Cold-Induced Thermogenesis and Inflammation-Associated Cold-Seeking Behavior Are Represented by Different Dorsomedial...

Area of Science:

• Neuroscience
• Physiology
• Behavioral Science

Background:

• The dorsomedial hypothalamus (DMH) is implicated in thermoregulation, but its precise role in opposing responses like cold defense and inflammation-induced behaviors is unclear.
• Previous studies showed DMH lesions paradoxically affect hypothermia in different contexts, suggesting complex regulatory roles.

Purpose of the Study:

• To elucidate the distinct thermoeffector mechanisms underlying cold-induced hypothermia and LPS-induced cold-seeking behavior.
• To map the specific DMH regions responsible for autonomic cold defense versus inflammation-associated cold-seeking behavior.

Main Methods:

• Inducing electrolytic or thermal lesions in specific DMH regions of rats.
• Exposing rats to cold environments and administering bacterial lipopolysaccharide (LPS) at varying doses.
• Measuring thermogenesis and monitoring behavioral responses (e.g., cold-seeking) in a thermogradient apparatus.

Main Results:

• Large DMH lesions suppressed thermogenesis, impairing cold defense and fever response to low-dose LPS.
• High-dose LPS-induced hypothermia attenuation was linked to suppressed cold-seeking behavior, not thermogenesis changes.
• Functional mapping identified the dorsal hypothalamic area for cold thermogenesis and the ventral DMH border for LPS-induced cold seeking.

Conclusions:

• The DMH contains separate neural substrates for autonomic thermogenesis and inflammation-associated cold-seeking behavior.
• These findings reveal a more complex functional topography of the DMH in thermoregulation and behavioral responses to inflammation.