Enriched environment rescues neonatal pain induced cognitive deficits and the impaired hippocampal synaptic plasticity later in life
Cuiting Min, Ru Ling, Mengying Chen, Dongqing Xia, Ran Chen, Xiao‐Nan Li
Abstract
Although extensive and untreated pain that occurs during a critical developmental window may impair cognition later in life, environmental interventions early in life might promote cognition. However, the underlying mechanism is poorly understood. Our current study utilized a rat model of "repetitive needle pricks" from the day of birth (P0) to postnatal day 7 (P7) to mimic the painful experience of preterm neonates in the neonatal intensive care unit. Enriched environment (EE) during development period (from P15 to P70) was implemented as a nonpharmacological intervention approach. Electrophysiological recording, behavioral tests, and biochemical analysis were performed after the end of EE (between P71 and P80). The results showed neonatal repetitive pain resulted in a reduction in mechanical withdrawal thresholds by the von Frey test in P70 (p < .001). Furthermore, neonatal repetitive pain impaired spatial learning and memory (p < .05) and even led to dysfunction in fear memory (p < .01). In contrast, EE rescued neonatal pain-induced cognitive deficits and normalized hippocampal long-term potentiation in rats exposed to neonatal pain (p << .05). The beneficial effect of EE might be the improvements in hippocampal synaptic plasticity via upregulating neurotrophic factors and N-methyl-d-aspartate (NMDA) receptors in the hippocampus. Our findings provide evidence that early environmental intervention might be a safe strategy to overcome neurodevelopmental abnormalities in preterm infants who experienced multiple procedural painful events during the early critical period.