[Electroacupuncture at "Taichong"(LR3) improves baroreflex sensitivity and α2-adrenergic receptor activity in nucleus tractus solitarii of hypertensive rats].

OBJECTIVE: To investigate the effect of electroacupuncture (EA) at "Taichong"(LR3) on blood pressure, sympathetic nerve activity, baroreflex sensitivity, and α 2-adrenergic receptor (α2AR) expression in nucleus tractus solitarii (NTS) in hypertensive rats, so as to reveal its mechanisms underlying improvement of hypertension. METHODS: Male Sprague Dawley rats were randomly divided into 4 groups: sham-operation, model, EA, and sham-EA (non-acupoint) groups, with 12 rats in each group. The hypertension model was established by occlusion of the right renal aorta (two-kidney-one clip method). Rats of the sham-operation group received the same surgery but without occlusion of the renal artery. EA (2 Hz/15 Hz, 2 mA) was applied to bilateral LR3 for 30 min, once a day for 28 days, and sham EA was applied to the skin of the rat tail near the buttock on both sides. The mean arterial pressure (MAP) of the abdominal aorta and heart rate (HR) were recorded. The autonomic nerve function was assessed by using frequency domain analysis of heart rate variability (HRV), and the baroreflex sensitivity detected by sequential method. Plasma norepinephrine (NE) level was measured by ELISA, and the α2AR positive neurons and α2AR protein expression in NTS were detected by using fluorescence immunohistochemistry and Western blot, respectively. The functions of α2AR within the NTS in modulating MBP and HR were verified by microinjection of its agonist (clonidine) and antagonist (yohimbine) separately. RESULTS: Compared to the sham operation rats, the hypertension rats displayed significant increases in the MAP (P<0.01), plasma norepinephrine content (P<0.01), ratios of low frequency/total power (LF/TP) and low frequency/high frequency (LF/HF) (P<0.01), and significant reduction in the overall gain, uplink sequence gain and downlink sequence gain of baroreflex (P<0.01), the number α2AR positive neurons and α2AR protein expression level in NTS (P<0.01). The rats in the EA group (rather than in the sham-EA group) showed significant reduction in MAP at the 3rd and 4th week, plasma NE content, LF/TP and LF/HF (P<0.01), and obvious increase in the overall gain, uplink sequence gain and downlink sequence gain of baroreflex (P<0.01), and the number of α2AR positive neurons and α2AR protein expression in comparison (P<0.05) with those of the model group. Microinjection of clonidine into NTS induced an evident decrease in both MAP and HR in the model group relevant to the sham operation group (P<0.01), while the MAP and HR changes of the EA (not sham EA) group were considerably bigger than those of the model group (P<0.05), being similar to those of the sham-operation group (P>0.05), which suggested an elimination of the BP-lowering effect of clonidine after EA. CONCLUSION: EA at LR3 can reduce MBP, sympathetic activities, improve baroreflex sensitivity in renovascular hypertensive rats, which may be associated with its effects in up-regulating the decreased NTS α2AR expression and functional activities.

Cardioprotective effects of polydatin against myocardial injury in diabetic rats via inhibition of NADPH oxidase and NF-κB activities.

BACKGROUND: Diabetic cardiomyopathy is a main cause of the increased morbidity in diabetic patients, no effective treatment is available so far. Polydatin, a resveratrol glucoside isolated from the Polygonum cuspidatum, was found by our and others have antioxidant and cardioprotective activities. Therapeutic effects of polydatin on diabetic cardiomyopathy and the possible mechanisms remains unclear. This study aimed to investigate the cardioprotective effects and underlying mechanisms of polydatin on myocardial injury induced by hyperglycemia. METHODS: Diabetes in rats was made by high-fat diet combined with multiple low doses of streptozotocin, and then treated with polydatin (100 mg·kg-1·day-1, by gavage) for 8 weeks. Cardiac function was examined by echocardiography. Myocardial tissue and blood samples were collected for histology, protein and metabolic characteristics analysis. In cultured H9c2 cells with 30 mM of glucose, the direct effects of polydatin on myocyte injury were also observed. RESULTS: In diabetic rats, polydatin administration significantly improved myocardial dysfunction and attenuated histological abnormalities, as evidenced by elevating left ventricular shortening fraction and ejection fraction, as well as reducing cardiac hypertrophy and interstitial fibrosis. In cultured H9c2 cells, pretreatment of polydatin dose-dependently inhibited high glucose-induced cardiomyocyte injury. Further observation evidenced that polydatin suppressed the increase in the reactive oxygen species levels, NADPH oxidase activity and inflammatory cytokines production induced by hyperglycemia in vivo and in vitro. Polydatin also prevented the increase expression of NOX4, NOX2 and NF-κB in the high glucose -stimulated H9c2 cells and diabetic hearts. CONCLUSIONS: Our results demonstrate that the cardioprotective effect of polydatin against hyperglycemia-induced myocardial injury is mediated by inhibition of NADPH oxidase and NF-κB activity. The findings may provide a novel understanding the mechanisms of the polydatin to be a potential treatment of diabetic cardiomyopathy.

