scholarly journals Neonatal maternal separation and sex-specific plasticity of the hypoxic ventilatory response in awake rat

2004 ◽  
Vol 554 (2) ◽  
pp. 543-557 ◽  
Author(s):  
Sophie-Emmanuelle Genest ◽  
Roumiana Gulemetova ◽  
Sylvie Laforest ◽  
Guy Drolet ◽  
Richard Kinkead
Keyword(s):  
Maternal Separation ◽  
Ventilatory Response ◽  
Hypoxic Ventilatory Response ◽  
Awake Rat ◽  
Neonatal Maternal Separation

Neonatal maternal separation enhances phrenic responses to hypoxia and carotid sinus nerve stimulation in the adult anesthetized rat

2005 ◽  
Vol 99 (1) ◽  
pp. 189-196 ◽  
Author(s):  
Richard Kinkead ◽  
Roumiana Gulemetova ◽  
Aida Bairam
Keyword(s):  
Nerve Stimulation ◽  
Maternal Separation ◽  
Carotid Sinus ◽  
Ventilatory Response ◽  
Male Rats ◽  
Hypoxic Ventilatory Response ◽  
Carotid Sinus Nerve ◽  
Neonatal Maternal Separation ◽  
Carotid Sinus Nerve Stimulation ◽  
Series Of Experiments

In awake animals, our laboratory recently showed that the hypoxic ventilatory response of adult male (but not female) rats previously subjected to neonatal maternal separation (NMS) is 25% greater than controls (Genest SE, Gulemetova R, Laforest S, Drolet G, and Kinkead R. J Physiol 554: 543–557, 2004). To begin mechanistic investigations of the effects of this neonatal stress on respiratory control development, we tested the hypothesis that, in male rats, NMS enhances central integration of carotid body chemoafferent signals. Experiments were performed on two groups of adult male rats. Pups subjected to NMS were placed in a temperature-controlled incubator 3 h/day from postnatal day 3 to postnatal day 12. Control pups were undisturbed. At adulthood (8–10 wk), rats were anesthetized (urethane; 1.6 g/kg), paralyzed, and ventilated with a hyperoxic gas mixture [inspired O2 fraction (FiO2) = 0.5], and phrenic nerve activity was recorded. The first series of experiments aimed to demonstrate that NMS-related enhancement of the inspiratory motor output (phrenic) response to hypoxia occurs in anesthetized animals also. In this series, rats were exposed to moderate, followed by severe, isocapnic hypoxia (FiO2 = 0.12 and 0.08, respectively, 5 min each). NMS enhanced both the frequency and amplitude components of the phrenic response to hypoxia relative to controls, thereby validating the use of this approach. In a second series of experiments, NMS increased the amplitude (but not the frequency) response to unilateral carotid sinus nerve stimulation (stimulation frequency range: 0.5–33 Hz). We conclude that enhancement of central integration of carotid body afferent signal contributes to the larger hypoxic ventilatory response observed in NMS rats.

Neonatal maternal separation induces sex-specific augmentation of the hypercapnic ventilatory response in awake rat

2007 ◽  
Vol 102 (4) ◽  
pp. 1416-1421 ◽  
Author(s):  
Sophie-Emmanuelle Genest ◽  
Roumiana Gulemetova ◽  
Sylvie Laforest ◽  
Guy Drolet ◽  
Richard Kinkead
Keyword(s):  
Tidal Volume ◽  
Maternal Separation ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Male Rats ◽  
Lower Tidal Volume ◽  
Hypercapnic Ventilatory Response ◽  
Specific Effects ◽  
Awake Rat ◽  
Neonatal Maternal Separation

