Cholinergic neurons in the pedunculopontine tegmental nucleus modulate breathing in rats by direct projections to the retrotrapezoid nucleus

Autor(es)

Lima, Janayna D. ^[1] ; Sobrinho, Cleyton R. ^[1] ; Falquetto, Barbara ^[2] ; Santos, Leonardo K. ^[1] ; Takakura, Ana C. ^[2] ; Mulkey, Daniel K. ^[3] ; Moreira, Thiago S. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Physiol & Biophys, Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, Dept Pharmacol, Sao Paulo, SP - Brazil

^[3] Univ Connecticut, Dept Physiol & Neurobiol, Storrs, CT 06269 - USA

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF PHYSIOLOGY-LONDON; v. 597, n. 7, p. 1919-1934, APR 2019.
• Citações Web of Science: 2

Resumo

Key points Cholinergic projections from the pedunculopontine tegmental nucleus (PPTg) to the retrotrapezoid nucleus (RTN) are considered to be important for sleep-wake state-dependent control of breathing. The RTN also receives cholinergic input from the postinspiratory complex. Stimulation of the PPTg increases respiratory output under control conditions but not when muscarinic receptors in the RTN are blocked. The data obtained in the present study support the possibility that arousal-dependent modulation of breathing involves recruitment of cholinergic projections from the PPTg to the RTN. The pedunculopontine tegmental nucleus (PPTg) in the mesopontine region has important physiological functions, including breathing control. The PPTg contains a variety of cell types, including cholinergic neurons that project to the rostral aspect of the ventrolateral medulla. In addition, cholinergic signalling in the retrotrapezoid nucleus (RTN), a region that contains neurons that regulate breathing in response to changes in CO2/H+, has been shown to activate chemosensitive neurons and increase inspiratory activity. The present study aimed to identify the source of cholinergic input to the RTN and determine whether cholinergic signalling in this region influences baseline breathing or the ventilatory response to CO2 in conscious male Wistar rats. Retrograde tracer Fluoro-Gold injected into the RTN labelled a subset of cholinergic PPTg neurons that presumably project directly to the chemosensitive region of the RTN. In unrestrained awake rats, unilateral injection of the glutamate (10 mm/100 nL) in the PPTg decreased tidal volume (V-T) but otherwise increased respiratory rate (f(R)) and net respiratory output as indicated by an increase in ventilation (V-E). All respiratory responses elicited by PPTg stimulation were blunted by prior injection of methyl-atropine (5 mm/50-75 nL) into the RTN. These results show that stimulation of the PPTg can increase respiratory activity in part by cholinergic activation of chemosensitive elements of the RTN. Based on previous evidence that cholinergic PPTg projections may simultaneously activate expiratory output from the pFRG, we speculate that cholinergic signalling at the level of RTN region could also be involved in breathing regulation. (AU)

• Processo FAPESP: 15/23376-1 - Núcleo retrotrapezóide, quimiossensibilidade central e automaticidade respiratória
• Beneficiário: Thiago dos Santos Moreira
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 16/23281-3 - Regiões encefálicas responsáveis pela neuroplasticidade observada na resposta respiratória induzida por hipercapnia em modelo animal de Doença de Parkinson
• Beneficiário: Ana Carolina Takakura Moreira
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 15/12827-2 - Sinalização colinérgica e ventilação: ação modulatória do núcleo tegmental peduncúlo-pontino sobre o núcleo retrotrapezóide
• Beneficiário: Cleyton Roberto Sobrinho
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 16/22069-0 - Melhora nos mecanismos de regulação do fluxo sanguíneo encefálico em animais espontaneamente hipertensos: participação do exercício físico
• Beneficiário: Thiago dos Santos Moreira
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 17/01380-2 - Interação entre o núcleo tegmental pedúnculo pontino e centros respiratórios bulbares na modulação do padrão respiratório
• Beneficiário: Janayna Dias Lima
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto