1
|
Casciato A, Bianchi L, Reverdy M, Joubert F, Delucenay-Clarke R, Parrot S, Ramanantsoa N, Sizun E, Matrot B, Straus C, Similowski T, Cayetanot F, Bodineau L. Serotonin and the ventilatory effects of etonogestrel, a gonane progestin, in a murine model of congenital central hypoventilation syndrome. Front Endocrinol (Lausanne) 2023; 14:1077798. [PMID: 36896185 PMCID: PMC9989262 DOI: 10.3389/fendo.2023.1077798] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Accepted: 02/06/2023] [Indexed: 02/23/2023] Open
Abstract
INTRODUCTION Congenital Central Hypoventilation Syndrome, a rare disease caused by PHOX2B mutation, is associated with absent or blunted CO2/H+ chemosensitivity due to the dysfunction of PHOX2B neurons of the retrotrapezoid nucleus. No pharmacological treatment is available. Clinical observations have reported non-systematic CO2/H+ chemosensitivity recovery under desogestrel. METHODS Here, we used a preclinical model of Congenital Central Hypoventilation Syndrome, the retrotrapezoid nucleus conditional Phox2b mutant mouse, to investigate whether etonogestrel, the active metabolite of desogestrel, led to a restoration of chemosensitivity by acting on serotonin neurons known to be sensitive to etonogestrel, or retrotrapezoid nucleus PHOX2B residual cells that persist despite the mutation. The influence of etonogestrel on respiratory variables under hypercapnia was investigated using whole-body plethysmographic recording. The effect of etonogestrel, alone or combined with serotonin drugs, on the respiratory rhythm of medullary-spinal cord preparations from Phox2b mutants and wildtype mice was analyzed under metabolic acidosis. c-FOS, serotonin and PHOX2B were immunodetected. Serotonin metabolic pathways were characterized in the medulla oblongata by ultra-high-performance liquid chromatography. RESULTS We observed etonogestrel restored chemosensitivity in Phox2b mutants in a non-systematic way. Histological differences between Phox2b mutants with restored chemosensitivity and Phox2b mutant without restored chemosensitivity indicated greater activation of serotonin neurons of the raphe obscurus nucleus but no effect on retrotrapezoid nucleus PHOX2B residual cells. Finally, the increase in serotonergic signaling by the fluoxetine application modulated the respiratory effect of etonogestrel differently between Phox2b mutant mice and their WT littermates or WT OF1 mice, a result which parallels with differences in the functional state of serotonergic metabolic pathways between these different mice. DISCUSSION Our work thus highlights that serotonin systems were critically important for the occurrence of an etonogestrel-restoration, an element to consider in potential therapeutic intervention in Congenital Central Hypoventilation Syndrome patients.
Collapse
Affiliation(s)
- Alexis Casciato
- Sorbonne Université, Inserm, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - Lola Bianchi
- Sorbonne Université, Inserm, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - Manon Reverdy
- Sorbonne Université, Inserm, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - Fanny Joubert
- Sorbonne Université, Inserm, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - Roman Delucenay-Clarke
- Sorbonne Université, Inserm, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - Sandrine Parrot
- Centre de Recherche en Neurosciences, NeuroDialyTics, Bron, France
| | | | - Eléonore Sizun
- Université de Paris, NeuroDiderot, Inserm, Paris, France
| | - Boris Matrot
- Université de Paris, NeuroDiderot, Inserm, Paris, France
| | - Christian Straus
- Sorbonne Université, Inserm, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - Thomas Similowski
- Sorbonne Université, Inserm, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - Florence Cayetanot
- Sorbonne Université, Inserm, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - Laurence Bodineau
