Behavioral effects of gut hormones in neonatal rats: II. Cholecystokinin administration during the first postnatal week.
This exploratory study attempted to uncover physical and behavioral consequences of changes in the peripheral cholecystokinin (CCK) system in the first postnatal week. Sprague-Dawley rat pups received s.c. injections of CCK (8 micrograms/kg) or saline, on postnatal days 1-7 (2 times/day). Physical growth and neurobehavioral development of the pups were assessed on days 3, 6, 9 & 12, their social play was assessed on day 35, and the maternal behavior of their dams was assessed on days 9-12. CCK administration was associated with slower maturation of physical characteristics, more rapid reflexive performance on day 9, and increased maternal licking of pups. These findings stress the importance of further examining the impact of CCK and other gut-hormones on physical and behavioral development and on the quality of the mother-infant interaction.