Nutrient removal and microbial community succession in moving bed biofilm reactor: Effects of influent carbon to nitrogen ratio fluctuation.

This study investigated the nutrient removal and microbial community succession in moving bed biofilm reactor under stable and three levels of influent carbon/nitrogen (C/N) ratio fluctuation (± 10%, ± 20%, and ± 30%). Under the conditions of influent C/N ratio fluctuation, the removal efficiency of COD and PO43--P decreased 4.7-6.4% and 3.7-12.9%, respectively, while the nitrogen removal was almost unaffected. A sharp decrease in the content of culturable functional bacteria related to nitrogen and phosphorus removal including nitrite-oxidizing bacteria (NOB), aerobic denitrifying bacteria (DNB), and polyphosphate-accumulating organisms (PAOs) from the carrier biofilm was observed. Sequencing analysis revealed that the abundance of Candidatus Competibacter increased 10.3-25.9% and became the dominant genus responsible for denitrification, potentially indicating that nitrate was removed via endogenous denitrification under the influent C/N ratio fluctuation. The above results will provide basic data for the nutrient removal in decentralized wastewater treatment under highly variable influent conditions.

Effects of electroacupuncture at Zusanli (ST36) on inflammatory cytokines in a rat model of smoke-induced chronic obstructive pulmonary disease.

OBJECTIVE: Improvement in lung function was reported after acupuncture treatment of chronic obstructive pulmonary disease (COPD), but little is known about the underlying mechanisms. Because an immune response imbalance could be seen in COPD, we hypothesize that electroacupuncture (EA) may play a role in regulating inflammatory cytokines and contribute to lung protection in a rat model of smoke-induced COPD. METHODS: A COPD model using male Sprague-Dawley rats exposed to cigarette smoke was established. The rats were randomly divided into four groups (control, sham, COPD, and COPD plus EA), and COPD model was evaluated by measuring pulmonary pathological changes and lung function. EA was applied to the acupuncture point Zusanli (ST36) for 30 min/d for 14 d in sham and COPD rats. Bronchoalveolar lavage fluid (BALF) was used to measure levels of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), and malonaldehyde (MDA). RESULTS: Compared with the control rats, COPD rats had significant changes in lung resistance (RL) and lung compliance (CL) (both P<0.01), bronchi and bronchiole airway obstruction (P<0.01), and levels of MDA, TNF-α, and IL-1ß (P<0.01). There were no significant differences between the control and the sham groups. Compared with the COPD rats, the COPD plus EA rats had decreased RL and increased CL (both P<0.05), and reduced bronchi and bronchiole airway obstruction (P<0.05, P<0.01, respectively), while levels of TNF-α, IL-1ß, and MDA in BALF were lowered (P<0.05 and P<0.01, respectively). However, TNF-α and IL-1ß levels of the EA group rats remained higher than those of the control group (P<0.05). CONCLUSION: EA at ST36 can reduce lung injury in a COPD rat model, and beneficial effects may be related to down-regulation of inflammatory cytokines. The anti-inflammatory and antioxidant effects may prolong the clinical benefit of EA.

[The antiepileptic role of 3α-androstanediol on the epileptic rats induced by pentylenetetrazole].

The influence of 3α-androstanediol (3α-diol) on twitch and electroencephalogram (EEG) of the epileptic rats induced by pentylenetetrazole (PTZ) has been observed in this experiment in order to comprehensively explore the role of 3α-diol on epileptic attack from the aspects of behavior and EEG. Thirty-two male Sprague-Dawley rats were evenly and randomly divided into 4 groups: the normal and supplied with oil epileptic (N+oil+PTZ) group, the normal and supplied with 3α-diol epileptic (N+3α-diol+PTZ) group, the gonadectomized and supplied with oil epileptic (GDX+oil+PTZ) group and the gonadectomized and supplied with 3α-diol epileptic (GDX+3α-diol+PTZ) group. The changes of the behavior and EEG of epileptic rats in every group were recorded and analyzed. The results of behavior observation showed that the latency to clonic seizure and tonic-clonic seizure was shortened and the number of tonic-clonic seizure was increased significantly in the GDX+oil+PTZ group in comparison with N+oil+PTZ group (P < 0.05); comparing GDX+3α-diol+PTZ group with GDX+oil+PTZ group, or N+3α-diol+PTZ group with N+oil+PTZ group, we found that the latency to clonic seizure and tonic-clonic seizure became prolonged significantly, and the number of clonic seizure and tonic-clonic seizure was decreased significantly (P < 0.05). The results of EEG showed that the latency to epileptic waves was cut and the number of epileptic waves was augmented significantly in the GDX+oil+PTZ group in comparison with N+oil+PTZ group (P < 0.05); comparing GDX+3α-diol+PTZ group with GDX+oil+PTZ group, or N+3α-diol+PTZ group with N+oil+PTZ group, we found that the latency to epileptic waves became lengthened significantly, the number of epileptic waves was reduced significantly and the percentage of change of TP (total power of spectrum) was lessened significantly (P < 0.05). These results indicate that 3α-diol has an antiepileptic activity in the gonadectomized and normal epileptic rats.