- Sorbonne Université, Inserm, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
- *Correspondence: Laurence Bodineau,
| |
Collapse
|
2
|
Matarazzo V, Caccialupi L, Schaller F, Shvarev Y, Kourdougli N, Bertoni A, Menuet C, Voituron N, Deneris E, Gaspar P, Bezin L, Durbec P, Hilaire G, Muscatelli F. Necdin shapes serotonergic development and SERT activity modulating breathing in a mouse model for Prader-Willi syndrome. eLife 2017; 6:32640. [PMID: 29087295 PMCID: PMC5711373 DOI: 10.7554/elife.32640] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 10/29/2017] [Indexed: 12/31/2022] Open
Abstract
Prader-Willi syndrome (PWS) is a genetic neurodevelopmental disorder that presents with hypotonia and respiratory distress in neonates. The Necdin-deficient mouse is the only model that reproduces the respiratory phenotype of PWS (central apnea and blunted response to respiratory challenges). Here, we report that Necdin deletion disturbs the migration of serotonin (5-HT) neuronal precursors, leading to altered global serotonergic neuroarchitecture and increased spontaneous firing of 5-HT neurons. We show an increased expression and activity of 5-HT Transporter (SERT/Slc6a4) in 5-HT neurons leading to an increase of 5-HT uptake. In Necdin-KO pups, the genetic deletion of Slc6a4 or treatment with Fluoxetine, a 5-HT reuptake inhibitor, restored normal breathing. Unexpectedly, Fluoxetine administration was associated with respiratory side effects in wild-type animals. Overall, our results demonstrate that an increase of SERT activity is sufficient to cause the apneas in Necdin-KO pups, and that fluoxetine may offer therapeutic benefits to PWS patients with respiratory complications. Prader-Willi syndrome results from the disruption of a cluster of neighboring genes, including one called Necdin. Symptoms begin in early infancy and worsen with age. Affected children tend to develop an insatiable appetite, which often leads to obesity. They also experience serious problems with their breathing. Chest infections, high altitude and intense physical activity can be dangerous for children with Prader-Willi syndrome. This is because a slight shortage of oxygen may trigger breathing difficulties that could prove fatal. The brain cells that produce a chemical messenger called serotonin help to control breathing. Several lines of evidence suggest that loss of Necdin may trigger breathing difficulties in Prader-Willi syndrome via effects on the serotonin system. First, serotonin neurons produce the Necdin protein. Second, laboratory mice that lack the gene for Necdin have abnormally shaped serotonin neurons. Third, these mice show breathing difficulties like those of individuals with Prader-Willi syndrome. But while this implies a connection between serotonin, Necdin and breathing difficulties, it falls short of establishing a causal link. Matarazzo et al. now reveal an increase in the quantity and activity of a protein called the serotonin transporter in mutant mice that lacked the gene for Necdin compared to normal mice. Serotonin transporter proteins mop up the serotonin that neurons release when they signal to one another. Neurons in the mutant mice take up more serotonin than their counterparts in normal mice; this means they have less serotonin available for signaling. This may make it harder for the mutant mice to regulate their breathing. Drugs called selective serotonin-reuptake inhibitors (or SSRIs for short) can block the serotonin transporter. These drugs, which include Fluoxetine (also called Prozac), are antidepressants. Matarazzo et al. show that SSRIs temporarily restore normal breathing in young mice that lack the gene for Necdin. However, these drugs have harmful long-term effects on breathing in non-mutant mice. Further studies should test whether short-term use of SSRIs could offer immediate relief for breathing difficulties in infants and children with Prader-Willi syndrome.
