Central chemoreception in the neonatal rat transverse medullary slice preparation by Sasha Aleksandar Necakov

Cover of: Central chemoreception in the neonatal rat transverse medullary slice preparation | Sasha Aleksandar Necakov

Published by National Library of Canada in Ottawa .

Written in English

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Thesis (M.Sc.) -- University of Toronto, 2001.

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SeriesCanadian theses = -- Thèses canadiennes
The Physical Object
Pagination2 microfiches : negative. --
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Open LibraryOL19079426M
ISBN 100612588661

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Central Chemoreception in the Neonatal Rat Transverse Medullary Slice Preparation University of Toronto, Department of Physiology Sasha Aleksandar Necakov Master of Science ( 1) This study investigates several aspects of central chemoreception in the neonatal rat.

transverseAuthor: Sasha Aleksandar Necakov. The aim of the present study was to test the hypothesis that maternal CSE during pregnancy depresses central chemoreception of the neonatal rats.

The pregnant rats were divided into two groups, control (n = 8) and CSE (n = 8). Experiments were performed on neonatal (0–3days) rat by: 7. Transverse medullary slices were prepared from neonatal rat pups, as previously described [ 24 ].

In brief, the neonates were decapitated after anaesthetization with ether to prevent suffer. Slice preparation. Medullary slices were prepared from neonatal Sprague-Dawley rats of postnatal (P) ages P1–19 (day P1 is the first day after the birth of the rats), as previously described (Dean et al.

; Ritucci et al. ; Dean et al., ; Ritucci et al., ).Rats aged P1–P13 were anesthetized by hypothermia and rapidly by:   Detailed descriptions of methods for producing rhythmic medullary slice preparations are available elsewhere (Funk et al.,Smith et al., ).In brief, the brainstem-spinal cord preparation is isolated from anesthetized, neonatal rats (P) submerged in hyper-oxygenated, bicarbonate-based buffer solution (artificial cerebrospinal fluid, aCSF), and dura and blood vessels by: Brain slice preparation.

The caudal portion of the NTS is thought to contribute to central chemoreception because a subset of neurons in this region respond to CO 2 with increased firing rate we found a subset of medullary raphe neurons in slices from neonatal rat pups that responded to 15% CO 2 with a modest increase or decrease of.

The fetal medullary slice preparation is amenable to whole-cell recordings of XII motoneurons (reviewed in Funk and Greer, ). Further, there is an extensive body of data on the development of.

Hypoglossal nerve rootlets in the transverse medullary slice prepared from neonatal rats exhibit a bursting ‘respiratory’ rhythm that increases in frequency with CO 2, presumably due to activation of chemosensitive cells such as the central ic anhydrase is associated with areas of central chemoreception and we propose a hypothesis for its involvement in the.

The transverse slice preparation isolates the minimal neural substrate sufficient for respiratory rhythmogenesis, but does not permit the study of neuronal signaling along the column.

Here, the sagittally sectioned rat hindbrain preparation is described. Combination of these two transections resulted in a transverse slice of medullary tissue, mm thick, which included structures lying FD rostral and FD caudal to the obex.

In 7 preparations the burst frequency and discharge profile of the transverse slice was compared to the brain stem-spinal cord preparation prior to resection. We have examined age-related changes in chemosensitivity of neurons from the rat medullary raphe, a putative site for central chemoreception, using perforated patch-clamp recordings in vitro.

In brain slices from rats younger than 12 days old, firing rate increased in 3% of neurons and decreased in 17% of neurons in response to respiratory. Our findings suggest that the central inspiratory neural network of the in vivo anesthetized neonatal rat exhibits lower complexity (i.e., more order) than that observed in the in vitro transverse medullary slice preparation, both of which are substantially lower than that observed in more intact in vitro (e.g., arterially-perfused rat) and.

Acetazolamide and respiratory chemosensitivity to CO2 in the neonatal rat transverse medullary slice Article in Respiratory Physiology & Neurobiology (3) October with 10 Reads. Slice Preparation.

Medullary tissue slices were prepared from 2- to day-old Sprague-Dawley rat pups of either gender, as previously described ().These procedures were performed Central chemoreception in the neonatal rat transverse medullary slice preparation book accordance with the guidelines stated in the Guide for the Care and Use of Laboratory Animals as put forth by the Public Health Service, National Institutes of Health.