Protective effects of electroacupuncture on cardiac function in rats subjected to thoracic surgery trauma.

The present study investigates the protective effects of electroacupuncture (EA) application on cardiac function, while simultaneously exploring the underlying neurobiological mechanisms, in rats that have experienced thoracic surgery-induced stress. Mean arterial and left intraventricular pressures were monitored as indicators of cardiac function. Meanwhile, the immunohistochemistry for c-Fos protein expression and electrophysiology in vitro in brain nuclei, known to regulate cardiac function, provide insights into the effects of EA on the central nervous system. The results show that cardiac function was dramatically suppressed with thoracic surgery trauma, the expression levels of c-Fos in the paraventricular nucleus (PVN) and the rostral ventrolateral medulla (RVLM) significantly increased, the rheobase intensity of the intracellular current injection needed to initiate the action potential decreased, membrane resistance in the PVN neurons significantly increased, and the inductivity of the postsynaptic potentials in the PVN neurons of the surgery-treated rats significantly decreased. EA application at the Neiguan acupoints (PC6) attenuated the decreases in almost all investigated functional parameters of the heart. EA significantly decreased the number of Fos-immunoreactive neurons in the PVN and RVLM, significantly decreased the Max L. slope of the PVN neurons, and increased the inductivity of the postsynaptic potentials in the PVN neurons of the surgery-treated rats. These data indicate the protective effects of EA application on cardiac function in rats that have experienced surgery-induced stress and show that EA application at the Neiguan acupoints may produce its protective effects through the neurons in the PVN and the RVLM.

Nitric oxide modulates cardiovascular function in the rat by activating adenosine A2A receptors and inhibiting acetylcholine release in the rostral ventrolateral medulla.

1. Nitric oxide (NO), a gas transmitter, modulates many physiological processes, including the central regulation of cardiovascular activity. However, the mechanisms underlying the regulation of cardiovascular activity remain relatively unexplored. In the present study, we hypothesized that central NO-dependent sympathetic inhibition is mediated by activation of adenosine A(2A) receptors (A(2A)R) and inhibition of acetylcholine (ACh) release in the rostral ventrolateral medulla (RVLM). 2. L-Arginine (L-Arg; an NO donor; 100 nmol/100 nL) was microinjected into the RVLM of male Sprague-Dawley rats and heart rate variability (HRV) was assessed as an index of cardiac sympathovagal balance. Following microinjection of L-Arg, decreases were seen in mean arterial pressure (MAP), heart rate (HR) and the ratio of the low- to high-frequency components (LF/HF) of HRV. Pretreatment of rats with SCH58261 (40 pmol/60 nL into the RVLM), a competitive antagonist of the A(2A) R, attenuated these effects. 3. Western blot analysis and ELISA revealed that adenosine and A(2A)R levels increased in the RVLM following L-Arg microinjection, whereas ACh and muscarinic M(1) receptor levels decreased significantly, in parallel with the cardiovascular responses to L-Arg microinjection. The decrease in ACh levels was abolished by SCH58261 pretreatment. 4. Microinjection of N(G)-nitro-L-arginine methyl ester (a non-selective inhibitor of NO synthase; 15 nmol/100 nL) into the RVLM significantly increased MAP, HR and sympathetic activity, as evidenced by HRV (LF, HF and the LF/HF ratio were all increased). 5. The results indicate that the central NO/NO synthase system in the RVLM may modulate cardiovascular activity by activating the A(2A)R, which subsequently inhibits activation of the muscarinic M(1) receptor.

