The effects of neonatal procedural pain and maternal isolation on hippocampal cell proliferation and reelin concentration in neonatal and adult male and female rats

Abstract

Preterm births accounted for over 10% of all U.S. live births in 2019 and the rate is rising. Neonatal stressors, especially procedural pain, experienced by preterm infants in the neonatal intensive care unit (NICU) have been associated with neurodevelopmental impairments. Parental care can alleviate stress during stressful or painful procedures; however, infants in the NICU often receive reduced parental care compared with their peers. Animal studies suggest that decreased maternal care similarly impairs neurodevelopment but also influences the effects of neonatal pain. It is important to mimic both stressors in animal models of neonatal stress exposure. In this study, researchers investigated the individual and combined impact of neonatal pain and maternal isolation on reelin protein levels and cellular proliferation in the hippocampal dentate gyrus of 8 days old and adult rats. Exposure to either stressor individually, but not both, increased reelin levels in the dentate gyrus of adult females without significantly altering reelin levels in adult males. However, cell proliferation levels at either age were unaffected by the early-life stressors. These results suggest that each earlylife stressor has a unique effect on markers of brain development and more research is needed to further investigate their distinct influences.

Alleviating Neonatal Intensive Care Unit Stress: A Chinese Medicine Approach in Neonatal Rats

“…Because their organs are not fully developed, most of these neonates must stay in the NICU for several weeks [3]. Although advances in the NICU care have markedly improved the survival rate of premature infants, they are exposed to various NICU stressors, such as high levels of sound and light, repeated pain stimuli, and maternal separation, during a crucial stage for brain development, resulting in unfavorable outcomes [4][5][6]. These stressors have profoundly influence pain sensi-tivity and emotional, cognitive, and behavioral development as well as the programming of hypothalamic-pituitaryadrenal (HPA) axis [4,[7][8][9][10][11][12][13].…”