Neural pathway between the nucleus accumbens and the rostral ventrolateral medulla in a rat model of anorexia nervosa / 南方医科大学学报

OBJECTIVE@#To investigate the potential neural pathway connecting the nucleus accumbens (NAc) and the rostral ventrolateral medulla (RVLM), and whether the pathway participates in the regulation of cardiovascular function in a model rat of anorexia nervosa (AN).@*METHODS@#Rat models of AN were established by allowing voluntary activity in a running wheel with restricted feeding, with the rats having free access to normal chow without exercise as the control group. FluoroGold (FG) retrograde tracing method and multi-channel simultaneous recording technique were used to explore the possible pathway between the NAc and the RVLM.@*RESULTS@#The rats in AN group exhibited significantly reduced systolic blood pressure (SBP), mean arterial pressure (MAP) and heart rate (HR) with significantly increased discharge frequency of RVLM neurons in comparison with the control rats. After the injection of FG into the RVLM, retrograde labeled neurons were observed in the NAc of the rats in both the normal control and AN groups. In both groups, SBP and HR were significantly decreased in response to 400 μA electrical stimulation of the NAc accompanied by an obvious increase in the discharge frequency of the RVLM neurons; the diastolic blood pressure (DBP) and MAP were significantly lower in AN model rats than in the normal rats in response to the stimulation.@*CONCLUSIONS@#We successfully established a rat model of AN via hyperactivity and restricted feeding and confirm the presence of a neural pathway connecting the NAc and the RVLM. This pathway might participate in the regulation of cardiovascular function in AN model rats.

Environmental Enrichment Promotes Antioxidant Effect in the Ventrolateral Medulla and Kidney of Renovascular Hypertensive Rats / O Enriquecimento Ambiental Promove Efeito Antioxidante no Bulbo Ventrolateral e Rins de Roedores com Hipertensão Renovascular

Abstract Background: Arterial hypertension is a precursor to the development of heart and renal failure, furthermore is associated with elevated oxidative markers. Environmental enrichment of rodents increases performance in memory tasks, also appears to exert an antioxidant effect in the hippocampus of normotensive rats. Objectives: Evaluate the effect of environmental enrichment on oxidative stress in the ventrolateral medulla, heart, and kidneys of renovascular hypertensive rats. Methods: Forty male Fischer rats (6 weeks old) were divided into four groups: normotensive standard condition (Sham-St), normotensive enriched environment (Sham-EE), hypertensive standard condition (2K1C-St), and hypertensive enriched environment (2K1C-EE). Animals were kept in enriched or standard cages for four weeks after all animals were euthanized. The level of significance was at p < 0.05. Results: 2K1C-St group presented higher mean arterial pressure (mmHg) 147.0 (122.0; 187.0) compared to Sham-St 101.0 (94.0; 109.0) and Sham-EE 106.0 (90.8; 117.8). Ventrolateral medulla from 2K1C-EE had higher superoxide dismutase (SOD) (49.1 ± 7.9 U/mg ptn) and catalase activity (0.8 ± 0.4 U/mg ptn) compared to SOD (24.1 ± 9.8 U/mg ptn) and catalase activity (0.3 ± 0.1 U/mg ptn) in 2K1C-St. 2K1C-EE presented lower lipid oxidation (0.39 ± 0.06 nmol/mg ptn) than 2K1C-St (0.53 ± 0.22 nmol/mg ptn) in ventrolateral medulla. Furthermore, the kidneys of 2K1C-EE (11.9 ± 2.3 U/mg ptn) animals presented higher superoxide-dismutase activity than those of 2K1C-St animals (9.1 ± 2.3 U/mg ptn). Conclusion: Environmental enrichment induced an antioxidant effect in the ventrolateral medulla and kidneys that contributes to reducing oxidative damage among hypertensive rats.

