Defining projections from the caudal pressor area of the caudal ventrolateral medulla

2004 ◽  
Vol 482 (3) ◽  
pp. 273-293 ◽  
Author(s):  
Wei Sun ◽  
W. Michael Panneton
Keyword(s):  
Ventrolateral Medulla ◽  
Caudal Ventrolateral Medulla ◽  
Caudal Pressor

Contribution of α2-adrenoceptors in caudal ventrolateral medulla to cardiovascular regulation in rat

1998 ◽  
Vol 274 (4) ◽  
pp. R1119-R1124 ◽  
Author(s):  
Shogo Sesoko ◽  
Hiromi Muratani ◽  
Masanobu Yamazato ◽  
Hiroshi Teruya ◽  
Shuichi Takishita ◽  
...  
Keyword(s):  
Cardiovascular Effect ◽  
Ventrolateral Medulla ◽  
Sprague Dawley ◽  
Renal Sympathetic Nerve Activity ◽  
Caudal Ventrolateral Medulla ◽  
Adrenoceptor Antagonist ◽  
Sprague Dawley Rats ◽  
Artificial Cerebrospinal Fluid ◽  
Cardiovascular Neurons ◽  
Selective Blocker

The inhibitory action of α2-agonists on the cardiovascular neurons has been elucidated in the rostral ventrolateral medulla (RVLM) but not in the caudal ventrolateral medulla (CVLM). Our study aimed to clarify whether microinjection of clonidine into the CVLM elicits any cardiovascular effect and whether endogenous α2-adrenoceptor-mediated mechanisms contribute to the tonic activity of the CVLM neurons. In male Sprague-Dawley rats (7–9 wk old, 270–320 g) anesthetized with urethan, unilateral microinjection of 8 nmol of clonidine into the CVLM ( n = 10) increased mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) by 12.1 ± 1.8 mmHg (mean ± SE, P < 0.01) and 25.8 ± 4.8% ( P < 0.01), while heart rate (HR) remained unaltered. Unilateral microinjection of 2 nmol of SKF-86466, a selective blocker of the α2-adrenoceptors, into the CVLM ( n = 10) decreased MAP, HR, and RSNA (−11.6 ± 2.6 mmHg, −26 ± 7 beats/min, and −15.3 ± 1.7%, respectively, P < 0.01 for each). Artificial cerebrospinal fluid caused neither a cardiovascular effect nor a sympathetic response. Prior injection of SKF-86466 into the ipsilateral CVLM attenuated the effects of clonidine. Bilateral microinjection of muscimol into the RVLM abolished the effects of both clonidine and SKF-86466 injected into the CVLM. The pressor and sympathoexcitatory effects of clonidine injected into the CVLM suggest a neuroinhibitory action of the drug on the CVLM neurons. In addition,the depressor and sympathoinhibitory effects of SKF-86466 injected into the CVLM indicated that activation of α2-adrenoceptors by endogenous ligand inhibits CVLM neurons. The effects of clonidine and the α2-adrenoceptor antagonist in the CVLM require the integrity of the RVLM.

Novel axonal projection from the caudal end of the ventrolateral medulla to the intermediolateral cell column

2007 ◽  
Vol 292 (2) ◽  
pp. R927-R936 ◽  
Author(s):  
Kamon Iigaya ◽  
Hiroo Kumagai ◽  
Hiroshi Onimaru ◽  
Akira Kawai ◽  
Naoki Oshima ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Optical Imaging ◽  
Cross Sections ◽  
Ventral Surface ◽  
Ventrolateral Medulla ◽  
Cell Column ◽  
Spontaneously Hypertensive ◽  
Optical Images ◽  
Caudal Pressor ◽  
Wistar Kyoto

