Paraventricular nucleus efferents influence area postrema neurons

1996 ◽  
Vol 270 (2) ◽  
pp. R342-R347 ◽  
Author(s):  
P. M. Smith ◽  
A. V. Ferguson
Keyword(s):  
Short Duration ◽  
Paraventricular Nucleus ◽  
Area Postrema ◽  
Short Latency ◽  
Sprague Dawley ◽  
Potential Significance ◽  
Influence Area ◽  
Long Duration ◽  
Sprague Dawley Rats ◽  
Single Unit Recordings

Extracellular single-unit recordings were obtained from area postrema neurons (AP), and peristimulus histograms were used to determine the effects of paraventricular nucleus (PVN) stimulation on these cells from anesthetized Sprague-Dawley rats. Of 91 AP cells tested, 30.8% responded to PVN stimulation with a short-latency (28.2 +/- 3.3 ms, mean +/- SE), short-duration (49.3 +/- 8.0 ms) excitation, whereas 8.6% were inhibited. In animals that had stimulation sites outside of PVN (non-PVN), only 4 of the 72 AP cells tested (5.6%) were influenced by stimulation. These excitatory effects of PVN stimulation on AP neurons were unaffected by V1-receptor blockade. Of 93 nucleus of the solitary tract (NTS) cells tested, 38.9% responded to PVN stimulation with a short-latency (18.5 +/- 2.4 ms), short-duration (48.8 +/- 9.6 ms) excitation and 22.2% with short-latency (20.75 +/- 4.1 ms), long-duration (204.4 +/- 44.9 ms) inhibitions. In contrast, non-PVN stimulation sites influenced only 19% of NTS neurons tested, all of which were excited. These data demonstrate that activation of PVN neurons elicits excitatory effects on the majority of AP neurons influenced. They further emphasize the potential significance of descending hypothalamic inputs in controlling neuronal activity in this circumventricular organ.

Vasopressin actions on area postrema neurons in vitro

1995 ◽  
Vol 269 (2) ◽  
pp. R463-R468
Author(s):  
V. L. Lowes ◽  
K. Sun ◽  
Z. Li ◽  
A. V. Ferguson
Keyword(s):  
Area Postrema ◽  
Brain Slices ◽  
Dorsal Surface ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Artificial Cerebrospinal Fluid ◽  
Single Unit Recordings ◽  
Excitatory Responses ◽  
Dose Dependent

The area postrema (AP) is a circumventricular organ located on the dorsal surface of the medulla. Substantial evidence suggests that the AP is an important site involved in cardiovascular regulation. Arginine vasopressin (AVP) is thought to act at the AP to increase the sensitivity of the baroreceptor reflex. We have therefore examined the effects of AVP on AP neurons with the use of extracellular single unit recordings in vitro. Coronal medullary brain slices (thickness = 400 microns) were obtained from male Sprague-Dawley rats and maintained in oxygenated artificial cerebrospinal fluid (aCSF). The slices were perfused with AVP (10(-8) to 10(-6) M), and the effect on single AP neurons was recorded. A total of 79 AP neurons was tested of which 50 (63.3%) were excited by AVP and 5 (6.3%) were inhibited, whereas the remaining 24 (30.3%) cells were unaffected. The excitatory effects of AVP were dose dependent: firing rate increased 92.6 +/- 25.8% at 10(-8) M, 289.4 +/- 53.9% at 10(-7) M, and 456.8 +/- 113.1% at 10(-6) M, respectively. We also examined whether these effects of AVP resulted from direct actions of this peptide on AP cells by testing if responses were retained during blockade of synaptic transmission (achieved by perfusion with a low Ca(2+)-high Mg2+ aCSF) in 11 cells excited by AVP. Nine of these cells were excited by AVP during such synaptic blockade. Finally, we demonstrated that the excitatory responses of five AP cells to AVP were all totally abolished by perfusion of slices with aCSF containing the V1 antagonist ([1-beta-mercapto-beta,beta-cyclopentamethylene propionic acid,2-(O-methyl)tyrosine]-Arg8-vasopressin; Peninsula Laboratories, 10(-6) M).(ABSTRACT TRUNCATED AT 250 WORDS)

Permeability of the microcirculation in area postrema of rat

1988 ◽  
Vol 46 ◽  
pp. 348-349
Author(s):  
Shams M. Ghoneim ◽  
Frank M. Faraci ◽  
Gary L. Baumbach
Keyword(s):  
Brain Stem ◽  
Area Postrema ◽  
Upper Body ◽  
Sprague Dawley ◽  
Sodium Cacodylate ◽  
Acute Hypertension ◽  
Sprague Dawley Rats ◽  
Ultrastructural Characteristics ◽  
The Brain ◽  
Adjacent Brain

