Patchareewan Pannangpetch’s research while affiliated with Khon Kaen University and other places

Objectives__ Aqueous extract of Moringa oleifera leaves (MOE) is a potent inducer of endothelium-dependent relaxation of mesenteric resistance arteries of rats induced to be hypertensive using Nω-nitro-L-arginine methyl ester (L-NAME). Hydrogen sulfide (H2S) has been shown to participate in endothelium-dependent relaxation of small resistance arteries. Therefore, this study aimed to investigate whether endothelial H2S-dependent signaling plays a role in the vasorelaxation in response to MOE. Methods__ Mesenteric arterial beds isolated from L-NAME hypertensive rats were set up in an ex vivo perfusion system for measurement of vasoreactivity. All experiments were performed in the presence of the nitric oxide synthase inhibitor, L-NAME (100 µM) and the cyclooxygenase inhibitor, indomethacin (10 µM) to prevent the formation of nitric oxide and prostanoids, respectively. Results__ In the presence of the nitric oxide synthase inhibitor, L-NAME and the cyclooxygenase inhibitor, indomethacin, the endothelium-dependent vasorelaxation induced by MOE (0.001–3 mg) was completely inhibited by DL-propargylglycine (100 µM), which inhibits the H2Sgenerating enzyme, cystathionine γ-lyase. This H2S dependent response was reduced by the KATP channel blocker; glibenclamide (10 µM), the KCa channel blocker; tetraethylammonium (1 µM), and the myo-endothelial gap-junctional uncoupler; 18α-glycyrrhetinic acid (10 µM). In contrast, the muscarinic receptor antagonist, atropine (100 µM), did not affect the response to MOE. Conclusions__ The results may suggest that H2S is the likely mediator of endothelium-dependent relaxation in response to MOE in mesenteric arterial beds of L-NAME-induced hypertensive rats. MOE-induced H2S-dependent vasorelaxation involves activation of KATP and KCa channels and requires myo-endothelial gap-junctional communication.

A mass of evidence has identified a promoting of nitric oxide (NO) production in endothelial cells using natural products as a potential strategy to prevent and treat hypertension. This study investigated whether the aqueous extract of Moringa oleifera leaves (MOE) could lower mean arterial pressure (MAP) and relax mesenteric arterial beds in rats via stimulating endothelium-derived NO production. Intravenous administration of MOE (1-30 mg/ kg) caused a dose-dependent reduction in MAP in anesthetized rats. In rats pretreated with the NO-synthase inhibitor, N ω-nitro-L-arginine methyl ester (L-NAME, 30 mg/kg, i.v.), the effect of MOE on MAP was significantly reduced. MOE (0.001-3 mg) induced relaxation in methoxamine (10 μM) pre-contracted mesenteric arterial beds, which was abolished by endothelium denudation. This endothelium-dependent vasorelaxation was reduced by L-NAME (100 μM) or the NO-sensitive guanylyl cyclase inhibitor, 1H-[1,2,4]-oxadiazolo-[4,3-a]-quinoxalin-1-one (10 μM). In primary human pulmonary artery endothelial cells, MOE (3-30 μg/mL) induced NO production, which was inhibited by L-NAME (100 μM) pretreatment. These findings show that MOE stimulates the endothelium-derived NO release for driving its vasorelaxation to lower arterial blood pressure. These suggest the development of MOE as a natural antihypertensive supplement.

