Inhalation of a pulmonary irritant modulates activity of lumbosacral spinal neurons receiving colonic input in rats

2007 ◽  
Vol 293 (5) ◽  
pp. R2052-R2058 ◽  
Author(s):  
Chao Qin ◽  
Robert D. Foreman ◽  
Jay P. Farber
Keyword(s):  
Afferent Input ◽  
Male Rats ◽  
Ammonia Vapor ◽  
Spinal Neurons ◽  
Afferent Fibers ◽  
Cervical Vagotomy ◽  
Nociceptive Pathway ◽  
Lower Airways ◽  
Increased Activity ◽  
Extracellular Potentials

The purpose of the present study was to determine whether an intraspinal nociceptive pathway from the lungs modulated activity of spinal neurons that also received afferent input from the colon. Extracellular potentials of single lumbosacral (L6–S2) spinal neurons were recorded in pentobarbital-anesthetized, paralyzed, and ventilated male rats. The lower airways and lungs were irritated by injecting ammonia vapor over a 30% NH4OH solution into the inspiratory line of the ventilator (0.5 ml, 20 s). Graded colorectal distension (CRD; 20–60 mmHg, 20 s) was produced by air inflation of a balloon. Inhaled ammonia (IA) altered activity of 31/51 (61%) lumbosacral spinal neurons responding to noxious CRD (60 mmHg, 20 s). In contrast, IA changed activity of 3/30 (10%) spinal neurons with somatic fields that did not respond to colorectal inputs. IA decreased activity of 16/31 (52%) spinal neurons and increased activity of the other 15 neurons with colorectal input. Multiple patterns of viscerovisceral convergent spinal neurons with excitatory and inhibitory responses to CRD and IA were observed; 87% (27/31) of the viscerovisceral convergent neurons also responded to innocuous and/or noxious stimuli of somatic fields. Bilateral cervical vagotomy abolished responses to IA in 2/8 tested neurons, indicating that the remaining 6 neurons had input originating from sympathetic afferent fibers. Rostral C1 spinal transection did not abolish inhibitory responses to IA in 4/4 neurons, but L2 transection eliminated inhibitory responses to IA in 3/3 neurons. These results indicated that irritation of the lower airways modulated activity of lumbosacral spinal neurons with colorectal input. It might contribute to intraspinal cross talk between the colon and lungs.

Responses and Afferent Pathways of C1–C2 Spinal Neurons to Cervical and Thoracic Esophageal Stimulation in Rats

2004 ◽  
Vol 91 (5) ◽  
pp. 2227-2235 ◽  
Author(s):  
Chao Qin ◽  
Margaret J. Chandler ◽  
Chuanchau J. Jou ◽  
Robert D. Foreman
Keyword(s):  
Male Rats ◽  
Thoracic Esophagus ◽  
Spinal Neurons ◽  
Afferent Pathways ◽  
Dorsal Roots ◽  
Upper Cervical ◽  
Cervical Vagotomy ◽  
Bilateral Vagotomy ◽  
Extracellular Potentials ◽  
Stimulation Of

Because vagal and sympathetic inputs activate upper cervical spinal neurons, we hypothesized that stimulation of the esophagus would activate C1–C2 neurons. This study examined responses of C1–C2 spinal neurons to cervical and thoracic esophageal distension (CED, TED) and afferent pathways for CED and TED inputs to C1–C2 spinal neurons. Extracellular potentials of single C1–C2 spinal neurons were recorded in pentobarbital-anesthetized male rats. Graded CED or TED was produced by water inflation (0.1–0.5 ml) of a latex balloon. CED changed activity of 48/219 (22%) neurons; 34 were excited (E), 12 were inhibited (I), and 2 were E-I. CED elicited responses for 18/18 neurons tested after ipsilateral cervical vagotomy, for 12/14 neurons tested after bilateral vagotomy and for 9/11 neurons tested after bilateral vagotomy and C6–C7 spinal cord transection. TED changed activity of 31/190 (16%) neurons (28E, 3 I). Ipsilateral cervical vagotomy abolished TED-evoked responses of 5/12 neurons. Bilateral vagotomy eliminated responses of 2/4 neurons tested, and C6–C7 spinal transection plus bilateral vagotomy eliminated responses of 2/2 neurons. Thus inputs from CED to C1–C2 neurons most likely entered upper cervical dorsal roots, whereas inputs from TED were dependent on vagal pathways and/or sympathetic afferent pathways that entered the thoracic dorsal roots. These results supported a concept that C1–C2 spinal neurons play a role in integrating visceral information from cervical and thoracic esophagus.

