A dissociation between temperature regulation and fever in the rabbit

Area of Science:

• Neuroscience
• Physiology
• Pharmacology

Background:

• 5-hydroxytryptamine (5-HT), a neurotransmitter, plays a role in various physiological processes.
• Its specific function in thermoregulation and fever induction in mammals requires further elucidation.

Purpose of the Study:

• To investigate the role of 5-HT in temperature regulation and fever in rabbits.
• To determine the effects of 5-HT manipulation on body temperature and thermoregulatory responses.

Main Methods:

• Intrahypothalamic microinjections of varying doses of 5-HT in conscious rabbits.
• Administration of p-chlorophenylalanine (PCPA) to deplete brain 5-HT.
• Assessment of body temperature changes under thermoneutral conditions, cold stress, and during pyrogen-induced fever.

Main Results:

• Intrahypothalamic 5-HT altered body temperature in a dose-dependent manner, inducing hyperthermia or a biphasic response.
• PCPA pretreatment impaired thermoregulation during cold stress but did not affect basal body temperature.
• PCPA pretreatment did not impede the febrile response to bacterial pyrogen or prostaglandin E1.

Conclusions:

• 5-HT plays a critical role in thermoregulation, distinct from its role in fever generation.
• The site of 5-HT action in temperature regulation is upstream of fever input pathways but downstream of peripheral and hypothalamic temperature integration.