Prenatal development of central rhythm generation.

Area of Science:

• Neuroscience
• Developmental Biology
• Respiratory Physiology

Background:

• Foetal breathing in mice originates from two coupled hindbrain oscillators: the pre-Bötzinger complex (preBötC) and the parafacial respiratory group (e-pF).
• These oscillators are critical for respiratory rhythm generation post-birth.

Purpose of the Study:

• To investigate the role of specific transcription factors in the development of prenatal respiratory oscillators.
• To understand the consequences of mis-specifying these neural progenitors on respiratory function.

Main Methods:

• Analysis of transcription factor roles (Hoxa1, Egr2, Phox2b, Lbx1, Atoh1, Dbx1, Evx1, Robo3) in neural progenitor specification.
• Examination of breathing patterns following gene inactivation in mouse models.

Main Results:

• Inactivation of key transcription factors leads to mis-specified neurons and distinct breathing defects, including apnea and loss of chemosensitivity (e-pF) or complete breathing loss (preBötC).
• Robo3 mutants exhibit desynchronized breathing, while pontine region mutations alter inspiratory drive shape but not rhythm.
• Primordial embryonic oscillators, active early in development, are silenced in foetuses to prevent interference with the respiratory rhythm.

Conclusions:

• The functional organization of the respiratory generator is established early in development.
• Evidence supports a dual-oscillator model for respiratory control, comprising two serially non-homologous oscillators specified during early development.