Briefly, the animal was killed by rapid. Linlin Shen's 5 research works with 73 citations and 48 reads, including: Inhibitory connections among rostral medullary expiratory neurons detected with cross-correlation in the decerebrate rat. In experiments using an isolated neonatal rat brainstem preparation, and in medullary slice preparations that contain the pre- Bötzinger region, neurons with spontaneous depolarizations are observed that are necessary for the production of the rhythmic respiratory `system' output observed Smith et al.,Feldman and Smith, An.

The transverse medullary slice preparation of neonatal rats has been used to study respiratory rhythm generation (Smith et al. ; Rekling & Feldman, ; Richter & Spyer, ).In this preparation, hypoglossal nerve rootlets generate spontaneous rhythmic discharges (Al-Zubaidy et al.

; Peever et al. ), which are synchronous with the firing of neurones in the pre-Bötzinger. As ATP and norepineprhine (NE) can be coreleased, we explored in neonatal rat the interaction between these cascades using whole-cell and nerve recording from rhythmic and nonrhythmic medullary.

To explore such interactions, we used the neonatal in vitro medullary slice preparation derived from wild-type (WT) mice (normal 5-HT function) and a knockout strain lacking all central 5-HT neurons (Lmx1b f/f/p mice). We examined effects of acidosis, hypocretin-1, a hypocretin receptor antagonist (SB), and the effect of the antagonist.

Olivier Pierrefiche, Mickael Naassila, Endogenous nitric oxide but not exogenous no-donor S-nitroprussiate facilitates NMDA excitation in spontaneous rhythmic neonatal rat brainstem slice, Brain Research, /es,(), ().

Key points Several brain regions are thought to sense changes in tissue CO2/H+ to regulate breathing (i.e. central chemoreceptors) including the nucleus of the solitary tract (NTS), medullary raphe and retrotrapezoid nucleus (RTN).

Mechanism(s) underlying RTN chemoreception involve direct activation of RTN neurons by H+‐mediated inhibition of a resting K+ conductance and. In a previous study (Peever et al., ) we found that the transverse medullary slice preparation from neonatal rats responded to the addition of CO 2 to the superfusing bathing medium, when pH was decreased toby increasing the hypoglossal nerve bursting frequency.

Interestingly, Gourine and coworkers used slice preparation of adult rats to argue that central chemoreception in the ventral medulla is mediated by ATP and its receptor.

In another study, the same group also showed that a fall in local tissue pH results in increase in Ca 2+ and release of ATP by astrocytes, but not neurons [ 78 ]. Introduction. Central respiratory chemoreception is the mechanism by which the brain senses changes in CO 2 and/or pH to regulate the rate and depth of breathing (Feldman et al., ).Despite intensive effort, the cellular mechanisms responsible for sensing pH in the context of respiratory control remain unknown, in part because of difficulties in identifying neurons that function.

In neonatal mouse slice preparations that retain the preBötC and Mari Kogo, Effects of riluzole on spinal seizure-like activity in the brainstem-spinal cord preparation of newborn rat, Neuroscience Research, /j transverse medullary slice preparation in respiratory neurobiology: Contributions and caveats.

The decerebrate in situ preparations of the juvenile and neonatal rat exhibit patterns of automatic ventilatory activity that are comparable to eupnea and gasping of in vivo preparations (14, 24–27). Using this preparation, we have evaluated the hypothesis that activation of serotonin 5-HT 2A subtype is essential for the neurogenesis of gasping.

The experiments demonstrate that glomus tissues at different sites in the rat produce significant and distinct contributions to respiratory regulation. Denervation of all known receptors shows that significant ventilatory responses to hypoxia are still produced, either by unrevealed peripheral chemoreceptors, or by central neural mechanisms.

ATP is released during hypoxia from the ventrolateral medulla (VLM) and activates purinergic P2 receptors (P2Rs) at unknown loci to offset the secondary hypoxic depression of breathing.

