Hypothalamic modulation of the arterial chemoreceptor reflex in the anaesthetized cat: role of the nucleus tractus solitarii.

Silva-Carvalho, L; Dawid-Milner, Marc Stefan; Goldsmith, G. E.; Spyer, K. M.

doi:10.1113/jphysiol.1995.sp020915

Cited by 41 publications

(25 citation statements)

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“…A large proportion of NTS neurones (63%) that were excited by SLN stimulation were either directly inhibited or the inputs onto them were effectively reduced during HDA stimulation. Our data argue strongly for a complex intranuclear chain of connections mediating SLN inputs and, as with baroreceptor inputs, these appear to be under the control of an intrinsic group of GABA-containing neurones that mediate inhibitory actions exerted by HDA stimulation (see Silva-Carvalho et al 1995a, b for discussion). Interestingly, a further group of NTS neurones that were excited by HDA stimulation were activated by SLN and SN stimulation.…”

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confidence: 96%

“…The bradycardia and hypotension may be elicited by the convergence of SLN inputs onto 'baroreceptor-sensitive' neurones within the NTS (Mifflin, Spyer & Withington-Wray, 1988a). There is evidence that the stimulation of the hypothalamic defence area (HDA), which produces a sustained increase in blood pressure together with tachycardia and tachypnoea, is partly mediated by facilitation of the chemoreceptor reflex within the NTS (Silva-Carvalho, Dawid-Milner, Goldsmith & Spyer, 1993, 1995a and an inhibition of the baroreceptor reflex that is due to hyperpolarization of baroreceptor-sensitive cells within the NTS and mediated by GABA acting at GABAA receptors (Miffin, Spyer & Withington-Wray, 1988b;Jordan, Mifflin & Spyer, 1988). Preliminary reports from this laboratory presented to the Physiological Society (Dawid-Milner, Silva-Carvalho, Goldsmith & Spyer, 1994) indicate that the stimulation of the HDA may counteract the cardiorespiratory responses induced by SLN stimulation, thus indicating an interaction between HDA and SLN inputs.…”

Section: S Dawid-milner and Othersmentioning

confidence: 99%

“…These were not excited by mechanical stimulation of the larynx or baroreceptor activation, but showed excitatory responses to arterial chemoreceptor stimulation. The potential role of these neurones is discussed at further length by Silva-Carvalho et al 1995a). The present results concerning the description of the synaptic interactions within the NTS and SLN, SN and HDA inputs may have considerable clinical significance in the context of the sudden infant death syndrome.…”

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confidence: 99%

“…If the reciprocal connections between the NTS and HDA remain ineffective through immaturity in some neonates this restorative mechanism would be absent. In these circumstances SLN inputs activated by upper airway stimulation would evoke apnoea, bradycardia and hypotension and, without the facilitating influence of the HDA on respiratory activity and the chemoreceptor reflex (see Silva-Carvalho et al 1995a), only the direct chemoreceptor-induced bradycardia would be observed (Daly, 1985). This would be expected to potentiate the existing bradycardia and could induce cardiac arrest.…”

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Hypothalamic modulation of laryngeal reflexes in the anaesthetized cat: role of the nucleus tractus solitarii.

