Repeated Inflammation-Related Pain Syndrome in Neonatal Male Rats Alters Adaptive Behavior during the Adolescent Period of Development

Abstract

We report here our studies on the effects of repeated inflammation-related pain syndrome in in neonatal male rat pups aged one and two days on the characteristics of adaptive behavior in the formalin test, elevated plus maze test, and forced swimming test, as well as in the Morris water maze, when the animals reached the age of 25 days. These experiments yielded new data providing evidence of increases in the functional activity of the tonic nociceptive system, increases in the tendency to depression-like behavior, and deterioration of spatial learning. Of particular importance is the fact that short-lived (60 min) repeated maternal deprivation of neonatal rats (a stressor) without the pain factor induced by inflammatory foci led to changes in adaptive behavior in 25-day-old animals. Assessment of pain responses organized at different levels of the central nervous system in the formalin test allowed the sequelae of the early effects of pain and stress on the behavioral measures studied to be discriminated.