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Abstract

Background: In the neonatal intensive care unit, preterm infants experience 7-17 clinically required but painful procedures daily. Oral sucrose is the standard treatment for minor procedural pain, but the combined short-term cumulative effects of sucrose treatment for pain on brain development are unknown. Using a neonatal mouse paradigm, previous studies found that during the 1st week of life, repeated pain and/or sucrose exposure impaired short-term memory and reduced regional and white matter structure volumes in adulthood, including the corpus callosum, fimbria, and the hippocampus. The objective of this study was to determine whether repeated neonatal pain and/or sucrose exposure altered pro/anti-inflammatory markers, specifically IL-1β, IL-6, and TNF-α, in hippocampal tissue and serum of 8-day old mouse pups. Hippocampal microglial density of male mouse pups was also examined. Methodology: Using a previously established neonatal mouse paradigm, neonatal mice were randomly assigned to receive water or 24% oral sucrose prior to being handled or needle-pricked, 10X/day from postnatal day (P) 1-6. Blood and hippocampal tissue were collected at P8 and assayed for various cytokines (e.g. IL-1β, IL-6, and TNF-α). In addition to cytokine levels, microglial density was assessed in the hippocampus of P8 male mice. Results: Although no sex effects were evident, a significant group effect was found for several inflammatory cytokines. Hippocampal IL-10 levels were significantly lower in sucrose + handling (p