Background__An aqueous extract of Moringa oleifera leaves (MOE) is known to cause relaxation of mesenteric resistance arteries of rats in which hypertension has been induced by the administration of L-NAME, but the mechanism(s) of action of MOE remains unclear. The purpose of this study was to investigate these mechanisms in mesenteric arterial beds isolated from L-NAME induced hypertensive rats. Methods__An investigation of vascular reactivity was conducted on isolated mesenteric arterial beds by measuring the changes in perfusion pressure using an in vitro system. Results__MOE (0.001–3 mg in 0.1 ml injection volume) caused a dose-dependent relaxation in methoxamine (5 µM) pre-contracted arterial beds, which was partially abolished by endothelium removal. The endothelium-dependent component of vasorelaxation was insensitive to both L-NAME (100 µM) and indomethacin (10 µM), while completely inhibited in high KCl (45 mM)-induced contraction. MOE (1 and 3 mg/ml) showed a dose-dependent inhibitory effect on CaCl2-induced contractions of denuded preparations in Ca²⁺-free medium containing a high KCl (60 mM) or methoxamine (10 µM). In Ca²⁺-free medium, MOE (3 mg/ml) also inhibited phenylephrine-induced contractions of denuded preparations. Conclusion__These findings suggest that MOE relaxes mesenteric arterial beds of L-NAME hypertensive rats via both endothelium-dependent and endothelium-independent mechanisms. The endothelium-dependent action occurred via endothelium-derived hyperpolarizing factor-mediated hyperpolarization. The endothelium-independent action was related to blocking the entry of extracellular Ca²⁺ via voltage-operated and receptor-operated Ca²⁺ channels, and inhibiting mobilization of sarcolemmal Ca²⁺ via inositol trisphosphate receptor Ca²⁺ channels. MOE may be potentially useful as a natural vasodilator against hypertension. Keywords: Calcium antagonist; Hyperpolarization; Hypertension; Moringa; Vasodilator.

Background__ Enhancing relaxation of resistance arteries and decreasing oxidative stress by using natural products are potential strategies for prevention and treatment of hypertension. Purpose__ This study investigated whether aqueous extract of Moringa oleifera leaves (MOE) could alleviate Nω-nitro-L-arginine-methyl ester (L-NAME)-induced high blood pressure via modulation of vascular function and antioxidant properties. Methods__ An experimental hypertensive model was established by administration of L-NAME (50 mg/kg/day) in drinking water to male Wistar rats for 3 weeks. Arterial pressure was measured indirectly by tail-cuff plethysmography and directly via femoral artery catheterization. Vasoreactivity of isolated rat mesenteric arterial bed was determined by the changes in perfusion pressure detected by a pressure transducer. Vascular superoxide anion (O2•−) production was determined by lucigenin-enhanced chemiluminescence. Other biochemical measurements including malondialdehyde (MDA) level, superoxide dismutase (SOD), and catalase (CAT) activities were measured by colorimetric assay. Results__ L-NAME-treated rats developed significantly increased blood pressure and heart rate. Concurrent oral treatment with MOE (30 and 60 mg/kg/day) could decrease the high blood pressure and tachycardia in a dose-dependent manner. MOE reduced the impairment of acetylcholine-induced relaxation and decreased the hyperreactivity of adrenergic-mediated contraction in response to periarterial nerve stimulation and phenylephrine in isolated mesenteric arterial beds. In addition, MOE exhibited antioxidant effects in the hypertensive rats, as indicated by suppression of vascular O2•− production, decrease of plasma and thoracic aorta MDA levels, and increase of antioxidant activities of SOD and CAT. Moreover, MOE (0.001-3 mg) produced a dose-dependent relaxation in methoxamine pre-contracted arterial beds isolated from L-NAME hypertensive rats, which was abolished by endothelium denudation. Conclusion__ These findings suggest that the antihypertensive effect of MOE in L-NAME-hypertensive rats may be mediated by alleviating vascular dysfunction and oxidative stress and promoting endothelium-dependent vasorelaxation. MOE may be potentially useful as a natural product against hypertension. Keywords: Antihypertensive effect, L-NAME, Mesenteric artery, Moringa oleifera, Oxidative stress, Vascular dysfunction

