Role of vasopressin in sympathetic response to paraventricular nucleus stimulation in anesthetized rats

1994 ◽  
Vol 266 (1) ◽  
pp. R228-R236 ◽  
Author(s):  
S. C. Malpas ◽  
J. H. Coote
Keyword(s):  
Paraventricular Nucleus ◽  
Neuronal Cell ◽  
Detection Algorithm ◽  
Homocysteic Acid ◽  
Renal Sympathetic Nerve Activity ◽  
Anesthetized Rats ◽  
Neuronal Cell Bodies ◽  
Peak Detection Algorithm ◽  
Glass Micropipette

Vasopressin may play an extrahypothalamic role in the central control of the cardiovascular system, specifically acting as a spinal neurotransmitter in the pathway where the paraventricular nucleus (PVN) alters sympathetic outflow. In this study, the effect of stimulating neuronal cell bodies in the PVN on renal sympathetic nerve activity (RSNA) and the possible involvement of vasopressin in the pathway was investigated in anesthetized rats. The PVN was stimulated by microinjection with 0.2 M D,L-homocysteic acid via a glass micropipette, and the hemodynamic and sympathetic responses were recorded. A computerized sympathetic peak-detection algorithm was applied to recordings of sympathetic discharges to retrieve information about the characteristics of RSNA during PVN stimulation. The algorithm scanned the series of RSNA voltages for significant increases followed by significant decreases in a small cluster of voltage values. Once each synchronized RSNA peak had been detected, its corresponding amplitude and peak-to-peak interval were calculated. PVN stimulation consistently increased the amplitude of RSNA (mean 30 +/- 5.6% over control), arterial pressure, and the peak-to-peak interval of discharges. A V1 vasopressin antagonist intrathecally administered as a 500-pmol dose was subsequently able to completely block the hemodynamic response (blood pressure increase of 14 +/- 5%) and a 35 +/- 6% increase in RSNA in response to PVN stimulation and intrathecal vasopressin. Thus spinal vasopressin is likely to be a neurotransmitter involved in the cardiovascular regulation involving the PVN.

Sympathetic responses to stimulation of area postrema in decerebrate and anesthetized rats

1995 ◽  
Vol 268 (3) ◽  
pp. H1086-H1095 ◽  
Author(s):  
A. A. Hegarty ◽  
L. F. Hayward ◽  
R. B. Felder
Keyword(s):  
Electrical Stimulation ◽  
Excitatory Amino Acid ◽  
Area Postrema ◽  
Neuronal Cell ◽  
Renal Sympathetic Nerve Activity ◽  
Pentobarbital Sodium ◽  
Anesthetized Rats ◽  
Neuronal Cell Bodies ◽  
Decerebrate Rat ◽  
Stimulation Of

The effects of electrical and chemical stimulation of the area postrema (AP) on mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) were examined in urethan- and pentobarbital sodium-anesthetized rats and in unanesthetized decerebrate rats. The AP was electrically stimulated over a range of frequencies (10–100 Hz) and intensities (10–80 microA) with a pulse duration of 0.2 or 1.0 ms. The excitatory amino acid L-glutamate (100 or 200 mM) was microinjected into the AP to preferentially stimulate neuronal cell bodies. In urethan-anesthetized rats, electrical stimulation of the AP decreased MAP and RSNA. In pentobarbital sodium-anesthetized rats, MAP and RSNA were markedly increased by AP stimulation. In unanesthetized decerebrate rats, increases in MAP and RSNA were also observed during electrical AP stimulation. Microinjection of L-glutamate had no effect on MAP and RSNA in anesthetized or in unanesthetized rats. These results indicate that electrical AP stimulation increases sympathetic output in the unanesthetized decerebrate rat and that anesthesia modifies this sympathetic response. The findings also suggest that peripheral responses to L-glutamate and electrical stimulation of the AP are mediated over different central pathways.

scholarly journals The central role of mitochondria in axonal degeneration in multiple sclerosis

