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Fever in pregnant, parturient, and lactating rats
S M Martin1, T J Malkinson, W L Veale
1Neuroscience Research Group, Faculty of Medicine, University of Calgary, Alberta, Canada.
The American Journal of Physiology
|April 1, 1995
Summary
Pregnant rats exhibit suppressed fever responses to Escherichia coli endotoxin around parturition, experiencing hypothermia and increased mortality. This indicates a critical period of altered immune response during childbirth.
Area of Science:
- Physiology
- Immunology
- Reproductive Biology
Background:
- Fever is a common immune response to bacterial endotoxins.
- The physiological state of pregnancy and parturition may influence immune system reactivity.
Purpose of the Study:
- To investigate the febrile and toxic responses of rats to Escherichia coli endotoxin during different reproductive states (virgin, pregnant, lactating).
- To determine if parturition affects the fever response to endotoxin.
Main Methods:
- Conscious virgin, pregnant, and lactating rats were administered intravenous Escherichia coli endotoxin.
- Body temperatures were monitored telemetrically.
- Responses were compared across different reproductive stages and time points relative to parturition.
Main Results:
- Virgin rats showed hypothermia followed by fever.
- Pregnant rats exhibited reduced fevers between 96 hours before and 24 hours after parturition.
- In the 24 hours before parturition, rats became hypothermic and mortality increased significantly upon endotoxin administration.
Conclusions:
- A suppression of fever response to endotoxin occurs in rats around the time of delivery.
- Parturition is associated with increased susceptibility to toxic effects of endotoxin, including hypothermia and mortality.
- These findings highlight a critical period of altered immune regulation during childbirth in rats.