The area postrema is a circumventricular organ in the brain stem and is one of the regions in the brain that lacks a fully functional blood-brain barrier. Recently, we found that disruption of the microcirculation during acute hypertension is greater in area postrema than in the adjacent brain stem. In contrast, hyperosmolar disruption of the microcirculation is greater in brain stem. The objective of this study was to compare ultrastructural characteristics of the microcirculation in area postrema and adjacent brain stem.We studied 5 Sprague-Dawley rats. Horseradish peroxidase was injected intravenously and allowed to circulate for 1, 5 or 15 minutes. Following perfusion of the upper body with 2.25% glutaraldehyde in 0.1 M sodium cacodylate, the brain stem was removed, embedded in agar, and chopped into 50-70 μm sections with a TC-Sorvall tissue chopper. Sections of brain stem were incubated for 1 hour in a solution of 3,3' diaminobenzidine tetrahydrochloride (0.05%) in 0.05M Tris buffer with 1% H2O2.

scholarly journals Differential Effects of Refeeding on Melanocortin-Responsive Neurons in the Hypothalamic Paraventricular Nucleus

Endocrinology ◽  
2008 ◽  
Vol 149 (9) ◽  
pp. 4329-4335 ◽  
Author(s):  
Edith Sánchez ◽  
Praful S. Singru ◽  
Runa Acharya ◽  
Monica Bodria ◽  
Csaba Fekete ◽  
...  
Keyword(s):  
Gene Expression ◽  
Paraventricular Nucleus ◽  
Hypothalamic Paraventricular Nucleus ◽  
Mrna Levels ◽  
Sprague Dawley ◽  
Early Action ◽  
Sprague Dawley Rats ◽  
Melanocortin Signaling ◽  
Agouti Related Protein ◽  
Serum Tsh

To explore the effect of refeeding on recovery of TRH gene expression in the hypothalamic paraventricular nucleus (PVN) and its correlation with the feeding-related neuropeptides in the arcuate nucleus (ARC), c-fos immunoreactivity (IR) in the PVN and ARC 2 h after refeeding and hypothalamic TRH, neuropeptide Y (NPY) and agouti-related protein (AGRP) mRNA levels 4, 12, and 24 h after refeeding were studied in Sprague-Dawley rats subjected to prolonged fasting. Despite rapid reactivation of proopiomelanocortin neurons by refeeding as demonstrated by c-fos IR in ARC α-MSH-IR neurons and ventral parvocellular subdivision PVN neurons, c-fos IR was present in only 9.7 ± 1.1% hypophysiotropic TRH neurons. Serum TSH levels remained suppressed 4 and 12 h after the start of refeeding, returning to fed levels after 24 h. Fasting reduced TRH mRNA compared with fed animals, and similar to TSH, remained suppressed at 4 and 12 h after refeeding, returning toward normal at 24 h. AGRP and NPY gene expression in the ARC were markedly elevated in fasting rats, AGRP mRNA returning to baseline levels 12 h after refeeding and NPY mRNA remaining persistently elevated even at 24 h. These data raise the possibility that refeeding-induced activation of melanocortin signaling exerts differential actions on its target neurons in the PVN, an early action directed at neurons that may be involved in satiety, and a later action on hypophysiotropic TRH neurons involved in energy expenditure, potentially mediated by sustained elevations in AGRP and NPY. This response may be an important homeostatic mechanism to allow replenishment of depleted energy stores associated with fasting.

Electroacupuncture at Zusanli Rescues the Enteric Neuronal Loss in the Stomach of Diabetic Rats

2012 ◽  
Vol 18 (1) ◽  
pp. 5-14 ◽  
Author(s):  
Min Hu ◽  
Fan Du ◽  
Shi Liu
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Neuronal Loss ◽  
Diabetic Rats ◽  
Enteric Neurons ◽  
Control Group ◽  
Sprague Dawley ◽  
Long Duration ◽  
Sprague Dawley Rats ◽  
Zusanli Acupoint

The purpose of this study was to investigate the effects of electroacupuncture at Zusanli acupoint on the enteric neuropathy in diabetic rats. Sprague–Dawley rats were divided into different groups depending on the total electroacupuncture span and frequency. The expression of nitric oxide synthase (nNOS), choline acetyltransferase (CHAT), protein gene product 9.5 (PGP9.5), and doublecortin was significantly decreased in the diabetic group compared with the control group. Long-term electroacupuncture at Zusanli with either high frequency or low frequency could increase the expression levels of nNOS, CHAT, PGP9.5, and doublecortin, and the increase was greater in the high-frequency group. But no obvious changes were seen in the short-term electroacupuncture groups. These results suggest that electroacupuncture at Zusanli can restore the deficiency of enteric neurons in diabetes partly but a comparative long duration of stimuli (6 weeks) is required. The increase of doublecortin may be involved in this positive process.

