Urinary bladder and hindlimb stimuli inhibit T1-T6 spinal and spinoreticular cells

1990 ◽  
Vol 258 (1) ◽  
pp. R10-R20 ◽  
Author(s):  
S. F. Hobbs ◽  
U. T. Oh ◽  
T. J. Brennan ◽  
M. J. Chandler ◽  
K. S. Kim ◽  
...  
Keyword(s):  
Urinary Bladder ◽  
Inhibitory Effect ◽  
Afferent Input ◽  
Spinal Neuron ◽  
Spinal Neurons ◽  
Lumbosacral Spinal Cord ◽  
Thoracic Spinal ◽  
Excitatory Responses ◽  
Upper Thoracic ◽  
Alpha Chloralose

Upper thoracic spinal neurons are primarily excited by cardiopulmonary spinal afferent input but are excited and inhibited by splanchnic afferent input. These data suggest that the greater the number of segments between a spinal neuron and spinal afferent input the greater the probability that the afferent input will inhibit the spinal neuron. Based on this idea we hypothesized that visceral (urinary bladder) and somatic (hindlimb) afferent input would inhibit upper thoracic spinal neurons. To test this hypothesis the activities of 69 spinal and 27 spinoreticular tract neurons in 45 alpha-chloralose-anesthetized cats were studied. Only neurons excited by both visceral and somatic thoracic afferent input were studied. Urinary bladder distension (UBD) inhibited 48 (50%), excited 6 (6%), and did not affect 41 (43%) of these neurons. Also, UBD inhibited the excitatory responses of these cells to noxious visceral and somatic stimuli. Hindlimb pinch also inhibited greater than 50% of the neurons. These data indicate that visceral and somatic afferent input to the lumbosacral spinal cord inhibits the activity of upper thoracic neurons. This inhibitory effect may play a role in localization of sensory and motor responses to noxious stimuli.

Effects of intracardiac bradykinin and capsaicin on spinal and spinoreticular neurons

1989 ◽  
Vol 257 (5) ◽  
pp. H1543-H1550 ◽  
Author(s):  
D. C. Bolser ◽  
M. J. Chandler ◽  
D. W. Garrison ◽  
R. D. Foreman
Keyword(s):  
Dynamic Range ◽  
Afferent Input ◽  
Inhibitory Neurons ◽  
High Threshold ◽  
Spinal Neurons ◽  
Wide Dynamic Range ◽  
Thoracic Spinal ◽  
Different Populations ◽  
Spinal Afferents ◽  
Alpha Chloralose

The responses of thoracic spinal and spinoreticular tract (SRT) neurons to activation of cardiac spinal afferents by injections of bradykinin (BK) and capsaicin (CAP) into the left atrium or pericardial sac were determined in vagotomized cats anesthetized with alpha-chloralose. Activities of spinal and SRT neurons in the T1-T5 spinal cord were recorded extracellularly. All neurons received excitatory somatic and cardiopulmonary sympathetic afferent input. Application of BK and CAP to the heart excited most SRT neurons and many spinal neurons but also inhibited some spinal neurons. The two drugs often affected spinal but not SRT neurons differently. Capsaicin excited high threshold and high threshold inhibitory neurons but not wide-dynamic range spinal neurons. In contrast, BK excited all three categories of spinal and SRT neurons. The differential responses of spinal neurons to intracardiac BK and CAP suggested that these compounds can stimulate functionally different populations of cardiac sympathetic afferents.

scholarly journals Cross-organ sensitization of thoracic spinal neurons receiving noxious cardiac input in rats with gastroesophageal reflux

2010 ◽  
Vol 298 (6) ◽  
pp. G934-G942 ◽  
Author(s):  
Chao Qin ◽  
Anna P. Malykhina ◽  
Ann M. Thompson ◽  
Jay P. Farber ◽  
Robert D. Foreman
Keyword(s):  
Gastroesophageal Reflux ◽  
Gastroesophageal Junction ◽  
Gastric Fundus ◽  
Control Group ◽  
Sprague Dawley ◽  
Spinal Neurons ◽  
Thoracic Spinal ◽  
Afferent Fibers ◽  
Excitatory Responses ◽  
Upper Thoracic