Orexin-A and respiration in a rat model of smoke-induced chronic obstructive pulmonary disease.

1. Orexins are neuropeptides synthesized in the hypothalamus that regulate many physiological functions, including energy homeostasis, stress responses, sleep/wake states etc. It is now emerging that orexins may also regulate breathing, but little is known as to how they do this, particularly in chronic obstructive pulmonary disease (COPD). In the present study, we used a rat model of cigarette smoke-induced COPD to investigate orexin-A expression in the hypothalamus and medulla and its effect on respiration. 2. Sprague-Dawley rats were exposed to cigarette smoke (1 h twice daily) for 12 weeks. Lung function and pathological changes associated with inflammation and emphysema were determined to confirm the validity of the COPD model. 3. Hypothalamic and medullary orexin-A levels, as determined by radioimmunoassay, were higher in smoke-exposed than control rats. Furthermore, the expression of prepro-orexin (PPO) mRNA in the hypothalamus and orexin OX(1) receptor mRNA in the medulla, as determined by real-time quantitative polymerase chain reaction, was higher in smoke-exposed than control rats. 4. The number of orexin-A-positive neurons in the hypothalamus and OX(1) and OX(2) receptor-positive neurons in the ventrolateral medulla was higher in smoke-exposed than control rats. 5. Microinjection of orexin-A (1 µmol/L, 0.1 µL) into the pre-Bötzinger complex enhanced phrenic nerve discharge to a greater extent in smoke-exposed compared with control rats (61% vs 36%, respectively). 6. The findings of the present study demonstrate that the increased respiratory activity in smoke-exposed rats is due to an increase in orexin-A as well as upregulation of orexin receptors in the ventrolateral medulla.

Hydrogen sulfide protects cardiomyocytes from hypoxia/reoxygenation-induced apoptosis by preventing GSK-3beta-dependent opening of mPTP.

Hydrogen sulfide (H(2)S) is an endogenously generated gaseous transmitter, which has recently been suggested to regulate cardiovascular functions. The present study aims to clarify the mechanisms underlying the cardioprotective effects of H(2)S. Signaling elements were examined in cardiomyocytes cultured under hypoxia/reoxygenation conditions and in a rat model of ischemia-reperfusion. In cultured cardiomyocytes, sodium hydrosulfide (NaHS; 10, 30, and 50 mumol/l) showed concentration-dependent inhibitory effects on cardiomyocyte apoptosis induced by hypoxia/reoxygenation. These effects were associated with an increase in phosphorylation of glycogen synthase kinase-3beta (GSK-3beta) (Ser9) and a decrease in Bax translocation, caspase-3 activation, and mitochondrial permeability transition pore (mPTP) opening. Transfection of a phosphorylation-resistant mutant of GSK-3beta at Ser9 attenuated the effects of NaHS in reducing cardiomyocyte apoptosis, Bax translocation, caspase-3 activation, and mPTP opening. In a rat model of ischemia-reperfusion, NaHS administration reduced myocardial infarct size and increased the phosphorylation of GSK-3beta (Ser9) at a dose of 30 mumol/kg. In conclusion, the H(2)S donor prevents cardiomyocyte apoptosis by inducing phosphorylation of GSK-3beta (Ser9) and subsequent inhibition of mPTP opening.

Adrenomedullin in the rostral ventrolateral medulla is involved in the regulation of cardiovascular component of defensive responses induced by electrical stimulation of dorsal periaquaductal gray of the midbrain.

