Nucleus raphe obscurus evokes 5-HT-1A receptor-mediated modulation of respiratory neurons

Lalley, Peter M.; Benacka, R; Bischoff, Anne M.; Richter, Diethelm W.

doi:10.1016/s0006-8993(96)01233-4

Cited by 65 publications

(43 citation statements)

References 2 publications

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“…Thus, techniques such as exogenous application of modulatory transmitters (Harris-Warrick et al, 1992b;McCormick, 1992;Pearson, 1993;Aston-Jones et al, 1996;Ramirez and Richter, 1996;Sillar et al, 1997) and the simultaneous activation of groups of input neurons (Aston-Jones et al, 1996;Grillner et al, 1997;Lalley et al, 1997;Wannier et al, 1998) are commonly used to study modulation of network activity in vertebrate and invertebrate systems. Information from such studies suggests a shared role for multiple input neurons that contain the same modulatory transmitter and influence the same behavior (McCormick, 1992;Aston-Jones et al, 1996;Page and Sofroniew, 1996;Edwards and Kravitz, 1997;Jacobs and Fornal, 1997).…”

Section: Discussionmentioning

confidence: 99%

Different Proctolin Neurons Elicit Distinct Motor Patterns from a Multifunctional Neuronal Network

et al. 1999

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Distinct motor patterns are selected from a multifunctional neuronal network by activation of different modulatory projection neurons. Subsets of these projection neurons can contain the same neuromodulator(s), yet little is known about the relative influence of such neurons on network activity. We have addressed this issue in the stomatogastric nervous system of the crab Cancer borealis. Within this system, there is a neuronal network in the stomatogastric ganglion (STG) that produces many versions of the pyloric and gastric mill rhythms. These different rhythms result from activation of different projection neurons that innervate the STG from neighboring ganglia and modulate STG network activity. Three pairs of these projection neurons contain the neuropeptide proctolin. These include the previously identified modulatory proctolin neuron and modulatory commissural neuron 1 (MCN1) and the newly identified modulatory commissural neuron 7 (MCN7). We document here that each of these neurons contains a unique complement of cotransmitters and that each of these neurons elicits a distinct version of the pyloric motor pattern. Moreover, only one of them (MCN1) also elicits a gastric mill rhythm. The MCN7-elicited pyloric rhythm includes a pivotal switch by one STG network neuron from playing a minor to a major role in motor pattern generation. Therefore, modulatory neurons that share a peptide transmitter can elicit distinct motor patterns from a common target network.

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Section: Discussionmentioning

confidence: 99%

Different Proctolin Neurons Elicit Distinct Motor Patterns from a Multifunctional Neuronal Network

et al. 1999

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“…This is attributable to the presence of multiple 5-HT-receptor subtypes (Barnes and Sharp, 1999) that cause diverse respiratory effects at the single-neuron and network level (Bohmer et al, 1979;Champagnat et al, 1979;Arita and Ochiishi, 1991;Lalley et al, 1997). Because of this complexity, we examined the endogenous role of only one receptor subtype, the 5-HT 2A receptor.…”

Section: Abstract: Respiratory Rhythm; Endogenous Serotonin; Pre-bö mentioning

confidence: 99%

Endogenous Activation of Serotonin-2A Receptors Is Required for Respiratory Rhythm GenerationIn Vitro

2002

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Endogenous amines and peptides continuously modulate the activity of neuronal networks and are required even for their normal operation. The respiratory rhythm generator, localized in the pre-Bö tzinger complex, is not an exception. This network is modulated by various neurotransmitters, including serotonin (5-HT). In this study, we isolated the respiratory network in brainstem slices and demonstrate that the endogenous activation of 5-HT 2A is required for the generation of the respiratory rhythm in vitro. At the network level, activation of 5-HT 2A receptors with 4-iodo-2,5-dimethoxyamphetamine or the 5-HT uptake blocker alaproclate increased the frequency of respiratory activity. Blockade of endogenously activated 5-HT 2A receptors with three different antagonists decreased the frequency, amplitude, and regularity of respiratory population activity, an effect that was blocked by protein kinase C (PKC) activators. At the cellular level, blockade of 5-HT 2A receptors reduced the action potential discharge in all examined respiratory neurons, which was associated with a reduction in the fast and the persistent sodium current. Continuous application of 5-HT 2A -receptor antagonists differentially affected pacemaker neurons. Pacemaker activity was eliminated in cadmiuminsensitive pacemaker neurons. In cadmium-sensitive pacemaker neurons, the frequency of pacemaker activity was unaffected and the amplitude of pacemaker bursts was enhanced. It is assumed that cadmium-insensitive pacemakers rely on the persistent sodium current, whereas cadmium-sensitive pacemakers depend on the activation of calcium currents. We conclude that endogenously activated 5-HT 2A receptors are required for maintaining fictive respiratory activity in the brainstem slice by modulating sodium conductances via a PKC pathway.

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“…Two hypotheses may be put forward to explain the different firing levels of the MINs in the two strains. First, the high level of 5-HT in adult Tg8 mice may increase their activity (Lalley et al, 1997); second, their morphology, excitability, and the medullary circuitry to PhMns and IntCMns may have been altered during maturation by the excess of 5-HT (Cases et al, 1996). Further work is needed to answer that question.…”

Section: Abnormal Breathing Pattern In Adult Tg8 Micementioning

confidence: 99%

Altered Respiratory Activity and Respiratory Regulations in Adult Monoamine Oxidase A-Deficient Mice

et al. 2001

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The abnormal metabolism of serotonin during the perinatal period alters respiratory network maturation at birth as revealed by comparing the monoamine oxidase A-deficient transgenic (Tg8) with the control (C3H) mice (Bou-Flores et al., 2000). To know whether these alterations occur only transiently or induce persistent respiratory dysfunction during adulthood, we studied the respiratory activity and regulations in adult C3H and Tg8 mice. First, plethysmographic and pneumotachographic analyses of breathing patterns revealed weaker tidal volumes and shorter inspiratory durations in Tg8 than in C3H mice. Second, electrophysiological studies showed that the firing activity of inspiratory medullary neurons and phrenic motoneurons is higher in Tg8 mice and that of the intercostal motoneurons in C3H mice. Third, histological studies indicated abnormally large cell bodies of Tg8 intercostal but not phrenic motoneurons. Finally, respiratory responses to hypoxia and lung inflation are weaker in Tg8 than in C3H mice. DL-p-chlorophenyl-alanine treatments applied to Tg8 mice depress the high serotonin level present during adulthood; the treated mice recover normal respiratory responses to both hypoxia and lung inflation, but their breathing parameters are not significantly affected. Therefore in Tg8 mice the high serotonin level occurring during the perinatal period alters respiratory network maturation and produces a permanent respiratory dysfunction, whereas the high serotonin level present in adults alters the respiratory regulatory processes. In conclusion, the metabolism of serotonin plays a crucial role in the maturation of the respiratory network and in both the respiratory activity and the respiratory regulations.

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Nucleus raphe obscurus evokes 5-HT-1A receptor-mediated modulation of respiratory neurons

Cited by 65 publications

References 2 publications

Different Proctolin Neurons Elicit Distinct Motor Patterns from a Multifunctional Neuronal Network

Different Proctolin Neurons Elicit Distinct Motor Patterns from a Multifunctional Neuronal Network

Endogenous Activation of Serotonin-2A Receptors Is Required for Respiratory Rhythm GenerationIn Vitro

Altered Respiratory Activity and Respiratory Regulations in Adult Monoamine Oxidase A-Deficient Mice

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