In this study, we used rhythmically active medullary slices from neonatal rat to map, in relation to anatomical and molecular markers of the pre-Bötzinger complex (preBötC) (a proposed site of rhythm. Serotonin (5-HT)-synthesizing neurons of the medullary raphe are putative central chemoreceptors, proposed to be one of potentially multiple brain stem chemosensitive cell types and loci interactin.

Anatomical description of the tilted transversal slice preparation. a Schematic drawing of a midline sagittal section through the pontomedullary brainstem showing the 47° cutting angle for the tilted slice preparation.

Note that the laterally located respiratory centers are projected onto this mediolateral section to allow for better comparison with the transversal sections below.

The medullary slice was continuously perfused in physiological solution similar to that used for the brainstem–spinal cord preparation except for the potassium concentration, which was increased to 9 m m to stimulate the spontaneous rhythmic respiratory motor discharge in the medullary slice (Smith et al., ).

Recording and analysis. Effects of transverse section and DAMGO. We next examined the effects of transverse section at the medullary level between the pre-Bötzinger complex and the pFRG (at the approximate level of the Xth cranial nerve roots or the most rostral roots of the XIIth cranial nerve; see Fig.

8A) on facial and C4 nerve ately after transection, rhythmic burst activity from these nerves. This slice preparation contains at least three main nuclei that show central chemoreception: the raphe nucleus, the NTS and the pre-Bötzinger complex.

Raphe nucleus 5HTergic neurons are relevant for central chemoreception and transverse medullary slice preparation in respiratory neurobiology. The rhythmic, transverse medullary slice preparation in respiratory neurobiology: contributions and caveats. Respir Physiol Neurobiol ; – Crossref, Medline, Google Scholar.

Interestingly, Gourine and coworkers used slice preparation of adult rats to argue that central chemoreception in the ventral medulla is mediated by ATP and its receptor. In another study, the same group also showed that a fall in local tissue pH results in increase in Ca 2+ and release of ATP by astrocytes, but not neurons [ 78 ].

Materials and Methods. Experiments were performed with in vitro medullary slice preparations from neonatal rats, which allowed us to combine detailed cellular and network level analyses, and with in situ perfused brainstem–spinal cord preparations from juvenile rats, which generate patterns of cranial and spinal motoneuron activity similar to those in vivo (Paton, ; Smith et al.

In severe hypoxia or ischemia, normal eupneic breathing is replaced by gasping, which can serve as a powerful mechanism for “autoresuscitation.” We have proposed that gasping is generated by medull. The role of excitatory amino acids in the generation and transmission of respiratory drive in the neonatal rat.

transverse medullary slice preparation in respiratory neurobiology: and central chemoreception in the control of breathing in the fetus and the neonate.

Respiratory activities are produced by medullary respiratory rhythm generators and are modulated from various sites in the lower brainstem, and which are then output as motor activities through premotor efferent networks in the brainstem and spinal cord.

Over the past few decades, new knowledge has been accumulated on the anatomical and physiological mechanisms underlying the. The medullary slice preparation is a derivative of the BSSC preparation. 2 Similarly to past studies, the frequency of rhythmic respiratory discharge in medullary slice preparations was markedly suppressed by the bath application of DAMGO ( nM, n = 5) to ± % of control levels before DAMGO (P.

The level of the transverse section used for optical recordings. a Ventral view of a brainstem–spinal cord preparation from a neonatal rat. The preparation was cut at the level of the dotted line.b Rostral cut surface view of a preparation at a level of mm rostral to the caudal end of the facial nucleus (ΔFNc).The square denotes the approximate recording area.Distribution of serotonin-immunoreactivity in the central nervous system of the rat—cell bodies and terminals.

J Neurosci 6: –, Crossref | ISI Google Scholar; 37 Wang W, Bradley SR, and Richerson GB. Quantification of the response of rat medullary raphe neurones to independent changes in pH O and P co 2.

J Physiol –Carbenoxolone (CBX), a gap junction uncoupler, alters the functioning of the pre-Bötzinger Complex (preBötC), a central pattern generating neuronal network important for the production of respiratory rhythm in mammals.

Even when isolated in a 1/2 mm-thick slice of medulla oblongata from neonatal mouse the preBötC continues producing periodic bursts of action potentials, termed population.

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