In this study, we used techniques of in situ hybridization, immunohistochemistry, electric stimulation of the dorsal periaquaductal gray of the midbrain (dPAG) and microinjection to investigate the changes of preproadrenomedullin (ppADM) gene expression encoding adrenomedullin (ADM) and ADM-like immunoreactivity (ADM-IR) in the medulla oblongata, especially in the rostral ventrolateral medulla (rVLM) of the rats receiving foot-shock and noise stress for 5 d, and the potential role of ADM in cardiovascular component of defense response in the rVLM. The results showed that ppADM mRNA and ADM-IR were widely distributed throughout the medulla oblongata. Highly labeled neurons were found in the ventrolateral reticular nucleus and hypoglossal nucleus. Moderately labeled neurons were seen in the facial, ambiguus, lateral reticular, paragigantocellular reticular, and inferior olivary nuclei. Weak signal was present over neurons of nucleus of the solitary tract. The expression of ppADM mRNA and ADM-IR increased significantly after foot shock and noise stress for 5 d as compared with that in control group (P<0.01). On the other hand, stimulation of the right dPAG raised the artery pressure (AP) rapidly from (116.4+/-8.9) mmHg to (140.0+/-9.8) mmHg, and heart rate (HR) from (378.0+/-7.5) beats/min to (413.0+/-8.2) beats/min, respectively, in the normotensive rats. After unilaterally microinjection of hADM(22-52) (a specific antagonist of ADM receptor, 1 pmol) into the right rVLM of the normotensive rats for 10 min, the rats received the stimulation of the dPAG again. Then we found that the DeltaAP and DeltaHR were lowered significantly within 60 min compared with those without hADM(22-52) application (P<0.05). After unilaterally microinjection of 0.1 pmol rat ADM (rADM) into the rVLM, dPAG stimulation caused no significant changes in DeltaAP and DeltaHR. Our results that foot-shock and noise stress induced significant increases of ppADM mRNA and ADM-IR in the rVLM, and microinjection of ADM receptor antagonist hADM(22-52) into the rVLM partly blocked the cardiovascular component of stress-defensive response induced by stimulation of the dPAG, suggest that ADM in the rVLM might be an important neurotransmitter or neuroregulator in the regulation of cardiovascular function in the stress-related defensive response.

Effects of N(omega)-nitro-L-arginine methyl ester and aminoguanidine on lipopolysaccharide-induced airway hyperresponsiveness in guinea pigs.

BACKGROUND: The down-regulation of constitutive nitric oxide synthase (cNOS) and up-regulation of inducible nitric oxide synthase (iNOS) are associated with the allergen-provocated airway hyperresponsiveness (AHR). This study aimed to determine whether their alteration also plays an important role in the AHR induced by lipopolysaccharide (LPS). METHODS: Hartley male guinea pigs, weighing between 250 g and 350 g, were injected with LPS at a dose of 1 mg/kg every 24 hours for three days. A non-selective NOS inhibitor, N(omega)-nitro-L-arginine methyl ester (L-NAME), or a selective inducible NOS inhibitor, aminoguanidine (AG), were used thirty minutes before each injection of LPS. Airway reactions, nitric oxide (NO) production and inflammatory changes were detected 24 hours after the last dose of LPS. RESULTS: AG significantly decreased the NO production in the bronchoalveolar lavage fluid (BALF) and sharply reduced the intensity of bronchoconstriction to histamine challenge. L-NAME also significantly decreased the NO production in the BALF, but had no effect on airway reactions or, perhaps, a tendency to enhance the intensity of AHR. CONCLUSIONS: The data suggest that inducible NOS contributes to the AHR induced by repetitive intraperitoneal LPS, and constitutive NOS was also involved.

Differential expressions of nNOS and iNOS in the rostral ventrolateral medulla induced by electroacupuncture in acute myocardial ischemia rats.

Increasing lines of evidence has been accumulated that nitric oxide (NO) and nitric oxide synthase (NOS) distribute plentifully in the rostral ventrolateral medulla (RVLM) and contribute to cardiovascular regulation. In the present study, the expressions of neuronal and inducible isoform of NOS (nNOS and iNOS) were observed in the RVLM of acute myocardial ischemia (AMI) Wistar rats experienced electroacupuncture (EA) treatment, thereby the cardiovascular effects of NO in the RVLM were investigated and the mechanism of acupuncture effect on AMI was inferred. The results indicated that in the AMI rats, cardiac functions were markedly attenuated with high serum level of brain natriuretic peptide (BNP) and norepinephine (NE), the number of nNOS-immunoreactive cells and nNOS mRNA exprossion in the RVLM area were increased, while those of iNOS were lowered. EA at "Neiguan" acupoints (Pe 6) 30 min daily for successive 5 d resulted in an improvement of the cardiac functions, decreases in NE and BNP levels; it also increased the expression of iNOS and decreased the expression of nNOS in the RVLM. These results suggest that the curative effect of acupuncture on AMI is possibly attributable to the differential regulation of NOS/NO in the RVLM, leading to decreased sympathetic outflow and improvement of cardiac functions.

