Raphespinal and reticulospinal axon collaterals to the hypoglossal nucleus in the rat

Manaker, Scott; Tischler, Laura J.; Morrison, Adrian R.

doi:10.1002/cne.903220106

Cited by 56 publications

(37 citation statements)

References 67 publications

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“…The raphe pallidus, obscurus, and magnus are the main regions containing 5-HT-positive neurons projecting to the trigeminal, hypoglossal, and facial nucleus (376, 740,789,790). The raphe nuclei also contain premotor neurons positive for several neuropeptides.…”

Section: B Afferent Projections To Orofacial Motor Nucleimentioning

confidence: 99%

Synaptic Control of Motoneuronal Excitability

Rekling

Funk

Bayliss

et al. 2000

Physiological Reviews

531

482

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Movement, the fundamental component of behavior and the principal extrinsic action of the brain, is produced when skeletal muscles contract and relax in response to patterns of action potentials generated by motoneurons. The processes that determine the firing behavior of motoneurons are therefore important in understanding the transformation of neural activity to motor behavior. Here, we review recent studies on the control of motoneuronal excitability, focusing on synaptic and cellular properties. We first present a background description of motoneurons: their development, anatomical organization, and membrane properties, both passive and active. We then describe the general anatomical organization of synaptic input to motoneurons, followed by a description of the major transmitter systems that affect motoneuronal excitability, including ligands, receptor distribution, pre-and postsynaptic actions, signal transduction, and functional role. Glutamate is the main excitatory, and GABA and glycine are the main inhibitory transmitters acting through ionotropic receptors. These amino acids signal the principal motor commands from peripheral, spinal, and supraspinal structures. Amines, such as serotonin and norepinephrine, and neuropeptides, as well as the glutamate and GABA acting at metabotropic receptors, modulate motoneuronal excitability through pre-and postsynaptic actions. Acting principally via second messenger systems, their actions converge on common effectors, e.g., leak K + current, cationic inward current, hyperpolarization-activated inward current, Ca 2+ channels, or presynaptic release processes. Together, these numerous inputs mediate and modify incoming motor commands, ultimately generating the coordinated firing patterns that underlie muscle contractions during motor behavior.

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Section: B Afferent Projections To Orofacial Motor Nucleimentioning

confidence: 99%

Synaptic Control of Motoneuronal Excitability

Rekling

Funk

Bayliss

et al. 2000

Physiological Reviews

531

482

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“…At this time, it is difficult to conclude where or through which cellular and/or synaptic mechanisms CIH enhanced XII LTF. The XII nuclei receive serotonergic input from the caudal raphe nuclei, but the relative capacity for serotonergic influence may be more limited (43,44).…”

Section: Ltfmentioning

confidence: 99%

Selected Contribution: Chronic intermittent hypoxia enhances respiratory long-term facilitation in geriatric female rats

Zabka¹,

Mitchell²,

Olson³

et al. 2003

Journal of Applied Physiology

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Zabka, A. G., G. S. Mitchell, E. B. Olson, Jr., and M. Behan. Selected Contribution: Chronic intermittent hypoxia enhances respiratory long-term facilitation in geriatric female rats. J Appl Physiol 95: 2614-2623. First published August 22, 2003 10.1152/japplphysiol.00476.2003.-Age and the estrus cycle affect time-dependent respiratory responses to episodic hypoxia in female rats. Respiratory long-term facilitation (LTF) is enhanced in middle-aged vs. young female rats (72). We tested the hypothesis that phrenic and hypoglossal (XII) LTF are diminished in acyclic geriatric rats when fluctuating sex hormone levels no longer establish conditions that enhance LTF. Chronic intermittent hypoxia (CIH) enhances LTF (41); thus we further predicted that CIH would restore LTF in geriatric female rats. LTF was measured in young (3-4 mo) and geriatric (20-22 mo) female Sasco Sprague-Dawley rats and in a group of geriatric rats exposed to 1 wk of nocturnal CIH (11 vs. 21% O 2 at 5-min intervals, 12 h/night). In anesthetized, paralyzed, vagotomized, and ventilated rats, time-dependent hypoxic phrenic and XII responses were assessed. The short-term hypoxic response was measured during the first of three 5-min episodes of isocapnic hypoxia (arterial PO 2 35-45 Torr). LTF was assessed 15, 30, and 60 min postepisodic hypoxia. Phrenic and XII short-term hypoxic response was not different among groups, regardless of CIH treatment (P Ͼ 0.05). LTF in geriatric female rats was smaller than previously reported for middle-aged rats but comparable to that in young female rats. CIH augmented phrenic and XII LTF to levels similar to those of middle-aged female rats without CIH (P Ͻ 0.05). The magnitude of phrenic and XII LTF in all groups was inversely related to the ratio of progesterone to estradiol serum levels (P Ͻ 0.05). Thus CIH and sex hormones influence the magnitude of LTF in geriatric female rats. respiratory control; plasticity; age; sex hormones AGE AFFECTS THE CONTROL OF breathing in humans and other mammals (6,12,61,63), and there are striking differences between males and females with advancing age. For example, responses to hypoxia are decreased in middle-aged male rats but increased in middle-aged female rats (19,62,71,72). A form of serotonin (5-HT)-dependent respiratory plasticity, long-term facilitation (LTF), increases in middleaged female rats but decreases dramatically in middle-aged male rats (71, 72). The control of breathing is also influenced by sex hormones (7, 60, 66). However, relatively little is known concerning specific mechanisms of respiratory control affected by age and/or sex hormones.In the present study, we investigated the effects of old age on selected time-dependent respiratory responses during and after episodic hypoxia in female rats, with a focus on the short-term hypoxic response (STHR) and LTF. STHR and LTF have been studied extensively in young and middle-aged, but not in geriatric, male and female rats (20,50,58,71,72).Respiratory LTF is a form of plasticity elicited by episodic hypoxia or e...

