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Mode of ACTH antipyretic action
1Department of Physiology and Developmental Biology, Faculty of Science, Charles University, Prague, Czechoslovakia.
Brain Research Bulletin
|October 1, 1988
Summary
Adrenocorticotropic hormone (ACTH) administered centrally during fever in rabbits lowers the threshold for cold thermogenesis. This suggests ACTH may help terminate fever by reducing heat production.
Area of Science:
- Neuroendocrinology
- Physiology
- Thermoregulation
Background:
- The role of centrally administered Adrenocorticotropic hormone (ACTH) in fever regulation is not fully understood.
- Hypothalamic centers control thermoregulatory outputs like cold thermogenesis (CT), peripheral vasomotor tone (PVMT), and respiratory evaporative heat loss (REHL).
Purpose of the Study:
- To investigate the effects of centrally administered ACTH on hypothalamic thermoregulatory centers during normal and febrile states in rabbits.
- To analyze ACTH's impact on cold thermogenesis, peripheral vasomotor tone, and respiratory evaporative heat loss.
Main Methods:
- Intestinal cooling method used to monitor thermoregulatory responses.
- ACTH administered into the supraoptic area of the anterior hypothalamus in rabbits.
- Fever induced by intravenous injection of exogenous pyrogen (endotoxin).
Main Results:
- Central ACTH had no significant effect on body temperature control in normal rabbits.
- During early fever, ACTH lowered the temperature threshold for cold thermogenesis and reduced its sensitivity and maximal output.
- During late fever, ACTH's effects were less pronounced, with minimal changes in cold thermogenesis threshold and sensitivity.
Conclusions:
- Central ACTH administration alters thermoregulatory responses during fever, primarily by reducing cold defense mechanisms.
- The observed effects of ACTH in febrile rabbits resemble natural fever-termination processes.
- Increased ACTH production during fever may act as a negative feedback to help resolve the febrile state.