Neonatal maternal separation (NMS) is a form of stress that exerts persistent, sex-specific effects on the hypoxic ventilatory response. Adult male rats previously subjected to NMS show a 25% increase in the response, whereas NMS females show a response 30% lower than controls ( 8 ). To assess the extent to which NMS affects ventilatory control development, we tested the hypothesis that NMS alters the ventilatory response to hypercapnia in awake, unrestrained rats. Pups subjected to NMS were placed in a temperature- and humidity-controlled incubator 3 h/day for 10 consecutive days (P3 to P12). Control pups were undisturbed. At adulthood (8 to 10 wk old), rats were placed in a plethysmography chamber for measurement of ventilatory parameters under baseline and hypercapnic conditions (inspired CO2 fraction = 0.05). After 20 min of hypercapnia, the minute ventilation response measured in NMS males was 47% less than controls, owing to a lower tidal volume response (22%). Conversely, females previously subjected to NMS showed minute ventilation and tidal volume responses 63 and 18% larger than controls respectively. Although a lower baseline minute ventilation contributes to this effect, the higher minute ventilation/CO2 production response observed in NMS females suggests a greater responsiveness to CO2/H+ in this group. We conclude that NMS exerts sex-specific effects on the hypercapnic ventilatory response and that the neural mechanisms affected by NMS likely differ from those involved in the hypoxic chemoreflex.

Neonatal maternal separation and early life programming of the hypoxic ventilatory response in rats

2005 ◽  
Vol 149 (1-3) ◽  
pp. 313-324 ◽  
Author(s):  
Richard Kinkead ◽  
Sophie-Emmanuelle Genest ◽  
Roumiana Gulemetova ◽  
Yves Lajeunesse ◽  
Sylvie Laforest ◽  
...  
Keyword(s):  
Early Life ◽  
Maternal Separation ◽  
Ventilatory Response ◽  
Hypoxic Ventilatory Response ◽  
Early Life Programming ◽  
Neonatal Maternal Separation

Neonatal stress and attenuation of the hypercapnic ventilatory response in adult male rats: the role of carotid chemoreceptors and baroreceptors

2010 ◽  
Vol 299 (5) ◽  
pp. R1279-R1289 ◽  
Author(s):  
Frédéric S. Dumont ◽  
Richard Kinkead
Keyword(s):  
Adult Male ◽  
Maternal Separation ◽  
Ventilatory Response ◽  
Respiratory Control ◽  
Pressure Change ◽  
Male Rats ◽  
Arterial Blood ◽  
Carotid Bodies ◽  
Neonatal Maternal Separation ◽  
Underlying Mechanisms

Neonatal maternal separation (NMS) is a form of stress that disrupts respiratory control development. Awake adult male rats previously subjected to NMS show a ventilatory response to hypercapnia (HCVR; FiCO2 = 0.05) 47% lower than controls; however, the underlying mechanisms are unknown. To address this issue, we first tested the hypothesis that carotid bodies contribute to NMS-related attenuation of the HCVR by using carotid sinus nerve section or FiO2 manipulation to maintain PaO2 constant (iso-oxic) during hypercapnic hyperpnea. We then determined whether NMS-related augmentation of baroreflex sensitivity contributes to the reduced HCVR in NMS rats. Nitroprusside and phenylephrine injections were used to manipulate arterial blood pressure in both groups of rats. Pups subjected to NMS were separated from their mother 3 h/day from postnatal days 3 to 12. Control rats were undisturbed. At adulthood, rats were anesthetized [urethane (1g/kg) + isoflurane (0.5%)], and diaphragmatic electromyogram (dEMG) was measured under baseline and hypercapnic conditions (PaCO2: 10 Torr above baseline). The relative minute activity response to hypercapnia of anesthetized NMS rats was 34% lower than controls. Maintaining PaO2 constant during hypercapnia reversed this phenotype; the HCVR of NMS rats was 45% greater than controls. Although the decrease in breathing frequency during baroreflex activation was greater in NMS rats, the change observed within the range of pressure change observed during hypercapnia was minimal. We conclude that NMS-related changes in carotid body sensitivity to chemical stimuli and/or its central integration is a key mechanism in the attenuation of HCVR by NMS.

scholarly journals Release of ATP by pre-Bötzinger complex astrocytes contributes to the hypoxic ventilatory response via a Ca2+ -dependent P2Y1 receptor mechanism

2017 ◽  
Vol 596 (15) ◽  
pp. 3245-3269 ◽  
Author(s):  
Vishaal Rajani ◽  
Yong Zhang ◽  
Venkatesh Jalubula ◽  
Vladimir Rancic ◽  
Shahriar SheikhBahaei ◽  
...  
Keyword(s):  
Ventilatory Response ◽  
P2y1 Receptor ◽  
Hypoxic Ventilatory Response ◽  
Bötzinger Complex
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