Resumo Fundamento: A hipertensão arterial é um precursor para o desenvolvimento da insuficiência cardíaca e renal e, além disso, está associada com o aumento dos marcadores oxidativos. O enriquecimento ambiental dos roedores melhora o desempenho em tarefas de memória, e também parece ter um efeito antioxidante sobre o hipocampo dos ratos normotensos. Objetivos: Avaliar o efeito do enriquecimento ambiental sobre o estresse oxidativo no bulbo ventrolateral, coração, e rins de ratos com hipertensão renovascular. Métodos: Quarenta ratos machos, tipo Fischer (6 semanas de idade), foram divididos em quatro grupos: normotensos em condições padrão (Sham-CP), normotensos em ambiente enriquecido (Sham-AE), hipertensos em condições padrão (2R1C-CP), e hipertensos em ambiente enriquecido (2R1C-AE). Os animais foram mantidos em gaiolas enriquecidas ou padrão durante quatro semanas e, por fim, todos os animais foram eutanasiados. O nível de significância foi p < 0,05. Resultados: O grupo 2R1C-CP apresentou pressão arterial média maior (mmHg) 147,0 (122,0; 187,0) quando comparado com os grupos Sham-CP 101,0 (94,0; 109,0) e Sham-AE 106,0 (90,8; 117,8). Observou-se maior atividade das enzimas superóxido dismutase (SOD) (49,1 ± 7,9 U/mg ptn) e da catalase (0,8 ± 0,4 U/mg ptn) no bulbo ventrolateral do grupo 2R1C-AE, em relação à atividade da SOD (24,1 ± 9,8 U/mg ptn) e da catalase (0,3 ± 0,1 U/mg ptn) no grupo 2R1C-CP. No grupo 2R1C-AE, a oxidação lipídica no bulbo ventrolateral foi menor (0,39 ± 0,06 nmol/mg ptn) quando comparado com o grupo 2R1C-CP (0,53 ± 0,22 nmol/mg ptn). Ademais, foi observada maior atividade das enzimas superóxido dismutase nos rins dos animais 2R1C-AE (11,9 ± 2,3 U/mg ptn) em relação aos animais 2R1C-CP (9,1 ± 2,3 U/mg ptn). Conclusão: O enriquecimento ambiental provocou efeito antioxidante no bulbo ventrolateral e nos rins, o que contribuiu para a redução do dano oxidante nos ratos hipertensos.

The inhibitory effect of α-lipoic acid on the high salt-induced hypertension rats / 重庆医学

Objective To investigate whether the excessive production of reactive oxygen species (ROS) in the mitochondria of the rostral ventrolateral medulla (RVLM) can inhibit the high salt-induced hypertension response.Methods A total off 32 male rats were divided into two groups:two groups were given normal salt diet (0.3％ NaCl) for 8 weeks (n=16) and high salt diet (8％ NaCl) for 8 weeks (n=16,induced hypertension model) respectively.The two groups were divided into four groups,two groups were given α-lipoic dissolving in 0.9％ normal saline (60 mg/kg),two groups were fed with saline for 9 weeks.There were ffour groups:the experimental group (n=8,the hypertension model sample fed α-lipoic acid),the model group (n=8,the hypertension model sample fed saline),the control group (n=8,normal salt diet sample fed α-lipoic acid) and the blank control group (n=8,normal salt diet sample ffed saline).Monitored the change of the arterial pressure and detected the expression off superoxide by immunofluorescence at the end of the experiment,measured the expression of NAD(P)H NOX2,NOX4 and Cu/Zn-SOD in RVLM by Western blot;determined the expression differences of oxidative stress related substances such as mitochondrial malondialdehyde(MDA)in RVLM by ELISA.Results The mean arterial pressure (MAP) in the experimental group was lower than that in the model group,the difference was statistically significant (P＜0.05);in the experimental group and the model group the intensities of fluorescent-labled dihydroethidium(DHE) were 60.2±3.1,99.1±3.8;the numbers of positive neurons in Cu/Zn-SOD were 20.8±1.1,6.9 ± 1.2;the numbers of NOX2 positive neurons were 12.3 ± 3.5,25.1 ±5.4;the numbers of NOX4 positive neurons were 10.1±2.2,13.3±4.1,the difference was statistically significant (P＜0.05).Western blot showed that the NOX2 levels of the experimental group and the model group were 78.9 ± 2.0,112.7 ± 3.8;the levels of NOX4 were 63.2± 2.1,99.4 ± 1.7.The levels of Cu/Zn-SOD in RVLM of the experimental group and the model group were 19.7 ±1.6,10.3± 1.2,the difference was statistically significant (P＜0.05);the levels of mitochondrial superoxide dismutase (SOD) were (33.1±3.8),(15.2±1.7)U/mg,the difference was statistically significant (P＜0.05).The levels of mitochondrial glutathione (GSH) in the experimental group and the model group were (5.2±0.9),(2.3±0.5)μmol/g;the levels of norepinephrine (NE) were (325.8 ± 7.3),(467.9 ± 6.1) pg/mL,the difference was statistically significant (P＜0.05).Conclusion α-lipoic acid could decrease the expression of NOX2,NOX4 and the bioenergy of mitochondria enzyme,and increase the intracellular antioxidant ability in the RVLM during the development of hypertension to inhibit the oxidative stress response in the development of hypertension.

