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A CCK(A)-receptor antagonist administered to the neonate alters mother-infant interactions in the rat
The importance of the infant's cholecystokinin (CCK) system for eliciting optimal maternal care was examined in 6-9-day-old Sprague-Dawley rats. After administration of either vehicle, CCK-8 (1 or 8 microg/kg) or devazepide (1 mg/kg; a selective CCK(A) receptor antagonist), pups were either individually isolated (Experiment 1) or individually reunited with their dam (Experiment 2) and the rats' behavior was observed. When isolated, pups that received devazepide displayed significantly more head-lifting and wall-climbing attempts than vehicle-treated controls, suggesting that endogenous CCK dampens activity. Devazepide-treated rats were found more frequently in proximity with their mothers when reunited with them, and they emitted more ultrasonic vocalizations compared to vehicle controls. Pups treated with 1 microg/kg CCK received less body licking than vehicle controls. In addition, dams hovered and crouched over devazepide-treated pups more than over pups treated with 1 microg/kg CCK. The results suggest that endogenous CCK has a calming, quieting effect in the neonatal pup and that this, in turn, results in less infant-mother attractivity and reduced levels of maternal care.
The importance of the infant's cholecystokinin (CCK) system for eliciting optimal maternal care was examined in 6-9-day-old Sprague-Dawley rats. After administration of either vehicle, CCK-8 (1 or 8 microg/kg) or devazepide (1 mg/kg; a selective CCK(A) receptor antagonist), pups were either individually isolated (Experiment 1) or individually reunited with their dam (Experiment 2) and the rats' behavior was observed. When isolated, pups that received devazepide displayed significantly more head-lifting and wall-climbing attempts than vehicle-treated controls, suggesting that endogenous CCK dampens activity. Devazepide-treated rats were found more frequently in proximity with their mothers when reunited with them, and they emitted more ultrasonic vocalizations compared to vehicle controls. Pups treated with 1 microg/kg CCK received less body licking than vehicle controls. In addition, dams hovered and crouched over devazepide-treated pups more than over pups treated with 1 microg/kg CCK. The results suggest that endogenous CCK has a calming, quieting effect in the neonatal pup and that this, in turn, results in less infant-mother attractivity and reduced levels of maternal care.