The expiration reflex during ontogenesis in the rat

Area of Science:

• * Physiology
• * Neonatal Physiology
• * Respiratory Physiology

Background:

• * Respiratory reflexes are vital for protecting the airways and maintaining breathing.
• * Understanding the developmental trajectory of these reflexes is essential for neonatal care and aging research.

Purpose of the Study:

• * To investigate the developmental changes in the elicitability and characteristics of the expiration reflex, aspiration reflex, and tracheobronchial respiratory reaction in rats.
• * To compare these reflexes across different age groups: neonatal (1-15 days), adult, and biologically old rats.

Main Methods:

• * 131 anesthetized rats of varying ages (neonatal, adult, old) were used.
• * The elicitability and intensity of expiration reflex, aspiration reflex, and respiratory reaction from the tracheobronchial area were assessed.

Main Results:

• * The expiration reflex is reliably elicited from the first day of life in rats, preceding the stabilization of other respiratory reflexes.
• * Young rats exhibited a cough reaction following the expiration reflex, which was absent in adults.
• * In biologically old rats, the expiration reflex showed reduced frequency and intensity compared to adults, while aspiration and bronchial reflexes were less easily elicited but capable of greater expiratory effort.

Conclusions:

• * The expiration reflex is a primary respiratory protective mechanism in early postnatal life for rats.
• * Respiratory reflexes undergo significant changes with age, with diminished efficacy in older animals.
• * The findings highlight the importance of the expiration reflex during the critical early postnatal period in rats.