Systemic ghrelin and reward: effect of cholinergic blockade

Area of Science:

• Neuroscience
• Endocrinology
• Behavioral Science

Background:

• Ghrelin, a potent orexigen, is implicated in food reward processes.
• Neuronal pathways for ghrelin's energy balance regulation are known, but its role in reward is unclear.

Purpose of the Study:

• To investigate the role of ghrelin receptor (GHSR1a) in food reward seeking behaviors.
• To determine if cholinergic pathways mediate ghrelin's effects on reward.

Main Methods:

• Used conditioned place preference (CPP) in C57BL6J and GHSR1a-null mice.
• Administered mecamylamine to assess cholinergic pathway involvement.

Main Results:

• GHSR1a-null mice did not develop food CPP, indicating receptor necessity.
• Pharmacological ghrelin increased CPP, an effect reduced by mecamylamine.
• Physiological ghrelin increases during caloric restriction enhanced reward-seeking behavior.

Conclusions:

• Ghrelin receptor is obligatory for acquiring food-associated reward.
• Plasma ghrelin levels during conditioning modulate the strength of food reward seeking.
• Cholinergic pathways partially mediate enhanced reward from pharmacological ghrelin, not physiological increases.