Effects of melatonin on blood pressure in stress-induced hypertension in rats.

Melatonin, acting through its receptors, is involved in numerous physiological processes, including blood pressure (BP) regulation. In present study, the effect of melatonin inhibition on stress-induced hypertension was investigated. The hypertensive model consisted of male Sprague-Dawley rats subjected to electrical foot-shock combined with noise. Microinjection of melatonin (0.1 and 1.0 mmol/L) into the anterior hypothalamic area (AHA) produced a fall in BP in nomortensive rats and stress-induced hypertensive rats (SIHR). Luzindole (10 mmol/L), a competitive antagonist of melatonin MT1 and MT2 receptors, almost completely abolished the depressor effect of melatonin, the MT2 receptor-specific antagonist 4-phenyl-2-propionamidotetralin (10 mmol/L) partially blocked (by approximately 60%) the depressor effect of melatonin, whereas the MT3 receptor-selective antagonist prazosin (10 mmol/L) failed to antagonize the effects of melatonin. Brain microdialysis was performed in the AHA and the rostral ventrolateral medulla (RVLM). Melatonin and amino acids in the dialysate samples collected were detected by high-performance liquid chromatography combined with fluorescence detection. The results indicated that melatonin concentrations in the AHA were reduced in SIHR. Microinjection of melatonin into the AHA decreased glutamate release and increased GABA and taurine release in the RVLM, which were paralleled by a decrease in arterial pressure. The mRNA expression of MT2 in the AHA of SIHR was higher than that in normotensive control rats, whereas there was no significant difference in MT1 mRNA expressin between the two groups. The results of the present study suggest that both a decrease of melatonin and an increase in the MT2 receptor in the AHA are involved in the manifestation of stress-induced hypertension. Both MT1 and MT2 receptors participated in the antihypertensive effect of melatonin in the AHA. The antihypertensive effect of melatonin was related to the decreases in the excitatory amino acid glutamate and increases in the inhibitory amino acids taurine and GABA in the RVLM.

Hydrogen sulphide is an inhibitor of L-type calcium channels and mechanical contraction in rat cardiomyocytes.

AIMS: Hydrogen sulphide (H(2)S) is an endogenously generated gaseous transmitter that has recently been suggested to regulate cardiovascular functions. To date, there is no direct evidence for a potential role of H(2)S in regulating calcium channels in the heart. The present study aims to examine the hypothesis that H(2)S is a novel inhibitor of the L-type calcium channel current (I(Ca,L)). METHODS AND RESULTS: Electrophysiological measurements were performed in cardiomyocytes isolated from Wistar-Kyoto and spontaneously hypertensive rats. Bath application of 100 microM NaHS (a H(2)S donor) significantly reduced the time required for the repolarization of the action potential. Inhibition of the peak I(Ca,L) by NaHS was determined to be concentration-dependent (25, 50, 100, 200, and 400 microM). NaHS inhibited the recovery from depolarization-induced inactivation. Electric field-induced [Ca(2+)]i transients and contraction of single cardiomyocytes and isolated papillary muscles were reduced by NaHS treatment. In contrast, caffeine induced an increase in [Ca(2+)]i that was not altered by NaHS. NaHS had no effect on the K(ATP) current or on the levels of cAMP and cGMP in the current study. CONCLUSION: H(2)S is a novel inhibitor of L-type calcium channels in cardiomyocytes. Moreover, H(2)S-induced inhibition of [Ca(2+)]i appears to be a secondary effect owing to its initial action towards I(Ca,L). The inhibitory effect of H(2)S on I(Ca,L) requires further investigation, particularly in the exploration of new pathways involved in cardiac calcium homeostasis and disease pathology.

Hemodynamic-independent anti-natriuretic effect of urotensin II in spontaneously hypertensive rats.

