Dose-dependent interaction between cholecystokinin and sham feeding.

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Physiology

Background:

• Previous research suggests cholecystokinin octapeptide (CCK-8) synergizes with feeding signals to decrease feeding motivation.
• The specific contribution of oral signals to this CCK-8 interaction remains unclear.

Purpose of the Study:

• To investigate the role of oral signals in CCK-8-induced feeding inhibition using a runway paradigm in rats.
• To differentiate the effects of oral stimulation from post-oral signals in CCK-8's action.

Main Methods:

• Rats were tested on a runway to measure performance after administration of CCK-8.
• Sham feeding (oral stimulation without ingestion) and normal prefeeding were used to isolate the effects of oral signals.
• Varying doses of CCK-8 (1, 2, and 4 µg/kg) were combined with sham feeding intervals.

Main Results:

• A low dose of CCK-8 (1 µg/kg) combined with sham feeding did not impair runway performance more than CCK-8 alone.
• Higher doses of CCK-8 (2 and 4 µg/kg) combined with sham feeding significantly reduced running speed.
• These results indicate that while oral signals contribute, signals distal to the oropharynx are also involved in CCK-8's inhibitory effects.

Conclusions:

• Synergy between CCK-8 and oral signals contributes to CCK-8's feeding inhibitory effects.
• The potentiation of CCK-8's effects requires signals beyond the oral cavity, suggesting a role for post-ingestive signals.