CHANGES IN AMBIENT TEMPERATURE TRIGGER YAWNING BUT NOT STRETCHING IN RATS

Area of Science:

• Comparative physiology
• Animal behavior
• Thermoregulation

Background:

• Yawning is linked to arousal, state change, and vigilance.
• The thermoregulatory hypothesis suggests yawning aids cerebral cooling for optimal brain function.

Purpose of the Study:

• To investigate the relationship between yawning, state change, and thermoregulation in rats.
• To determine if ambient temperature influences yawning frequency and locomotor activity.

Main Methods:

• 12 Sprague-Dawley rats were exposed to controlled ambient temperature manipulations (22°C to 32°C and vice versa) over 48 hours.
• Yawning, stretching, and locomotor activity were recorded during periods of increasing, decreasing, and constant temperatures.
• A repeated measures design was employed to analyze individual rat responses.

Main Results:

• Yawning and locomotor activity peaked during initial temperature shifts, regardless of direction.
• Yawning rates were lower at constant high temperatures (32°C) compared to low temperatures (22°C).
• Stretching behavior was not significantly affected by ambient temperature variations.

Conclusions:

• Findings support the thermoregulatory hypothesis of yawning, particularly its role in arousal and state changes.
• Yawning appears crucial for adapting to environmental thermal challenges and maintaining optimal physiological states.
• Results align with comparative studies in other vertebrates, like budgerigars, highlighting conserved functions of yawning.