Optogenetic Stimulation of C1 and Retrotrapezoid Nucleus Neurons Causes Sleep State–Dependent Cardiorespiratory Stimulation and Arousal in Rats

Abstract

C1 catecholaminergic neurons and neurons of the retrotrapezoid nucleus are integrative nodes within the brainstem network regulating cardiorespiratory reflexes elicited by hypoxia and hypercapnia, stimuli that also produce arousal from sleep. In the present study, Channelrhodopsin2 was selectively introduced into these neurons with a lentiviral vector in order to determine if their selective activation also produces arousal in sleeping rats. Sleep stages were identified from electroencephalographic and neck muscle electromyographic recordings. Breathing was measured using unrestrained whole body plethysmography and blood pressure by telemetry. During non-rapid eye movement sleep, unilateral photostimulation of the C1 region caused arousal in 83.0 ± 14.7% of trials and immediate and intense cardiorespiratory activation. Arousal during photostimulation was also observed during rapid eye movement sleep (41.9 ± 5.6% of trials), but less reliably than during non-rapid eye movement sleep. The cardiorespiratory responses elicited by photostimulation were dramatically smaller during rapid eye movement sleep than non-rapid eye movement sleep or wakefulness. Systemic alpha1-adrenoreceptor blockade reduced the cardiorespiratory effects of photostimulation, but had no effect on the arousal caused by photostimulation during non-rapid eye movement sleep. Postmortem histology showed that neurons expressing Channelrhodopsin2-mCherry were predominantly catecholaminergic (81%). These results show that selective activation of C1 and retrotrapezoid nucleus neurons produces state dependent arousal and cardiorespiratory stimulation. These neurons, which are powerfully activated by chemoreceptor stimulation, may contribute to the sleep disruption associated with obstructive sleep apnea.

5-HT2A receptor activation is necessary for CO2-induced arousal

“…These include noradrenergic neurons of the locus coeruleus (Pineda and Aghajanian 1997), histaminergic neurons of the tuberomammillary nucleus (Johnson et al 2005), and orexinergic neurons in the lateral hypothalamus (Johnson et al 2010(Johnson et al , 2012Williams et al 2007). Another chemosensitive region, the retrotrapezoid nucleus, may be involved in sleep-wake regulation (Abbott et al 2013;Guyenet and Abbott 2013). Glutamatergic neurons of the parabrachial nucleus have also been implicated in CO 2 -induced arousal (Kaur et al 2013), although these neurons are not known to be intrinsically chemosensitive.…”

Interação entre o grupamento parafacial/núcleo retrotrapezóide e a região de kölliker-fuse na modulação do padrão respiratório.

“…Sabemos que a atividade dos músculos expiratórios é aumentada pela estimulação dos quimiorreceptores centrais e/ou periféricos ou mesmo com a estimulação dos neurônios da região do pFRG/RTN (presentes resultados, ABBOTT et al, 2013;TANABE et al, 2013). Experimentos prévios do nosso laboratório também mostraram que a inibição bilateral do pFRG/RTN, não mais observamos atividade expiratória durante uma situação de hipercapnia e/ou hipóxia (TANABE et al, 2013).…”

“…A musculatura da laringe esta envolvida em diversas funções fisiológicas como o funcionamento adequado das cordas vocais, na regulação da abertura da glote, no controle da resistência das vias aéreas e em reflexos protetores das vias aéreas (HORNER, 2013 (TAKAKURA et al, 2006;, mas uma região integradora de respostas autônomas (MOREIRA et al, 2007a;TAKAKURA et al, 2011; TAKAKURA; MOREIRA, 2011) e respiratórias (ABBOTT et al, 2011(ABBOTT et al, , 2013MOREIRA et al, 2007b;presentes resultados).…”

“…Dessa maneira, gostaríamos de classificar a região do pFRG/RTN não somente como uma região do encéfalo que contém neurônios quimiossensíveis (MULKEY et al, 2004;TAKAKURA et al, 2006TAKAKURA et al, , 2008TAKAKURA et al, , 2014, mas uma região crucial para a manutenção do padrão respiratório eupneico (ABBOTT et al, 2013;BASTING et al, 2015;HUCKSTEPP et al, 2015;MARINA et al, 2010) (Fig. 17).…”

Mecanismos purinérgicos no bulbo ventrolateral rostral modulam respostas cardiovasculares e respiratórias promovidas pela ativação dos quimiorreceptores centrais e periféricos.

“…14,43 Present and previous 15 evidence shows that targeted destruction of C1 cells virtually eliminated the sympathoexcitatory response to peripheral chemoreceptor activation in anesthetized rats. Furthermore, selective acti vation of C1 cells by channelrhodopsin2 has been shown to increase breathing, sympathetic activity, and blood pres sure, [44][45][46] whereas inhibition of C1 cells by activation of the allostatin receptor did the opposite. 47 However, despite the critical role of C1 cells in regulation of cardiorespiratory function, the identity of neurotransmitters and downstream effectors responsible for peripheral chemoreflex control of autonomic function at the level of the ventrolateral medulla remains incomplete.…”