Visceromotor Reflex Research Articles

Cholinergic sensitivity and pseudoaffective visceromotor reflex response (VMR) to colorectal distention (CRD) in FSL and FRL rats

Cholinergic sensitivity and pseudoaffective visceromotor reflex response (VMR) to colorectal distention (CRD) in FSL and FRL rats

Inflammation enhances reflex and spinal neuron responses to noxious visceral stimulation in rats.

To improve understanding of sensory processes related to visceral inflammation, the effect of turpentine-induced inflammation on reflex (cardiovascular/visceromotor) and extracellularly recorded lumbosacral dorsal horn neuron responses to colorectal distension (CRD) was investigated. A 25% solution of turpentine, applied to the colorectal mucosa, produced inflammation, decreased compliance of the colonic wall, and enhanced reflex responses in unanesthetized rats within 2-6 h. At 24 h posttreatment, pressor responses to CRD (80 mmHg, 20 s) were 20% greater, and intraluminal pressures needed to evoke visceromotor reflexes were 30% lower than controls. Parallel electrophysiological experiments in spinal cord-transected, decerebrate rats demonstrated that two neuronal subgroups excited by CRD were differentially affected by turpentine administered 24 h before testing. During CRD, abrupt neurons were 70% less active and sustained neurons were 25% more active than similar neurons in controls. In summary, reflex and neuronal subgroup (sustained neurons) responses to CRD were both potentiated by chemical inflammation. This suggests that the neurophysiological basis for inflammation-induced increases in reflex responses to CRD is increased activity of this neuronal subgroup.

Evidence for thoracolumbar spinal cord processing of inflammatory, but not acute colonic pain.

The lower bowel is innervated by visceral afferents projecting to the lumbosacral and thoracolumbar spinal segments. The present study tested the hypothesis that sensory processing from the normal colon occurs in the lumbosacral spinal cord with little or no activity in the thoracolumbar segments. Following colonic inflammation, viscerosensory processing in the thoracolumbar spinal cord is recruited, contributing to visceral hyperalgesia. A baseline visceromotor reflex to colorectal distention recorded in intact rats was eliminated following bilateral L6-S3 dorsal rhizotomies. The visceromotor reflex recovered to 29% of baseline following colonic inflammation. These results suggest that visceral hyperalgesia and referred pain in patients with lower bowel disorders partly result from novel viscerosensory processing in the thoracolumbar spinal cord.

Evidence for visceral hypersensitivity in high-anxiety rats

In patients with irritable bowel syndrome, anxiety is often associated with visceral pain. Based on this information we hypothesized that rats genetically predisposed to anxiety have an increased visceral sensitivity. To test this hypothesis, visceromotor reflex recordings in response to colorectal distention were used to estimate the level of visceral stimulation in high; moderate-, and low-anxiety rats. We compared the effect of innocuous colorectal distension in rats with and without sensitized colons. In nonsensitized rats visceromotor responses were increased by colorectal distention with the greatest response in the high-anxiety Wistar–Kyoto strain. Sensitization of the colon significantly increased visceromotor responses to colorectal distention in all rat strains. In summary, our data suggested that a manifestation of a genetically determined anxiety level appeared to be abnormal neural responsiveness of the gastrointestinal tract leading to visceral hypersensitivity in high-anxiety animals.

Neurokinin-1 receptor immunoreactivity in the nucleus of the solitary tract in the hamster.

Substance P (SP) modulates the activity of taste-responsive neurons in the gustatory zone of the nucleus of the solitary tract (NST) in the hamster. The distribution of the neurokinin-1 (NK1) receptor (i.e. the SP receptor) was mapped and compared with the distribution of SP immunoreactivity to identify the sites of ligand-receptor interactions. NK1-immunoreactive puncta and somata were located mostly in the rostral lateral, upper half of the rostral central and medial NST subnuclei. These subnuclei also contained intense SP-immunoreactive puncta, and are known to receive substantial inputs via gustatory and somatosensory afferent fibers. The ventral subnucleus, which is involved in visceromotor reflexes accompanying ingestion, contained little NK1 or lighter SP-immunoreactivity. These findings suggest that SP modulates taste activity destined for the ascending gustatory pathway at the level of the first central synapse in the gustatory pathway.