Comparison of electrophysiological properties of two types of pre-sympathetic neurons intermingled in the hypothalamic paraventricular nucleus

The hypothalamic paraventricular nucleus (PVN) contains two types of neurons projecting to either the rostral ventrolateral medulla (PVN(RVLM)) or the intermediolateral horn (IML) of the spinal cord (PVN(IML)). These two neuron groups are intermingled in the same subdivisions of the PVN and differentially regulate sympathetic outflow. However, electrophysiological evidence supporting such functional differences is largely lacking. Herein, we compared the electrophysiological properties of these neurons by using patch-clamp and retrograde-tracing techniques. Most neurons (>70%) in both groups spontaneously fired in the cell-attached mode. When compared to the PVN(IML) neurons, the PVN(RVLM) neurons had a lower firing rate and a more irregular firing pattern (p < 0.05). The PVN(RVLM) neurons showed smaller resting membrane potential, slower rise and decay times, and greater duration of spontaneous action potentials (p < 0.05). The PVN(RVLM) neurons received greater inhibitory synaptic inputs (frequency, p < 0.05) with a shorter rise time (p < 0.05). Taken together, the results indicate that the two pre-sympathetic neurons differ in their intrinsic and extrinsic electrophysiological properties, which may explain the lower firing activity of the PVN(RVLM) neurons. The greater inhibitory synaptic inputs to the PVN(RVLM) neurons also imply that these neurons have more integrative roles in regulation of sympathetic activity.

Anatomy and Physiology of the Autonomic Nervous System / 대한평형의학회지

The autonomic nervous system (ANS) integrates the function of the internal organs for the homeostasis against various external environmental changes. The efferent components of the ANS are regulated by sensory signals arising from the viscera as well as non-visceral organs. The central neural networks that integrate these sensory signals and modify visceral motor output are complex, and synaptic reflexes formed in the brainstem and spinal cord integrate behavioral responses and visceral responses through the central neural networks. A detailed understanding of the neural network presented above may explain the role of the vestibular system on the homeostasis more extensively.

Role of hydrogen sulfide in central cardiovascular regulation / 第二军医大学学报

Hydrogen sulfide (H2S) is the third endogenous gaseous mediator following nitric oxide and carbon monoxide. It has been demonstrated that H2S plays important regulatory roles in modulating the physiological and pathophysiological processes of the nervous system, respiratory system, digestive system, and cardiovascular system. Recently, regulatory roles of H2S in cardiovascular system are widely focused and seem to be complex. Here we sum up the roles of H2S in mediating the cardiovascular regulation and illustrate its underlying mechanisms and perspectives.

Analysis of the Baroreceptor and Vestibular Receptor Inputs in the Rostral Ventrolateral Medulla following Hypotension in Conscious Rats

Input signals originating from baroreceptors and vestibular receptors are integrated in the rostral ventrolateral medulla (RVLM) to maintain blood pressure during postural movement. The contribution of baroreceptors and vestibular receptors in the maintenance of blood pressure following hypotension were quantitatively analyzed by measuring phosphorylated extracellular regulated protein kinase (pERK) expression and glutamate release in the RVLM. The expression of pERK and glutamate release in the RVLM were measured in conscious rats that had undergone bilateral labyrinthectomy (BL) and/or sinoaortic denervation (SAD) following hypotension induced by a sodium nitroprusside (SNP) infusion. The expression of pERK was significantly increased in the RVLM in the control group following SNP infusion, and expression peaked 10 min after SNP infusion. The number of pERK positive neurons increased following SNP infusion in BL, SAD, and BL+SAD groups, although the increase was smaller than seen in the control group. The SAD group showed a relatively higher reduction in pERK expression when compared with the BL group. The level of glutamate release was significantly increased in the RVLM in control, BL, SAD groups following SNP infusion, and this peaked 10 min after SNP infusion. The SAD group showed a relatively higher reduction in glutamate release when compared with the BL group. These results suggest that the baroreceptors are more powerful in pERK expression and glutamate release in the RVLM following hypotension than the vestibular receptors, but the vestibular receptors still have an important role in the RVLM.