Gastroesophageal reflux (GER) frequently triggers or worsens cardiac pain or symptoms in patients with coronary heart disease. This study aimed to determine whether GER enhances the activity of upper thoracic spinal neurons receiving noxious cardiac input. Gastric fundus and pyloric ligations as well as a longitudinal myelotomy at the gastroesophageal junction induced acute GER in pentobarbital-anesthetized, paralyzed, and ventilated male Sprague-Dawley rats. Manual manipulations of the stomach and lower esophagus were used as surgical controls in another group. At 4–9 h after GER surgery, extracellular potentials of single neurons were recorded from the T3 spinal segment. Intrapericardial bradykinin (IB) (10 μg/ml, 0.2 ml, 1 min) injections were used to activate cardiac nociceptors, and esophageal distensions were used to activate esophageal afferent fibers. Significantly more spinal neurons in the GER group responded to IB compared with the control group (69.1 vs. 38%, P < 0.01). The proportion of IB-responsive neurons in the superficial laminae of GER animals was significantly different from those in deeper layers (1/8 vs. 46/60, P < 0.01); no difference was found in control animals (7/25 vs. 20/46, P > 0.05). Excitatory responses of spinal neurons to IB in the GER group were greater than in the control group [32.4 ± 3.5 impulses (imp)/s vs. 13.3 ± 2.3 imp/s, P < 0.01]. Forty-five of 47 (95.7%) neurons responded to cardiac input and ED, which was higher than the control group (61.5%, P < 0.01). These results indicate that acute GER enhanced the excitatory responses of thoracic spinal neurons in deeper laminae of the dorsal horn to noxious cardiac stimulus.

scholarly journals Characterization of upper thoracic spinal neurons receiving noxious cardiac and/or somatic inputs in diabetic rats

2011 ◽  
Vol 165 (2) ◽  
pp. 168-177 ◽  
Author(s):  
Marie Louise M. Ghorbani ◽  
Chao Qin ◽  
Mingyuan Wu ◽  
Jay P. Farber ◽  
Majid Sheykhzade ◽  
...  
Keyword(s):  
Diabetic Rats ◽  
Spinal Neurons ◽  
Thoracic Spinal ◽  
Upper Thoracic

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.

Axonal projection patterns of ventrolateral medullospinal sympathoexcitatory neurons

1985 ◽  
Vol 53 (6) ◽  
pp. 1551-1566 ◽  
Author(s):  
S. M. Barman ◽  
G. L. Gebber
Keyword(s):  
Gray Matter ◽  
Sympathetic Nerve ◽  
Action Potentials ◽  
Spinal Neurons ◽  
Spinal Segment ◽  
Axonal Conduction ◽  
Thoracic Spinal ◽  
Branching Patterns ◽  
Reflex Activation ◽  
Upper Thoracic

