Respiratory effects on pontine, medullary and spinal cord midline sections in the rabbit

Janczewski, Wiktor A.; Karczewski, W

doi:10.1016/0034-5687(84)90078-1

Cited by 12 publications

(9 citation statements)

References 12 publications

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“…Our findings confirm the existence of mechanisms in the split-medulla cat that lead to amplitude modulations of the two desynchronized phrenic bursts, similar to those reported in the rabbit (Janczewski & Karczewski, 1984;Budzinska & Romaniuk, 1985), with both sides being larger when in phase and both smaller when out of phase. That these modulations are due to mechanisms at the phrenic motoneurone level is shown by their disappearance after splitting of the cord between C4 and C7.…”

Section: Amplitude Modulationssupporting

confidence: 90%

“…That these modulations are due to mechanisms at the phrenic motoneurone level is shown by their disappearance after splitting of the cord between C4 and C7. Splitting the cord from C2 to C6 also abolished the amplitude interactions in the rabbit (Janczewski & Karczewski, 1984). Our findings rule out cross-over between Cl and C4, below C7 and above the pons as responsible for the interactions.…”

Section: Amplitude Modulationsmentioning

confidence: 48%

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Desynchronized respiratory rhythms and their interactions in cats with split brain stems.

Eldridge

Paydarfar

1989

The Journal of Physiology

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SUMMARY1. The effects on activities and rhythms of the two opposing phrenic nerves (C5 roots) of mid-line sagittal splitting of the medulla were determined in anaesthetized or decorticate, vagotomized, paralysed and ventilated cats.2. Splitting the medulla above the obex led to marked decreases of phrenic activity on both sides, but no desynchronization of the two phrenic rhythms occurred. Further splitting to more than 3 mm below the obex led to desynchronized phrenic rhythms in fourteen of the fifteen animals that survived the necessary surgery, although it was often necessary to increase respiratory drive by means of hypercapnia, stimulatory drugs or electrical stimulation of the mesencephalon to cause the rhythms to occur.3. When only the brain stem had been split, the two desynchronized rhythms showed interactions that led to modulations of amplitude of phrenic bursts, both being larger when in phase than when out of phase. In addition each side modulated the rhythm of the opposite side, demonstrating a 'magnet' effect.4. Both types of modulation were eliminated after additional splitting of the spinal cord at the level (C5-C6) of the phrenic motoneurone pools.5. Potential explanations for the amplitude modulations include cross-over of activity from one phrenic motoneurone pool to the opposite side and cross-over from the medulla of one side to the opposite phrenic motoneurone pool at the phrenic level.6. Since the rhythm generators were independent in our preparation and located in the split halves of the medulla and since peripheral sensory feed-back was not important in these paralysed animals, we propose that the phase modulations must be due to a corollary discharge, an afferent feed-back driven by phrenic motoneurone activity that crosses the mid-line at C5-C6, ascends to the brain and affects respiratory rhythm in the opposite medullary half.

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Section: Amplitude Modulationssupporting

confidence: 90%

Section: Amplitude Modulationsmentioning

confidence: 48%

Desynchronized respiratory rhythms and their interactions in cats with split brain stems.

Eldridge

Paydarfar

1989

The Journal of Physiology

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“…We cannot exclude the possibility that other preBötC neurons also project to contralateral preBötC. In rabbits and cats, respiratory rhythm continues after midline transection of the medulla but synchrony of left and right phrenic nerve activity is abolished, accompanied by a reduction in inspiratory motor output (Janczewski and Karczewski, 1984; Janczewski and Karczewski, 1990). This decussation of preBötC Sst axons may therefore play some roles in the bilateral symmetry of respiratory movements.…”

