A parabrachial-hypothalamic parallel circuit governs cold defense in mice

Area of Science:

• Neuroscience
• Physiology
• Mammalian thermoregulation

Background:

• Mammalian thermal homeostasis relies on complex brain neurocircuits.
• Neural pathways regulating cold defense are not fully understood.

Purpose of the Study:

• To investigate the neural pathways involved in cold defense regulation.
• To identify novel circuits contributing to thermoregulation.

Main Methods:

• Utilized optogenetic and chemogenetic techniques in mice.
• Investigated neural pathways from the lateral parabrachial nucleus (LPB) to the dorsomedial hypothalamus (DMH).
• Examined the role of somatostatin neurons in cold defense.

Main Results:

• Identified a parallel LPB→DMH pathway crucial for cold defense.
• Activation of this pathway significantly increased thermogenesis in brown adipose tissue (BAT), muscle shivering, heart rate, and locomotion.
• Somatostatin neurons in the LPB targeting the DMH were found to promote BAT thermogenesis.

Conclusions:

• Revealed a parallel neural circuit governing cold defense in mice.
• This circuit contributes equally and cumulatively with the canonical LPB→POA pathway.
• The findings reshape understanding of neural circuit regulation of homeostatic behaviors and hypothermia resilience.