Responses of thoracic spinal neurons to activation and desensitization of cardiac TRPV1-containing afferents in rats

2006 ◽  
Vol 291 (6) ◽  
pp. R1700-R1707 ◽  
Author(s):  
Chao Qin ◽  
Jay P. Farber ◽  
Kenneth E. Miller ◽  
Robert D. Foreman
Keyword(s):  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Male Rats ◽  
Transient Receptor Potential Vanilloid ◽  
Spinal Neurons ◽  
Thoracic Spinal ◽  
Afferent Fibers ◽  
Study Results ◽  
Transient Receptor ◽  
Excitatory Responses

The purpose of this study was to examine how upper thoracic spinal neurons responded to activation and desensitization of cardiac transient receptor potential vanilloid-1 (TRPV1)-containing afferent fibers. Extracellular potentials of single T3 spinal neurons were recorded in pentobarbital-anesthetized, paralyzed, and ventilated male rats. To activate cardiac nociceptive receptors, a catheter was placed in the pericardial sac to administer various chemicals: bradykinin (BK; 10 μg/ml, 0.2 ml), capsaicin (CAP, 10 μg/ml, 0.2 ml), or a mixture of algesic chemicals (AC; 0.2 ml) containing adenosine 10−3 M, BK, serotonin, histamine, and PGE2, 10−5 M for each. Spinal neurons that responded to intrapericardial BK and/or CAP were used in this study. Results showed that 81% (35/43) of the neurons had excitatory responses to both intrapericardial BK and CAP, and the remainder responded to either BK or CAP. Intrapericardial resiniferatoxin (RTX) (0.2 μg/ml, 0.2 ml, 1 min), which desensitizes TRPV1-containing nerve endings, abolished excitatory responses to both BK ( n = 8) and CAP ( n = 7), and to AC ( n = 5) but not to somatic stimuli. Intrapericardial capsazepine (1 mg/ml, 0.2 ml, 3 min), a specific antagonist of TRPV1, sharply attenuated excitatory responses to CAP in 5/5 neurons, but responses to BK in 5/5 neurons was maintained. Additionally, intrapericardial capsazepine had no significant effect on excitatory responses to AC in 3/3 neurons. These data indicated that intrapericardial BK-initiated spinal neuronal responses were linked to cardiac TRPV1-containing afferent fibers, but were not dependent on TRPV1. Intraspinal signaling for cardiac nociception was mediated through CAP-sensitive afferent fibers innervating the heart.

Responses and Afferent Pathways of Superficial and Deeper C1–C2 Spinal Cells to Intrapericardial Algogenic Chemicals in Rats

2001 ◽  
Vol 85 (4) ◽  
pp. 1522-1532 ◽  
Author(s):  
Chao Qin ◽  
Margaret J. Chandler ◽  
Kenneth E. Miller ◽  
Robert D. Foreman
Keyword(s):  
Afferent Input ◽  
Vagal Afferents ◽  
Male Rats ◽  
Prostaglandin E ◽  
Joint Movement ◽  
Spinal Neurons ◽  
Afferent Pathways ◽  
Bilateral Vagotomy ◽  
Cardiac Afferents ◽  
Stimulation Of