Sympathetic nervous activity and hypertensive disorder complicating pregnancy / 第二军医大学学报

Hypertensive disorder complicating pregnancy is a commonly seen pregnancy complication that may pose serious problem to maternity and infant health, and is one of the major causes for morbidity and mortality in pregnant women and neonates, with the specific etiology and pathogenesis remain unclear. Recent studies have found that sympathetic nervous activity hyperthyroidism plays a role in the pathogenesis of hypertensive disorders in pregnancy. This review focused on the relationship between the sympathetic nerve activity and hypertensive disorder complicating pregnancy.

The pressor effect of angiotensin-(1-7) in the rat rostral ventrolateral medulla involves multiple peripheral mechanisms

OBJECTIVE: In the present study, the peripheral mechanism that mediates the pressor effect of angiotensin-(1-7) in the rostral ventrolateral medulla was investigated. METHOD: Angiotensin-(1-7) (25 pmol) was bilaterally microinjected in the rostral ventrolateral medulla near the ventral surface in urethane-anesthetized male Wistar rats that were untreated or treated (intravenously) with effective doses of selective autonomic receptor antagonists (atenolol, prazosin, methyl-atropine, and hexamethonium) or a vasopressin V1 receptor antagonist [d(CH2)5 -Tyr(Me)-AVP] given alone or in combination. RESULTS: Unexpectedly, the pressor response produced by angiotensin-(1-7) (16 ± 2 mmHg, n = 12), which was not associated with significant changes in heart rate, was not significantly altered by peripheral treatment with prazosin, the vasopressin V1 receptor antagonist, hexamethonium or methyl-atropine. Similar results were obtained in experiments that tested the association of prazosin and atenolol; methyl-atropine and the vasopressin V1 antagonist or methyl-atropine and prazosin. Peripheral treatment with the combination of prazosin, atenolol and the vasopressin V1 antagonist abolished the pressor effect of glutamate; however, this treatment produced only a small decrease in the pressor effect of angiotensin-(1-7) at the rostral ventrolateral medulla. The combination of hexamethonium with the vasopressin V1 receptor antagonist or the combination of prazosin, atenolol, the vasopressin V1 receptor antagonist and methyl-atropine was effective in blocking the effect of angiotensin-(1-7) at the rostral ventrolateral medulla. CONCLUSION: These results indicate that angiotensin-(1-7) triggers a complex pressor response at the rostral ventrolateral medulla that involves an increase in sympathetic tonus, release of vasopressin and possibly the inhibition of a vasodilatory mechanism.

Additive Role of the Vestibular End Organ and Baroreceptors on the Regulation of Blood Pressure in Rats

Contribution of the vestibular end organ to regulation of arterial pressure was quantitatively compared with the role of baroreceptors in terms of baroreflex sensitivity and c-Fos protein expression in the rostral ventrolateral medulla (RVLM). Baroreflex sensitivity and c-Fos protein expression in the RVLM were measured in conscious rats that had undergone bilateral labyrinthectomy (BL) and/or baroreceptor unloading. BL attenuated baroreflex sensitivity during intravenous infusion of sodium nitroprusside (SNP), but did not significantly affect the sensitivity following infusion of phenylephrine (PE). Baroreflex sensitivity became positive following sinoaortic denervation (SAD) during infusion of PE and attenuated sensitivity during infusion of SNP. Baroreflex sensitivity also became positive following double ablation (BL+SAD) during infusion of PE, and attenuated sensitivity during infusion of SNP. c-Fos protein expression increased significantly in the RVLM in the sham group after SNP administration. However, the BL, SAD, and SAD+BL groups showed significant decreases in c-Fos protein expression compared with that in the sham group. The SAD group showed more reduced c-Fos protein expression than that in the BL group, and the SAD+BL group showed less expression than that in the SAD group. These results suggest that the vestibular system cooperates with baroreceptors to maintain arterial pressure during hypotension but that baroreceptors regulate arterial pressure during both hypotension and hypertension. Additionally, afferent signals for maintaining blood pressure from the vestibular end organs and the baroreceptors may be integrated in the RVLM.