Collapse
Affiliation(s)
| | | | | | - Yuri Shvarev
- Department of Women's and Children's Health, Karolinska Institute, Solna, Sweden
| | | | | | | | | | - Evan Deneris
- Department of Neurosciences, Case Western Reserve University, Cleveland, United States
| | - Patricia Gaspar
- UPMC Univ Paris 6, Institut du Fer à Moulin, INSERM, Paris, France
| | - Laurent Bezin
- Lyon Neuroscience Research Center, Université de Lyon, INSERM, CNRS, Lyon, France
| | | | | | | |
Collapse
|
3
|
Bravo K, Eugenín JL, Llona I. Perinatal Fluoxetine Exposure Impairs the CO2 Chemoreflex. Implications for Sudden Infant Death Syndrome. Am J Respir Cell Mol Biol 2017; 55:368-76. [PMID: 27018763 DOI: 10.1165/rcmb.2015-0384oc] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
High serotonin levels during pregnancy affect central nervous system development. Whether a commonly used antidepressant such as fluoxetine (a selective serotonin reuptake inhibitor) taken during pregnancy may adversely affect respiratory control in offspring has not been determined. The objective was to determine the effect of prenatal-perinatal fluoxetine exposure on the respiratory neural network in offspring, particularly on central chemoreception. Osmotic minipumps implanted into CF-1 mice on Days 5-7 of pregnancy delivered 7 milligrams per kilogram per day of fluoxetine, achieving plasma levels within the range found in patients. Ventilation was assessed in offspring at postnatal Days 0-40 using head-out body plethysmography. Neuronal activation was evaluated in the raphe nuclei and in the nucleus tractus solitarius by c-Fos immunohistochemistry during normoxic eucapnia and hypercapnia (10% CO2). Respiratory responses to acidosis were evaluated in brainstem slices. Prenatal-perinatal fluoxetine did not affect litter size, birth weight, or the postnatal growth curve. Ventilation under eucapnic normoxic conditions was similar to that of control offspring. Fluoxetine exposure reduced ventilatory responses to hypercapnia at P8-P40 (P < 0.001) but not at P0-P5. At P8, it reduced hypercapnia-induced neuronal activation in raphe nuclei (P < 0.05) and nucleus tractus solitarius (P < 0.01) and the acidosis-induced increase in the respiratory frequency in brainstem slices (P < 0.05). Fluoxetine applied acutely on control slices did not modify their respiratory response to acidosis. We concluded that prenatal-perinatal fluoxetine treatment impairs central respiratory chemoreception during postnatal life. These results are relevant in understanding the pathogenesis of respiratory failures, such as sudden infant death syndrome, associated with brainstem serotonin abnormalities and the failure of respiratory chemoreflexes.
Collapse
Affiliation(s)
- Karina Bravo
- Laboratorio de Sistemas Neurales, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Jaime L Eugenín
- Laboratorio de Sistemas Neurales, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Isabel Llona
- Laboratorio de Sistemas Neurales, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| |
Collapse
|
4
|
Laouafa S, Perrin-Terrin AS, Jeton F, Elliot-Portal E, Tam R, Bodineau L, Voituron N, Soliz J. Pharmacological, but not genetic, alteration of neural Epo modifies the CO 2/H + central chemosensitivity in postnatal mice. Respir Physiol Neurobiol 2017; 242:73-79. [PMID: 28396201 DOI: 10.1016/j.resp.2017.04.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 03/24/2017] [Accepted: 04/05/2017] [Indexed: 11/24/2022]
Abstract
Cerebral erythropoietin (Epo) plays a crucial role for respiratory control in newborn rodents. We showed previously that soluble Epo receptor (sEpoR: an Epo antagonist) reduces basal ventilation and hypoxic hyperventilation at postnatal day 10 (P10) and in adult mice. However, at these ages (P10 and adulthood), Epo had no effect on central chemosensitivity. Nevertheless, it is known that the sensitivity to CO2/H+ during the mammalian respiratory network maturation process is age-dependent. Accordingly, in this study we wanted to test the hypothesis that cerebral Epo is involved in the breathing stimulation induced by the activation of central CO2/H+ chemoreceptors at earlier postnatal ages. To this end, en bloc brainstem-spinal cord preparations were obtained from P4 mice and the fictive breathing response to CO2-induced acidosis or metabolic acidosis was analyzed. This age (P4) was chosen because previous research from our laboratory showed that Epo altered (in a dose- and time-dependent manner) the fictive ventilation elicited in brainstem-spinal cord preparations. Moreover, as it was observed that peripheral chemoreceptors determined the respiratory sensitivity of central chemoreceptors to CO2, the use of this technique restricts our observations to central modulation. Our results did not show differences between preparations from control and transgenic animals (Tg21: overexpressing cerebral Epo; Epo-TAgh: cerebral Epo deficient mice). However, when Tg21 brainstem preparations were incubated for 1h with sEpoR, or with inhibitors of ERK/Akt (thus blocking the activation of the Epo molecular pathway), the fictive breathing response to CO2-induced acidosis was blunted. Our data suggest that variation of the Epo/sEpoR ratio is central to breathing modulation during CO2 challenges, and calls attention to clinical perspectives based on the use of Epo drugs at birth in hypoventilation cases.
Collapse
Affiliation(s)
- Sofien Laouafa
- Université Laval, Faculté de Médecine, Centre de Recherche Institut universitaire de cardiologie et de pneumologie de Québec, Département de Pédiatrie, Québec, QC, Canada; LEHNA, UMR CNRS 5023, Ecologie des Hydrosystèmes Naturels et Anthropisés, Université de Lyon, Université Lyon 1, ENTPE, 6 rue Raphael Dubois, 69622 Villeurbanne, France
| | - Anne-Sophie Perrin-Terrin
- Université Paris 13, Sorbonne Paris Cité, UFR SMBH, Laboratoire "Hypoxie et poumons", EA 2363, 93017 Bobigny, France; Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, F-75013, Paris, France
| | - Florine Jeton
- Université Paris 13, Sorbonne Paris Cité, UFR SMBH, Laboratoire "Hypoxie et poumons", EA 2363, 93017 Bobigny, France
| | - Elizabeth Elliot-Portal
- Université Laval, Faculté de Médecine, Centre de Recherche Institut universitaire de cardiologie et de pneumologie de Québec, Département de Pédiatrie, Québec, QC, Canada; Molecular biology and Biotechnology Institute, Universidad Mayor de San Andres, La Paz, Bolivia
| | - Rose Tam
- Université Laval, Faculté de Médecine, Centre de Recherche Institut universitaire de cardiologie et de pneumologie de Québec, Département de Pédiatrie, Québec, QC, Canada
| | - Laurence Bodineau
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, F-75013, Paris, France
| | - Nicolas Voituron
- Université Paris 13, Sorbonne Paris Cité, UFR SMBH, Laboratoire "Hypoxie et poumons", EA 2363, 93017 Bobigny, France
| | - Jorge Soliz
- Université Laval, Faculté de Médecine, Centre de Recherche Institut universitaire de cardiologie et de pneumologie de Québec, Département de Pédiatrie, Québec, QC, Canada; Molecular biology and Biotechnology Institute, Universidad Mayor de San Andres, La Paz, Bolivia.
| |
Collapse
|
5
|
Remote control of respiratory neural network by spinal locomotor generators. PLoS One 2014; 9:e89670. [PMID: 24586951 PMCID: PMC3930745 DOI: 10.1371/journal.pone.0089670] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 01/21/2014] [Indexed: 12/03/2022] Open
Abstract
During exercise and locomotion, breathing rate rapidly increases to meet the suddenly enhanced oxygen demand. The extent to which direct central interactions between the spinal networks controlling locomotion and the brainstem networks controlling breathing are involved in this rhythm modulation remains unknown. Here, we show that in isolated neonatal rat brainstem-spinal cord preparations, the increase in respiratory rate observed during fictive locomotion is associated with an increase in the excitability of pre-inspiratory neurons of the parafacial respiratory group (pFRG/Pre-I). In addition, this locomotion-induced respiratory rhythm modulation is prevented both by bilateral lesion of the pFRG region and by blockade of neurokinin 1 receptors in the brainstem. Thus, our results assign pFRG/Pre-I neurons a new role as elements of a previously undescribed pathway involved in the functional interaction between respiratory and locomotor networks, an interaction that also involves a substance P-dependent modulating mechanism requiring the activation of neurokinin 1 receptors. This neurogenic mechanism may take an active part in the increased respiratory rhythmicity produced at the onset and during episodes of locomotion in mammals.
