Cotinine enhances the nicotine‐mediated decrease in respiratory burst amplitude recorded from the hypoglossal nerve in the brainstem spinal cord preparation from nicotine‐exposed neonatal rats

Obstetrical brachial plexus injury refers to injury observed at the time of delivery, which may lead to major functional impairment in the upper limb. In this study, the neuroprotective effect of early nerve repair following complete brachial plexus injury in neonatal rats was examined. Brachial plexus injury induced 90% loss of spinal motoneurons and 70% decrease in biceps muscle weight at 28 days after injury. Retrograde degeneration in spinal cord was associated with decreased density of dendritic branches and presynaptic boutons and increased density of astrocytes and macrophages/microglial cells. Early repair of the injured brachial plexus significantly delayed retrograde degeneration of spinal motoneurons and reduced the degree of macrophage/microglial reaction but had no effect on muscle atrophy. The results demonstrate that early nerve repair of neonatal brachial plexus injury could promote survival of injured motoneurons and attenuate neuroinflammation in spinal cord.

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Identification of a subsurface area in the ventral medulla sensitive to local changes in PCO2

Journal of Applied Physiology ◽

10.1152/jappl.1992.72.2.439 ◽

1992 ◽

Vol 72 (2) ◽

pp. 439-446 ◽

Cited By ~ 55

Author(s):

F. G. Issa ◽

J. E. Remmers

Keyword(s):

Spinal Cord ◽

Neural Activity ◽

Ventral Surface ◽

Sudden Increase ◽

Neonatal Rats ◽

Central Chemoreceptors ◽

Ventral Medulla ◽

Ventromedial Medulla ◽

Stimulation Of

The exact location of the central respiratory chemoreceptors sensitive to changes in PCO2 has not yet been determined. To avoid the confounding effects of the cerebral circulation, we used the in vitro brain stem-spinal cord of neonatal rats (1–5 days old) to identify areas within 500 microns of the ventral surface of the medulla where changes in PCO2 evoked a sudden increase in the rate of respiratory neural activity. The preparation was superfused with mock cerebrospinal fluid (CSF) while maintained at constant temperature (26 +/- 1 degrees C) and pH (7.34). Respiratory frequency increased linearly with decreases in superfusate pH (r2 = 0.92, P less than 0.001), indicating that the respiratory circuitry for the detection of CO2 and stimulation of breathing was intact in this preparation. The search for central chemoreceptors was performed with a specially designed micropipette that allowed microejection of 2–10 nl of mock CSF equilibrated with different CO2-O2 gas mixtures. The pipette was advanced in 50- to 100-microns steps by use of a microdrive to a maximum depth of 500 microns from the surface of the ventral medulla. Depending on the location of the micropipette, ejection of CO2-acidified mock CSF at depths of 100–350 microns below the ventral surface of the medulla stimulated neural respiratory output. Using this response as an indication of the location of central respiratory chemoreceptors, we found that chemoreceptive elements were located in a column in the ventromedial medulla extending from the hypoglossal rootlets caudally to an area 0.75 mm caudal to VI nerve in the rostral medulla.(ABSTRACT TRUNCATED AT 250 WORDS)

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Modulation of the extrinsic tongue muscle activity in response to bronchopulmonary C-fiber activation following midcervical contusion in the rat

Journal of Applied Physiology ◽

10.1152/japplphysiol.00857.2019 ◽

2020 ◽

Vol 128 (5) ◽

pp. 1130-1145

Author(s):

Hsiao-Sen Chang ◽

Kun-Ze Lee

Keyword(s):

Spinal Cord ◽

Muscle Activity ◽

Cervical Spinal Cord ◽

Upper Airway ◽

Airway Patency ◽

Tongue Muscle ◽

Cord Injury ◽

Burst Amplitude ◽

C Fiber ◽

Spinal Cord Contusion

Tongue muscle activity plays an important role in the regulation of upper airway patency. This study aimed to investigate the respiratory activity of the extrinsic tongue muscle in response to capsaicin-induced bronchopulmonary C-fiber activation following cervical spinal cord contusion. Midcervical spinal-contused animals exhibited a greater baseline preinspiratory burst amplitude of the extrinsic tongue muscle and were resistant to inhaled capsaicin-induced reduction of respiratory tongue muscle activity at the acute injured stage. However, inhalation of capsaicin caused a more severe attenuation of preinspiratory activity of the extrinsic tongue muscle at the chronic injured stage. These results suggest that the upper airway may be predisposed to collapse in response to bronchopulmonary C-fiber activation following chronic cervical spinal cord injury.

