Cardiovascular effects of microinjections of angiotensin II into the nucleus tractus solitarii

Rettig, Rainer; Healy, Dennis P.; Printz, Morton P.

doi:10.1016/0006-8993(86)90835-8

Cited by 103 publications

(57 citation statements)

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“…Moreover, microinjection of Ang II into the dorsal motor nucleus of vagus resulted in increased vagal outflow to the heart and GI tract (Diz et al, 1984). In addition, microinjection of low (femtomolar) doses of Ang II into the dorsal medial region of the NTS produced a transient fall in blood pressure and heart rate in anesthetized rats (Fow et al, 1994;Mosqueda-Garcia et al, 1990;Rettig et al, 1986), however, higher doses evoked pressor responses (Casto and Phillips, 1986;Luoh and Chan, 1998;Michelini and Bonagamba, 1990) creating a bisphasic dose-response curve. Interestingly, the mucosal protective effect of i.c.v.…”

Section: Discussionmentioning

confidence: 99%

Angiotensin II-induced activation of central AT1 receptors exerts endocannabinoid-mediated gastroprotective effect in rats

Gyires

Rónai

Zádori

et al. 2014

Molecular and Cellular Endocrinology

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The aim of the present study was to analyze whether angiotensin II via the endocannabinoid system can induce gastric mucosal protection, since transactivation of cannabinoid CB1 receptors by angiotensin AT1 receptor in CHO cells was described. Experimental ulcer was induced by acidified ethanol given orally in male Wistar rats, CB1(+/+) wild type and CB1(-/-) knock out mice. The compounds were administered intracerebroventricularly. It was found, that 1./ Angiotensin II inhibited the ethanol-induced gastric lesions (11.9-191 pmol); the effect of angiotensin II (191 pmol) was inhibited by the CB1 receptor inverse agonist AM 251 (1.8 nmol) and the inhibitor of diacylglycerol lipase (DAGL), tetrahydrolipstatin (0.2 nmol). 2./ Angiotensin II exerted gastroprotection in wild type, but not in CB1(-/-) mice. 3./ The gastroprotective effect of angiotensin II (191 pmol) was reduced by atropine (1 mg/kg i.v.) and bilateral cervical vagotomy. In conclusion, stimulation of central angiotensin AT1 receptors via activation of cannabinoid CB1 receptors induces gastroprotection in a DAGL-dependent and vagus-mediated mechanism.

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Section: Discussionmentioning

confidence: 99%

Angiotensin II-induced activation of central AT1 receptors exerts endocannabinoid-mediated gastroprotective effect in rats

Gyires

Rónai

Zádori

et al. 2014

Molecular and Cellular Endocrinology

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“…Depending on the dose, microinjection of Ang II into the NTS elicits an increase or decrease in blood pressure. [32][33][34] Although those studies were performed under anesthesia, there might be a connection between the renin-angiotensin system and ROS in the NTS. 35 Another possibility is that reduced availability of NO is involved in the mechanisms.…”

Section: Discussionmentioning

confidence: 99%

Inhibition of Rac1-Derived Reactive Oxygen Species in Nucleus Tractus Solitarius Decreases Blood Pressure and Heart Rate in Stroke-Prone Spontaneously Hypertensive Rats