Collapse
|
6
|
Gestational stress promotes pathological apneas and sex-specific disruption of respiratory control development in newborn rat. J Neurosci 2013; 33:563-73. [PMID: 23303936 DOI: 10.1523/jneurosci.1214-12.2013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Recurrent apneas are important causes of hospitalization and morbidity in newborns. Gestational stress (GS) compromises fetal brain development. Maternal stress and anxiety during gestation are linked to respiratory disorders in newborns; however, the mechanisms remain unknown. Here, we tested the hypothesis that repeated activation of the neuroendocrine response to stress during gestation is sufficient to disrupt the development of respiratory control and augment the occurrence of apneas in newborn rats. Pregnant dams were displaced and exposed to predator odor from days 9 to 19 of gestation. Control dams were undisturbed. Experiments were performed on male and female rats aged between 0 and 4 d old. Apnea frequency decreased with age but was consistently higher in stressed pups than controls. At day 4, GS augmented the proportion of apneas with O(2) desaturations by 12%. During acute hypoxia (12% O(2)), the reflexive increase in breathing augmented with age; however, this response was lower in stressed pups. Instability of respiratory rhythm recorded from medullary preparations decreased with age but was higher in stressed pups than controls. GS reduced medullary serotonin (5-HT) levels in newborn pups by 32%. Bath application of 5-HT and injection of 8-OH-DPAT [(±)-8-hydroxy-2-di-(n-propylamino) tetralin hydrobromide; 5-HT(1A) agonist; in vivo] reduced respiratory instability and apneas; these effects were greater in stressed pups than controls. Sex-specific effects were observed. We conclude that activation of the stress response during gestation is sufficient to disrupt respiratory control development and promote pathological apneas in newborn rats. A deficit in medullary 5-HT contributes to these effects.
Collapse
|
7
|
Hodges MR, Echert AE, Puissant MM, Mouradian GC. Fluoxetine augments ventilatory CO2 sensitivity in Brown Norway but not Sprague Dawley rats. Respir Physiol Neurobiol 2013; 186:221-8. [PMID: 23454023 DOI: 10.1016/j.resp.2013.02.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 02/20/2013] [Accepted: 02/20/2013] [Indexed: 11/30/2022]
Abstract
The Brown Norway (BN; BN/NHsdMcwi) rat exhibits a deficit in ventilatory CO2 sensitivity and a modest serotonin (5-HT) deficiency. Here, we tested the hypothesis that the selective serotonin reuptake inhibitor fluoxetine would augment CO2 sensitivity in BN but not Sprague Dawley (SD) rats. Ventilation during room air or 7% CO2 exposure was measured before, during and after 3 weeks of daily injections of saline or fluoxetine (10mg/(kgday)) in adult male BN and SD rats. Fluoxetine had minimal effects on room air breathing in BN and SD rats (p>0.05), although tidal volume (VT) was reduced in BN rats (p<0.05). There were also minimal effects of fluoxetine on CO2 sensitivity in SD rats, but fluoxetine increased minute ventilation, breathing frequency and VT during hypercapnia in BN rats (p<0.05). The augmented CO2 response was reversible upon withdrawal of fluoxetine. Brain levels of biogenic amines were largely unaffected, but 5-HIAA and the ratio of 5-HIAA/5-HT were reduced (p<0.05) consistent with selective and effective 5-HT reuptake inhibition. Thus, fluoxetine increases ventilatory CO2 sensitivity in BN but not SD rats, further suggesting altered 5-HT system function may contribute to the inherently low CO2 sensitivity in the BN rat.
