MOTHERS AND THEIR INFANTS - PEPTIDE-MEDIATED PHYSIOLOGICAL, BEHAVIORAL AND AFFECTIVE CHANGES DURING SUCKLING

Milk delivery through suckling lowers human newborn heart and metaboli c rates. In rat and human infants pain threshold is markedly elevated and crying is arrested. These changes are induced by milli flavor or s ugar taste which release central endorphins. In rats the changes are n aloxone reversible; human infants born to women who were maintained on methadone during pregnancy were not quieted by sweet taste. Cholecyst okinin (CCK) released during milk absorption quiets infant rats as doe s beta-casomorphine derived from casein hydrolysis. Through opioid and CCK mediation, milk also causes affective change that facilitates inf ant-mother bonding.