Medullary projections to the vagus nerve and posterolateral hypothalamus.

Vagal visceromotor reflexes are dependent upon reciprocal neural connections existing between the medulla and the hypothalamus. Medullohypothalamic neurons may provide feedback cues to the hypothalamus regarding the activity of vagal motor neurons. As yet, however, studies investigating the spatial relationships between medullohypothalamic neurons and vagal motor neurons have not been performed. A variety of retrogradely transported tracers were used for the purpose of mapping the relative locations of medullovagal and medullohypothalamic neurons. Tracers were injected into the cervical vagus nerve and/or the posterolateral hypothalamus, and subsequently the retrogradely labeled medullary neurons were plotted. Labeling of the two neuronal populations was primarily observed within the ventrolateral and dorsomedial medulla. Within the ventrolateral medulla, medullovagal neurons were found within the retrofacial nucleus and nucleus retroambiguus, whereas medullohypothalamic neurons were located subjacent to these nuclei. Within the dorsomedial medulla, labeling of the two neuronal populations was primarily limited to the vagal-solitary complex. At this location medullovagal neurons were found within the dorsal vagal nucleus, whereas medullohypothalamic neurons were largely confined to the caudal aspect of the solitary nucleus. Because of the spatial proximity existing between medullovagal and medullohypothalamic neurons, it is suggested that functional interrelationships may exist between these two neuronal populations. Specifically, it is suggested that the medullohypothalamic neurons identified in this study may support vagal-related functions by providing feedback cues to the posterolateral hypothalamus.

Differences between 5‐HT3 receptor antagonists in modulation of visceral hypersensitivity

1. Noxious colo-rectal distension was applied in conscious rats by acute balloon inflation and the effects observed as abdominal muscle contraction with the threshold typically between 10-40 mmHg. The effects of 5-HT3 receptor antagonists on responses to noxious colo-rectal distension were then studied in both normal rats and those pretreated with 5-hydroxytryptophan (5-HTP). 2. Granisetron and ondansetron (10 micrograms kg-1 and 1 mg kg-1, s.c.) had no effect on visceromotor thresholds to colo-rectal distension in normal rats. 3. Hypersensitivity of the colo-rectum was achieved by systemic administration of a low dose of 5-HTP (10 mg kg-1, s.c.) which lowered the distension pressure required to induce the visceromotor reflex; analysis of variance showed a highly significant treatment effect (F1,11 = 84.26, P < 0.001). 4. Granisetron, zatosetron, bemesetron and renzapride equi-potently increased the threshold values at which distension evoked a visceromotor reflex after dosing with 5-HTP, with a maximal response 3.6 to 4.2 fold above saline controls, at 10 micrograms kg-1, s.c. Metoclopramide (10 micrograms kg-1) also raised the level of distension required to elicit a response. By comparison, tropisetron caused a small, non-significant increase in visceromotor threshold values and only at high doses (1 mg kg-1), whilst ondansetron and BRL 46470 had no significant effects at doses up to 10 mg kg-1. 5. The response to granisetron (10 micrograms kg-1, s.c.) in 5-HTP-treated rats was unaltered by pre-administration of naloxone (5 mg kg-1, s.c.). 6. These results suggest that a 5-HT3-like receptor modulates 5-HTP- evoked visceral hypersensitivity.However, the rank order of antagonist potency does not correlate with their order of potency against the classically defined 5-HT3 receptor.