Mechanism of the cardiovascular action of salusin-a within caudal ventrolateral medulla in rats / 中国药学杂志

OBJECTIVE: To determine the cardiovascular actions of salusin-α in the caudal ventrolateral medulla (CVLM) in anesthetized rats. METHODS: Sixty-one anesthetic male SD rats were employed in the present study. The dose-dependant effects of salusin-α (0.04-4 pmol) on blood pressure and heart rate in the CVLM were determined by unilateral microinjection of salusin-α or artificial cerebrospinal fluid (aCSF) into the CVLM in 25 rats. In the other 36 rats, a CSF, kynurenic acid (Kyn), atropine, hexametho-nium (Hex) in the CVLM or a CSF/muscimol in the RVLM were given in advance to determine the mechanism of the cardiovascular actions of intra-CVLM salusin-α. RESULTS: Unilateral microinjection of salusin-a into the CVLM produced a dose-dependent hypotension and bradycardia. Prior administration of Kyn (1 nmol) or Hex (120 pmol) into the CVLM did not alter the hypotension and bradycardia induced by intra-CVLM salusin-α (P>0.05). But prior administration of atropine into the CVLM or pretreatment with muscimol within RVLM almost completely abolished the hypotension and bradycardia evoked by intra-CVLM salusin-α (P<0.05). CONCLUSION: Microinjection of salusin-α into the CVLM produces significantly hypotension and bradycardia, which probably originates from suppressing the activities of presympathetic neurons in the RVLM.

Multi-effect of central nitric oxide on cardiovascular activity / 第二军医大学学报

Objective To observe the effect of nitric oxide(NO)on cardiovascular activities in the nucleus tractus solitarii (NTS) and the rostral ventrolateral medulla (RVLM), so as to understand the role of central NO in cardiovascular regulation. Methods The changes of blood pressure (BP), heart rate (HR), and renal sympathetic nerve activity (RSNA) were observed following treatments with increased or decreased NO in the NTS and RVLM of anaesthetized SD rats. Results Microinjection of the NO precusor L-arginine (L-Arg, 2 nmol in 50 nl) into the NTS, a key relay of cardiovascular reflex transmission, produced significant decreases in BP, HR, and RSNA (P<0. 05), and injection of NO synthase inhibitor NG-nitro-L-arginine methyl ester(L-NAME, 10 nmol in 50 nl) into the NTS produced significant increases in these cardiovascular parameters (P<0. 05). However, injection of L-Arg (2 nmol in 100 nl) into the RVLM, a key region controlling sympathetic outflow, significantly increased basal BP, HR, and RSNA (P<0. 05), and injection of L-NAME (10 nmol in 100 nl) into the RVLM showed a cardiovascular inhibition effect (P<0. 05). Conclusion NO exhibits different effects in different cardiovascular centers, suggesting that it plays a special role in maintaining the basal cardiovascular activity.

Angiotensin-II-induced reactive oxygen species along the SFO-PVN-RVLM pathway: implications in neurogenic hypertension

Neurogenic hypertension has been the subject of extensive research worldwide. This review is based on the premise that some forms of neurogenic hypertension are caused in part by the formation of angiotensin-II (Ang-II)-induced reactive oxygen species along the subfornical organ-paraventricular nucleus of the hypothalamus-rostral ventrolateral medulla pathway (SFO-PVN-RVLM pathway). We will discuss the recent contribution of our laboratory and others regarding the mechanisms by which neurons in the SFO (an important circumventricular organ) are activated by Ang-II, how the SFO communicates with two other important areas involved in sympathetic activity regulation (PVN and RVLM) and how Ang-II-induced reactive oxygen species participate along the SFO-PVN-RVLM pathway in the pathogenesis of neurogenic hypertension.

