Neural pathways of cardiovascular depressor reflex during gastric distension and its modulation by electroacupuncture

Duodenal infusions of macronutrients inhibit sham and normal feeding. Neural substrates of this response were studied by infusing glucose, linoleic acid, an amino acid mixture, saline, or water into the duodenum of unanesthetized rats and then measuring sham feeding of 30% sucrose or Fos expression in the dorsal vagal complex. Linoleic acid and amino acids (both 1.5 kcal) and glucose (4.5 kcal) suppressed sham feeding relative to control infusions, and all three macronutrients triggered Fos expression in the nucleus of the solitary tract and area postrema. Although there were significant quantitative differences, the subnuclear distribution pattern of Fos-expressing neurons was not different for the three macronutrients and was largely localized to the medial, dorsomedial, and commissural subnuclei of the nucleus of the solitary tract and the area postrema. Linoleic acid suppressed intake and stimulated Fos expression similarly to glucose infusions of three times the caloric value. Amino acids strongly suppressed sham feeding but triggered relatively little Fos expression. These results indicate that the intake-suppressing potency of duodenal macronutrients is dependent on nutrient type, rather than simply caloric value, and that amino acids, although potent inducers of satiety, affect ingestion by processes different from those subserving lipids and carbohydrates. Furthermore, the similar patterns of neuronal activation after different duodenal infusions may indicate a large degree of convergence at the level of primary and second-order sensory neurons, whereas the distinctly different pattern obtained earlier with gastric distension indicates partially separate neural pathways for satiety signals generated by duodenal nutrients and gastric mechanoreceptors.

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Gastric distension induces c-Fos in medullary GLP-1/2-containing neurons

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00732.2002 ◽

2003 ◽

Vol 285 (2) ◽

pp. R470-R478 ◽

Cited By ~ 130

Author(s):

Niels Vrang ◽

Curtis B. Phifer ◽

Michele M. Corkern ◽

Hans-Rudolf Berthoud

Keyword(s):

Food Intake ◽

Mechanical Stimulus ◽

Gastric Distension ◽

Neural Pathways ◽

Appetite Control ◽

Balloon Distension ◽

Different Types ◽

Inhibit Food Intake ◽

Freely Moving ◽

Caudal Medulla

A group of neurons in the caudal nucleus of the solitary tract (NTS) processes preproglucagon to glucagon-like peptides (GLP)-1 and -2, peptides that inhibit food intake when administered intracerebroventricularly. The GLP-1/2-containing neural pathways have been suggested to play a role in taste aversion and nausea because LiCl activates these neurons, and LiCl-induced suppression of food intake can be blocked by the GLP-1 receptor antagonist exendin-9. As many gastrointestinal signals related to both satiety and nausea/illness travel via the vagus nerve to the caudal medulla, the present study assessed the capacity of different types of gastric distension (a purely mechanical stimulus) to activate GLP-1 neurons in the caudal NTS. Gastric balloon distension (1.4 ml/min first 5 min, 0.4 ml/min next 5 min, 9 ml total, held for 60 min) in nonanesthetized, freely moving rats produced 12- and 17-fold increases in c-Fos-expressing NTS neurons when distension was mainly in the fundus or corpus, respectively. Fundus and corpus distension increased the percentage of c-Fos-activated GLP-1 neurons to 21 ± 9% and 32 ± 5% compared with 1 ± 1% with sham distension ( P < 0.01). Thus gastric distension that may be considered within the physiological range activates GLP-1/2-containing neurons, suggesting some role in normal satiety. The results support the view that the medullary GLP system is involved in appetite control and is activated by stimuli within the behavioral continuum, ranging from satiety to nausea.

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Pseudoaffective cardioautonomic responses to gastric distension in rats

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1999.277.1.r272 ◽

1999 ◽

Vol 277 (1) ◽

pp. R272-R278 ◽

Cited By ~ 4

Author(s):

Gervais Tougas ◽

Lu Wang

Keyword(s):

Heart Rate ◽

Heart Rate Response ◽

Vagal Afferents ◽

Celiac Plexus ◽

Cardiac Response ◽

Gastric Distension ◽

Neural Pathways ◽

Sensory Afferents ◽

Anesthetized Rats ◽

Subdiaphragmatic Vagotomy

We examined the heart rate response to gastric distension, the involvement of vagal and sympathetic sensory afferents, adrenergic and cholinergic neural pathways, and the effects of capsaicin on this response in anesthetized rats. Gastric distension volume dependently decreased heart rate by 24.5% (resting rate = 219.87 ± 14.06 beats/min, mean rate during gastric distension with 15 ml = 165.97 ± 17.36 beats/min, P < 0.05). The bradycardic response was significantly decreased after removal of the celiac plexus (9.71 ± 1.77 vs. 38.03 ± 7.06% in controls, P < 0.05) or after bilateral subdiaphragmatic vagotomy (6.38 ± 2.65%, P = 0.05). The response to gastric distension was largely prevented by systemic capsaicin (29.92 ± 4.93% in controls, 2.58 ± 4.19% after systemic capsaicin, P < 0.05) and decreased by perivagal capsaicin (18.72 ± 4.75%, P < 0.05). Atropine almost completely prevented the cardiac response to distension, while propranolol and bretylium partially blocked it, implying the response is primarily mediated by cholinergic efferents but also involves adrenergic pathways. We conclude that unmyelinated, capsaicin-sensitive vagal afferents are essential to the pseudoaffective cardioautonomic response to a noxious gastric stimulus.

