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A Structured Approach to Extubation in Mechanically Ventilated Rats
Published on: July 18, 2025
Gender considerations in ventilatory and metabolic development in rats: special emphasis on the critical period
Qiuli Liu1, Margaret T T Wong-Riley
1Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
Insights
Both male and female rats show similar developmental trends in respiratory and metabolic responses to hypoxia. A critical period for weakened responses exists in both genders during early development.
Area of Science:
- Physiology
- Developmental Biology
- Comparative Medicine
Background:
- A critical developmental period (postnatal days 12-13) in rats is characterized by a weakened ventilatory and metabolic response to hypoxia.
- It was previously unknown if this critical period affects male and female rats differently.
Purpose of the Study:
- To investigate sex-based differences in developmental trends of ventilatory and metabolic responses to hypoxia.
- To determine if the critical period of weakened hypoxic response occurs in one or both sexes in rats.
Main Methods:
- Large-scale, in-depth study of ventilatory and metabolic rates in male and female rats.
- Measurements conducted under normoxia and acute hypoxia across the first three postnatal weeks (P0-P21).
Main Results:
- Ventilatory and metabolic rates were comparable between sexes under both normoxia and hypoxia from P0 to P21.
- Age significantly impacted all measured parameters in both sexes.
- Both male and female rats demonstrated a significantly weakened response to acute hypoxia during the identified critical period.
Conclusions:
- Male and female rats exhibit comparable developmental trajectories in their physiological responses to hypoxia.
- The critical period of heightened vulnerability to hypoxia is present in both male and female rats.
- These findings highlight conserved developmental patterns in respiratory and metabolic regulation between sexes in rats.
Abstract:
In rats, a critical period exists around postnatal day (P) 12-13, when an imbalance between heightened inhibition and suppressed excitation led to a weakened ventilatory and metabolic response to acute hypoxia. An open question was whether the two genders follow the same or different developmental trends throughout the first 3 postnatal weeks and whether the critical period exists in one or both genders. The present large-scale, in-depth ventilatory and metabolic study was undertaken to address this question. Our data indicated that: (1) the ventilatory and metabolic rates in both normoxia and acute hypoxia were comparable between the two genders from P0 to P21; thus, gender was never significant as a main effect; and (2) the age effect was highly significant in all parameters studies for both genders, and both genders exhibited a significantly weakened response to acute hypoxia during the critical period. Thus, the two genders have comparable developmental trends, and the critical period exists in both genders in rats.
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