Orexin Receptor-1 in the Rostral Ventrolateral Medulla Mediates the Antihypertensive Effects of Electroacupuncture.

Electroacupuncture (EA) has been used to treat numerous diseases, including hypertension. This study aimed to investigate the long-term effect and underlying mechanisms of EA stimulation at the LI11 point on the hypertension and sympathetic nerve activity in two-kidney, one-clip (2K1C) hypertensive rats. EA (0.1-0.4 mA, 2 and 15 Hz) was applied to the acupoints LI11 overlying the deep radial nerve once a day for 6 weeks. The mean arterial pressure (MAP) and heart rate (HR) were determined by radiotelemetry, and the sympathetic nerve activity was evaluated by telemetric analyses of the low-frequency component of blood pressure (BP) and by plasma epinephrine and norepinephrine levels. The results showed 6 weeks of EA significantly lowered the increased BP effectively, inhibited the enhanced sympathetic nerve activities and attenuated cardiac hypertrophy in 2K1C hypertensive rats. The level of orexin receptor-1 (OX1R) in the rostral ventrolateral medulla (RVLM) after EA treatment was markedly reduced in 2K1C rats, while there was no difference in the RVLM expression of orexin receptor-2 (OX2R) in 2K1C and 2K1C+EA rats. Moreover, the increased pressor and depressor responses to microinjection of orexin A or OX1R antagonist SB408124 into the RVLM of 2K1C rats were significantly blunted by the EA treatment. These findings suggest that BP-lowering effect of EA on renovascular hypertension may be through inhibition of central sympathetic activities and modulation of functional orexin receptors in the RVLM.

ATP redirects cytokine trafficking and promotes novel membrane TNF signaling via microvesicles.

Cellular stress or injury induces release of endogenous danger signals such as ATP, which plays a central role in activating immune cells. ATP is essential for the release of nonclassically secreted cytokines such as IL-1ß but, paradoxically, has been reported to inhibit the release of classically secreted cytokines such as TNF. Here, we reveal that ATP does switch off soluble TNF (17 kDa) release from LPS-treated macrophages, but rather than inhibiting the entire TNF secretion, ATP packages membrane TNF (26 kDa) within microvesicles (MVs). Secretion of membrane TNF within MVs bypasses the conventional endoplasmic reticulum- and Golgi transport-dependent pathway and is mediated by acid sphingomyelinase. These membrane TNF-carrying MVs are biologically more potent than soluble TNF in vivo, producing significant lung inflammation in mice. Thus, ATP critically alters TNF trafficking and secretion from macrophages, inducing novel unconventional membrane TNF signaling via MVs without direct cell-to-cell contact. These data have crucial implications for this key cytokine, particularly when therapeutically targeting TNF in acute inflammatory diseases.-Soni, S., O'Dea, K. P., Tan, Y. Y., Cho, K., Abe, E., Romano, R., Cui, J., Ma, D., Sarathchandra, P., Wilson, M. R., Takata, M. ATP redirects cytokine trafficking and promotes novel membrane TNF signaling via microvesicles.

Electroacupuncture Improves Baroreflex and γ-Aminobutyric Acid Type B Receptor-Mediated Responses in the Nucleus Tractus Solitarii of Hypertensive Rats.