Collapse
Affiliation(s)
- Matthew R Hodges
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, United States.
| | | | | | | |
Collapse
|
8
|
Miot S, Voituron N, Sterlin A, Vigneault E, Morel L, Matrot B, Ramanantsoa N, Amilhon B, Poirel O, Lepicard E, Mestikawy SE, Hilaire G, Gallego J. The vesicular glutamate transporter VGLUT3 contributes to protection against neonatal hypoxic stress. J Physiol 2012; 590:5183-98. [PMID: 22890712 DOI: 10.1113/jphysiol.2012.230722] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Neonates respond to hypoxia initially by increasing ventilation, and then by markedly decreasing both ventilation (hypoxic ventilatory decline) and oxygen consumption (hypoxic hypometabolism). This latter process, which vanishes with age, reflects a tight coupling between ventilatory and thermogenic responses to hypoxia. The neurological substrate of hypoxic hypometabolism is unclear, but it is known to be centrally mediated, with a strong involvement of the 5-hydroxytryptamine (5-HT, serotonin) system. To clarify this issue, we investigated the possible role of VGLUT3, the third subtype of vesicular glutamate transporter. VGLUT3 contributes to glutamate signalling by 5-HT neurons, facilitates 5-HT transmission and is expressed in strategic regions for respiratory and thermogenic control. We therefore assumed that VGLUT3 might significantly contribute to the response to hypoxia. To test this possibility, we analysed this response in newborn mice lacking VGLUT3 using anatomical, biochemical, electrophysiological and integrative physiology approaches. We found that the lack of VGLUT3 did not affect the histological organization of brainstem respiratory networks or respiratory activity under basal conditions. However, it impaired respiratory responses to 5-HT and anoxia, showing a marked alteration of central respiratory control. These impairments were associated with altered 5-HT turnover at the brainstem level. Furthermore, under cold conditions, the lack of VGLUT3 disrupted the metabolic rate, body temperature, baseline breathing and the ventilatory response to hypoxia. We conclude that VGLUT3 expression is dispensable under basal conditions but is required for optimal response to hypoxic stress in neonates.
Collapse
Affiliation(s)
- Stéphanie Miot
- Institut National de la Santé et de la Recherche Médicale (INSERM), U952, 75005 Paris, France
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Voituron N, Hilaire G, Quintin L. Dexmedetomidine and clonidine induce long-lasting activation of the respiratory rhythm generator of neonatal mice: possible implication for critical care. Respir Physiol Neurobiol 2011; 180:132-40. [PMID: 22108092 DOI: 10.1016/j.resp.2011.11.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 11/05/2011] [Accepted: 11/05/2011] [Indexed: 11/19/2022]
Abstract
Dexmedetomidine and clonidine are alpha-2 adrenoceptor agonists increasingly used in the critical care unit as sedative agents for their benzodiazepine-sparing effects and their limited depressing effect on breathing. However adverse effects on breathing have been also reported with alpha-2 adrenoceptor agonists and their central effects on the respiratory rhythm generator are poorly known. We therefore examined the effects of dexmedetomidine, clonidine, the alpha-2 adrenoceptor antagonist yohimbine and the benzodiazepine midazolam on the activity of the isolated respiratory rhythm generator of neonatal mice using medullary preparations where the respiratory rhythm generator continued to function in vitro. For the first time, we showed that 5min bath applications of dexmedetomidine or clonidine activated the respiratory rhythm generator for periods over than 30min. Second, we showed that the long-lasting effect of dexmedetomidine implicated receptors other than alpha-2 adrenoceptors as it persisted after their blockade with yohimbine. Third, we reported that 5min bath applications of the benzodiazepine midazolam significantly depressed the respiratory rhythm generator, and that this depression was prevented by pre-treatment with either dexmedetomidine or clonidine. Although further experiments are still required to identify the mechanisms through which dexmedetomidine and clonidine activate the respiratory rhythm generator, our current in vitro results in neonatal mice support the use of dexmedetomidine and clonidine in the critical care unit.