We studied the following properties of cat ventrolateral medullary (VLM) neurons that projected to the thoracic spinal cord: the relationship between their spontaneous activity and that in the inferior cardiac postganglionic sympathetic nerve, their responses to baroreceptor-reflex activation, their axonal conduction velocities, the funicular trajectories of their axons, the likely sites of termination of their axons, and their axonal branching patterns. Microstimulation in the second thoracic spinal segment (T2) antidromically activated 67 VLM neurons (as determined with time-controlled collision of spontaneous and evoked action potentials), whose activity was correlated to inferior cardiac sympathetic nerve discharge (as determined with spike-triggered averaging). We tested the effect of baroreceptor-reflex activation on the firing rate of 20 of these VLM-spinal neurons. Because the firing rate decreased in each instance, these neurons apparently subserved a sympathoexcitatory function. The axonal branching patterns of 51 VLM-spinal sympathoexcitatory neurons were studied. Thirty-four neurons were antidromically activated by stimulation in the T2 gray matter and in more caudal thoracic spinal segments (T11 and/or T6). In each case, the antidromic response evoked by stimulation in the T2 gray matter was due to activation of an axonal branch rather than the main axon (via current spread to the white matter). This was demonstrated with tests that included time-controlled collision of the action potentials initiated by stimulation in T2 and a more caudal thoracic spinal segment. Some VLM-spinal axons that projected to T11 branched in T6 as well as in T2. These data indicate that some VLM-spinal neurons exerted widespread excitatory influences on sympathetic outflow. Seventeen VLM sympathoexcitatory neurons that innervated the T2 gray matter could not be antidromically activated by stimulation in T5, T6, and T11 despite an extensive search at each level. Thus the axonal projections of some VLM-spinal neurons were restricted to upper thoracic segments. Antidromic mapping in T2 revealed that the axons of VLM sympathoexcitatory neurons coursed through the dorsolateral or ventrolateral funiculus to innervate the region of the intermediolateral nucleus. Mean axonal conduction velocity was 3.5 +/- 0.3 m/s. Those VLM-spinal axons restricted to upper thoracic segments generally were located dorsally and/or medially to those that innervated widely separated thoracic segments. The discharges of 35 other VLM neurons that were antidromically activated by T2 stimulation were not related to sympathetic nerve activity.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Mechanically stimulating the lumbar region inhibits locomotor-like activity and increases the gain of cutaneous reflexes from the paws in spinal cats

2020 ◽  
Vol 123 (3) ◽  
pp. 1026-1041
Author(s):  
Angèle N. Merlet ◽  
Jonathan Harnie ◽  
Madalina Macovei ◽  
Adam Doelman ◽  
Nathaly Gaudreault ◽  
...  
Keyword(s):  
Nerve Stimulation ◽  
Inhibitory Effect ◽  
Short Latency ◽  
Lumbar Region ◽  
Cutaneous Reflexes ◽  
Cutaneous Reflex ◽  
Thoracic Spinal ◽  
Weight Support ◽  
Reflex Gain ◽  
Excitatory Responses

Mechanically stimulating the dorsal lumbar region inhibits locomotion and reduces weight support during standing in rabbits and cats. However, how this inhibitory effect from the lumbar skin is mediated is poorly understood. Here we evaluated the effect of mechanically stimulating (vibration or pinch) the dorsal lumbar region on short-latency (8- to 13-ms onset) cutaneous reflex responses, evoked by electrically stimulating the superficial peroneal or distal tibial nerves, in seven adult cats with a low thoracic spinal transection (spinal cats). Cutaneous reflexes were evoked before, during, and after mechanical stimulation of the dorsal lumbar region. We found that mechanically stimulating the lumbar region by vibration or manual pinch abolished alternating bursts of activity between flexors and extensors initiated by nerve stimulation. The activity of extensor muscles was abolished bilaterally, whereas the activity of some ipsilateral flexor muscles was sustained during vibration/pinch. Mechanically stimulating the lumbar region increased ipsilateral and contralateral short-latency excitatory responses evoked by cutaneous inputs, a phenomenon that was generalized to muscles crossing different joints and located in different limbs. Our results indicate that the inhibitory effect on locomotion and weight support is not mediated by reducing cutaneous reflex gain and instead points to an inhibition of central pattern-generating circuitry, particularly the extensor component. The results provide greater insight into interactions between different types of somatosensory inputs within spinal motor circuits. NEW & NOTEWORTHY Vibration or pinch of the lumbar region in spinal-transected cats abolished alternating bursts of activity between flexors and extensors initiated by nerve stimulation. Mechanically stimulating the lumbar region increased ipsilateral and contralateral short-latency excitatory responses evoked by cutaneous inputs in hindlimb muscles. Sensory inputs from mechanoreceptors of the lumbar region do not mediate their inhibitory effect on locomotion and weight support by reducing the gain of short-latency excitatory cutaneous reflexes from the foot.

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.

