The endocannabinoid system controls food intake via olfactory processes.

Area of Science:

• Neuroscience
• Olfactory System
• Appetite Regulation

Background:

• Hunger increases sensory perception and food intake, but the mechanisms are unclear.
• Cannabinoid type-1 (CB1) receptors are implicated in appetite regulation.

Purpose of the Study:

• To investigate the role of CB1 receptors in mediating hunger-induced increases in food intake.
• To elucidate the neural circuits through which CB1 receptors influence olfactory perception and feeding behavior.

Main Methods:

• Utilized fasted mice models.
• Employed local pharmacological and genetic manipulations.
• Investigated CB1 receptor expression on specific neuronal populations.
• Performed in vivo optogenetic stimulation and cannabinoid agonist administration.

Main Results:

• CB1 receptors were found on glutamatergic neurons projecting from the cortex to the main olfactory bulb (MOB).
• Endocannabinoids and cannabinoids increased odor detection and food intake in fasted mice.
• This effect was mediated by a decrease in excitatory drive from olfactory cortex to the MOB.
• Cannabinoid agonists reduced optogenetically stimulated excitatory transmission in this circuit.

Conclusions:

• Cortical feedback projections to the MOB are critical for regulating food intake.
• CB1 receptor signaling in these projections links hunger states to enhanced odor processing.
• This pathway demonstrates how internal states influence sensory perception and behavior via olfactory circuits.