DIRECT SPINAL EFFECT OF INTRATHECAL AND EXTRADURAL MIDAZOLAM ON VISCERAL NOXIOUS STIMULATION IN RABBITS

We measured alterations in a noxious visceromotor reflex in rabbits subjected to intestinal distension, after i.m., extradural or intrathecal injection of midazolam or saline. Spinal catheters were inserted and tunnelled surgically and the animals allowed to recover for 2 weeks. A balloon catheter was placed in the distal part of the descending colon, in the awake rabbit. Intraluminal pressures were increased continuously by water instillation until a sudden withdrawal of the pelvis was observed. Pressure values at withdrawal threshold were recorded immediately before the injection and after 5, 15 and 30 min. Pain thresholds were unaltered after saline. Extradural midazolam 12.5-250 micrograms kg-1 produced a dose-dependent increase in the percent maximum possible effect ranging from 7% after the smallest dose to 80%. Similar dose-dependent effects were observed after intrathecal injection of midazolam 25-62.5 micrograms kg-1. Extradural and intrathecal, but not i.v. injection of flumazenil 25 micrograms kg-1 (a benzodiazepine receptor antagonist) reduced the antinociceptive effect of extradural and intrathecal midazolam to pretreatment levels. A segmental effect of intrathecal midazolam was demonstrated using transcutaneous electrical stimulation in the areas of the neck and the lower back. The effect of intrathecal midazolam 62.5 microrgrams kg-1 was restricted to the lumbar region, demonstrating a selective action on the spinal cord. Thus extradural and intrathecal midazolam produced a dose-dependent effect on the reflex response to visceral distension in rabbits. This effect is caused by a direct spinal action on benzodiazepine receptors in the spinal cord.

Direct spinal effect of intrathecal acetaminophen on visceral noxious stimulation in rabbits.

The aim of this study was to investigate the effect of intrathecal acetaminophen on visceral and somatic noxious stimulation in the intact, non-anesthetized rabbit. Sixteen rabbits had intrathecal catheters implanted surgically. Visceral noxious stimulation was induced by intestinal distension of the distal colon and somatic stimulation with increasing electrical current through skin electrodes placed in either the cervical or the lumbar area. The effect on visceral noxious stimulation was assessed following intrathecal injection of 0.5, 2.5 and 5 mg of acetaminophen and following 10 and 50 mg acetaminophen intravenously. Naloxone 0.2 mg and yohimbine 0.1 mg were administered intrathecally prior to intrathecal injection of acetaminophen 5 mg. A dose-dependent effect of intrathecal acetaminophen against the visceromotor reflex produced by intestinal distension was shown. No effects on thresholds to lumbar or cervical electrical stimulation or intestinal distension were observed following i.v. administration. Thresholds to noxious electrical stimulation were only significantly elevated at the lumbar level following i.t. injection of 5 mg acetaminophen. Naloxone failed to antagonize the effect of intrathecal acetaminophen, whereas intrathecal yohimbine attenuated the effect of intrathecal acetaminophen in both tests. In conclusion, a spinal, dose-dependent, naloxone-irreversible, and yohimbine-reversible effect of intrathecal acetaminophen on electrical and visceral noxious stimulation was demonstrated.

Differential attenuation of somatovisceral and viscerosomatic reflexes by diazepam, phenobarbital and diphenylhydantoin

In the chloralose-anaesthetized cat, stimulation of forelimb cutaneous afferent nerves evoked a response in the preganglionic splanchnic nerve, consisting of a short duration spinal reflex followed by a supraspinal component of longer duration. Diazepam (0·1–1·4 mg/kg, i.v.) markedly attenuated the supraspinal reflex but had a considerably lesser effect on the segmental response. On the other hand, diphenylhydantoin (10–40 mg/kg, i.v.) reduced predominantly the spinal component, whilst the supraspinal reflex was frequently enhanced after the initial dose of 10 mg/kg. This effect of diphenylhydantoin on the spinal reflex was direct, since it also occurred in the spinal cat. Phenobarbital (10–40 mg/kg, i.v.) was approximately equally potent in reducing both the spinal and supraspinal reflex. Visceromotor reflexes were markedly depressed by very small doses of diazephm (0·001 mg/kg, i.v.) and by larger doses of phenobarbital (10–20 mg/kg, i.v.). Diphenylhydantoin, although reducing this reflex, did not completely block it at the highest total dose tested (40 mg/kg, i.v.). The results indicate that the three CNS depressants differentially affect the spinal and supraspinal components of the somatosymphetic reflex. Furthermore, the three drugs also differ quantitatively from each other in depressing the spino-bulbo-spinal transmission of the viscerosomatic reflex.