2014 ◽  
Vol 20 (14) ◽  
pp. 1806-1813 ◽  
Author(s):  
Graham R Campbell ◽  
Joseph T Worrall ◽  
Don J Mahad
Keyword(s):  
Multiple Sclerosis ◽  
Axonal Degeneration ◽  
Neuronal Cell ◽  
Mitochondrial Respiratory Chain ◽  
Respiratory Chain Complexes ◽  
Autoimmune Encephalomyelitis ◽  
Mitochondrial Abnormalities ◽  
Neuronal Cell Bodies ◽  
Chain Complexes

Neurodegeneration in multiple sclerosis (MS) is related to inflammation and demyelination. In acute MS lesions and experimental autoimmune encephalomyelitis focal immune attacks damage axons by injuring axonal mitochondria. In progressive MS, however, axonal damage occurs in chronically demyelinated regions, myelinated regions and also at the active edge of slowly expanding chronic lesions. How axonal energy failure occurs in progressive MS is incompletely understood. Recent studies show that oligodendrocytes supply lactate to myelinated axons as a metabolic substrate for mitochondria to generate ATP, a process which will be altered upon demyelination. In addition, a number of studies have identified mitochondrial abnormalities within neuronal cell bodies in progressive MS, leading to a deficiency of mitochondrial respiratory chain complexes or enzymes. Here, we summarise the mitochondrial abnormalities evident within neurons and discuss how these grey matter mitochondrial abnormalities may increase the vulnerability of axons to degeneration in progressive MS. Although neuronal mitochondrial abnormalities will culminate in axonal degeneration, understanding the different contributions of mitochondria to the degeneration of myelinated and demyelinated axons is an important step towards identifying potential therapeutic targets for progressive MS.

scholarly journals Ischemic Cerebral Endothelial Cell–Derived Exosomes Promote Axonal Growth

Stroke ◽  
2020 ◽  
Vol 51 (12) ◽  
pp. 3701-3712
Author(s):  
Yi Zhang ◽  
Yi Qin ◽  
Michael Chopp ◽  
Chao Li ◽  
Amy Kemper ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Neuronal Cell ◽  
Axonal Growth ◽  
Mature Mirnas ◽  
Bioinformatic Analysis ◽  
Axonal Outgrowth ◽  
Ischemic Brain ◽  
Neuronal Homeostasis ◽  
Neuronal Cell Bodies

Background and Purpose: Cerebral endothelial cells (CECs) and axons of neurons interact to maintain vascular and neuronal homeostasis and axonal remodeling in normal and ischemic brain, respectively. However, the role of exosomes in the interaction of CECs and axons in brain under normal conditions and after stroke is unknown. Methods: Exosomes were isolated from CECs of nonischemic rats and is chemic rats (nCEC-exos and isCEC-exos), respectively. A multicompartmental cell culture system was used to separate axons from neuronal cell bodies. Results: Axonal application of nCEC-exos promotes axonal growth of cortical neurons, whereas isCEC-exos further enhance axonal growth than nCEC-exos. Ultrastructural analysis revealed that CEC-exos applied into distal axons were internalized by axons and reached to their parent somata. Bioinformatic analysis revealed that both nCEC-exos and isCEC-exos contain abundant mature miRNAs; however, isCEC-exos exhibit more robust elevation of select miRNAs than nCEC-exos. Mechanistically, axonal application of nCEC-exos and isCEC-exos significantly elevated miRNAs and reduced proteins in distal axons and their parent somata that are involved in inhibiting axonal outgrowth. Blockage of axonal transport suppressed isCEC-exo–altered miRNAs and proteins in somata but not in distal axons. Conclusions: nCEC-exos and isCEC-exos facilitate axonal growth by altering miRNAs and their target protein profiles in recipient neurons.

Role of the paraventricular nucleus in the reflex diuresis to pulmonary lymphatic obstruction in rabbits

2016 ◽  
Vol 94 (1) ◽  
pp. 18-27 ◽  
Author(s):  
Rishabh Charan Choudhary ◽  
Ravindra Kumar Sharma ◽  
Kavita Gulati ◽  
Krishnan Ravi
Keyword(s):  
Paraventricular Nucleus ◽  
External Jugular Vein ◽  
Urine Flow ◽  
Renal Sympathetic Nerve Activity ◽  
Cervical Vagotomy ◽  
Reflex Arc ◽  
The Right ◽  
Renal Sympathetic ◽  
Lymphatic Obstruction

