Isoflurane potency in mice from the first and second parity.

Area of Science:

• Anesthesiology
• Pharmacology
• Genetics

Background:

• Investigating anesthetic mechanisms often involves selective breeding of animal models.
• Mice are ideal for this research due to their genetic background and reproductive cycle.
• However, the stability of anesthetic potency across successive litters has not been established.

Purpose of the Study:

• To determine if isoflurane anesthetic potency is consistent between successive litters from the same parent mice.
• To assess the viability of using offspring from second litters for anesthesia research and stock conservation.

Main Methods:

• 24 outbred ICR mice (12 male, 12 female) were mated to produce two successive litters.
• Reproductive parameters (litter size, sex ratio, mortality) were recorded.
• Median effective dose (ED50) of isoflurane was measured in offspring (65-75 days old) using loss of righting reflex.

Main Results:

• No significant differences were observed in reproductive parameters between the two litters.
• Isoflurane ED50 values did not differ significantly between offspring from the first and second litters.
• These findings support the reliability of using successive litters.

Conclusions:

• Offspring from the second litter exhibit similar isoflurane sensitivity to those from the first litter.
• This validates the use of second litters for maintaining mouse stocks and conducting anesthesia research.
• Consistent anesthetic potency across litters simplifies breeding strategies in genetic studies.