Electroacupuncture (EA) has been reported to benefit hypertension, but the underlying mechanisms are still unclear. We hypothesized that EA attenuates hypertension, in part, through modulation of γ-aminobutyric acid (GABA) receptor function in the nucleus tractus solitarii (NTS). In the present study, the long-term effect of EA on GABA receptor function and expression was examined in the NTS of two-kidney, one-clip (2K1C) renovascular hypertensive rats. EA (0.1-0.4 mA, 2 and 15 Hz) was applied at Zusanli (ST36) acupoints overlying the deep fibular nerve for 30 min once a day for two weeks. The results showed that long-term EA treatment improved blood pressure (BP) and markedly restored the baroreflex response in 2K1C hypertensive rats. The increased pressor and depressor responses to microinjection of GABAB receptor agonist and antagonist into the NTS in the hypertensive rats were blunted by the EA treatment. Moreover, EA treatment attenuated the increased GABAB receptor expression in the NTS of hypertensive rats. In contrast, EA had no significant effect on the GABAA receptor function and expression in the NTS of 2K1C hypertensive rats. These findings suggest that the beneficial effects of EA on renovascular hypertension may be through modulation of functional GABAB receptors in the NTS.

[Electroacupuncture of "Quchi" (LI 11) Inhibits the Elevation of Arterial Blood Pressure and Abnormal Sympathetic Nerve Activity in Hypertension Rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) stimulation of "Quchi" (LI 11) on arterial blood pressure (BP), sympathetic nerve activity, barorefiex sensitivity (BRS) and expression of brain derived neurotrophic factor (BDNF) and nicotinamide adenine dinucleotide phosphate (NADPH) enzyme subunit p 47 phox in the rostral ventrolateral medulla (RVML) in hypertension rats. METHODS: A total of 45 male SD rats were randomly divided into sham operation, artificial cerebro-spinal fluid (aCSF) , model, "Quchi"(LI 11), and Jianyu (LI 15) groups (n = 9 in each group). The hypertension model was established by microinjection of Ang II (200 pg x kg(-1) x day(-1)) into the lateral ventricle (A-C: 1.0 mm, L: 1.4 mm, H: 4.5 mm) for 2 weeks (aCSF for aCSF group). After 1 week's Ang II perfusion, EA (2 Hz/15 Hz, 1 mA) was applied to bilateral "Quchi" (LI 11)or "Jianyu" (LI 15) for 20 min, once daily for two weeks. The mean arterial pressure (MAP) and heart rate (HR) were detected by using a Non-Invasive Blood Pressure System (tail cuff method). The BRS (BP-to-HR transfer function) was determined by calculating the ratio of HR fluctuation (HR : HR, between post- and pre-intravenous injection of phenylephrine)/MAP fluctuation (MAP : MAP, between post- and pre-phenylephrine injection) , the urinary norepinephrine (NE) level in 24 h was assayed by ELISA. Real-time PCR and Western blot were used to detect the mRNA and protein expression of BDNF and p 47phox in the RVML region tissue. RESULTS: Following modeling, the MAP, HR and 24 h-urinary NE levels and p 47phox mRNA and protein expression levels in the RVML were significantly increased (P<0.01), and the BRS was decreased significantly (P<0.01). After EA intervention, the MAP, HR and 24 h-urinary NE levels and p 47 phox mRNA and protein expression levels in the RVML were considerably lower in the LI 11 group than in the model group (P<0.05), while the BRS level was markedly increased in the LI 11 group compared with the model group (P<0.05). The expression levels of BDNF mRNA and protein in the RVLM region were obviously up-regulated in the LI 11 group compared with the model group (P<0.05). No significant differences were found between the LI 15 group and the model group in the MAP, HR, 24 h-urinary NE, BRS, BDNF mRNA and protein and p 47 phox mRNA and protein expression levels (P>0.05). CONCLUSION: EA stimulation of "Quchi" (LI 11) can down-regulate arterial blood pressure, sympathetic nerve activity, and increase the baroreflex sensitivity in hypertension rats, which may be related to its effects in down-regulating p 47 phox mRNA and protein expression in the RVML.