The present study aims to test the hypothesis that U-II might have a direct anti-natriuretic action in spontaneously hypertensive rats (SHR). Bolus U-II injection (15 nmol kg(-1)) caused a transient decrease in glomerular filtration rate (GFR), urine flow rate (UV), urinary sodium (UNaV) and potassium excretion (U(K)V) that corresponded with a committed decrease in mean arterial pressure (MAP) and renal blood flow (RBF) during the first 30 min. Continuous U-II infusion (0.2 nmol kg(-1)h(-1)) following a bolus U-II injection (0.3 nmol kg(-1)) caused an anti-natriuretic effect without any significant change in MAP, RBF, GFR, UV and UKV during the entire 1.5-h perfusion period in SHR. The levels of aldosterone and angiotensin II were not altered in the plasma and kidney, while plasma antidiuretic hormone decreased in response to U-II injection (15 nmol kg(-1)). Protein levels of U-II receptors (UT) were significantly increased in the kidney of 17-week-old SHR when compared with the age-matched WKY rats, while mRNA transcripts of both U-II and UT were increased in the kidney, left ventricle and thoracic aorta. In conclusion, U-II exerts a hemodynamic-independent anti-natriuretic action in adult SHR. The anti-natriuretic action of U-II in SHR is probably associated with an increased expression of the U-II-UT system in the kidney, suggesting a potential renal role of U-II in the pathogenesis of hypertension.

Effect of adrenomedullin on the activity of barosensitive neurons in the rostral ventrolateral medulla of rats.

To investigate the eletrophysiological effect of rat adrenomedullin (rADM) on barosensitive neurons in the rostral ventrolateral medulla (rVLM) and its potential mechanisms, the extracellular recording and multi-barrel iontophoresis methods were used. Of the 29 barosensitive neurons in the rVLM, 20 neurons demonstrated excitatory response to iontophoretically applied rADM and increased the firing rate from (10.8 +/- 2.7) spikes/s to (14.6 +/- 3.6), (19.8 +/- 4.7) and (31.9 +/- 6.4) spikes/s (P<0.05, n=20) at the current of 30, 60 and 90 nA, respectively. Application of human adrenomedullin (22-52) [hADM (22-52)], a specific antagonist of rADM receptor, distinctly attenuated the augmentation of firing rate induced by rADMjthe firing rate was increased by 15.4% [(11.4 +/- 2.5) spikes/s, P<0.05, n=10]. Another antagonist, human calcitonin gene-related peptide (8-37) [hCGRP (8-37)] had no significant effect on rADM-induced excitation. Other 23 barosensitive neurons were recorded to test the influence of nitric oxide synthase (NOS) inhibitors on the excitatory effect of rADM. In 10 neurons, 7-NiNa (neuronal NOS inhibitor) decreased the firing rate from (10.1 +/- 3.5) spikes/s to (7.5 +/- 2.5), (5.3 +/- 2.1) and (3.1 +/- 1.4) spikes/s (P<0.05, n=10) at the current of 10, 20 and 40 nA, respectively. The excitatory effect of rADM (60 nA, 30 s) during 7-NiNa application was nearly eliminated and the magnitude of firing rate was increased only by 17% of the basal level (6.2 +/- 1.9) spikes/s (P<0.05, n=7). While aminoguanidine (AG, iNOS inhibitor) increased the firing rate at the resting level from (11.5 +/- 5.1) spikes/s to (17.8 +/- 5.6), (22.5 +/- 6.3) and (29.1 +/- 6.4) spikes/s (P<0.05, n=8) at the current of 10, 20 and 40 nA in 8 barosensitive neurons, respectively. When rADM (60 nA, 30 s) was delivered during AG iontophoresis period, the firing rate significantly increased by 60% of the basal level [(22.5 +/- 6.3) spikes/s, n=5]. These results indicate that rADM activates the barosensitive neurons in the rVLM directly and acts as a cardiovascular regulator, and that this function might be mediated by its specific receptor. NO, mainly neuronal NOS-originated might be involved in the excitatory effect of rADM in the rVLM.

Effects of acupuncture on nNOS and iNOS expression in the rostral ventrolateral medulla of stress-induced hypertensive rats.