Electrical stimulation of vagal afferents or cardiopulmonary sympathetic afferent fibers excites C1–C2spinal neurons. The purposes of this study were to compare the responses of superficial (depth <0.35 mm) and deeper C1–C2 spinal neurons to noxious chemical stimulation of cardiac afferents and determine the relative contribution of vagal and sympathetic afferent pathways for transmission of noxious cardiac afferent input to C1–C2 neurons. Extracellular potentials of single C1–C2 neurons were recorded in pentobarbital anesthetized and paralyzed male rats. A catheter was placed in the pericardial sac to administer a mixture of algogenic chemicals (0.2 ml) that contained adenosine (10− 3 M), bradykinin, histamine, serotonin, and prostaglandin E2(10− 5 M each). Intrapericardial chemicals changed the activity of 20/106 (19%) C1–C2 spinal neurons in the superficial laminae, whereas 76/147 (52%) deeper neurons responded to cardiac noxious input ( P < 0.01). Of 96 neurons responsive to cardiac inputs, 48 (50%) were excited (E), 41 (43%) were inhibited (I), and 7 were excited/inhibited (E-I) by intrapericardial chemicals. E or I neurons responsive to intrapericardial chemicals were subdivided into two groups: short-lasting (SL) and long-lasting (LL) response patterns. In superficial gray matter, excitatory responses to cardiac inputs were more likely to be LL-E than SL-E neurons. Mechanical stimulation of the somatic field from the head, neck, and shoulder areas excited 85 of 95 (89%) C1–C2 spinal neurons that responded to intrapericardial chemicals; 31 neurons were classified as wide dynamic range, 49 were high threshold, 5 responded only to joint movement, and no neuron was classified as low threshold. For superficial neurons, 53% had small somatic fields and 21% had bilateral fields. In contrast, 31% of the deeper neurons had small somatic fields and 46% had bilateral fields. Ipsilateral cervical vagotomy interrupted cardiac noxious input to 8/30 (6 E, 2 I) neurons; sequential transection of the contralateral cervical vagus nerve (bilateral vagotomy) eliminated the responses to intrapericardial chemicals in 4/22 (3 E, 1 I) neurons. Spinal transection at C6–C7 segments to interrupt effects of sympathetic afferent input abolished responses to cardiac input in 10/10 (7 E, 3 I) neurons that still responded after bilateral vagotomy. Results of this study support the concept that C1–C2 superficial and deeper spinal neurons play a role in integrating cardiac noxious inputs that travel in both the cervical vagal and/or thoracic sympathetic afferent nerves.

Responses of T2-4 spinal cord neurons to irritation of the lower airways in the rat

1997 ◽  
Vol 273 (3) ◽  
pp. R1147-R1157 ◽  
Author(s):  
T. Hummel ◽  
J. N. Sengupta ◽  
S. T. Meller ◽  
G. F. Gebhart
Keyword(s):  
Spinal Cord ◽  
Afferent Input ◽  
Sprague Dawley ◽  
Spinal Neurons ◽  
Thoracic Spinal Cord ◽  
Spinal Cord Neurons ◽  
Thoracic Spinal ◽  
Balloon Distension ◽  
Sprague Dawley Rats ◽  
Lower Airways

The aim of the study was to investigate the information processing in the thoracic spinal cord (T2-4) after chemical irritation of the lower airways. Experiments were performed in pentobarbital sodium-anesthetized and pancuronium-paralyzed male Sprague-Dawley rats. Balloon distension of the esophagus was used as the search stimulus. Ammonia and smoke were applied by means of a tracheal cannula; they produced excitatory, inhibitory, and biphasic responses in a concentration-related manner (ammonia 39/39; smoke 23/ 39). Inhaled irritant-responsive neurons exhibited a number of similarities that have been described for neurons responding to stimulation of other thoracic viscera. These similarities relate to the distribution of neurons in the deeper laminae of the thoracic spinal cord, the relatively small number of neurons receiving input from the lower airways, the extensive convergent input from the skin and other thoracic viscera, and the pattern of responses. In addition, both stimulus-induced responses and spontaneous activity are subject to modulation from supraspinal sites. On the basis of responses to inhaled irritants after either spinal cord or vagus nerve block/transection, these T2-4 spinal neurons are likely to receive spinal afferent input that is modulated by vagal-brain stem input.

Segmental organization of visceral and somatic input onto C3-T6 spinothalamic tract cells of the monkey

1992 ◽  
Vol 68 (5) ◽  
pp. 1575-1588 ◽  
Author(s):  
S. F. Hobbs ◽  
M. J. Chandler ◽  
D. C. Bolser ◽  
R. D. Foreman
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Urinary Bladder ◽  
Visceral Pain ◽  
Cell Activity ◽  
Afferent Input ◽  
Spinothalamic Tract ◽  
Afferent Fibers ◽  
Increased Activity ◽  
Stimulation Of

