Background: Feeding intolerance is commonly documented in premature infants. Caffeine is routinely utilized for apnea of prematurity treatment and known to reduce the lower esophageal sphincter (LES) muscle tone, but the caffeine effect on the newborn gastrointestinal function is unknown. We hypothesized that caffeine impairs esophageal and gastrointestinal motor function. As such, we investigated the drug effect on the tissue's mechanical properties and the newborn rat's in vivo gastric emptying rate.
Methods: The effects of caffeine on LES, gastric fundal and antrum, as well as ileal and colonic muscle force potential and relaxation response, were measured in newborn and adult rats. The caffeine-induced (10 mg/kg i.p.) newborn gastric emptying rate changes were evaluated following 3 h of fasting.
Results: Caffeine relaxed the precontracted LES and fundal muscle (P < 0.01), reduced the gastric and intestinal muscle contraction (P < 0.01), and delayed the pups' gastric emptying time (P < 0.01). The caffeine-induced muscle relaxant effect was independent of age and mediated via ryanodine receptors.
Conclusion: Caffeine administration to newborn rats at a dose comparable to the one therapeutically used for preterm neonates impairs LES and gastrointestinal motor function. Further clinical investigation on the possible contribution of caffeine to neonatal feeding intolerance is warranted.