Central chemoreceptors and neural mechanisms of cardiorespiratory control

The arterial partial pressure (P CO2) of carbon dioxide is virtually constant because of the close match between the metabolic production of this gas and its excretion via breathing. Blood gas homeostasis does not rely solely on changes in lung ventilation, but also to a considerable extent on circulatory adjustments that regulate the transport of CO2 from its sites of production to the lungs. The neural mechanisms that coordinate circulatory and ventilatory changes to achieve blood gas homeostasis are the subject of this review. Emphasis will be placed on the control of sympathetic outflow by central chemoreceptors. High levels of CO2 exert an excitatory effect on sympathetic outflow that is mediated by specialized chemoreceptors such as the neurons located in the retrotrapezoid region. In addition, high CO2 causes an aversive awareness in conscious animals, activating wake-promoting pathways such as the noradrenergic neurons. These neuronal groups, which may also be directly activated by brain acidification, have projections that contribute to the CO2-induced rise in breathing and sympathetic outflow. However, since the level of activity of the retrotrapezoid nucleus is regulated by converging inputs from wake-promoting systems, behavior-specific inputs from higher centers and by chemical drive, the main focus of the present manuscript is to review the contribution of central chemoreceptors to the control of autonomic and respiratory mechanisms.

Differential brain angiotensin-II type I receptor expression in hypertensive rats

Blood-borne angiotensin-II (Ang-II) has profound effects in the brain. We tested the hypothesis that Ang-II-dependent hypertension involves differential Ang-II type I (AT1) receptors expression in the subfornical organ (SFO) and the rostral ventrolateral medulla (RVLM). Male Wistar rats were implanted with 14-day osmotic minipump filled with Ang-II (150 ng/kg/min) or saline. AT1 receptor mRNA levels were detected in the SFO and RVLM by reverse transcription-polymerase chain reaction (RT-PCR). Ang-II caused hypertension (134 +/- 10 mmHg vs. 98 +/- 9 mmHg, n = 9, p < 0.05). RT-PCR revealed that Ang-II infusion induced increased AT1 receptor mRNA levels in RVLM and decreased in SFO. Our data suggest that Ang-II-induced hypertension involves differential expression of brain AT1 receptors.

Role of the caudal pressor area in the regulation of sympathetic vasomotor tone

It is well known that the ventrolateral medulla contains neurons involved in the tonic and reflex control of the cardiovascular system. Two regions within the ventrolateral medulla were initially identified: the rostral ventrolateral medulla (RVLM) and the caudal ventrolateral medulla (CVLM). Activation of the RVLM raises arterial blood pressure and sympathetic nerve activity, and activation of the CVLM causes opposite effects. The RVLM premotor neurons project directly to sympathetic preganglionic neurons and are involved in the maintenance of resting sympathetic vasomotor tone. A significant proportion of tonic activity in the RVLM sympathetic premotor neurons is driven by neurons located in a third region of the ventrolateral medulla denominated caudal pressor area (CPA). The CPA is a pressor region located at the extreme caudal part of the ventrolateral medulla that appears to have an important role controlling the activity of RVLM neurons. In this brief review, we will address the importance of the ventrolateral medulla neurons for the generation of resting sympathetic tone related to arterial blood pressure control focusing on two regions, the RVLM and the CPA.

Autonomic neurosurgery: from microvascular decompression to image guided stimulation

The paper reviews mechanisms underlying autonomic disorders, with a focus on cardiovascular dysfunction. Neurosurgical approaches are described for medically refractory hypertension and orthostatic hypotension. After review of microvascular decompression of the rostral ventrolateral medulla, stereotactic CT and MRI guided deep brain stimulation of the periaqueductal grey matter (PAG) is evaluated. Results are presented from patient studies showing reductions in blood pressure with ventral PAG stimulation and increases in blood pressure with dorsal PAG stimulation. A rationale for the treatment of autonomic disorders by neurosurgical intervention is discussed.

Relationship Between the Central Hypotensive Effect of Acupuncture or Melatonin and the Changes of Medullary Amino Acid Neurotransmitter / 针灸推拿医学（英文版）