1. Referred pain of visceral origin has three major characteristics: visceral pain is referred to somatic areas that are innervated from the same spinal segments as the diseased organ; visceral pain is referred to proximal body regions and not to distal body areas; and visceral pain is felt as deep pain and not as cutaneous pain. The neurophysiological basis for these phenomena is poorly understood. The purpose of this study was to examine the organization of viscerosomatic response characteristics of spinothalamic tract (STT) neurons in the rostral spinal cord. Interactions were determined among the following: 1) segmental location, 2) effects of input by cardiopulmonary sympathetic, greater splanchnic, lumbar sympathetic, and urinary bladder afferent fibers, 3) location of excitatory somatic field, e.g., hand, forearm, proximal arm, or chest, 4) magnitude of response to hair, skin, and deep mechanoreceptor afferent input, and 5) regional specificity of thalamic projection sites. 2. A total of 89 STT neurons in segments C3-T6 were characterized for responses to visceral and somatic stimuli. Neurons were activated antidromically from the contralateral ventroposterolateral oralis or caudalis nuclei of the thalamus. Cell responses to visceral and somatic stimuli were not different on the basis of the thalamic site of antidromic activation. Recording sites for 61 neurons were located histologically; 87% of lesion sites were located in laminae IV-VII or X. There was no relationship between response properties of the neurons and spinal laminar location. 3. Different responses to visceral stimuli were observed in three zones of the rostral spinal cord: C3-C6, C7-C8, and T1-T6. In C3-C6, urinary bladder distension (UBD) and electrical stimulation of greater splanchnic and lumbar sympathetic afferent fibers inhibited STT cells. Electrical stimulation of cardiopulmonary sympathetic afferents increased cell activity in C5 and C6 and either excited or inhibited STT cells in C3 and C4. In the cervical enlargement (C7-C8), STT cells generally were either inhibited or showed little response to stimulation of visceral afferent fibers. In T1-T6, input from greater splanchnic and cardiopulmonary sympathetic afferent nerves increased activity of STT cells. Lumbar sympathetic afferent input inhibited cells in T1-T2 and had little effect on cells in T3-T6, whereas UBD decreased cell activity in all segments studied. 4. In general, stimulation of somatic structures increased activity of STT neurons in segments that received primary afferent innervation from the excitatory somatic receptive field or in the segments immediately adjacent to these segments. Only input from the forelimb, especially the hand, markedly excited cells in C7 and C8.+

scholarly journals INPUT-OUTPUT RELATION IN A FLEXOR REFLEX

1957 ◽  
Vol 41 (2) ◽  
pp. 297-306 ◽  
Author(s):  
David P. C. Lloyd
Keyword(s):  
Spinal Cord ◽  
Afferent Input ◽  
Surprising Result ◽  
Input Output ◽  
Flexor Reflex ◽  
Afferent Fibers ◽  
Closed Chain ◽  
Central Paths ◽  
Reflex Threshold ◽  
Reflex Discharge

Observations have been made upon a typical flexor reflex with the aim of disclosing the changes in amount, latency, and temporal configuration of reflex discharge that take place as afferent input is varied from zero to maximal for the band of cutaneous myelinated afferent fibers that extends upward from approximately 6 µ in diameter (group II fibers). Reflex threshold is reached at 6 to 12 per cent maximal afferent input. From threshold to maximal input the relation between input and amount of output is essentially linear, latency on the average decreases, the shorter central paths in general gain preference, but the known minimum pathway, one of three neurons, does not transmit unless aided by convergent activity. Flexor reflex discharge may occur in several bursts suggesting the existence of closed chain connections in the internuncial pools of the spinal cord. At any given input there is, in successively elicited reflexes, little correlation between latency and amount of discharge, at first sight a surprising result for each variable can be taken as a measure of excitability status of the motoneuron population. However, latency of discharge indicates excitability at the beginning of the reflex event whereas amount of discharge is an expression of excitability over the entire period of discharge. Given a constantly and rapidly fluctuating excitability absence of correlation between these variables would be an anticipated result.

Depressor responses to stimulation of sympathetic afferents in monkeys and dogs

1981 ◽  
Vol 240 (1) ◽  
pp. R23-R28 ◽  
Author(s):  
D. R. Kostreva ◽  
F. A. Hopp ◽  
J. P. Kampine
Keyword(s):  
Fiber Type ◽  
Depressor Response ◽  
Stellate Ganglia ◽  
Afferent Fibers ◽  
Pressor Responses ◽  
Conduction Velocities ◽  
C Fiber ◽  
Cervical Vagotomy ◽  
Left And Right ◽  
Stimulation Of

