Projections of supraspinal structures to the phrenic motor nucleus in rats studied by a horseradish peroxidase microinjection method

Onai, Takeshi; Saji, Makoto; Miura, Mitsuhiko

doi:10.1016/0165-1838(87)90026-9

Cited by 87 publications

(36 citation statements)

References 15 publications

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“…Projections to phrenic motoneurons do also exist (Dobbins and Feldman, 1994), and in the cat these may be serotonergic (Pilowsky et al, 1990). Connections between GiA, at levels where we found Fos-positive neurons, and phrenic motoneurons have also been reported (Dobbins and Feldman, 1994;Onai et al, 1987). Electrophysiological data in the cat showed that medullary raphe nuclei contain neurons with respiratory modulated activity, some of which show respiratory-phasedependent synchrony with respiratory neurons in the ventrolateral medulla (Hosogai et al, 1993;Lindsey et al, 1994).…”

Section: Ventral Medullamentioning

confidence: 62%

Expression of c‐fos in the rat brainstem after exposure to hypoxia and to normoxic and hyperoxic hypercapnia

et al. 1997

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In this study, Fos immunohistochemistry was used to map brainstem neuronal pathways activated during hypercapnia and hypoxia. Conscious rats were exposed to six different gas mixtures: (a) air; (b) 8% CO2 in air; (c) 10% CO2 in air; (d) 15% CO2 in air; (e) 15% CO2 + 60% O2, balance N2; (f) 9% O2, balance N2. Double-staining was performed to show the presence of tyrosine hydroxylase. Hypercapnia, in a dose-dependent way caused Fos expression in the following areas: caudal nucleus tractus solitarius (NTS), with few labeled A2 noradrenergic neurons; noradrenergic A1 cells and noncatecholaminergic neurons in the caudal ventrolateral medulla; raphe magnus and gigantocellular nucleus pars alpha (GiA); many noncatecholaminergic (and relatively few C1) neurons in the lateral paragigantocellular nucleus (PGCl), and in the retrotrapezoid nucleus (RTN); locus coeruleus (LC), external lateral parabrachial and Kölliker-Fuse nuclei, and A5 noradrenergic neurons at pontine level; and in caudal mesencephalon, the ventrolateral column of the periaqueductal gray (vlPAG). In most of these nuclei, hypoxia also induced Fos expression, albeit generally less than after hypercapnia. However, hypoxia did not cause labeling in RTN, juxtafacial PGCl, GiA, LC, or vlPAG. After normoxic hypercapnia, more labeled cells were present in NTS and PGCl than after hyperoxic hypercapnia. Part of the observed labeling could be caused by stress- or cardiovascular-related sequelae of hypoxia and hypercapnia. Possible implications for the neural control of breathing are also discussed, particularly with regard to the finding that several nuclei, not belonging to the classical brainstem respiratory centres, contained labeled cells.

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Section: Ventral Medullamentioning

confidence: 62%

Expression of c‐fos in the rat brainstem after exposure to hypoxia and to normoxic and hyperoxic hypercapnia

et al. 1997

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“…Histological analysis confirmed moreover that the nervous pathways were intact in the medial part and that the damage was restricted to the lateral zone. Such effect of the lateral lesions on hemidiaphragm function is probably due to the central deafferentation and inactivation of phrenic motoneurons (located at C3-C6) which receive input from inspiratory neurons originating principally from the ventral respiratory group in the medulla (Dobbins and Feldman, 1994;Onai et al, 1987). The effect of medial sections in VINIT ET AL.…”

Section: Incidence Of Partial Lesions On Respiratory Activitymentioning

confidence: 95%

High Cervical Lateral Spinal Cord Injury Results in Long-Term Ipsilateral Hemidiaphragm Paralysis