Complications arising from infection with the carcinogenic liver fluke Opisthorchis viverrini cause substantial morbidity and mortality in Thailand and adjacent lower Mekong countries. In parallel, the incidence rate of diabetes mellitus (DM) is increasing in this same region, and indeed worldwide. Many residents in opisthorchiasis-endemic regions also exhibit DM, but the hepatobiliary disease arising during the co-occurrence of these two conditions remains to be characterized. Here, the histopathological profile during co-occurrence of opisthorchiasis and DM was investigated in a rodent model of human opisthorchiasis in which diabetes was induced with streptozotocin. The effects of excretory/secretory products from the liver fluke, O. viverrini (OVES) on hepatocyte and cholangiocyte responses during hyperglycemic conditions also were monitored. Both the liver fluke-infected hamsters (OV group) and hamsters with DM lost weight compared to control hamsters. Weight loss was even more marked in the hamsters with both opisthorchiasis and DM (OD group). Hypertrophy of hepatocytes, altered biliary canaliculi, and biliary hyperplasia were more prominent in the OD group, compared with OV and DM groups. Profound oxidative DNA damage, evidenced by 8-oxo-2'-deoxyguanosine, proliferating cell nuclear antigen, and periductal fibrosis characterized the OD compared to OV and DM hamsters. Upregulation of expression of cytokines in response to infection and impairment of the pathway for insulin receptor substrate (IRS)/phosphatidylinositol-3-kinases (PI3K)/protein kinase B (AKT) signaling attended these changes. In vitro, OVES and glucose provoked time- and dose-dependent effects on the proliferation of both hepatocytes and cholangiocytes. In overview, the co-occurrence of opisthorchiasis and diabetes exacerbated pathophysiological damage to the hepatobiliary tract. We speculate that opisthorchiasis and diabetes together aggravate hepatobiliary pathogenesis through an IRS/PI3K/AKT-independent pathway.

Constriction and relaxation of resistance arteries are the important mechanisms for maintaining normal blood pressure. Functions of perivascular nerves that innervate vascular walls enable prompt alteration of total peripheral resistance. Rat mesenteric arteries have been used as a model for the study of the pathophysiological and pharmacological aspects of roles of nervous system in the function of resistance arteries. Mesenteric arteries are innervated by several types of nerve fibers including adrenergic, CGRPergic, nitrergic, and cholinergic nerves. The ability of each type of nerve in controlling vascular function depends on the type of neurotransmitter as well as nerve fiber density. Neurotransmitters may be released and act directly on vascular smooth muscle cells or indirectly by modulating presynaptic function on axons of the same or different types of nerve fibers. Dysfunction of certain types of nerve fibers may be related to abnormal blood pressure. Therefore, understanding the nature of these nerve fibers would be helpful in the development of antihypertensive medication which specifically acts on perivascular nerves of resistance arteries. https://li01.tci-thaijo.org/index.php/SRIMEDJ/article/view/115795/89333

Moringa oleifera leaf extract decreases arterial blood pressure and vascular reactivity to adrenergic stimulation in L-NAME hypertensive rats Direk Aekthammarat, Patchareewan Pannangpetch and Panot Tangsucharit* Department of Pharmacology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand *Corresponding author: pantan@kku.ac.th Abstract Sympathetic overactivity resulting in increased total peripheral resistance plays a major role in pathogenesis of hypertension. Moringa oleifera is a tropical plant distributed in Thailand. The leaf of M. oleifera is used in Thai food as well as folk medicine for treatment of many diseases including cardiovascular problems. This study aimed to investigate the preventive effect of aqueous leaf extract of M. oleifera (MOE) on hemodynamic status and adrenergic reactivity in Nω-nitro-L-arginine-methylester (L-NAME) induced hypertensive rats. Male Wistar rats were administered daily with L-NAME (50 mg/kg/day) in drinking water for three weeks. On the last day, hemodynamic measurements on anesthetized rats were done via femoral artery catheterization. They developed significant increases in systolic and diastolic blood pressure (SBP and DBP), and heart rate (HR). Isolated mesenteric vascular reactivity to adrenergic stimulation, a selective α1-adrenoceptor agonist; phenylephrine (Phe; 0.01-1 mmol) and perivascular nerve stimulation (PNS; 2-16 Hz) were significantly increased. Concurrent orally treatment with MOE at doses of 30 and 60 mg/kg/day caused the decreases in SBP, DBP and HR. MOE administration resulted in dose-dependent reduction of hyper-reactivity of vascular response to Phe. Moreover, MOE-treatment at both doses significantly reduced the hyper-reactivity to PNS to the normal levels. It can be concluded that MOE has an antihypertensive activity in L-NAME induced hypertensive rats. The antihypertensive effect may be due to its suppressing activity on adrenergic hyperactivity of resistance vascular bed. This result suggests that MOE may be useful as a dietary supplement against hypertension and could probably alleviate sympathetic symptoms. Keywords: Moringa oleifera, blood pressure, adrenergic reactivity, hypertension