To investigate whether changes of amino acid neurotransmitter releases in the rostral ventrolateral medulla (rVLM) were related to acupuncture and to the antihypertensive effect of melatonin (Mel) microinjected into the anterior hypothalamic area (AHA) of rats with stress-induced hypertension (SIH), as well as to compare and analyze the relationship between the both antihypertensive mechanisms of acupuncture and of Mel in the AHA. Methods: Animal model of SIHR was made by electric foot shocks combined with noises. Electroacupuncture (EA) was used and Zusanli acupoint of both side was selected. The technique of drug microinjection into the brain was used to observe the change of blood pressure (BP), and synchronously, brain microdialysis was performed for collecting dialysate samples, and then the concentration of amino acid neurotransmitters in the dialysate samples was determined by high performance liquid chromatography combined with fluorescent detection (HPLC-FD). Results: After the animal received stress treatment, the BP elevated, synchronously, the release of glutamate (Glu) in the rVLM increased, and when EA was performed, the elevated BP of the rats with SIH decreased,simultaneously, the release of Glu in the rVLM decreased also. After Mel was microinjected of into the AHA of the SIHR, the elevated BP attenuated, meanwhile, the release of Glu decreased,and those of γ-aminobutyric acid (GABA) and taurine (Tau) increased in the rVLM.Administration ofbicuculline, an antagonist of GABAA receptor, into the rVLM prior to microinjection of Mel into the AHA could partially block the depressor effect of Mel in the AHA. Conclusion: The decrease in the release of Glu in the rVLM contributes to the antihypertensive effect of both acupuncture and Mel in the AHA in the rats with SIH, and the increase in the release of GABA and Tau in the rVLM is also important to Mel in the AHA.

Mechanism of the Reversal Effect of Acupuncture on the Fall of Blood Pressure Induced by Angiotensin-(1-7) in the Caudal Ventrolateral Medulla of Rats / 针灸推拿医学（英文版）

Objective:To investigate the mechanism of the reversal effect of acupuncture on the fall of blood pressure induced by angiotensin-(1-7)[Ang-(1-7)] in the caudal ventrolateral medulla(CVLM) of rats. Methods: Ang-(1-7) and its selective receptor antagonist (D-Ala7), Ang-(1-7) and Ang-(779) were microinjected into the CVLM respectively to induce the change of blood pressure, during which, the concentrations of amino acid neurotransmitters were detected by means of microdialysis and high performance liquid chromatography(HPLC)combined with fluorescent detector, on the other hand, the effects of electro-acupuncture (EA) on the level of blood pressure and the concentrations of amino acid neurotransmitters were also observed. Results:Unilateral microinjection of Ang-(1-7) into the CVLM could decrease the blood pressure (BP), which was accompanied by an increase in the release of Glu and a decrease in the release of Tau in the same site; Whereas microinjection of Ang-779 into the CVLM could elevate BP, which was accompanied by a decrease in the release of Glu and an increase in the release of Tau; EA at acupoint Zusanli (ST 36) for 20 min could inhibit the fall of blood pressure induced by microinjection of Ang-(1-7) into the CVLM and the elevation of blood pressure induced by microinjection of Ang-779 into the CVLM, and in the meantime, it could inhibit the changes of the release of Glu and Tau induced by microinjection of Ang-(1-7) and Ang-779 into the CVLM. Conclusion: The reversal effect of EA on the fall or elevation of blood pressure induced by microinjection of Ang-(1-7) or Ang-779 into the CVLM might be related to the changes of Glu and Tau release.

Role of the rostral ventrolateral medulla in pressor response of lateral hypothalamus-perifornical region to glutamate in rats / 中国康复理论与实践

@#ObjectiveTo investigate the effect and mechanisms of rostral ventrolateral medulla (RVL) on the pressor response of lateral hypothalamus-perifornical region (LH/PF) in rats.Methods30 healthy Wistar rats were randomly divided into four groups: the phentolamine group; propranolol group; atropine group and glutamate diethyl ester group, saline was as the control in every group. After microinjection of Glu into LH/PF, the blood pressure and heart rate were observed. Then phentolamine, propranolol, atropine and glutamate diethyl ester were microinjected into RVL and the blood pressure and heart rate changes induced by microinjection of Glu were observed again.ResultsMicroinjection of Glu into LH/PF can cause the blood pressure elevating and heart rate accelerating. The pressor response of Glu to excited LH/PF could be attenuated after response of phentolamine, propranolol, atropine and glutamate diethyl ester microinjected into RVL. The blood pressures of phentolamine group; propranolol group; atropine group and glutamate diethyl ester group reduced significantly different from those in the saline control group (P<0.01).ConclusionThe α-,β-,M- and Glu-receptors in the RVL induce the pressor response of LH/PF region.