The changes in urine flow and renal sympathetic nerve activity (RSNA) due to pulmonary lymphatic obstruction (PLO) were examined in anesthetized, artificially ventilated New Zealand white rabbits. PLO was produced by pressurizing an isolated pouch created in the right external jugular vein at the points of entry of the right lymphatic ducts. During this maneuver, urine flow increased from 8.5 ± 0.3 mL/10 min to 12 ± 0.5 mL/10 min (P < 0.0001) and RSNA increased from 24.0 ± 4 to 40.0 ± 5 μV·s (P < 0.0001). Bilateral lesioning of the paraventricular nucleus (PVN) of the hypothalamus or cervical vagotomy abolished these responses. PLO increased c-fos gene expression in the PVN. The increase in urine flow due to PLO was attenuated by muscimol and abolished by kynurenic acid microinjections into the PVN. The results show that (i) neurons in the PVN are an important relay site in the reflex arc, which is activated by PLO; and (ii) this activation is regulated by glutamatergic and partly by GABAergic input to the PVN.

Role of paraventricular nucleus in the cardiogenic sympathetic reflex in rats

2005 ◽  
Vol 288 (2) ◽  
pp. R420-R426 ◽  
Author(s):  
Matthew R. Zahner ◽  
Hui-Lin Pan
Keyword(s):  
Blood Pressure ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Paraventricular Nucleus ◽  
Reflex Response ◽  
Renal Sympathetic Nerve Activity ◽  
Basal Blood Pressure ◽  
Blood Pressure Responses ◽  
Spinal Afferents

Myocardial ischemia stimulates cardiac spinal afferents to initiate a sympathoexcitatory reflex. However, the pathways responsible for generation of increased sympathetic outflow in this reflex are not fully known. In this study, we determined the role of the paraventricular nucleus (PVN) in the cardiogenic sympathetic reflex. Renal sympathetic nerve activity (RSNA) and blood pressure were recorded in anesthetized rats during epicardial application of 10 μg/ml bradykinin. Bilateral microinjection of muscimol (0.5 nmol), a GABAA receptor agonist, was performed to inhibit the PVN. In 10 vehicle-injected rats, epicardial bradykinin significantly increased RSNA 178.4 ± 48.5% from baseline, and mean arterial pressure from 76.9 ± 2.0 to 102.3 ± 3.3 mmHg. Microinjection of muscimol into the PVN significantly reduced the basal blood pressure and RSNA ( n = 12). After muscimol injection, the bradykinin-induced increases in RSNA (111.6 ± 35.9% from baseline) and mean arterial pressure (61.2 ± 1.3 to 74.5 ± 2.7 mmHg) were significantly reduced compared with control responses. The response remained attenuated even when the basal blood pressure was restored to the control. In a separate group of rats ( n = 9), bilateral microinjection of the ionotropic glutamate antagonist kynurenic acid (4.82 or 48.2 nmol in 50 nl) had no significant effect on the RSNA and blood pressure responses to bradykinin compared with controls. These results suggest that the tonic PVN activity is important for the full manifestation of the cardiogenic sympathoexcitatory response. However, ionotropic glutamate receptors in the PVN are not directly involved in this reflex response.

scholarly journals A multicellular rosette-mediated collective dendrite extension

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Li Fan ◽  
Ismar Kovacevic ◽  
Maxwell G Heiman ◽  
Zhirong Bao
Keyword(s):  
Adhesion Molecules ◽  
Molecular Mechanisms ◽  
Neural Circuits ◽  
Sensory Nerve ◽  
Neuronal Cell ◽  
Sensory Organ ◽  
Neurite Extension ◽  
C Elegans ◽  
Neuronal Cell Bodies

Coordination of neurite morphogenesis with surrounding tissues is crucial to the establishment of neural circuits, but the underlying cellular and molecular mechanisms remain poorly understood. We show that neurons in a C. elegans sensory organ, called the amphid, undergo a collective dendrite extension to form the sensory nerve. The amphid neurons first assemble into a multicellular rosette. The vertex of the rosette, which becomes the dendrite tips, is attached to the anteriorly migrating epidermis and carried to the sensory depression, extruding the dendrites away from the neuronal cell bodies. Multiple adhesion molecules including DYF-7, SAX-7, HMR-1 and DLG-1 function redundantly in rosette-to-epidermis attachment. PAR-6 is localized to the rosette vertex and dendrite tips, and promotes DYF-7 localization and dendrite extension. Our results suggest a collective mechanism of neurite extension that is distinct from the classical pioneer-follower model and highlight the role of mechanical cues from surrounding tissues in shaping neurites.