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Central and peripheral mechanisms underlying gastric distention inhibitory reflex responses in hypercapnic-acidotic rats

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01131.2010 ◽

2011 ◽

Vol 300 (3) ◽

pp. H1003-H1012 ◽

Cited By ~ 7

Author(s):

Stephanie C. Tjen-A-Looi ◽

An-Fu Hsiao ◽

John C. Longhurst

Keyword(s):

Cardiovascular Response ◽

Nucleus Ambiguus ◽

Reflex Response ◽

Ventrolateral Medulla ◽

Gastric Distension ◽

Adrenergic Blockade ◽

Neural Pathways ◽

Chronotropic Response ◽

Reflex Responses ◽

Central Processing

We have observed that in chloralose-anesthetized animals, gastric distension (GD) typically increases blood pressure (BP) under normoxic normocapnic conditions. However, we recently noted repeatable decreases in BP and heart rate (HR) in hypercapnic-acidotic rats in response to GD. The neural pathways, central processing, and autonomic effector mechanisms involved in this cardiovascular reflex response are unknown. We hypothesized that GD-induced decrease in BP and HR reflex responses are mediated during both withdrawal of sympathetic tone and increased parasympathetic activity, involving the rostral (rVLM) and caudal ventrolateral medulla (cVLM) and the nucleus ambiguus (NA). Rats anesthetized with ketamine and xylazine or α-chloralose were ventilated and monitored for HR and BP changes. The extent of cardiovascular inhibition was related to the extent of hypercapnia and acidosis. Repeated GD with both anesthetics induced consistent falls in BP and HR. The hemodynamic inhibitory response was reduced after blockade of the celiac ganglia or the intraabdominal vagal nerves with lidocaine, suggesting that the decreased BP and HR responses were mediated by both sympathetic and parasympathetic afferents. Blockade of the NA decreased the bradycardia response. Microinjection of kainic acid into the cVLM reduced the inhibitory BP response, whereas depolarization blockade of the rVLM decreased both BP and HR inhibitory responses. Blockade of GABAA receptors in the rVLM also reduced the BP and HR reflex responses. Atropine methyl bromide completely blocked the reflex bradycardia, and atenolol blocked the negative chronotropic response. Finally, α1-adrenergic blockade with prazosin reversed the depressor. Thus, in the setting of hypercapnic-acidosis, a sympathoinhibitory cardiovascular response is mediated, in part, by splanchnic nerves and is processed through the rVLM and cVLM. Additionally, a vagal excitatory reflex, which involves the NA, facilitates the GD-induced decreases in BP and HR responses. Efferent chronotropic responses involve both increased parasympathetic and reduced sympathetic activity, whereas the decrease in BP is mediated by reduced α-adrenergic tone.

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Interaction of GLP-1 with gastric distension in regulating food intake and satiety in humans

Gastroenterology ◽

10.1016/s0016-5085(01)81036-2 ◽

2001 ◽

Vol 120 (5) ◽

pp. A208-A208

Author(s):

L DEGEN ◽

D MATZINGER ◽

B FISCHER ◽

F ZIMMERLI ◽

M KNUPP ◽

...

Keyword(s):

Food Intake ◽

Gastric Distension

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Transcutaneous ultrasonographic evaluation of gastric distension with fluid in horses

Journal of the American Veterinary Medical Association ◽

10.2460/javma.230.4.554 ◽

2007 ◽

Vol 230 (4) ◽

pp. 554-554

Author(s):

Marcos Lores ◽

Henrik Stryhn ◽

Laurie McDuffee ◽

Patricia Rose ◽

Tammy Muirhead

Keyword(s):

Gastric Distension

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Optometric Vision Therapy for Visual Deficits and Dysfunctions: A Suggested Model for Evidence-Based Practice

Vision Development & Rehabilitation ◽

10.31707/vdr2015.1.4.p290 ◽

2015 ◽

pp. 290-339

Keyword(s):

Speech Therapy ◽

Evidence Based Practice ◽

Behavioural Therapy ◽

Evidence Based ◽

Neural Pathways ◽

Central Processing ◽

Visual Deficits ◽

Visual Spatial ◽

Functional Vision ◽

Vision Therapy

Evidence from neural science supports a neuroplasticity thesis where the development and rehabilitation of functional neural pathways can be facilitated by management of biological factors, central processing and environmental interactions. Healthy eyes and clear sight are not themselves sufficient for efficient functional vision. How a person uses vision determines their operational skill. Efficient functional vision requires dynamic interactions between and within visual receptive and reflexive biology, acquired neural networks that serve basic visual inspection processes and visuo-cognitive operational patterns driving top down visual – spatial analysis and problem solving. This presentation is a review and discussion of evidence-based practice (EBP) principles that we utilise in clinical neuro-developmental and rehabilitative optometric vision therapy (OVT) for selected visual deficits and dysfunctions. OVT services, like other collaborative therapies such as cognitive behavioural therapy, speech therapy and occupational therapy, must progressively adapt to new knowledge and advancing technology through EBP. Clinical services directed at treatable neuro-developmental and acquired dynamic functional vision problems require the application of an emerging set of principles resulting from systematic logic and EBP related to the art and science of case analysis, practice management and OVT delivery.

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