Development of chemosensitivity in neurons from the nucleus tractus solitarii (NTS) of neonatal rats

Conrad, Susan C.; Nichols, Nicole L.; Ritucci, Nick A.; Dean, J. Michael; Putnam, Robert W.

doi:10.1016/j.resp.2008.11.005

Cited by 32 publications

(52 citation statements)

References 50 publications

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“…We found that SC neurons from adult rats had a maintained acidification with a lack of pH i recovery in response to HA, which is similar to what has been found in SC neurons from neonates (23,42), and that the percentage of SC neurons activated or inhibited by HA and the magnitude of these responses were unchanged in adult rats compared with neonates (5). This developmental profile did not coincide with previously described patterns for the development of the rat ventilatory response to hypercapnia (6,49).…”

supporting

confidence: 63%

“…Synaptic blockade (SNB) solution was modified from aCSF and contained 0.2 mM CaCl 2 and 11.4 mM MgSO 4 ([NaCl] was adjusted to maintain osmotic balance) (5, 7). Carbenoxolone (CARB; 100 M) was added to SNB solution to block electrical transmission (5,9). Isohydric hypercapnic (IH) solution was modified from aCSF with NaHCO 3 Ϫ increased to 77 mM and NaCl decreased to 73 mM to keep pH o and osmotic pressure the same.…”

Section: Solutionsmentioning

confidence: 99%

“…The whole cell patch intracellular solution contained (in mM): 130 K ϩ -gluconate, 10 K ϩ -HEPES, 0.4 EGTA, 1 MgCl2, 0.3 GTP, and 2 ATP (pH ϭ 7.45 at room temperature). This solution was used to reduce potential washout of the chemosensitive response (5,15). The high K ϩ /nigericin solution that was used for calibration (50) Slice preparation.…”

Section: Solutionsmentioning

confidence: 99%

“…The blind whole cell patch-clamp technique was used to measure neuronal membrane potential (V m) and integrated firing rate, as described previously (1). The experimental setup that was used has been previously described (5,8,14,18). Briefly, a whole cell patch pipette (5 M⍀) was fabricated from borosilicate glass using a Narishige PP-830 dual-stage pipette puller.…”

Section: Solutionsmentioning

confidence: 99%

“…PUTATIVE CENTRAL CHEMOSENSITIVE neurons have mostly been studied in neonatal rats in various localized regions within the brain stem, including the solitary complex [SC, including neurons from both the nucleus tractus solitarius (NTS) and the dorsal motor nucleus of the vagus (DMN)] (5,7,10,22), ventrolateral medulla (54), retrotrapezoid nucleus (RTN) (24,44), medullary raphé (40,53), pre-Bötzinger region (47), and the locus coeruleus (LC) (14,32,35). All of these regions increase ventilation when focally acidified (4,26).…”

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confidence: 99%

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Characterization of the chemosensitive response of individual solitary complex neurons from adult rats

Nichols¹,

Mulkey²,

Wilkinson³

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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(pH i) and electrical responses to hypercapnic acidosis (HA). SC neurons were recorded using the blind whole cell patchclamp technique and loading the soma with the pH-sensitive dye pyranine through the patch pipette. We found that SC neurons from adult rats have a lower steady-state pH i than SC neurons from neonatal rats. In the presence of chemical and electrical synaptic blockade, adult SC neurons have firing rate responses to HA (percentage of neurons activated or inhibited and the magnitude of response as determined by the chemosensitivity index) that are similar to SC neurons from neonatal rats. They also have a typical response to isohydric hypercapnia, including decreased ⌬pHi, followed by pHi recovery, and increased firing rate. Thus, the chemosensitive response of SC neurons from adults is similar to the chemosensitive response of SC neurons from neonatal rats. Because our findings for adults are similar to previously reported values for neurons from neonatal rats, we conclude that intrinsic chemosensitivity is established early in development for SC neurons and is maintained throughout adulthood.

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supporting

confidence: 63%

Section: Solutionsmentioning

confidence: 99%

Section: Solutionsmentioning

confidence: 99%

Section: Solutionsmentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Characterization of the chemosensitive response of individual solitary complex neurons from adult rats

Nichols¹,

Mulkey²,

Wilkinson³

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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Central respiratory chemoreception

Guyenet¹,

Stornetta²,

Bayliss³

2010

J of Comparative Neurology

214

187

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Summary By definition central respiratory chemoreceptors (CRCs) are cells that are sensitive to changes in brain PCO2 or pH and contribute to the stimulation of breathing elicited by hypercapnia or metabolic acidosis. CO2 most likely works by lowering pH. The pertinent proton receptors have not been identified and may be ion channels. CRCs are probably neurons but may also include acid-sensitive glia and vascular cells that communicate with neurons via paracrine mechanisms. Retrotrapezoid nucleus (RTN) neurons are the most completely characterized CRCs. Their high sensitivity to CO2 in vivo presumably relies on their intrinsic acid-sensitivity, excitatory inputs from the carotid bodies and brain regions such as raphe and hypothalamus, and facilitating influences from neighboring astrocytes. RTN neurons are necessary for the respiratory network to respond to CO2 during the perinatal period and under anesthesia. In conscious adults, RTN neurons contribute to an unknown degree to the pH-dependent regulation of breathing rate, inspiratory and expiratory activity. The abnormal prenatal development of RTN neurons probably contributes to the congenital central hypoventilation syndrome. Other CRCs presumably exist but the supportive evidence is less complete. The proposed locations of these CRCs are the medullary raphe, the nucleus tractus solitarius, the ventrolateral medulla, the fastigial nucleus and the hypothalamus. Several wake-promoting systems (serotonergic and catecholaminergic neurons, orexinergic neurons) are also putative CRCs. Their contribution to central respiratory chemoreception may be behavior-dependent or vary according to the state of vigilance.

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The Cellular Building Blocks of Breathing

Ramirez

Doi

Garcia

et al. 2012

Comprehensive Physiology

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Respiratory brainstem neurons fulfill critical roles in controlling breathing: they generate the activity patterns for breathing and contribute to various sensory responses including changes in O2 and CO2. These complex sensorimotor tasks depend on the dynamic interplay between numerous cellular building blocks that consist of voltage-, calcium-, and ATP-dependent ionic conductances, various ionotropic and metabotropic synaptic mechanisms, as well as neuromodulators acting on G-protein coupled receptors and second messenger systems. As described in this review, the sensorimotor responses of the respiratory network emerge through the state-dependent integration of all these building blocks. There is no known respiratory function that involves only a small number of intrinsic, synaptic, or modulatory properties. Because of the complex integration of numerous intrinsic, synaptic, and modulatory mechanisms, the respiratory network is capable of continuously adapting to changes in the external and internal environment, which makes breathing one of the most integrated behaviors. Not surprisingly, inspiration is critical not only in the control of ventilation, but also in the context of “inspiring behaviors” such as arousal of the mind and even creativity. Far-reaching implications apply also to the underlying network mechanisms, as lessons learned from the respiratory network apply to network functions in general.

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Development of chemosensitivity in neurons from the nucleus tractus solitarii (NTS) of neonatal rats

Cited by 32 publications

References 50 publications

Characterization of the chemosensitive response of individual solitary complex neurons from adult rats

Characterization of the chemosensitive response of individual solitary complex neurons from adult rats

Central respiratory chemoreception

The Cellular Building Blocks of Breathing

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