Dawid-Milner¹,

Silva-Carvalho²,

Goldsmith³

et al. 1995

The Journal of Physiology

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1. This investigation was initiated because activation of laryngeal afferents, either by electrical stimulation of the superior laryngeal nerve (SLN) or by natural stimulation of receptors in the laryngeal mucosa, results in a cardiorespiratory response comprising bradycardia, hypotension and apnoea (phrenic nerve activity was suppressed). This pattern of response is qualitatively equivalent to the response that is evoked on activation of the arterial baroreceptors. 2. Preliminary studies indicated that the effects of activating the SLN were suppressed during stimulation in the hypothalamic defence area (HDA) at points that also blocked the effects of baroreceptor stimulation. 3. Recordings were taken from seventy-two neurones localized within the ipsilateral nucleus tractus solitarii (NTS) whose activity was modified by SLN stimulation. Sixty neurones responded with an EPSP on SLN stimulation; nine of these had an inspiratory firing pattern. Five neurones were seen to receive an IPSP on SLN stimulation. 4. Five respiratory SLN-activated neurones were unresponsive to stimulation of the other nerve inputs, whilst four received convergent EPSP inputs on sinus nerve (SN) stimulation. One cell of these four also received inputs from the aortic and the vagus nerves. Sixty-one non-respiratory SLN-activated neurones also received convergent inputs from the sinus nerve. Of these, fifty displayed an EPSP, four an IPSP and seven an EPSP-IPSP. Fifteen neurones also received inputs from the aortic nerve and seventeen from the vagus. 5. From the population of neurones affected by SLN stimulation, twenty-four of seventy were also influenced by HDA stimulation (3 were respiratory cells). Sixteen of these responses consisted of an EPSP (2 respiratory cells), five of an IPSP (1 respiratory cell) and three of an EPSP-IPSP. 6. In neurones receiving an IPSP on HDA stimulation, the SLN-evoked excitatory response was reduced throughout the period of HDA-evoked inhibition. These neurones were all shown to receive excitatory inputs from the arterial baroreceptors and laryngeal mechanoreceptors. 7. Additionally, in the thirty-seven neurones that were excited by SLN stimulation but received no direct synaptic input on HDA stimulation, a conditioning stimulus to the HDA evoked a block of SLN-evoked responses without an accompanying change in membrane potential. Several of these neurones were also affected by both baroreceptor and laryngeal mechanoreceptor stimulation. 8. These observations are discussed in the context of the role of the NTS in cardiorespiratory control. The potential importance of these interactions in respiratory distress are highlighted and the implications for the organization of central pathways for the control of autonomic and respiratory function are discussed.

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Section: S Dawid-milner and Othersmentioning

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Hypothalamic modulation of laryngeal reflexes in the anaesthetized cat: role of the nucleus tractus solitarii.

Dawid-Milner¹,

Silva-Carvalho²,

Goldsmith³

et al. 1995

The Journal of Physiology

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“…Their role is made even more significant by the fact that many of the NTS neurones that are known to receive an input from the arterial baroreceptors, and an inhibitory control from the hypothalamus, also respond to activation of vagal afferents, including those that relay in the superior laryngeal nerve (Biscoe & Sampson, 1970;Mufflin et al 1988a, b). Hence, the activation of the HDA has the potential to modulate other reflexes (Lopes & Palmer, 1978) and this is considered in fuller detail in accompanying papers (Dawid-Milner, SilvaCarvalho, Goldsmith & Spyer, 1995; Silva-Carvalho, Dawid-Milner, Goldsmith & Spyer, 1995 (VN) and superior laryngeal nerve (SLN) were isolated for electrical stimulation (1-2 pulses, 0-1ms, 1-20 V given at 1 Hz). A SwanGanz catheter was advanced via the external carotid artery into the right carotid sinus.…”

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The pattern of excitatory inputs to the nucleus tractus solitarii evoked on stimulation in the hypothalamic defence area in the cat.

Silva-Carvalho

Dawid-Milner

Spyer

1995

The Journal of Physiology

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Neuronal Control of Breathing: Sex and Stress Hormones

Behan

Kinkead

2011

Comprehensive Physiology

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There is a growing public awareness that hormones can have a significant impact on most biological systems, including the control of breathing. This review will focus on the actions of two broad classes of hormones on the neuronal control of breathing: sex hormones and stress hormones. The majority of these hormones are steroids; a striking feature is that both groups are derived from cholesterol. Stress hormones also include many peptides which are produced primarily within the paraventricular nucleus of the hypothalamus (PVN) and secreted into the brain or into the circulatory system. In this article we will first review and discuss the role of sex hormones in respiratory control throughout life, emphasizing how natural fluctuations in hormones are reflected in ventilatory metrics and how disruption of their endogenous cycle can predispose to respiratory disease. These effects may be mediated directly by sex hormone receptors or indirectly by neurotransmitter systems. Next, we will discuss the origins of hypothalamic stress hormones and their relationship with the respiratory control system. This relationship is 2-fold: (i) via direct anatomical connections to brainstem respiratory control centers, and (ii) via steroid hormones released from the adrenal gland in response to signals from the pituitary gland. Finally, the impact of stress on the development of neural circuits involved in breathing is evaluated in animal models, and the consequences of early stress on respiratory health and disease is discussed.

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Hypothalamic modulation of the arterial chemoreceptor reflex in the anaesthetized cat: role of the nucleus tractus solitarii.

Cited by 41 publications

References 20 publications

Hypothalamic modulation of laryngeal reflexes in the anaesthetized cat: role of the nucleus tractus solitarii.

Hypothalamic modulation of laryngeal reflexes in the anaesthetized cat: role of the nucleus tractus solitarii.

The pattern of excitatory inputs to the nucleus tractus solitarii evoked on stimulation in the hypothalamic defence area in the cat.

Neuronal Control of Breathing: Sex and Stress Hormones

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