title: Long-term maternal separation differentially alters serum corticosterone levels and blood neutrophil activity in A/J and C57BL/6 mouse offspring.
abstract: OBJECTIVE
  In this work, we searched for maternal separation effects on serum corticosterone levels and blood neutrophil activity in adult male A/J and C57BL/6 mouse offspring.
  
  
  METHODS
  40 male A/J mice and 40 male C57BL/6 mice were divided within each strain into two groups. Mice in the maternal separation group were separated from their mothers (1 h/day) on postnatal days 0-13. Mice in the control group were left undisturbed. On postnatal day 45, blood was drawn from all mice and used to assess neutrophil activity by flow cytometry and serum corticosterone levels by radioimmunoassay.
  
  
  RESULTS
  The results showed that each mouse strain responded differently to maternal separation, but in both cases, serum corticosterone levels were affected. In both strains, adult mice that experienced maternal separation showed lower serum corticosterone levels than control mice. In relation to control mice kept together with their mothers, the levels of serum corticosterone were 72.7 and 36.36% lower in A/J and C57BL/6 mice submitted to maternal separation, respectively. The current findings showed that maternal separation increased neutrophil activity in mice after reaching adulthood. The observed effects, although in the same direction, differed between A/J and C57BL/6 mice. Maternal separation increased both the percentage and intensity of phagocytosis in C57BL/6 mice, but had no effects on A/J mice. Furthermore, maternal separation increased basal and propidium iodide-labeled Staphylococcus aureus-induced oxidative burst in A/J mice but did not affect oxidative burst in C57BL/6 mice. Finally, phorbol myristate acetate-induced oxidative burst increased in both strains.
  
  
  CONCLUSIONS
  These results indicate that early maternal separation increases innate immunity, most likely by modifying hypothalamus-pituitary-adrenal axis activity. This suggests that maternal separation is a good model for stress which produces long-term neuroimmune changes whatever the animal species and strain used.
authors.affiliation: Laboratory of Neuroimmunomodulation, Department of Pathology, School of Veterinary Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Milena Lobão
authors.initials: ML
authors.lastname: Pinheiro
authors.forename: Viviane
authors.initials: V
authors.lastname: Ferraz-de-Paula
authors.forename: Alison
authors.initials: A
authors.lastname: Ribeiro
authors.forename: Monica
authors.initials: M
authors.lastname: Sakai
authors.forename: Maria Martha
authors.initials: MM
authors.lastname: Bernardi
authors.forename: João
authors.initials: J
authors.lastname: Palermo-Neto
mesh_terms: D000818:Animals; D002908:Chronic Disease; D003345:Corticosterone / Q000097:blood*; D004195:Disease Models, Animal; D005260:Female; D007108:Immune Tolerance / Q000276:immunology*; D008297:Male; D008426:Maternal Deprivation; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D015213:Neuroimmunomodulation / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D013045:Species Specificity; D013315:Stress, Psychological / Q000097:blood* / Q000276:immunology / Q000473:pathology*; D013995:Time
chemical_list: D003345:Corticosterone