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“…However, the activity of RO and RP neurons under the two conditions must also be considered. Under in vivo conditions, upper airway tone will be modulated in phase with state-dependent changes in the activity of peptidergic neurons in raphe pallidus and obscurus (Jacobs & Azmitia, 1992;Jacobs & Fornal, 1993;Veasey et al 1995) that project to the XII nucleus (Manaker et al 1992;Manaker & Tischler, 1993;Dobbins & Feldman, 1995). Whether activity of raphe obscurus and raphe pallidus neurons in vitro is relevant to any state in vivo is not known.…”

Section: Functional Significance Relevance Of In Vitro Rhythm To Eupnmentioning

confidence: 99%

“…Neurons in the raphe nuclei provide a powerful, diverse and largely excitatory modulation of MN excitability (Rekling et al 2000). Neurons in raphe obscurus and pallidus (Manaker et al 1992;Manaker & Tischler, 1993), which innervate cranial, including XII, motor nuclei, contain 5HT and TRH or 5HT and SP (Kachidian et al 1991;Henry & Manaker, 1998). These compounds appear to modulate excitability, at least in part, by blocking the two-pore domain K + channel TASK-1 (Talley et al 2000).…”

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confidence: 99%

Modulation of hypoglossal motoneuron excitability by NK1 receptor activation in neonatal mice in vitro

Yasuda

Robinson

Selvaratnam

et al. 2001

The Journal of Physiology

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The effects of substance P (SP), acting at NK1 receptors, on the excitability and inspiratory activity of hypoglossal (XII) motoneurons (MNs) were investigated using rhythmically active medullary‐slice preparations from neonatal mice (postnatal day 0‐3). Local application of the NK1 agonist [SAR9,Met (O2)11]‐SP (SPNK1) produced a dose‐dependent, spantide‐ (a non‐specific NK receptor antagonist) and GR82334‐(an NK1 antagonist) sensitive increase in inspiratory burst amplitude recorded from XII nerves. Under current clamp, SPNK1 significantly depolarized XII MNs, potentiated repetitive firing responses to injected currents and produced a leftward shift in the firing frequency‐current relationships without affecting slope. Under voltage clamp, SPNK1 evoked an inward current and increased input resistance, but had no effect on inspiratory synaptic currents. SPNK1 currents persisted in the presence of TTX, were GR82334 sensitive, were reduced with hyperpolarization and reversed near the expected EK. Effects of the α1‐noradrenergic receptor agonist phenylephrine (PE) on repetitive firing behaviour were virtually identical to those of SPNK1. Moreover, SPNK1 currents were completely occluded by PE, suggesting that common intracellular pathways mediate the actions of NK1 and α1‐noradrenergic receptors. In spite of the similar actions of SPNK1 and PE on XII MN responses to somally injected current, α1‐noradrenergic receptor activation potentiated inspiratory synaptic currents and was more than twice as effective in potentiating XII nerve inspiratory burst amplitude. GR82334 reduced XII nerve inspiratory burst amplitude and generated a small outward current in XII MNs. These observations, together with the first immunohistochemical evidence in the newborn for SP immunopositive terminals in the vicinity of SPNK1‐sensitive inspiratory XII MNs, support the endogenous modulation of XII MN excitability by SP. In contrast to phrenic MNs (Ptak et al. 2000), blocking NMDA receptors with AP5 had no effect on the modulation of XII nerve activity by SPNK1. In conclusion, SPNK1 modulates XII motoneuron responses to inspiratory drive primarily through inhibition of a resting, postsynaptic K+ leak conductance. The results establish the functional significance of SP in controlling upper airway tone during early postnatal life and indicate differential modulation of motoneurons controlling airway and pump muscles by SP.

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Raphespinal and reticulospinal axon collaterals to the hypoglossal nucleus in the rat

Cited by 56 publications

References 67 publications

Synaptic Control of Motoneuronal Excitability

Synaptic Control of Motoneuronal Excitability

Selected Contribution: Chronic intermittent hypoxia enhances respiratory long-term facilitation in geriatric female rats

Modulation of hypoglossal motoneuron excitability by NK1 receptor activation in neonatal mice in vitro

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