scholarly journals A multicellular rosette-mediated collective dendrite extension

2018 ◽  
Author(s):  
Li Fan ◽  
Ismar Kovacevic ◽  
Maxwell Heiman ◽  
Zhirong Bao
Keyword(s):  
Adhesion Molecules ◽  
Molecular Mechanisms ◽  
Neural Circuits ◽  
Sensory Nerve ◽  
Neuronal Cell ◽  
Sensory Organ ◽  
Neurite Extension ◽  
C Elegans ◽  
Neuronal Cell Bodies

Coordination of neurite morphogenesis with surrounding tissues is crucial to the establishment of neural circuits, but the underlying cellular and molecular mechanisms remain poorly understood. We show that neurons in a C. elegans sensory organ, called the amphid, undergo a collective dendrite extension to initiate formation of the sensory nerve. The amphid neurons first assemble into a multicellular rosette. The vertex of the rosette, which becomes the dendrite tips, is attached to the anteriorly migrating epidermis and carried to the sensory depression, extruding the dendrites away from the neuronal cell bodies. Multiple adhesion molecules including DYF-7, SAX-7, HMR-1 and DLG-1 function redundantly in rosette-to-epidermis attachment. PAR-6 is localized to the rosette vertex and dendrite tips, and promotes DYF-7 localization and dendrite extension. Our results suggest a collective mechanism of neurite extension that is distinct from the classical pioneer-follower model and highlight the role of mechanical cues from surrounding tissues in shaping neurites.

Neuronal cell bodies in paraventricular nucleus affect renal hemodynamics and excretion via the renal nerves

1998 ◽  
Vol 275 (4) ◽  
pp. R1334-R1342 ◽  
Author(s):  
James R. Haselton ◽  
Richard C. Vari
Keyword(s):  
Receptor Antagonist ◽  
Paraventricular Nucleus ◽  
Renal Plasma Flow ◽  
Neuronal Cell ◽  
Urinary Sodium Excretion ◽  
Renal Nerves ◽  
Neural Pathway ◽  
Water Excretion ◽  
Renal Vasoconstriction ◽  
Neuronal Cell Bodies

Several lines of evidence support the existence of an oligosynaptic projection from the paraventricular nucleus of the hypothalamus (PVN) to the kidney in the rat. We sought to provide evidence that this neural pathway is capable of influencing renal function in rats. Bilateral microinjections of bicuculline (Bic; 1 nmol) into the PVN decreased glomerular filtration rate (59%), effective renal plasma flow (71%), urine flow (UV; 57%), and urinary sodium excretion (UNaV; 54%), accompanied by increased mean arterial pressure (17%) and heart rate (17%). These results were not obtained when Bic was injected outside the PVN or when vehicle (0.9% saline) was injected into the PVN. Bilateral renal denervation (5–7 days before the experiments) significantly reduced the renal vasoconstriction, attenuated the antidiuresis, and abolished the antinatriuresis evoked by PVN stimulation. On the other hand, both the antidiuresis and antinatriuresis evoked by PVN stimulation were undiminished after treatment with either of two vasopressin receptor antagonists ([β-mercapto-β,β-cyclopentamethylenepropionyl1, O-Et-Tyr2,Val4,Arg8]vasopressin, a vasopressin V1 receptor antagonist, or [adamantaneacetyl1, O-Et-d-Tyr2,Val4,aminobutyryl6,Arg8,9]-vasopressin, a V2 receptor antagonist). In renal-denervated rats treated with the same V2 receptor antagonist, PVN stimulation produced highly variable increases in both UV and UNaV, which overall were not statistically different than zero. We conclude that the activation of neurons in PVN evokes 1) renal vasoconstriction accompanied by antinatriuresis, both of which are attributable to the renal nerves, and 2) decreased water excretion, which is mediated by the renal nerves and vasopressin V2 receptors.

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