In dogs and monkeys anesthetized with pentobarbital sodium, stimulation of the cut central ends of the stellate cardiac nerve, the left and right anterior ansae subclavia, and the stellate ganglia resulted in a depressor response when stimulating fibers with conduction velocities in the range of 2.5-10 m/s. These afferents are in the A delta-fiber-type range. Pressor responses could be elicited by stimulating afferent fibers with conduction velocities in the range of 0.5-3.0 m/s. These fibers are in the C-fiber-type range. Stimulation of the abdominal sympathetic afferents always resulted in a depressor response regardless of the conduction velocities of the fibers. No changes in heart rate were observed. Bilateral cervical vagotomy did not alter the pressor or depressor responses.

scholarly journals INFLUENCE OF ALIMENTARY INSUFFICIENCY OF CALCIUM, MAGNESIUM AND IODINE ON RAT VITAMIN STATUS

2021 ◽  
Vol 22 (1) ◽  
pp. 52-59
Author(s):  
O.A. Vrzhesinskaya ◽  
◽  
V.M. Kodentsova ◽  
N.A. Beketova ◽  
O.V. Kosheleva ◽  
...  
Keyword(s):  
Blood Plasma ◽  
Vitamin B1 ◽  
Male Rats ◽  
Molar Ratio ◽  
Vitamin Status ◽  
Iron And Zinc ◽  
Calcium Magnesium ◽  
Increased Activity ◽  
Experimental Group ◽  
In Blood Plasma

The diet of the majority of the population of Russia is characterized by an insufficient content of a number of micronutrients, including macro- and micronutrients. The aim of the study is to characterize in a rat model experiment the effect of combined nutritional deficiency of calcium, magnesium and iodine on the availability of other mineral substances, vitamin metabolism and biochemical parameters blood plasma. The lack of minerals in growing Wistar male rats with an initial body weight (51.4 ± 0.5) g was created for 23 days by halving of a calcium, magnesium and iodine in the salt mixture. Alimentary deficiency of calcium, magnesium and iodine in growing rats significantly and multidirectionally affected the metabolism of other minerals and vitamins, as well as a number of diagnostically significant indicators of blood and urine. In rats of the experimental group, the liver concentration of α-tocopherol, vitamin B1 and retinol palmitate decreased, the concentration of iron and zinc increased, the copper content in the whole brain decreased significantly. The molar ratio of γ- and α-tocopherols in blood plasma was increased, the concentration of the circulating form of vitamin D decreased. The ratio of AlAT / AsAT (de Ritis coefficient) markedly decreased due to increased activity of AlAT. Phosphate reabsorption decreased slightly. Increased urinary excretion of riboflavin was accompanied by a decrease in its concentration in blood plasma. The conclusion that insufficient intake of calcium, magnesium and iodine may disturb vitamin-mineral status of organism has been made.

Reflex vasodilatation in the cat lip elicited by stimulation of nasal mucosa by chemical irritants

1993 ◽  
Vol 265 (4) ◽  
pp. R733-R738 ◽  
Author(s):  
H. Izumi ◽  
K. Karita
Keyword(s):  
Blood Flow ◽  
Electrical Stimulation ◽  
Nasal Mucosa ◽  
Threshold Dose ◽  
Ammonia Vapor ◽  
Autonomic Ganglion ◽  
Afferent Fibers ◽  
Autonomic Reflex ◽  
Chemical Irritants ◽  
Stimulation Of

Local application of capsaicin (threshold dose 150 microM) or nicotine (threshold dose 15 mM) to the nasal mucosa as well as electrical stimulation (threshold intensity 10 V) of the nasal mucosa elicited dose- or intensity-dependent blood flow increases in the ipsilateral lower lips of the anesthetized cats. Pretreatment with 3 mM capsaicin applied locally to the nasal mucosa abolished or reduced the vasodilation in response to capsaicin, nicotine, and ammonia vapor but not to light mechanical or electrical stimulation of the nasal mucosa. The blood flow increases elicited by all above stimuli were greatly reduced by pretreatment with hexamethonium, an autonomic ganglion blocker. These results suggest that stimulation of the nasal mucosa by chemical (capsaicin, nicotine, ammonia), mechanical, or electrical methods elicits the autonomic reflex vasodilatation in the cat lower lips. Furthermore, there seem to be at least two types of afferent fibers in the nasal mucosa of the cats: one type is capsaicin-sensitive fibers, while another type is capsaicin-resistant fibers involved in reflex vasodilatation.

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