This study was to observe the changes of the neuronal and inducible nitric oxide synthase (nNOS & iNOS) as well as their mRNAs in the rostral ventrolateral medulla (RVLM) of stress-induced hypertensive rats before and after acupuncture, and thereby to infer the curative mechanism of acupuncture on hypertension. The result indicated that the systolic blood pressure (SBP) of stress group rats was increased significantly (P < 0.01), it was accompanied that the expression of nNOS in the RVLM, including the immunoreactive neuron number (P < 0.05), the optical density (OD) (P < 0.01), and the mRNA (P < 0.01) were obviously elevated, while those of iNOS (P < 0.05, P < 0.01 and P < 0.01) were evidently lowered in the stress-induced hypertensive rats. Electroacupuncture (EA) points at "Zusanli" (St. 36) and "Lanwei" (Extra 37) on the same hindlimb were stimulated by an EA apparatus (Type G6805-2) with dense sparse wave (4-20Hz) and 4mA intensity. EA application could return the SBP (P < 0.05), and the changes on the expression of both nNOS and iNOS (P < 0.05, P < 0.01 and P < 0.01). These results suggest that the curative mechanism of acupuncture on stress-induced hypertension is related to the changes of nNOS and iNOS in the RVLM of rats.

Changes of adrenomedullin and its receptor components mRNAs expression in the brain stem and hypothalamus-pituitary-adrenal axis of stress-induced hypertensive rats.

In this study, reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the changes in mRNAs levels of preproadrenomedullin (ppADM) gene encoding adrenomedullin (ADM) and the essential receptor components of ADM, calcitonin receptor-like receptor (CRLR), and the receptor activity modifying protein 2 and 3 (RAMP2 and RAMP3) in the medulla oblongata, hypothalamus, midbrain, pituitary gland and adrenal gland of the stress-induced hypertensive rats. It was shown that chronic foot-shock and noise stress for 15 consecutive days induced a significant increase in systolic blood pressure (SBP) and unique changes in ppADM and its receptor components mRNAs in all areas studied. As compared with the control group, the level of ppADM mRNA, normalized against a glyceraldehydes-3-phosphate dehydrogenase (GAPDH) control, was up-regulated in the hypothalamus-pituitary-adrenal (HPA) axis, but down-regulated in the medulla oblongata and midbrain (P<0.01 and P<0.05, respectively). The relative amount of CRLR mRNA was higher in the hypothalamus than that in other areas. The level of CRLR mRNA expression was significantly increased in the medulla oblongata of the stress group (P<0.01), but decreased in the midbrain (P<0.01) as well as hypothalamus(P<0.05), as compared with that of the control group. Chronic stress for 15 consecutive days produced an increase in the level of RAMP2 mRNA expression in the medulla oblongata (P<0.01) and a decrease in the adrenal gland (P<0.01), as compared with the control. No significant stress-related changes in RAMP2 mRNA were observed in the midbrain, hypothalamus and pituitary gland. The amount of RAMP3 mRNA was relatively higher in the midbrain and hypothalamus than that in the medulla oblongata, adrenal gland and adrenal gland. Stress-induced hypertensive rats exhibited an increased RAMP3 mRNA expression in the hypothalamus and pituitary gland (P<0.01 and P<0.05, respectively) and a decrease in the adrenal gland and midbrain (P<0.05). No significant stress-related change in RAMP3 mRAN was observed in the medulla oblongata. Taken together, our results indicate that the significant changes in ppADM and its receptor components mRNAs expression in the HPA axis and autonomic centers may be related to the development of the stress-induced hypertension. Nevertheless, the pathophysiological significance of brain-derived ADM and its receptors in stress and blood pressure regulation and their roles in stress-induced hypertension still await further investigation.

Medullary ventrolateral nitric oxide mediates the cardiac effect of electroacupuncture at "Neiguan" acupoint on acute myocardial ischemia in rats.

Experiments were performed on male Sprague-Dawley (SD) rats anesthetized with a mixture of urethane and chloralose. A rat model of acute myocardial ischemia (AMI) was made by ligation of the left anterior descending branch of the coronary artery (LAD). After the LAD ligation, the ischemia area of the left ventricular wall became somewhat pale immediately. Under a light microscope, the pathological examination revealed that all the cells were swollen and in red color when the cardiac section was stained with hematoxylin basic fuchsin picric acid (HBFP), which indicated a typical change in the myocardial ischemia. In the AMI model, it was found that cardiac functions were markedly attenuated, such as decreases in the heart rate (HR), mean arterial pressure (MAP), left ventricular systolic pressure (LVSP), maximal rate for left ventricular pressure rising and declining (+/-dp/dt(max)), velocity of contractile element (V(CE)) and total area of cardiac force loop (L(0)), and an increase in the left ventricular end diastolic pressure (LVEDP). In such AMI rats, application of electroacupuncture (EA) at "Neiguan" acupoints (Pe 6) for 20 min could obviously improve the above-mentioned cardiac functions. After microinjection of nitro-L-arginine (L-NNA), an inhibitor of nitric oxide synthase (NOS), was made into the rostral ventrolateral medulla (RVLM), the curative effect of EA on myocardial ischemia was reduced significantly or abolished, while after microinjection of normal saline of the same volume was made into the RVLM, the improving effect of EA remained. These results suggest that the effect of EA on myocardial ischemia is possibly mediated by the nitric oxide (NO) in the RVLM.