We used an optical imaging technique to investigate whether axons of neurons in the caudal end of the ventrolateral medulla (CeVLM), as well as axons of neurons in the rostral ventrolateral medulla (RVLM), project to neurons in the intermediolateral cell column (IML) of the spinal cord. Brain stem-spinal cord preparations from neonatal normotensive Wistar-Kyoto and spontaneously hypertensive rats were stained with a voltage-sensitive dye, and responses to electrical stimulation of the IML at the Th2 level were detected as changes in fluorescence intensity with an optical imaging apparatus (MiCAM-01). The results were as follows: 1) depolarizing responses to IML stimulation during low-Ca high-Mg superfusion were detected on the ventral surface of the medulla at the level of the CeVLM, as well as at the level of the RVLM, 2) depolarizing responses were also detected on cross sections at the level of the CeVLM, and they had a latency of 24.0 ± 5.5 (SD) ms, 3) antidromic action potentials in response to IML stimulation were demonstrated in the CeVLM neurons where optical images were detected, and 4) glutamate application to the CeVLM increased the frequency of excitatory postsynaptic potentials (EPSPs) and induced depolarization of the IML neurons. The optical imaging findings suggested a novel axonal and functional projection from neurons in the CeVLM to the IML. The increase in EPSPs of the IML neurons in response to glutamate application suggests that the CeVLM participates in the regulation of sympathetic nerve activity and blood pressure and may correspond to the caudal pressor area.

scholarly journals Altered regulation of the rostral ventrolateral medulla in hypertensive obese Zucker rats

2011 ◽  
Vol 301 (1) ◽  
pp. H230-H240 ◽  
Author(s):  
Domitila A. Huber ◽  
Ann M. Schreihofer
Keyword(s):  
Sympathetic Nerve Activity ◽  
Nucleus Tractus Solitarius ◽  
Excitatory Input ◽  
Rostral Ventrolateral Medulla ◽  
Male Rats ◽  
Ventrolateral Medulla ◽  
Zucker Rats ◽  
Caudal Ventrolateral Medulla ◽  
Obese Zucker Rats ◽  
Altered Regulation

Obese Zucker rats (OZR) have elevated sympathetic nerve activity (SNA) and mean arterial pressure (MAP) compared with lean Zucker rats (LZR). We examined whether altered tonic glutamatergic, angiotensinergic, or GABAergic inputs to the rostral ventrolateral medulla (RVLM) contribute to elevated SNA and MAP in OZR. Male rats (14–18 wk) were anesthetized with urethane (1.5 g/kg iv), ventilated, and paralyzed to record splanchnic SNA, heart rate (HR), and MAP. Inhibition of the RVLM by microinjections of muscimol eliminated SNA and evoked greater decreases in MAP in OZR vs. LZR ( P < 0.05). Antagonism of angiotensin AT1 receptors in RVLM with losartan yielded modest decreases in SNA and MAP in OZR but not LZR ( P < 0.05). However, antagonism of ionotropic glutamate receptors in RVLM with kynurenate produced comparable decreases in SNA, HR, and MAP in OZR and LZR. Antagonism of GABAA receptors in RVLM with gabazine evoked smaller rises in SNA, HR, and MAP in OZR vs. LZR ( P < 0.05), whereas responses to microinjections of GABA into RVLM were comparable. Inhibition of the caudal ventrolateral medulla, a major source of GABA to the RVLM, evoked attenuated rises in SNA and HR in OZR ( P <0.05). Likewise, inhibition of nucleus tractus solitarius, the major excitatory input to caudal ventrolateral medulla, produced smaller rises in SNA and HR in OZR. These results suggest the elevated SNA and MAP in OZR is derived from the RVLM and that enhanced angiotensinergic activation and reduced GABAergic inhibition of the RVLM may contribute to the elevated SNA and MAP in the OZR.

Excitatory somato-sympathetic reflexes are relayed in the caudal ventrolateral medulla in the cat

1994 ◽  
Vol 179 (1-2) ◽  
pp. 71-74 ◽  
Author(s):  
Johannes Zanzinger ◽  
Jens Doutheil ◽  
Jürgen Czachurski ◽  
Horst Seller
Keyword(s):  
Ventrolateral Medulla ◽  
Caudal Ventrolateral Medulla ◽  
Sympathetic Reflexes
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