A brainstem peptide system activated at birth protects postnatal breathing

Area of Science:

• Neuroscience
• Respiratory Physiology
• Developmental Biology

Background:

• Breathing regulation is fragile in early development.
• The neural mechanisms supporting the first breath are not fully understood.
• The transition to extrauterine life presents significant respiratory challenges.

Purpose of the Study:

• To identify neural systems regulating breathing at birth.
• To investigate the role of neuropeptides in neonatal respiratory control.
• To elucidate the molecular mechanisms of respiratory adjustment after birth.

Main Methods:

• Utilized genetically modified mice lacking specific neuropeptide systems.
• Investigated the function of pituitary adenylate cyclase-activating polypeptide (PACAP) in retrotrapezoid nucleus (RTN) neurons.
• Examined the impact of PACAP and its receptor (PAC1) on respiratory activity and CO2 stimulation.

Main Results:

• Mice lacking PACAP in RTN neurons exhibited increased apneas and reduced CO2-stimulated breathing.
• Deletion of the PACAP receptor PAC1 in the pre-Bötzinger complex mimicked these respiratory deficits.
• A specific postnatal surge of PACAP expression in RTN neurons was observed at birth, correlating with environmental exposure.

Conclusions:

• Well-timed PACAP expression in RTN neurons provides essential respiratory drive post-birth.
• PACAP acts via its receptor PAC1 in the pre-Bötzinger complex to support breathing.
• This peptidergic neural circuit is vital for respiratory stability during the vulnerable neonatal period.