Spinal and spino-bulbo-spinal neuronal mechanisms of transmission of somatomotor and visceromotor reflexes in the thoracic spinal cord

Early (spinal) and late (spino-bulbo-spinal) responses of interneurons in segments T9–10 to stimulation of the splanchnic and intercostal nerves and the dorso-lateral and ventral funiculi of the spinal cord (at the C3 level) were investigated in experiments on cats anesthetized with chloralose. The experiments showed that interneurons activated by spinal and spino-bulbo-spinal mechanisms differ in their distribution in the dorso-ventral plane of the spinal cord. Cells of layers I–V were excited by spinal pathways only, but those of layers VII and VIII by both spinal and spino-bulbo-spinal or only by the latter. Spino-bulbo-spinal effects were evoked in interneurons by both somatic and visceral afferent waves. A conditioning spino-bulbo-spinal wave evoked deep and prolonged inhibition of late activity induced by somatic or visceral afferent impulses. Early (spinal) activity was inhibited only partially under these circumstances. This inhibition was shown to take place with the participation of supraspinal structures. The possible types of spinal and supraspinal mechanisms of inhibition of early and late activity in spinal neurons are discussed.

Suprasegmentary control of the intraspinal pathways of visceromotor reflexes

Experiments on spinal cats under chloraeose-nembutal anesthesia (45 mg and 15 mg per kg of body weight) were carried out to study the time and spatial sequence of activation of different neuron structures of the 5th lumbar segment of the spinal cord in stimulation of the ipsilateral splanchnic nerve.

The intersegmental pathways of the visceromotor reflexes of the spinal cord

The intersegmental pathways of the visceromotor reflexes of the spinal cord

Supraspinal control of synaptic processes in visceromotor reflexes

Supraspinal control of synaptic processes in visceromotor reflexes

Patterns of response of the paravertebral musculature to visceral stimuli.

Stimulation of abdominal viscera provokes reflex contractions of the paravertebral muscles. The reflex contractions change in intensity and in number of segments involved with variations in degree of stimulus. With minimal stimuli the response is limited to two or three segments. With increasing intensity of stimuli the response spreads to include adjacent segments and can extend to the contralateral side. Such visceromotor reflexes have been shown for the renal pelvis, ureter, small intestine and fallopian tube. When an unpaired organ such as the intestine is stimulated, the response is bilateral even to minimal stimuli. To a prolonged stimulus there is a build-up to a peak activity followed by a decrease which is then maintained for variable periods from seconds to hours. Such prolonged activity also frequently follows very brief stimuli. The influences of drugs and other stimuli on these visceromotor reflexes are demonstrated.

Spinal reflex activity from the vesical mucosa in paraplegic patients.

Introduction The reciprocal innervation of the smooth vesical detrusor and striated muscles of the pelvic floor has been well documented by cystometry, electromyography, a combination of the two, and various anesthetic procedures. Thus a good working hypothesis has been provided for physiological and pathological micturition.1-5According to common neurological nomenclature, therefore, only proprioceptive reflex activity has been studied. In contrast, the reflex activity which correlates stimuli of the bladder mucosa and responses of the detrusor and pelvic floor musculature has not been explored. Three factors motivated the present study. 1. A continuing interest in the bulbocavernosus reflex,6which is diagnostically important in differentiating somatomotor lesions above and below the conus; this reflex becomes significant in the proper classification and treatment of patients with traumatic cord bladder because the conus contains the spinal visceromotor reflex centers of the bladder. Experience with sacral neurotomy on patients with spinal cord injury

Splanchnic afferent pathways in the central nervous system.

Splanchnic afferent pathways in the central nervous system.

Fiber groups and spinal pathways of cortically represented visceral afferents.

Fiber groups and spinal pathways of cortically represented visceral afferents.