Collapse
Affiliation(s)
- Nicolas Voituron
- Centre de Recherche en Neurobiologie et Neurophysiologie de Marseille, Unité Mixte de Recherche 6231 Centre National Recherche Scientifique/Université Aix-Marseille II et III, Team mp3-Respiration, Faculté Saint-Jérôme (case 362), 13397 Marseille Cedex 20, France
| | | | | |
Collapse
|
10
|
Menuet C, Borghgraef P, Matarazzo V, Gielis L, Lajard AM, Voituron N, Gestreau C, Dutschmann M, Van Leuven F, Hilaire G. Raphé tauopathy alters serotonin metabolism and breathing activity in terminal Tau.P301L mice: possible implications for tauopathies and Alzheimer's disease. Respir Physiol Neurobiol 2011; 178:290-303. [PMID: 21763469 DOI: 10.1016/j.resp.2011.06.030] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 06/14/2011] [Accepted: 06/30/2011] [Indexed: 11/30/2022]
Abstract
Tauopathies, including Alzheimer's disease are the most frequent neurodegenerative disorders in elderly people. Patients develop cognitive and behaviour defects induced by the tauopathy in the forebrain, but most also display early brainstem tauopathy, with oro-pharyngeal and serotoninergic (5-HT) defects. We studied these aspects in Tau.P301L mice, that express human mutant tau protein and develop tauopathy first in hindbrain, with cognitive, motor and upper airway defects from 7 to 8 months onwards, until premature death before age 12 months. Using plethysmography, immunohistochemistry and biochemistry, we examined the respiratory and 5-HT systems of aging Tau.P301L and control mice. At 8 months, Tau.P301L mice developed upper airway dysfunction but retained normal respiratory rhythm and normal respiratory regulations. In the following weeks, Tau.P301L mice entered terminal stages with reduced body weight, progressive limb clasping and lethargy. Compared to age 8 months, terminal Tau.P301L mice showed aggravated upper airway dysfunction, abnormal respiratory rhythm and abnormal respiratory regulations. In addition, they showed severe tauopathy in Kolliker-Fuse, raphé obscurus and raphé magnus nuclei but not in medullary respiratory-related areas. Although the raphé tauopathy concerned mainly non-5-HT neurons, the 5-HT metabolism of terminal Tau.P301L mice was altered. We propose that the progressive raphé tauopathy affects the 5-HT metabolism, which affects the 5-HT modulation of the respiratory network and therefore the breathing pattern. Then, 5-HT deficits contribute to the moribund phenotype of Tau.P301L mice, and possibly in patients suffering from tauopathies, including Alzheimer's disease.
Collapse
Affiliation(s)
- Clément Menuet
- Maturation, Plasticity, Physiology and Pathology of Respiration (MP3-Respiration), Unité Mixte de Recherche 6231, Centre National de la Recherche Scientifique, Université de la Méditerranée, Université Paul Cézanne, Faculté Saint Jérôme (Service 362), 13397 Marseille Cedex 20, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Menuet C, Kourdougli N, Hilaire G, Voituron N. Differences in serotoninergic metabolism possibly contribute to differences in breathing phenotype of FVB/N and C57BL/6J mice. J Appl Physiol (1985) 2011; 110:1572-81. [PMID: 21415169 DOI: 10.1152/japplphysiol.00117.2011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mouse readiness for gene manipulation allowed the production of mutants with breathing defects reminiscent of breathing syndromes. As C57BL/6J and FVB/N inbred strains were often used as background strains for producing mutants, we compared their breathing pattern from birth onwards. At birth, in vivo and in vitro approaches revealed robust respiratory rhythm in FVB/N, but not C57BL/6J, neonates. With aging, rhythm robustness difference persisted, and interstrain differences in tidal volume, minute ventilation, breathing regulations, and blood-gas parameters were observed. As serotonin affected maturation and function of the medullary respiratory network, we examined the serotoninergic metabolism in the medulla of C57BL/6J and FVB/N neonates and aged mice. Interstrain differences in serotoninergic metabolism were observed at both ages. We conclude that differences in serotoninergic metabolism possibly contribute to differences in breathing phenotype of FVB/N and C57BL/6J mice.
Collapse
Affiliation(s)
- Clément Menuet
- Laboratoire Réponses Cellulaires et Fonctionnelles à l'Hypoxie, EA 2363, UFR Santé, Médecine, Biologie Humaine, Université Paris 13, 74 rue Marcel Cachin, Bureau 128, 93017 BOBIGNY Cedex, France
| | | | | | | |
Collapse
|