Experimental allergic encephalomyelitis in adult DA rats subjected to neonatal handling or gentling

The present study investigated the effect of daily handling and gentling between postnatal days 1 and 28 on experimental allergic encephalomyelitis (EAE) in 8-week old DA rats. Handling consisted of removing pups from the mother, and placing them in the novel cage for 15 min. The gentling procedure included handling accompanied by 3 min of dorsal tactile stimulation before returning the pups to the nest cage. Adult rats of both sexes handled in infancy showed increased susceptibility to EAE, as revealed by higher incidence of the disease, and more severe clinical signs. Anti-myelin basic protein (MBP) autoantibodies were increased in handled males, and decreased in handled females, compared to controls. Gentling induced aggravation of clinical signs and histopathological lesions of EAE in males, while in gentled females suppression was observed. These results indicated that both neonatal handling and gentling aggravated EAE induced in adult male rats. In female rats handling exacerbated, and gentling suppressed clinical EAE. The overall effect of neonatal manipulations was more pronounced in males. Furthermore, in mothers separated from their offspring due to handling and gentling, and immunized for EAE at day 28 postpartum, earlier appearance of clinical signs, and increased frequency of relapses compared to control dams was recorded.