THE EFFECTS OF NOVOCAIN INJECTIONS ON SIMULATED VISCERAL PAIN

Article1 November 1943THE EFFECTS OF NOVOCAIN INJECTIONS ON SIMULATED VISCERAL PAINDENNISON YOUNG, M.D.DENNISON YOUNG, M.D.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-19-5-749 SectionsAboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail ExcerptPeripheral manifestations of nerve root involvement in spondylitis have been known since the days of von Bechterew,1but it was not recognized until many years later that similarly radicular pain secondary to hypertrophic or infectious arthritis of the spine2, 3, 4, 5, 6or narrowing of the intervertebral spaces7, 8could mimic intrathoracic disease or acute abdominal emergencies. The usual treatment of this type of pain has consisted of various drugs, physical measures including baking and massage, manipulations of the affected joints, and often roentgen-ray therapy. Unfortunately most of these measures yield but transient relief and frequently the pain has...Bibliography1. VON BECHTEREW W: Steifigkeit der Wirbelsäule und ihre Verkrümmung als besondere Erkrankungsform, Neurol. Centralbl., 1893, xii, 426. Google Scholar2. GUNTHERKERR LWJ: The radicular syndrome in hypertrophic osteoarthritis of the spine, Arch. Int. Med., 1929, xliii, 212. CrossrefGoogle Scholar3. GUNTHERSAMPSON LJJ: The radicular syndrome in hypertrophic osteoarthritis of the spine. Root pain and its differentiation from heart pain, Jr. Am. Med. Assoc., 1929, xciii, 514. CrossrefGoogle Scholar4. NACHLAS IW: Pseudo-angina pectoris originating in the cervical spine, Jr. Am. Med. Assoc., 1934, ciii, 323. CrossrefGoogle Scholar5. HANFLIG SS: Pain in the shoulder girdle, arm and precordium due to cervical arthritis, Jr. Am. Med. Assoc., 1936, cvi, 523. CrossrefGoogle Scholar6. KELLY LC: Chronic hypertrophic osteoarthritis in the cervical spine with radiculitis. 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Sci., 1939, iv, 47. Google Scholar20. LIVINGSTON WK: Back disabilities due to strain of the multifidus muscle. Cases treated by novocain injection, West. Jr. Surg., Obst., and Gynec., 1941, xlix, 259. Google Scholar21. GUTSTEIN-GOOD M: Idiopathic myalgia. Simulating visceral and other diseases, Lancet, 1940, i, 326. CrossrefGoogle Scholar22. MOYNAHAN EJ: Treatment of acute sprains by procaine infiltration (Leriche's method), Lancet, 1939, i, 672. Google Scholar This content is PDF only. To continue reading please click on the PDF icon. Author, Article, and Disclosure InformationAffiliations: Tallahassee, Florida*Received for publication June 8, 1942.From the Medical Division, Montefiore Hospital for Chronic Diseases, New York, N. Y. PreviousarticleNextarticle Advertisement FiguresReferencesRelatedDetails Metrics Cited byAbdominal and pelvic painLetters to the editorReferences 1 November 1943Volume 19, Issue 5Page: 749-756KeywordsAbdominal painAnkylosing spondylitisArthralgiaArthritisDrug therapyInfectious diseasesNervesSpondylitis ePublished: 1 December 2008 Issue Published: 1 November 1943 PDF downloadLoading ...

THE VISCEROGALVANIC REACTION

The differential diagnosis of visceral diseases is often aided by a study of the associated referred pain of the hyperalgetic zones of the skin and the tender areas of the muscles. Such a study, however, fails in many cases because the subjective complaints of the patients may be unreliable. It is desirable in such cases to localize pain by objective methods. It is known from the work of Head 1 and of MacKenzie 2 that diseases of visceral organs produce many reflexes in the skin, such as viscerovasomotor and visceropilomotor reflexes. There are also segmental reflexes from the viscera which cause localized hypertonicity of certain muscles, the so-called visceromotor reflexes. These phenomena are of clinical importance; however, they are not always found. A more delicate objective method for the demonstration of referred pain in cases of visceral disease seems therefore to be desirable. In such cases the segments of the