CD8+ T lymphocytes in spleen of diabetic rats
ABSTRACT
Vascular remodelling is an adaptive mechanism, which counteracts pressure changes in blood circulation. Nicotine content in cigarette increases the risk of hypertension. The exact relationship between nicotine and vascular remodelling still remain unknown. Current study was aimed to determine the effect of clinically relevant dosage of nicotine (equivalent to light smoker) on aortic reactivity, oxidative stress markers and histomorphological changes. Twelve age-matched male Sprague-Dawley rats were randomly divided into two groups, i.e.: normal saline as control or 0.6 mg/kg nicotine for 28 days (i.p., n=6 per group). On day-29, the rats were sacrificed and the thoracic aorta was dissected immediately for further studies. Mean arterial pressure (MAP) and pulse pressure (PP) of nicotine-treated vs. control were significantly increased (p<0.05). Nicotine-treated group showed significant (p<0.05) increase tunica media thickness, and decrease in lumen diameter, suggesting vascular remodelling which lead to prior hypertension state. The phenylephrine (PE)-induced contractile response in nicotine group was significantly higher than control group (ED50=1.44x10(5) M vs. 4.9x10(6) M) (p<0.05~0.001). However, nicotine-treated rat showed significantly lower endothelium-dependent relaxation response to acetylcholine (ACh) than in control group (ED50=6.17x10(7) M vs. 2.82x10(7) M) (p<0.05), indicating loss of primary vascular function. Malondialdehyde (MDA), a lipid peroxidation marker was significantly higher in nicotine group. Superoxide dismutase (SOD) enzymatic activity and glutathione (GSH) were all reduced in nicotine group (p<0.05) vs. control, suggesting nicotine induces oxidative imbalance. In short, chronic nicotine administration impaired aortic reactivity, probably via redox imbalance and vascular remodelling mechanism.