Development and regulation of breathing rhythms in embryonic and hatchling birds

Whitaker‐Fornek, Jessica R.; Nelson, Jennie K.; Lybbert, Casetin W.; Pilarski, Jason Q.

doi:10.1016/j.resp.2019.06.003

Cited by 6 publications

(3 citation statements)

References 139 publications

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“…then rises progressively until postnatal day 15 and then stabilizes until adulthood (Hempleman and Pilarski, 2011;Putnam et al, 2005). In birds, the response is complex; depending on the embryonic stage, acidosis and alkalosis can both stimulate fictive breathing (Whitaker-Fornek et al, 2019). The stimulatory action of CO 2 and H + on fictive breathing measured from reduced Fig.…”

Section: Discussionmentioning

confidence: 99%

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Orexin-A inhibits fictive air breathing responses to respiratory stimuli in the bullfrog tadpole (Lithobates catesbeianus)

Fonseca

Janes

Fournier

et al. 2021

Journal of Experimental Biology

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In pre-metamorphic tadpoles, the neural network generating lung ventilation is present but actively inhibited; the mechanisms leading to the onset of air breathing are not well understood. Orexin (ORX) is a hypothalamic neuropeptide that regulates several homeostatic functions, including breathing. While ORX has limited effects on breathing at rest, it potentiates reflexive responses to respiratory stimuli mainly via ORX receptor 1 (OX1Rs). Here, we tested the hypothesis that OXR1 facilitate the expression of the motor command associated with air breathing in pre-metamorphic bullfrog tadpoles (Lithobates catesbeianus). To do so, we used an isolated diencephalic-brainstem preparation to determine the contributions of OX1Rs to respiratory motor output during baseline breathing, hypercapnia, and hypoxia. A selective OX1R antagonist (SB-334867; 5 – 25 µM) or agonist (ORX-A; 200 nM-1 µM) was added to the superfusion media. Experiments were performed under basal conditions (media equilibrated with 98.2% O2+1.8% CO2), hypercapnia (5% CO2) or hypoxia (5-7% O2). Under resting conditions gill, but not lung, motor output was enhanced by the OX1R antagonist and ORX-A. Hypercapnia alone did not stimulate respiratory motor output, but its combination with SB-334867 increased lung burst frequency and amplitude, lung burst episodes, and the number of bursts/episode. Hypoxia alone increased lung burst frequency and its combination with SB-334867 enhanced this effect. Inactivation of OX1Rs during hypoxia also increased gill burst amplitude, but not frequency. In contrast with our initial hypothesis, we conclude that ORX neurons provide inhibitory modulation of the CO2 and O2 chemoreflexes in pre-metamorphic tadpoles.

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Section: Discussionmentioning

confidence: 99%

“…The ventilatory response to CO 2 of vertebrates undergoes significant changes during early life (Eugenín et al, 2006;Hempleman and Pilarski, 2011;Putnam et al, 2005;Whitaker-Fornek et al, 2019). In rodents, the response is greatest at birth and then declines to nearly undetectable values near postnatal day 5; it Fig.…”

Section: Discussionmentioning

confidence: 99%

Orexin-A inhibits fictive air breathing responses to respiratory stimuli in the bullfrog tadpole (Lithobates catesbeianus)

Fonseca

Janes

Fournier

et al. 2021

Journal of Experimental Biology

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show abstract

“…The mechanical production of tidal flows employs air sacs that require active muscle contractions for both inspiration and expiration (Bouverot, 1978). There are limited examples of respiration-related neural recordings from nuclei in the avian hindbrain, but data suggest the presence of a rostrocaudal column extending from the pons to the spinomedullary junction, with respiration-related regions possibly corresponding to those observed in mammals (Whitaker-Fornek et al, 2019). A recent study in birds reports the presence of two independent embryonic respiratory rhythms recorded from the IX cranial nerve.…”

Section: A Few Notes On Evolutionary Aspects Of Vertebrate Respirationmentioning

confidence: 99%

The lamprey respiratory network: Some evolutionary aspects

Mutolo

Bongianni

Pantaleo

et al. 2021

Respiratory Physiology & Neurobiology

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Chloride Modulates Central pH Sensitivity and Plasticity of Brainstem Breathing‐Related Biorhythms in Zebra Finch Embryos

Whitaker‐Fornek,

Nelson,

Pilarski

2024

Developmental Psychobiology

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All terrestrial vertebrate life must transition from aquatic gas exchange in the embryonic environment to aerial or pulmonary respiration at birth. In addition to being able to breathe air, neonates must possess functional sensory feedback systems for maintaining acid–base balance. Respiratory neurons in the brainstem act as pH sensors that can adjust breathing to regulate systemic pH. The central pH sensitivity of breathing‐related motor output develops over the embryonic period in the zebra finch (Taeniopygia guttata). Due to the key role of chloride ions in electrochemical stability and developmental plasticity, we tested chloride's role in the development of central pH sensitivity. We blocked gamma‐aminobutyric acid‐A receptors and cation‐chloride cotransport that subtly modulated the low‐pH effects on early breathing biorhythms. Further, chloride‐free artificial cerebrospinal fluid altered the pattern and timing of breathing biorhythms and blocked the stimulating effect of acidosis in E12–14 brainstems. Early and middle stage embryos exhibited rebound plasticity in brainstem motor outputs during low‐pH treatment, which was eliminated by chloride‐free solution. Results show that chloride modulates low‐pH sensitivity and rebound plasticity in the zebra finch embryonic brainstem, but work is needed to determine the cellular and circuit mechanisms that control functional chloride balance during acid–base disturbances.

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Development and regulation of breathing rhythms in embryonic and hatchling birds

Cited by 6 publications

References 139 publications

Orexin-A inhibits fictive air breathing responses to respiratory stimuli in the bullfrog tadpole (Lithobates catesbeianus)

Orexin-A inhibits fictive air breathing responses to respiratory stimuli in the bullfrog tadpole (Lithobates catesbeianus)

The lamprey respiratory network: Some evolutionary aspects

Chloride Modulates Central pH Sensitivity and Plasticity of Brainstem Breathing‐Related Biorhythms in Zebra Finch Embryos

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