A hypothalamic circuit for anticipating future changes in energy balance

Area of Science:

• Neuroscience
• Endocrinology
• Metabolism

Background:

• AgRP neurons drive hunger and food seeking, crucial for survival.
• Fasting activates AgRP neurons via low energy feedback, but environmental cues also play a role.
• Environmental cues predicting food intake inhibit AgRP neurons.

Purpose of the Study:

• To investigate if predicting future fasting can rapidly activate AgRP neurons.
• To identify the neural circuits mediating this anticipatory hunger response.
• To understand the role of this circuit in energy balance regulation.

Main Methods:

• Electrophysiological recordings in hypothalamic slices.
• Viral tracing and genetic manipulation in mouse models.
• Behavioral analysis of feeding patterns following neuronal silencing.

Main Results:

• Rapid activation of AgRP neurons upon prediction of future fasting was observed.
• Excitatory input from Sim2-expressing paraventricular hypothalamic (PVH^Sim2) neurons drives this response.
• Chronic silencing of PVH^Sim2 neurons led to persistent hypophagia (reduced appetite).

Conclusions:

• A novel circuit involving PVH^Sim2 neurons rapidly activates AgRP neurons in anticipation of fasting.
• This circuit integrates cognitive and contextual information to regulate hunger.
• The PVH^Sim2-AgRP pathway plays a critical role in preventing negative energy balance and regulating appetite.