STEAMBOAT SPRINGS, Colorado (July 19, 2005) -- There's littlecontroversy about the benefits of breastfeeding infants over givingthem formula. Mother's milk is the perfect food, providing exactly thecorrect nourishment for newborns, while protecting them from manyillnesses.
There also are good economic and maternal health reasons that wouldseem to make a compelling case for breastfeeding for the six-to-12months recommended by the American Academy of Pediatrics.
"However one major reason why women stop breastfeeding is lowweight gain and growth rate of their baby," Steven L. Bealer of theUniversity of Utah points out. His team of researchers decided to findout what factors might cause low weight gain.
They studied how blocking the oxytocin (OT) hormonal system,which serves several functions in the birth process and milk deliveryduring nursing (lactation), would affect offspring during and afterbirth. They found that if the central OT receptors in the pregnantfemales' brain are blocked during pregnancy, then their offspring'sgrowth was reduced from the third day after birth through the two-weekexperiment.
Interestingly, the actual delivery itself wasn't affected norwas the number of "pups" in each litter. Even the delivery weights ofthe test females' offspring was the same as "control dams" pups'delivery weights.
A blocked OT system reduces post-natal weight gains
However what they did find was that in the mothers with blockedOT systems, the initial release of OT following the onset of pupssuckling was significantly delayed compared to untreated females."Finally, litter weight gain during a three-hour suckling period wassignificantly smaller in pups nursing dams that were treated with OTreceptor blocker during gestation," Bealer reports.
"What we learned is that OT receptor stimulation duringgestation is necessary for normal OT responsiveness and consequentlyfor normal pup development during lactation," Bealer notes. "Moreefficient and longer lasting breastfeeding results in better humanhealth throughout life," he adds, "so if the efficiency of the oxytocinsystem can be improved, perhaps it will encourage mothers to lengthenhow long they breast feed their children."
Bealer is presenting at the American Physiological Society's2005 Conference, "Neurohypophyseal Hormones: From Genomics andPhysiology to Disease," and the latest developments toward clinicalapplications, July 16-20 in Steamboat Springs, Colorado.
He also is participating in the symposium, "Central controllactation," chaired by Bill Armstrong of the University of TennesseeSchool of Medicine, and Glenn Hatton, University of California,Riverside.
"Central oxytocin receptor blockade during gestation alters oxytocinrelease and pup development during lactation." Steven L. Bealer,William R. Crowley, David L. Lipschitz, University of Utah. Funded byU.S. Public Health Service grants.
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