Section: Discussionmentioning

confidence: 99%

Projections of preBötzinger Complex neurons in adult rats

Tan

Pagliardini

Yang

et al. 2010

J of Comparative Neurology

130

134

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The preBötzinger Complex (preBötC) contains neural microcircuitry essential for normal respiratory rhythm generation in rodents. A subpopulation of preBötC neurons expresses somatostatin, a neuropeptide with a modulatory action on breathing. Acute silencing of a subpopulation of preBötC neurons transfected by a virus driving protein expression under the somatostatin promoter results in persistent apnea in awake adult rats. Given the profound effect of silencing these neurons, their projections are of interest. We used an adeno-associated virus to overexpress enhanced green fluorescent protein driven by the somatostatin promoter in preBötC neurons to label their axons and terminal fields. These neurons send brainstem projections to: 1) contralateral preBötC; 2) ipsi- and contralateral Bötzinger Complex; 3) ventral respiratory column caudal to preBötC; 4) parafacial respiratory group / retrotrapezoid nucleus; 5) parahypoglossal nucleus/nucleus of the solitary tract; 6) parabrachial/Kölliker-Fuse nuclei; and 7) periaqueductal gray. We did not find major projections to either cerebellum or spinal cord. We conclude that there are widespread projections from preBötC somatostatin-expressing neurons specifically targeted to brainstem regions implicated in control of breathing, and provide a network basis for the profound effects and the essential role of the preBötC in breathing.

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“…John, 1983; Eldridge and Paydarfar, 1989), rabbits (Janczewski and Karczewski, 1984), and monkeys (Gromysz and Karczewski, 1982). These midline sagittal cuts typically started at 1-3 mm caudal to obex and extended to 5-7 mm rostral to obex.…”

Section: Discussionmentioning

confidence: 99%

“…For example, small (5-10 mm) midsagittal cuts at the level of the obex in cats and rabbits uncouple left and right XII and phrenic motor output (St. John, 1983; Janczewski and Karczewski, 1984; Kubin et al, 1987; Eldridge and Paydarfar, 1989). In contrast, left and right respiratory motor output on cranial nerve roots of frog and lamprey brainstems are synchronized as long as one-third of crossed connections are intact anywhere along the midline (Mc Lean et al, 1995a; Rovainen, 1985).…”

Section: Introductionmentioning

confidence: 99%

Respiratory pattern in midline-lesioned brainstems and hemibrainstems from adult turtles

Majewski

Wiegel

Johnson

2008

Respiratory Physiology & Neurobiology

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Discrete midline lesions uncouple left and right respiratory motor output in mammals, but not in frogs and lampreys. To address this question in reptiles, isolated adult turtle brainstems were cut along the midline while recording respiratory motor output (bursts of action potentials) on left and right hypoglossal (XII) nerves. XII motor bursts were synchronized as long as a small portion of the midline was still intact. When turtle brainstems were completely cut along the midline and separated into hemibrainstems, XII motor bursts were produced that could be abolished by mu-opioid receptor (MOR) activation or exposure to high pH (7.80) solution. Also, 13/57 hemibrainstems expressed episodic discharge (>1.75 bursts/episode). To test whether crossed connections were necessary to express a long-lasting increase in burst frequency (i.e., frequency plasticity), phenylbiguanide (PBG, 5-HT 3 receptor agonist, 20 μM) was bath-applied to hemibrainstems. Although PBG significantly increased burst frequency by 0.43 ± 0.10 bursts/min after 60 min, no frequency plasticity was observed because burst frequency returned to near baseline levels after a 2-h washout. Thus, crossed connections in turtle brainstems synchronize respiratory motor output and are not required for normal respiratory pattern formation, but are required for PBG-dependent frequency plasticity.

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Respiratory effects on pontine, medullary and spinal cord midline sections in the rabbit

Cited by 12 publications

References 12 publications

Desynchronized respiratory rhythms and their interactions in cats with split brain stems.

Desynchronized respiratory rhythms and their interactions in cats with split brain stems.

Projections of preBötzinger Complex neurons in adult rats

Respiratory pattern in midline-lesioned brainstems and hemibrainstems from adult turtles

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