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Electrophysiological Changes in Adult Rat Dorsal Horn Neurons After Neonatal Peripheral Inflammation

Journal of Neurophysiology ◽

10.1152/jn.01019.2002 ◽

2003 ◽

Vol 90 (1) ◽

pp. 73-80 ◽

Cited By ~ 32

Author(s):

Yuan Bo Peng ◽

Qing Dong Ling ◽

M. A. Ruda ◽

Daniel R. Kenshalo

Keyword(s):

Spinal Cord ◽

Receptive Field ◽

Dorsal Horn ◽

Dynamic Range ◽

High Threshold ◽

Peripheral Inflammation ◽

Mechanical Stimuli ◽

Neonatal Rats ◽

Adult Rats ◽

Dorsal Horn Neurons

Neonatal peripheral inflammation has been shown to produce profound anatomical changes in the dorsal horn of adult rats. In this study, we explored whether parallel physiological changes exist. Neonatal rats were injected with complete Freund's adjuvant (CFA) into the left hind paw. At 8–10 wk of age, single dorsal horn neurons were recorded in response to graded intensities of mechanical stimuli delivered to the receptive field. In addition, cord dorsum potentials, produced by electrical stimuli delivered to the left sciatic nerve at 2.5× threshold, were recorded bilaterally from L2 to S3. There were significant increases in background activity and responses to brush and pinch in neonatal rats that were treated with CFA, as compared with control rats. Further analysis showed similar significant changes when dorsal horn neurons were categorized into wide dynamic range (WDR), high-threshold (HT), and low-threshold (LT) groups. The receptive field was significantly larger in neonatally treated rats as compared with control rats. Additionally, there was a significant increase in the response to a 49°C heat stimulus in neonatally treated rats as compared with control rats. There was also a trend for the amplitudes of N1, N2, and P waves of the cord dorsum potential to increase and latencies to decrease in neonatally treated rats, but no significant differences were detected between different levels of the spinal cord (L2 to S3). These data further support the notion that anatomical and physiological plasticity changes occurred in the spinal cord following early neonatal CFA treatment.

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Neural Pathways Between Sacrocaudal Afferents and Lumbar Pattern Generators in Neonatal Rats

Journal of Neurophysiology ◽

10.1152/jn.00716.2002 ◽

2003 ◽

Vol 89 (2) ◽

pp. 773-784 ◽

Cited By ~ 39

Author(s):

I. Strauss ◽

A. Lev-Tov

Keyword(s):

Spinal Cord ◽

Nmda Receptors ◽

Neural Control ◽

Nmda Receptor Antagonist ◽

Neural Pathways ◽

Synaptic Activation ◽

Neonatal Rats ◽

Artificial Cerebrospinal Fluid ◽

Pattern Generators ◽

Lumbar Cord

Projections of sacrocaudal afferents (SCA) onto lumbar pattern generators were studied in isolated spinal cords of neonatal rats. A locomotor-like pattern could be produced by SCA stimulation in the majority of the preparations. The SCA-induced lumbar rhythm was abolished after blocking synaptic transmission in the sacrococcygeal (SC) cord by bathing its segments in a low-calcium, high-magnesium artificial cerebrospinal fluid and restored when the synaptic block was alleviated by local application of calcium onto specific SC segments prior to SCA stimulation. Thus the SCA evoked lumbar rhythm involves synaptic activation of relay neurons in the SC cord. Functional activation of these relays depends on non– N-methyl-d-aspartate (NMDA) receptors because the lumbar rhythm was abolished when the non-NMDA receptor antagonist CNQX was added to the SC cord. By contrast, pharmacological block of the rhythmicity in the SC cord by specific antagonists of NMDA receptors and α1 and α2 adrenoceptors did not impair the SCA-induced lumbar rhythm. Midsagittal splitting experiments of parts of the SC and lumbar cord revealed that crossed and uncrossed ascending/propriospinal pathways are coactivated by SCA stimulation. We suggest that these pathways ascend onto the thoracolumbar cord through the lateral, ventrolateral, and ventral funiculi, because a complete block of the lumbar rhythm could only be obtained with a bilateral interruption of all of these funiculi. The relevance of our findings to the neural control of the rhythmogenic networks in the spinal cord is discussed.

