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Optogenetic perturbation of preBötzinger complex inhibitory neurons modulates respiratory pattern.

Sherman D, Worrell JW, Cui Y, Feldman JL - Nat. Neurosci. (2015)

Bottom Line: Inhibitory neurons make up a substantial fraction of the neurons in the preBötzinger complex (preBötC), a site that is critical for mammalian eupneic breathing.Channelrhodopsin-2 (ChR2) or Archaerhodopsin (Arch) were expressed in glycinergic preBötC neurons of glycine transporter 2 (Glyt2, also known as Slc6a5)-Cre mice.We conclude that glycinergic preBötC neurons modulate inspiratory pattern and are important for reflex apneas, but that the rhythm can persist after substantial dampening of their activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, California, USA.

ABSTRACT
Inhibitory neurons make up a substantial fraction of the neurons in the preBötzinger complex (preBötC), a site that is critical for mammalian eupneic breathing. We investigated the role of glycinergic preBötC neurons in respiratory rhythmogenesis in mice using optogenetically targeted excitation and inhibition. Channelrhodopsin-2 (ChR2) or Archaerhodopsin (Arch) were expressed in glycinergic preBötC neurons of glycine transporter 2 (Glyt2, also known as Slc6a5)-Cre mice. In ChR2-transfected mice, brief inspiratory-phase bilateral photostimulation targeting the preBötC prematurely terminated inspiration, whereas expiratory-phase photostimulation delayed the onset of the next inspiration. Prolonged photostimulation produced apneas lasting as long as the light pulse. Inspiratory-phase photoinhibition in Arch-transfected mice during inspiration increased tidal volume without altering inspiratory duration, whereas expiratory-phase photoinhibition shortened the latency until the next inspiration. During persistent apneas, prolonged photoinhibition restored rhythmic breathing. We conclude that glycinergic preBötC neurons modulate inspiratory pattern and are important for reflex apneas, but that the rhythm can persist after substantial dampening of their activity.

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Prolonged photostimulation of preBötC GlyT2 neurons results in apnea(a) Representative airflow trace illustrating effect of 1 s pulse train of photostimulation (black bars beneath trace; 7× 100ms pulses with a 50 ms interpulse interval; n = 5). (b) Overlay of airflow traces aligned to the laser onset at various phases of respiratory cycle (7× 100 ms pulses with a 50 ms interpulse interval) reveals that the next breath occurred at a fairly constant delay after the laser shuts off. (c) Representative graph of latency to next breath as a function of initial phase of photostimulation. Dotted line indicates mean latency. (d, e, f) Photostimulation with a 1 s pulse train (7× 100 ms pulses with 50 ms interpulse interval) of awake, behaving mice in a plethysmograph under eupneic (d; n = 5), hypoxic (e; n = 5), or hypercapnic (f; n = 5) states. (g) Airflow during bilateral 20 s pulse train of light (100 ms pulses with 50 ms interpulse interval; n = 3) in anesthetized mouse.
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Figure 3: Prolonged photostimulation of preBötC GlyT2 neurons results in apnea(a) Representative airflow trace illustrating effect of 1 s pulse train of photostimulation (black bars beneath trace; 7× 100ms pulses with a 50 ms interpulse interval; n = 5). (b) Overlay of airflow traces aligned to the laser onset at various phases of respiratory cycle (7× 100 ms pulses with a 50 ms interpulse interval) reveals that the next breath occurred at a fairly constant delay after the laser shuts off. (c) Representative graph of latency to next breath as a function of initial phase of photostimulation. Dotted line indicates mean latency. (d, e, f) Photostimulation with a 1 s pulse train (7× 100 ms pulses with 50 ms interpulse interval) of awake, behaving mice in a plethysmograph under eupneic (d; n = 5), hypoxic (e; n = 5), or hypercapnic (f; n = 5) states. (g) Airflow during bilateral 20 s pulse train of light (100 ms pulses with 50 ms interpulse interval; n = 3) in anesthetized mouse.

Mentions: Bilateral photostimulation during early inspiration (ϕstim: 0° – 30°; see Fig. 2a right) resulted in premature inspiratory burst termination, i.e., a breath with truncated peak inspiratory airflow (decreased to 56.4 ± 5.9% of control; P = 10−10; n = 5; Fig. 2c, e) and shortened inspiratory duration (decreased to 67.5 ± 5.4% of control; P = 10−10; n = 5; Fig. 2c, f). In contrast, stimulation during expiration (ϕstim: 180° – 360°) delayed the onset of the subsequent inspiration, with the strongest effect during the late expiratory (ϕstim: 330° – 360°; often referred to as the preinspiratory (pre-I)) phase (Fig. 2b, d) with a 233° ± 20° shift (P = 2×10−10; n = 5), while stimulations falling earlier in expiration, i.e., (ϕstim: 150° – 180°), produced a smaller 94° ± 16° shift (P = 0.007; n = 5; Fig. 2b). Following this phase shift, the next inspiration had no significant change in amplitude (101 ± 3% of control; P = 1; n = 5) or duration (104 ± 3% of control; P = 1; n = 5).


