Role of ventral medullary catecholaminergic neurons for respiratory modulation of sympathetic outflow in rats

Author(s)

Moraes, Davi J. A. ^[1] ; Bonagamba, Leni G. H. ^[1] ; da Silva, Melina P. ^[1] ; Paton, Julian F. R. ^{[2, 3]} ; Machado, Benedito H. ^[1]

Affiliation

^[1] Univ Sao Paulo, Sch Med Ribeirao Preto, Dept Physiol, Ribeirao Preto, SP - Brazil

^[2] Univ Bristol, Biomed Sci, Sch Physiol Pharmacol & Neurosci, Bristol, Avon - England

^[3] Univ Auckland, Dept Physiol, Fac Med & Hlth Sci, Auckland - New Zealand

• Document type: Journal article
• Source: SCIENTIFIC REPORTS; v. 7, DEC 4 2017.
• Web of Science Citations: 5

Abstract

Sympathetic activity displays rhythmic oscillations generated by brainstem inspiratory and expiratory neurons. Amplification of these rhythmic respiratory-related oscillations is observed in rats under enhanced central respiratory drive or during development of neurogenic hypertension. Herein, we evaluated the involvement of ventral medullary sympatho-excitatory catecholaminergic C1 neurons, using inhibitory Drosophila allatostatin receptors, for the enhanced expiratory-related oscillations in sympathetic activity in rats submitted to chronic intermittent hypoxia (CIH) and following activation of both peripheral (hypoxia) and central chemoreceptors (hypercapnia). Pharmacogenetic inhibition of C1 neurons bilaterally resulted in reductions of their firing frequency and amplitude of inspiratory-related sympathetic activity in rats in normocapnia, hypercapnia or after CIH. In contrast, hypercapnia or hypoxia-induced enhanced expiratory-related sympathetic oscillations were unaffected by C1 neuronal inhibition. Inhibition of C1 neurons also resulted in a significant fall in arterial pressure and heart rate that was similar in magnitude between normotensive and CIH hypertensive rats, but basal arterial pressure in CIH rats remained higher compared to controls. C1 neurons play a key role in regulating inspiratory modulation of sympathetic activity and arterial pressure in both normotensive and CIH hypertensive rats, but they are not involved in the enhanced late-expiratory-related sympathetic activity triggered by activation of peripheral or central chemoreceptors. (AU)

• FAPESP's process: 13/06077-5 - Changes in the neural networks involved with the generation and control of sympathetic and respiratory activities in different experimental models of hypoxia
• Grantee: Benedito Honorio Machado
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 15/01073-7 - Electrophysiological characterization of expiratory motoneurons in rats submitted to sustained hypoxia
• Grantee: Melina Pires da Silva
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 13/10484-5 - Electrophysiological and molecular characterization of neurons involved in the generation of respiratory rhythm and pattern of rats during postnatal development
• Grantee: Davi José de Almeida Moraes
• Support Opportunities: Research Grants - Young Investigators Grants