Infralimbic cortex controls core body temperature in a histamine dependent manner

Area of Science:

• Neuroscience
• Physiology
• Behavioral Science

Background:

• Body temperature influences biochemical reactions and physiological responses.
• The prefrontal cortex, specifically the infralimbic cortex, is linked to motivated behavior organization.
• Histamine levels increase with infralimbic cortex disinhibition, suggesting a role in arousal.

Purpose of the Study:

• To investigate if infralimbic cortex activation triggers a thermogenic mechanism during motivated behavior.
• To determine the role of histaminergic pathways in infralimbic cortex-induced arousal and temperature increase.
• To explore the involvement of sympathetic pathways in this thermogenic response.

Main Methods:

• Core body temperature and motor activity were measured in rats.
• Pharmacological manipulations included picrotoxin injection (disinhibition) and muscimol (inhibition) in the infralimbic cortex.
• H1 receptor antagonist (pyrilamine) and beta-adrenergic blocker (propranolol) were administered.

Main Results:

• Infralimbic cortex disinhibition and food-enticement increased core temperature and motor activity.
• Pyrilamine blocked thermal and motor responses to enticement, and thermal response to picrotoxin.
• Muscimol abolished both motor and temperature responses to enticement.
• Propranolol reduced temperature increase without affecting motor activity, indicating a non-locomotor-dependent thermogenic mechanism.

Conclusions:

• Infralimbic cortex activation is crucial for initiating appetitive behavior.
• Central histamine mediates motor and vegetative arousal increases, including thermogenesis, during motivated states.
• This suggests an active, histamine-dependent sympathetic thermogenic mechanism regulated by the infralimbic cortex.