Representation of the urinary bladder in the lateral thalamus of the cat

1993 ◽  
Vol 70 (2) ◽  
pp. 482-491 ◽  
Author(s):  
J. Bruggemann ◽  
C. Vahle-Hinz ◽  
K. D. Kniffki
Keyword(s):  
Urinary Bladder ◽  
Receptive Fields ◽  
The Body ◽  
Intravesical Pressure ◽  
Thalamic Neurons ◽  
Electrolytic Lesions ◽  
Low Threshold ◽  
Excitatory Responses ◽  
Ventral Posterolateral Nucleus ◽  
Alpha Chloralose

1. In alpha-chloralose-anesthetized cats the region surrounding the ventral posterolateral nucleus (VPL) of the thalamus was investigated to locate foci with input from the urinary bladder stimulated by application of intravesical pressure. The locations of the recording sites were verified in Nissl-stained histological sections with reference to electrolytic lesions. 2. Of the 23 visceroceptive thalamic neurons identified, 4 (17%) were located in the periphery of the VPL (VPLp) and 19 (83%) in the lateral and dorsal aspects of the posterior complex (POl and POd, respectively) adjoining VPLp. 3. The neurons responded to noxious intensities of intravesical pressure in the range of 50-100 mmHg. Excitatory responses were elicited in 8 (35%) neurons, "inhibitory" responses in 13 (57%) neurons, and 2 (9%) neurons responded with an increase and a decrease of their discharge to subsequent stimuli. 4. Of the 22 visceroceptive thalamic neurons tested for this parameter, 73% had low-threshold cutaneous receptive fields (RFs). These were located in the region of the lower back, the hip, the thigh, and the proximal tail (12 PO neurons), or covered the entire postcranial contralateral part of the body (3 PO neurons). For only one of the VPLp neurons, a somatic RF was found and this was located on the distal tail. The neurons responded to tap stimuli applied at a low repetition rate. None of the 11 neurons tested with noxious pinching of the skin was activated by this kind of stimulus. 5. It is concluded that the cat's lateral thalamic region, around but not within VPL proper, contains neurons that play a role in the processing of information about noxious events in the urinary bladder. A comparison with results from experiments in the monkey indicates differences in the organization of the visceroceptive systems between both species, regarding the thalamic localization of visceroceptive neurons, the occurrence of convergent low-threshold somatic RFs, and the association of excitatory and inhibitory effects of urinary bladder stimulation with the location of somatic RFs.

PNMT-containing neurons of the C1 cell group express c-fos in response to changes in baroreceptor input

1994 ◽  
Vol 266 (2) ◽  
pp. R361-R367 ◽  
Author(s):  
A. F. Sved ◽  
D. L. Mancini ◽  
J. C. Graham ◽  
A. M. Schreihofer ◽  
G. E. Hoffman
Keyword(s):  
Afferent Input ◽  
Protein Product ◽  
Early Gene ◽  
Ventrolateral Medulla ◽  
Cell Group ◽  
Afferent Activity ◽  
Thoracic Spinal Cord ◽  
Thoracic Spinal ◽  
Upper Thoracic

The immunocytochemical detection of Fos, the protein product of the immediate-early gene c-fos, was used as a marker for activated neurons to examine whether the C1 neurons in the rat rostral ventrolateral medulla (RVLM) respond to changes in baroreceptor afferent activity. After hydralazine-induced hypotension or sinoaortic denervation, two treatments that reduce baroreceptor afferent activity, numerous Fos-positive neurons were observed in the RVLM. The number of Fos-positive neurons in the RVLM was counted in brain stem sections from hydralazine-treated rats that had been previously injected with Fluorogold into the upper thoracic spinal cord to label spinally projecting RVLM neurons as well as stained for phenylethanolamine-N-methyltransferase (PNMT) as a marker of C1 neurons. The results indicate that approximately 80% of the C1 neurons expressed Fos in response to hydralazine injection; this was true of spinally projecting C1 neurons as well as those C1 neurons that were not labeled with Fluorogold. Furthermore, in hydralazine-treated rats, the majority of Fluorogold-labeled Fos-positive neurons contained PNMT. These results suggest that C1 neurons are sensitive to baroreceptor afferent input and support a role of these neurons in cardiovascular regulation.

Sign in / Sign up

Export Citation Format

Share Document