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mRNA and protein expression and activities of nitric oxide synthases in the lumbar spinal cord of neonatal rats after sciatic nerve transection and melatonin administration

Neuroscience Letters ◽

10.1016/j.neulet.2006.08.035 ◽

2006 ◽

Vol 407 (2) ◽

pp. 182-187 ◽

Cited By ~ 10

Author(s):

Fábio Rogério ◽

Simone Aparecida Teixeira ◽

Hamilton Jordão Júnior ◽

Carla Cristina Judice Maria ◽

André Schwambach Vieira ◽

...

Keyword(s):

Nitric Oxide ◽

Spinal Cord ◽

Sciatic Nerve ◽

Lumbar Spinal Cord ◽

Nerve Transection ◽

Neonatal Rats ◽

Sciatic Nerve Transection ◽

Melatonin Administration ◽

Mrna And Protein Expression ◽

Lumbar Spinal

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Synaptic targets of commissural interneurons in the lumbar spinal cord of neonatal rats

The Journal of Comparative Neurology ◽

10.1002/cne.10696 ◽

2003 ◽

Vol 461 (4) ◽

pp. 429-440 ◽

Cited By ~ 37

Author(s):

András Birinyi ◽

Kornél Viszokay ◽

Ildikó Wéber ◽

Ole Kiehn ◽

Miklós Antal

Keyword(s):

Spinal Cord ◽

Lumbar Spinal Cord ◽

Neonatal Rats ◽

Lumbar Spinal

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Monoaminergic Establishment of Rostrocaudal Gradients of Rhythmicity in the Neonatal Mouse Spinal Cord

Journal of Neurophysiology ◽

10.1152/jn.00299.2005 ◽

2005 ◽

Vol 94 (2) ◽

pp. 1554-1564 ◽

Cited By ~ 26

Author(s):

Kimberly J. Christie ◽

Patrick J. Whelan

Keyword(s):

Spinal Cord ◽

Locomotor Activity ◽

Spinal Cord Injuries ◽

Neonatal Mouse ◽

Network Activity ◽

Neonatal Rats ◽

Mouse Spinal Cord ◽

Bath Application ◽

Rats And Mice ◽

Calcium Green

Bath application of monoamines is a potent method for evoking locomotor activity in neonatal rats and mice. Monoamines also promote functional recovery in adult animals with spinal cord injuries by activating spinal cord networks. However, the mechanisms of their actions on spinal networks are largely unknown. In this study, we tested the hypothesis that monoamines establish rostrocaudal gradients of rhythmicity in the thoracolumbar spinal cord. Isolated neonatal mouse spinal cord preparations (P0–P2) were used. To assay excitability of networks by monoamines, we evoked a disinhibited rhythm by bath application of picrotoxin and strychnine and recorded neurograms from several thoracolumbar ventral roots. We first established that rostral and caudal segments of the thoracolumbar spinal cord had equal excitability by completely transecting preparations at the L3 segmental level and recording the frequency of the disinhibited rhythm from both segments. Next we established that a majority of ventral interneurons retrogradely labeled by calcium green dextran were active during network activity. We then bath applied combinations of monoaminergic agonists [5-HT and dopamine (DA)] known to elicit locomotor activity. Our results show that monoamines establish rostrocaudal gradients of rhythmicity in the thoracolumbar spinal cord. This may be one mechanism by which combinations of monoaminergic compounds normally stably activate locomotor networks.

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