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The expiration reflex during ontogenesis in the rat
Insights
The expiration reflex is crucial in newborn rats, developing before other respiratory reflexes. This reflex diminishes in intensity and frequency in older rats.
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.
Abstract:
The authors studied the elicitability of the expiration and aspiration reflex and of the respiratory reaction from the tracheobronchial area in 131 anaesthetized rats (aged 1-15 days, adult and biologically old). They found that the expiration reflex could be elicited, in the rat, from the first day of life, at a time when other respiratory reflexes were not yet stable. In young rats, the expiration reflex was often followed by a cough reaction which was absent in adult animals. The findings indicate that the expiration reflex is one of the most important respiratory reflexes of the early postnatal period in the rat, because the aspiration reflex and the respiratory reaction from the bronchi were not stable until the 15th day of life. In biological old rats, the expiration reflex is less frequently elicited and its intensity attains about half the value found in adult animals. The aspiration reflex and the respiratory reaction from the bronchi are likewise less readily elicited than in adult animals, but when the intensity of their maximum expiratory effort is increased, it is far greater.