Vinit¹,

Gauthier²,

Stamegna³

et al. 2006

Journal of Neurotrauma

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Although axon regeneration is limited in the central nervous system, partial lesions of the spinal cord induce neuroplasticity processes that can lead to spontaneous functional improvement. To determine whether such compensatory mechanisms occur in the respiratory system, we analyzed the incidence of partial injury of the cervical spinal cord on diaphragm activity in adult rats. We show that a section of the lateral area of the C2 cervical spinal cord induces complete phrenic nerve inactivation and ipsilateral hemidiaphragm paralysis, whereas medial or dorsolateral sections had only a moderate effect on respiratory activity. In the case of lateral hemisection, activity of the ipsilateral phrenic nerve was partially restored after a lapse of 3 months. No spontaneous diaphragm recovery was observed, however, even after a lapse of several months in the case of hemisection or lateral section. Ipsilateral hemidiaphragm activity could however be restored after transection of the contralateral phrenic nerve, by activation of the "crossed phrenic phenomenon" (involving activation of previously latent respiratory contralateral pathways crossing the midline). These data suggest that the respiratory system develops important long-term plasticity processes at the level of phrenic motoneuron innervation. However, they do not by themselves allow substantial diaphragm recovery, underscoring the continued need for developing repair strategies. These studies also validates the use of the respiratory system as a model to evaluate the functional incidence of repair strategies not only after hemisection but also after more limited sectioning restricted to the lateral side of the cervical cord.

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“…In rats, inspiratory premotor neurones are generally believed to reside in the ventral medulla (Smith et al 1991;Bianchi et al 1995) since a dorsal respiratory group does not exist in rats and projections of NTS neurones to respiratory motor nuclei are weak or non-existent (see Bianchi et al 1995 for review). While anatomical investigations have demonstrated that many bulbospinal nuclei innervate phrenic and/or internal intercostal motor nuclei, including projections from the medullary lateral tegmental field, NTS, RVL, the Kolliker-Fuse parabrachial complex, the gigantocellular and medullary raphe nuclei, and the Botzinger complex (Onai, Saji & Miura, 1987;Yamada, Ezure & Manabe, 1988;Saji & Miura, 1990;Dobbins & Feldman, 1994), it has not been established whether the projections are from neurones with respiratory rhythmicity. The present study offers several lines of evidence to further endorse the view that RVL contains neurones whose functions are important in the inspiratory rhythmogenesis and that it is the Pre-I neurones which serve this function.…”

Section: Discussionmentioning

confidence: 99%

Excitatory amino acid‐mediated chemoreflex excitation of respiratory neurones in rostral ventrolateral medulla in rats.

Sun

Reis

1996

The Journal of Physiology

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1. In anaesthetized rats, extracellular and intracellular recordings were made from 119 respiratory neurones in the rostroventrolateral reticular nucleus (RVL) of the medulla oblongata. 2. Two types of active respiratory neurones were detected in RVL: expiratory (E) and preinspiratory (Pre-I), based on the relationship between their discharge and that of the phrenic nerve. Some Pre-I but none of the E neurones could be antidromically excited from the C3-C4 level of the spinal cord. 3. E and Pre-I neurones of RVL were excited by stimulation of the arterial chemoreceptors by a close arterial injection of sodium cyanide. The reflex excitation of RVL E neurones was preceded by increased phrenic nerve activity, while the excitation of RVL Pre-I neurones preceded the increases in phrenic nerve activity. 4. The chemoreflex excitation of the two types of RVL respiratory neurones as well as their resting discharge was abolished or significantly depressed by microionophoresis of kynurenate, a wide-spectrum antagonist of excitatory amino acid receptors, while xanthurenate, an inactive analogue of kynurenate, was without effect. 5. In ventilated rats, bilateral microinjection into RVL of kynurenate, but not xanthurenate, abolished resting activity and chemoreflex excitation of phrenic nerve activity, whilst in spontaneously breathing rats, kynurenate microinjection into RVL produced apnea and silenced phrenic nerves. 6. We conclude: (a) chemoreflex excitation of the phrenic nerves is mediated by stimulating Pre-I neurones of RVL by excitatory amino acidergic inputs and (b) RVL Pre-I neurones may directly and/or indirectly excite spinal phrenic motor neurones and hence are involved in inspiratory rhythmogenesis.

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Projections of supraspinal structures to the phrenic motor nucleus in rats studied by a horseradish peroxidase microinjection method

Cited by 87 publications

References 15 publications

Expression of c‐fos in the rat brainstem after exposure to hypoxia and to normoxic and hyperoxic hypercapnia

Expression of c‐fos in the rat brainstem after exposure to hypoxia and to normoxic and hyperoxic hypercapnia

High Cervical Lateral Spinal Cord Injury Results in Long-Term Ipsilateral Hemidiaphragm Paralysis

Excitatory amino acid‐mediated chemoreflex excitation of respiratory neurones in rostral ventrolateral medulla in rats.

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