Regional effect of naltrexone in the nucleus of the solitary tract in blockade of NPY-induced feeding

2000 ◽  
Vol 278 (2) ◽  
pp. R499-R503 ◽  
Author(s):  
C. M. Kotz ◽  
M. J. Glass ◽  
A. S. Levine ◽  
C. J. Billington
Keyword(s):  
Cerebrospinal Fluid ◽  
Food Intake ◽  
Paraventricular Nucleus ◽  
Opioid Receptors ◽  
The Other ◽  
Solitary Tract ◽  
Sprague Dawley ◽  
Regional Effect ◽  
Sprague Dawley Rats ◽  
Artificial Cerebrospinal Fluid

Naltrexone (NLTX) in the nucleus of the solitary tract (NTS) decreases feeding induced by neuropeptide Y (NPY) in the paraventricular nucleus (PVN). We sought to determine the NTS region most sensitive to NLTX blockade of PVN NPY-induced feeding. Male Sprague-Dawley rats were fitted with two cannulas; one in the PVN and one in a hindbrain region: caudal, medial, or rostral NTS or 1 mm outside the NTS. Animals received NLTX (0, 1, 3, 10, and 30 μg in 0.3 μl) into the hindbrain region just prior to PVN NPY (0.5 μg, 0.3 μl) or artificial cerebrospinal fluid (0.3 μl). Food intake was measured at 2 h following injection. PVN NPY stimulated feeding, and NLTX in the medial NTS significantly decreased NPY-induced feeding at 2 h, whereas administration of NLTX in the other hindbrain regions did not significantly influence PVN NPY induced feeding. These data suggest that opioid receptors in the medial NTS are most responsive to feeding signals originating in the PVN after NPY stimulation.

Adrenomedullin microinjection into the area postrema increases blood pressure

1997 ◽  
Vol 272 (6) ◽  
pp. R1698-R1703 ◽  
Author(s):  
M. A. Allen ◽  
P. M. Smith ◽  
A. V. Ferguson
Keyword(s):  
Blood Pressure ◽  
Area Postrema ◽  
Area Under The Curve ◽  
Physiological Role ◽  
Cardiovascular Responses ◽  
Hypotensive Effect ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Brain Site

Adrenomedullin (ADM) circulates in the blood at concentrations comparable to other vasoactive peptides with established roles in cardiovascular regulation. Intravenously administered ADM produces a clear hypotensive effect, whereas intracerebroventricular microinjections result in increases in blood pressure (BP). Recently, we demonstrated that ADM influences neurons of the area postrema (AP), a central nervous system site implicated in cardiovascular control. However, to address directly the physiological significance of the actions of ADM at the AP, an in vivo microinjection study was undertaken. ADM, at two concentrations (1 and 10 microM), in volumes of 50, 100, and 200 nl, was microinjected into the AP or NTS of 21 urethan-anesthetized male Sprague-Dawley rats. Microinjection of 10 microM ADM (100 nl) resulted in significant transient (2-5 min) increases in BP [120 s area under the curve (AUC): 684.3 +/- 268.6 mmHg/s (P < 0.05)], and heart rate (HR) [AUC: 12.5 +/- 4.5 beats/min (P < 0.05)]. The lower concentration of ADM (1 microM) had no effect on either BP (179.1 +/- 143.6 mmHg/s) or HR (0.8 +/- 2.6 beats/min). ADM was also microinjected into the immediately adjacent nucleus of the solitary tract, where it was found to be without effect on either BP or HR. This study demonstrates, for the first time, a physiological role for ADM acting at a specific brain site, the AP, to produce significant cardiovascular responses.

Level of satiety: GABA and pentose shunt activities in three brain sites associated with feeding

1985 ◽  
Vol 248 (4) ◽  
pp. R453-R458 ◽  
Author(s):  
T. R. Kasser ◽  
R. B. Harris ◽  
R. J. Martin
Keyword(s):  
Area Postrema ◽  
Ventromedial Hypothalamus ◽  
Aminobutyric Acid ◽  
Gamma Aminobutyric Acid ◽  
Energy Status ◽  
Sprague Dawley ◽  
Brain Areas ◽  
Gastric Intubation ◽  
Glucose Flux ◽  
Sprague Dawley Rats