et al. 2007

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Abstract-Reactive oxygen species (ROS) in the brain are thought to contribute to the neuropathogenesis of hypertension by enhancing sympathetic nervous system activity. The nucleus tractus solitarius (NTS), which receives afferent input from baroreceptors, has an important role in cardiovascular regulation. reduced nicotinamide-adenine dinucleotide phosphate oxidase is thought to be a major source of ROS in the NTS. Rac1 is a small G protein and a key component of reduced nicotinamide-adenine dinucleotide phosphate oxidase. The role of Rac1-derived ROS in the NTS in cardiovascular regulation of hypertension is unknown. Therefore, we examined whether inhibition of Rac1 in the NTS decreases ROS generation, thereby reducing blood pressure in stroke-prone spontaneously hypertensive rats (SHRSPs).The basal Rac1 activity level in the NTS was greater in SHRSPs than in Wistar-Kyoto rats. Inhibition of Rac1, induced by transfecting adenovirus vectors encoding dominant-negative Rac1 into the NTS, decreased blood pressure, heart rate, and urinary norepinephrine excretion in SHRSPs but not in Wistar-Kyoto rats. Inhibition of Rac1 also reduced nicotinamide-adenine dinucleotide phosphate oxidase activity and ROS generation. In addition, Cu/Zn-superoxide dismutase activity in the NTS of SHRSPs was decreased compared with that of Wistar-Kyoto rats, despite the increased ROS generation. Overexpression of Cu/Zn-superoxide dismutase in the NTS decreased blood pressure and heart rate in SHRSPs. These results indicate that the activation of Rac1 in the NTS generates ROS via reduced nicotinamide-adenine dinucleotide phosphate oxidase in SHRSPs, and this mechanism might be important for the neuropathogenesis of hypertension in SHRSPs. Key Words: blood pressure Ⅲ heart rate Ⅲ sympathetic nervous system Ⅲ hypertension Ⅲ brain T here is accumulating evidence that reactive oxygen species (ROS) in the cardiovascular regulatory nuclei in the brain have a crucial role in blood pressure regulation in hypertension via modulating the sympathetic nervous system. 1-5 Reduced nicotinamide-adenine dinucleotide phosphate [NAD(P)H] oxidase is a major source of ROS in hypertension 6 and has a critical role in generating ROS in the brain. 2,5,7 Rac1 is a small G protein that is an important signaling molecule involved in integrating intracellular transduction pathways toward NAD(P)H oxidase activation. 2,8,9 Rac1 requires lipid modifications to migrate from the cytosol to the plasma membrane, which is a necessary step for activating the ROSgenerating NAD(P)H oxidase enzyme system. 8,9 The nucleus tractus solitarius (NTS) in the brain stem has an important role in cardiovascular regulation. 10 -16 The NTS receives afferent input from baroreceptors and chemoreceptors 12 and has reciprocal interconnections with other nuclei involved in central autonomic regulation. 17 In addition, the essential NAD(P)H oxidase subunit gp91 phox is present in somatodendritic and axonal profiles that contain angiotensin II (Ang II) subtype 1 receptors in the NTS, and Ang I...

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“…Thus, the bradycardia and hypotension effects observed after NTS microinjections of ANGII (Rettig et al 1986;Fow et al 1994;Tseng et al 1994) are likely to be mediated by activation of non-baroreceptive NTS circuits or neurones such as those relaying the bradycardia elicited by stimulation of the peripheral chemoreceptors. In our experiments a significant bradycardia could only be evoked by 5 fmol ANGII and this was very short lasting (< 30 s) compared with that reported by Diz et al (1997) using 250 fmol dose or Rettig et al (1986) using •1000 fmol. In the present study ANGII doses of > 50 fmol evoked inconsistent heart rate changes with a tachycardia as the most frequent response (see Fig.…”

Section: Discussionmentioning

confidence: 99%

Differential effects of angiotensin II on cardiorespiratory reflexes mediated by nucleus tractus solitarii – a microinjection study in the rat

Paton

Kasparov

1999

The Journal of Physiology

101

120

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The nucleus tractus solitarii (NTS), the central site of termination of baroreceptive afferents, is intimately involved in arterial pressure control. This nucleus contains a high density of angiotensin II (ANGII) AT1 receptors located both presynaptically, on vagal and carotid sinus afferents, and on interneurones (Healy et al. 1989). It is well known that systemically injected ANGII has the unique ability to induce a pressor response with little or no reflex bradycardia. This is in striking contrast to virtually all other known pressor substances (reviewed in Reid, 1992;Bishop et al. 1995). One explanation of this phenomenon is that ANGII may attenuate the baroreceptor reflex by acting at the level of the NTS. In this regard, microinjection of ANGII into the NTS attenuated the baroreceptor reflex in both the anaesthetised normotensive adult rat (Casto & Phillips, 1986;Luoh & Chan, 1998) and the unanaesthetised rat (Michelini & Bonagamba, 1990). These data are consistent with results obtained following intracerebroventricular administration of ANGII (Hayashi et al. 1988). In our recent experiments, losartan blockade of AT1 receptors in the NTS increased baroreceptor reflex efficacy in the 10-20 day old rat (Kasparov et al. 1998) -an age when the baroreceptor reflex is depressed (Kasparov & Paton, 1997). In addition, AT1 receptor blockade in the NTS of mature

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Cardiovascular effects of microinjections of angiotensin II into the nucleus tractus solitarii

Cited by 103 publications

References 10 publications

Angiotensin II-induced activation of central AT1 receptors exerts endocannabinoid-mediated gastroprotective effect in rats

Angiotensin II-induced activation of central AT1 receptors exerts endocannabinoid-mediated gastroprotective effect in rats

Inhibition of Rac1-Derived Reactive Oxygen Species in Nucleus Tractus Solitarius Decreases Blood Pressure and Heart Rate in Stroke-Prone Spontaneously Hypertensive Rats

Differential effects of angiotensin II on cardiorespiratory reflexes mediated by nucleus tractus solitarii – a microinjection study in the rat

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