A cholecystokinin receptor antagonist blocks milk-induced but not maternal-contact-induced decrease of ultrasonic...

Area of Science:

• Neuroscience
• Behavioral Biology
• Developmental Psychology

Background:

• Separation distress in infant mammals is characterized by ultrasonic vocalizations (USV).
• Cholecystokinin (CCK) is a neuropeptide implicated in various physiological and behavioral processes, including feeding and stress responses.
• Previous research suggests CCK may play a role in modulating infant distress behaviors.

Purpose of the Study:

• To investigate the specific role of cholecystokinin (CCK) in reducing separation-induced ultrasonic vocalizations (USV) in rat pups.
• To differentiate the effects of CCK on milk-induced versus dam-induced quieting.

Main Methods:

• 10-11-day-old rat pups were isolated and their USV rates measured.
• The selective CCK(A) receptor antagonist devazepide was administered peripherally.
• USV rates were assessed following exposure to milk-scented paper or contact with an anesthetized dam.

Main Results:

• Devazepide administration blocked the reduction in USV typically observed when pups were exposed to milk.
• Devazepide did not affect feeding behavior.
• Devazepide did not alter the quieting effect of contact with the dam on USV.
• Opiate antagonist naltrexone's effects were also considered in comparison.

Conclusions:

• Cholecystokinin (CCK) specifically mediates the quieting of ultrasonic vocalizations (USV) induced by milk cues.
• CCK does not appear to mediate USV reduction caused by the presence of the dam.
• These findings suggest that CCK is part of a pathway for milk-induced calming, distinct from dam-induced calming, which may involve redundant pathways including opioids.