Optogenetic perturbation of preBötzinger complex inhibitory neurons modulates respiratory pattern.

Sherman D, Worrell JW, Cui Y, Feldman JL - Nat. Neurosci. (2015)

Prolonged photostimulation of preBötC GlyT2 neurons results in apnea(a) Representative airflow trace illustrating effect of 1 s pulse train of photostimulation (black bars beneath trace; 7× 100ms pulses with a 50 ms interpulse interval; n = 5). (b) Overlay of airflow traces aligned to the laser onset at various phases of respiratory cycle (7× 100 ms pulses with a 50 ms interpulse interval) reveals that the next breath occurred at a fairly constant delay after the laser shuts off. (c) Representative graph of latency to next breath as a function of initial phase of photostimulation. Dotted line indicates mean latency. (d, e, f) Photostimulation with a 1 s pulse train (7× 100 ms pulses with 50 ms interpulse interval) of awake, behaving mice in a plethysmograph under eupneic (d; n = 5), hypoxic (e; n = 5), or hypercapnic (f; n = 5) states. (g) Airflow during bilateral 20 s pulse train of light (100 ms pulses with 50 ms interpulse interval; n = 3) in anesthetized mouse.
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Related In: Results  -  Collection

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Figure 3: Prolonged photostimulation of preBötC GlyT2 neurons results in apnea(a) Representative airflow trace illustrating effect of 1 s pulse train of photostimulation (black bars beneath trace; 7× 100ms pulses with a 50 ms interpulse interval; n = 5). (b) Overlay of airflow traces aligned to the laser onset at various phases of respiratory cycle (7× 100 ms pulses with a 50 ms interpulse interval) reveals that the next breath occurred at a fairly constant delay after the laser shuts off. (c) Representative graph of latency to next breath as a function of initial phase of photostimulation. Dotted line indicates mean latency. (d, e, f) Photostimulation with a 1 s pulse train (7× 100 ms pulses with 50 ms interpulse interval) of awake, behaving mice in a plethysmograph under eupneic (d; n = 5), hypoxic (e; n = 5), or hypercapnic (f; n = 5) states. (g) Airflow during bilateral 20 s pulse train of light (100 ms pulses with 50 ms interpulse interval; n = 3) in anesthetized mouse.
Mentions: Bilateral photostimulation during early inspiration (ϕstim: 0° – 30°; see Fig. 2a right) resulted in premature inspiratory burst termination, i.e., a breath with truncated peak inspiratory airflow (decreased to 56.4 ± 5.9% of control; P = 10−10; n = 5; Fig. 2c, e) and shortened inspiratory duration (decreased to 67.5 ± 5.4% of control; P = 10−10; n = 5; Fig. 2c, f). In contrast, stimulation during expiration (ϕstim: 180° – 360°) delayed the onset of the subsequent inspiration, with the strongest effect during the late expiratory (ϕstim: 330° – 360°; often referred to as the preinspiratory (pre-I)) phase (Fig. 2b, d) with a 233° ± 20° shift (P = 2×10−10; n = 5), while stimulations falling earlier in expiration, i.e., (ϕstim: 150° – 180°), produced a smaller 94° ± 16° shift (P = 0.007; n = 5; Fig. 2b). Following this phase shift, the next inspiration had no significant change in amplitude (101 ± 3% of control; P = 1; n = 5) or duration (104 ± 3% of control; P = 1; n = 5).

Bottom Line: Inhibitory neurons make up a substantial fraction of the neurons in the preBötzinger complex (preBötC), a site that is critical for mammalian eupneic breathing.Channelrhodopsin-2 (ChR2) or Archaerhodopsin (Arch) were expressed in glycinergic preBötC neurons of glycine transporter 2 (Glyt2, also known as Slc6a5)-Cre mice.We conclude that glycinergic preBötC neurons modulate inspiratory pattern and are important for reflex apneas, but that the rhythm can persist after substantial dampening of their activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, California, USA.

ABSTRACT
Inhibitory neurons make up a substantial fraction of the neurons in the preBötzinger complex (preBötC), a site that is critical for mammalian eupneic breathing. We investigated the role of glycinergic preBötC neurons in respiratory rhythmogenesis in mice using optogenetically targeted excitation and inhibition. Channelrhodopsin-2 (ChR2) or Archaerhodopsin (Arch) were expressed in glycinergic preBötC neurons of glycine transporter 2 (Glyt2, also known as Slc6a5)-Cre mice. In ChR2-transfected mice, brief inspiratory-phase bilateral photostimulation targeting the preBötC prematurely terminated inspiration, whereas expiratory-phase photostimulation delayed the onset of the next inspiration. Prolonged photostimulation produced apneas lasting as long as the light pulse. Inspiratory-phase photoinhibition in Arch-transfected mice during inspiration increased tidal volume without altering inspiratory duration, whereas expiratory-phase photoinhibition shortened the latency until the next inspiration. During persistent apneas, prolonged photoinhibition restored rhythmic breathing. We conclude that glycinergic preBötC neurons modulate inspiratory pattern and are important for reflex apneas, but that the rhythm can persist after substantial dampening of their activity.

Show MeSH
Related in: MedlinePlus