The hypothesis addressed was that metabolic activity within specific brain areas may be altered to depict peripheral metabolic status. Sixty-three female Sprague-Dawley rats (225 g) received 150, 100, or 50% of normal intake by gastric intubation for 7 days. The incentive for spontaneous feeding would be inhibited in 150% fed rats (anoretic), stimulated in 50% fed rats (hungry), and maintained in 100% fed rats (control). Glucose flux through the gamma-aminobutyric acid shunt of the ventrolateral hypothalamus was 32% lower in hungry rats and 35% higher in anoretic rats relative to control values. Glucose flux through the pentose shunt of the ventromedial hypothalamus was 111% lower in hungry rats and 152% higher in anoretic rats relative to control values. Pentose shunt activity in the area postrema nucleus of the solitary tract (AP NTS) was 116% lower in hungry rats and 60% higher in anoretic rats relative to control values; however, hungry and anoretic rats had AP NTS pentose shunt activities that were not different from control values but were different from each other. The data demonstrate that within selective brain sites, specific pathways for glucose oxidation are affected by energy intake and may be used by the rat to assess and respond to changes in peripheral energy status.

Effect of circulating vasopressin on arterial pressure regulation in rats

1989 ◽  
Vol 257 (1) ◽  
pp. H209-H218 ◽  
Author(s):  
C. M. Pawloski ◽  
N. M. Eicker ◽  
L. M. Ball ◽  
M. L. Mangiapane ◽  
G. D. Fink
Keyword(s):  
Heart Rate ◽  
Arterial Pressure ◽  
Body Fluid ◽  
Area Postrema ◽  
Sodium Intake ◽  
Blood Levels ◽  
Fluid Composition ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Autonomic Cardiovascular Control

It has been hypothesized that moderately increased blood levels of arginine vasopressin (AVP) contribute to the development and/or maintenance of hypertension. In this study, male Sprague-Dawley rats on a fixed 1 meq daily sodium intake received 10-day intravenous infusions of 0.2 and 2.0 ng.kg-1.min-1 AVP. The higher infusion rate was above the acute vasoconstrictor threshold for AVP administration and also produced a maximal antidiuretic effect. During chronic AVP administration, however, daily mean arterial pressure, heart rate, and body fluid composition were not changed, despite a maintained antidiuresis. To test the hypothesis that circulating AVP failed to cause hypertension as a result of sensitization of the baroreflex or a direct sympathoinhibitory effect of the peptide, additional experiments were performed in rats subjected to sinoaortic denervation (SAD) or ablation of the area postrema (APX). Infusion of AVP for 10 days into SAD or APX rats caused a sustained antidiuresis but did not change arterial pressure, heart rate, or body fluid composition. In all groups of rats, the depressor response to ganglionic blockade (20 mg/kg hexamethonium) was used to estimate the autonomic component of resting arterial pressure; no change in autonomic cardiovascular control was found using this method in any of the groups during AVP infusion. Long-term elevation of plasma AVP in rats, therefore, does not cause hypertension or significantly affect autonomic regulation of arterial pressure.

Leptin acts in the rat hypothalamic paraventricular nucleus to induce gastric mucosal damage

1998 ◽  
Vol 275 (6) ◽  
pp. R2081-R2084
Author(s):  
Pauline M. Smith ◽  
Veronique Mollaret ◽  
Alastair V. Ferguson
Keyword(s):  
Paraventricular Nucleus ◽  
Area Under Curve ◽  
Mucosal Damage ◽  
System Structure ◽  
Gastric Mucosal Damage ◽  
Sprague Dawley ◽  
Specific Population ◽  
Regulate Body Weight ◽  
Sprague Dawley Rats ◽  
A Site

Leptin is produced and secreted by adipocytes to regulate body weight homeostasis. Leptin acts centrally to reduce weight by decreasing food intake and increasing energy expenditure. The paraventricular nucleus (PVN) is a central nervous system structure suggested as a site at which leptin acts to exert its central effects. Leptin microinjection (10−6 M, 0.5 μl) into the PVN of urethan-anesthetized male Sprague-Dawley rats (150–300 g) resulted in significant gastric damage (mean score = 1.75, n = 16). Damage scores were significantly different than those observed after saline microinjection into the PVN (mean score = 0.00, n = 5, P < 0.05), or leptin microinjection into non-PVN sites (mean score = 0.33, n = 6, P < 0.05). There were no changes in blood pressure (mean area under curve = 401.9 ± 224.2 mmHg * s, n = 11, P > 0.05) or heart rate (mean area under curve = 40.9 ± 25.9 beats, n= 10, P > 0.05) in response to leptin microinjection into PVN. These results suggest that leptin acts on a functionally specific population of PVN neurons involved in the control of gastrointestinal function.

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