Inhibition of nociceptin/orphanin FQ on penicillin-induced seizures in rats.

The opioid peptides were thought to be involved in specific types of seizures. Nociceptin/Orphanin FQ (NC) is the endogenous ligand of the nociceptin opioid peptide (NOP) receptor and may play a role in epilepsy. However, accumulated evidences indicated that NC had both anti- and pro-convulsive effects, and the direct effect of NC in modulating epilepsy in the hippocampus still remained unclear. In this study, we investigated the effect of NC on penicillin-induced seizures (PIS) in rats. Seizure model was produced by intra-hippocampus injection of penicillin in anesthetized rats. The electroencephalography (EEG) was then observed and estimated by power spectrum analysis. Pretreatment of NC (intracerebroventricular, i.c.v.) depressed PIS in a dose-dependent manner at doses of 0.055, 0.55 and 5.5 nmol in 2 microl saline, respectively. [Nphe1]Nociceptin(1-13)NH2, a selective NOP receptor antagonist reversed the effect of NC against PIS, and this antagonist was inactive to PIS itself. These results indicated that NC had a receptor-specific preventive effect against PIS.

Effects of electroacupuncture on pressor response to angiotensin-(1-7) by amino acid release in the rostral ventrolateral medulla.

Unilateral microinjection of Angiotensin-(1-7)[Ang-(1-7)] into the rostral ventrolateral medulla (RVLM) of anesthetized rats caused an increase in mean arterial pressure (MAP) accompanied by an increased release of excitatory amino acid (EAA) glutamate. In contrast, microinjection of Ang779, a selective antagonist of Ang-(1-7) receptor, into the RVLM caused a decrease in MAP accompanied by a deceased release of EAA glutamate as well as an increased release of inhibitory amino acid (IAA) glycine, taurine and gamma-aminobutyric acid. After electroacupuncture (EA) stimulation at "Zusanli"(St.36) for 20 min, the above effects of Ang-(1-7) or Ang779 attenuated. These results suggest that attenuation of EA on the pressor effect of Ang-(1-7) or the depressor effect of Ang779 may be through regulating the corresponding amino acid neurotransmitter release in the RVLM.

Chronic all-trans retinoic acid treatment prevents medial thickening of intramyocardial and intrarenal arteries in spontaneously hypertensive rats.

There are in vitro data linking all-trans retinoic acid (atRA) with inhibition of hypertrophy and hyperplasia in cardiomyocytes, vascular smooth muscle cells, and fibroblasts. In the present study, we tested the hypothesis that chronic treatment with atRA may blunt the process of myocardial remodeling in spontaneously hypertensive rats (SHR). Four-week-old male SHR were treated with atRA (5 or 10 mg.kg-1.day-1) given daily for 3 mo by gavage; age- and sex-matched Wistar-Kyoto rats (WKY) and placebo-treated SHR served as controls. At the end of the treatment period, cardiac geometry and function were assessed by Doppler echocardiography. Histological examination and RIA were performed to evaluate medial thickening of intramyocardial and renal arteries, perivascular and interstitial collagen content, and atrial natriuretic peptide (ANP) and IGF-I in the heart, respectively. The novel finding of the present study is that atRA prevented hypertrophy of intramyocardial and intrarenal arteries and ventricular fibrosis. However, atRA treatment did not lower blood pressure or left ventricular weight and left ventricular weight-to-body weight ratio in SHR. atRA did not change cardiac geometry and function as assessed by Doppler echocardiography. atRA showed no influence on either ANP or IGF-I levels. In conclusion, the present study suggests that chronic atRA treatment prevents medial thickening of intramyocardial and intrarenal arteries and ventricular fibrosis during the development of hypertension. Left ventricular hypertrophy and cardiac geometry and function are not changed by atRA treatment.