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Stress
The International Journal on the Biology of Stress
Volume 14, 2011 - Issue 3
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Research Article

Maternal separation in early life impairs tumor immunity in adulthood in the F344 rat

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Pages 335-343 | Received 07 Sep 2010, Accepted 11 Dec 2010, Published online: 27 Mar 2011
 

Abstract

Neonatal stress alters the hypothalamic–pituitary–adrenal (HPA) axis in rodents, such that, when these animals are exposed to stress as adults they hypersecrete corticosterone. Given that glucocorticoids are immunosuppressive, we examined the impact of maternal separation on HPA axis reactivity, natural killer (NK) cytotoxicity, and tumor growth in Fischer 344 rats following chronic restraint stress in adulthood. Pups underwent a chronic stress protocol whereby they were separated from their dams for 3 h on postnatal days 1–21. In adulthood, corticosterone responses were assessed following exposure to chronic (6 days for 10 h) restraint stress. Rats allocated to the chronic stress condition were inoculated with MADB106 tumor cells on day 4 of the restraint protocol. Blood was assessed for NK cytotoxicity on the final day of the chronic restraint protocol, and tumor colonization was assessed 3 weeks thereafter. Maternal separation impaired developmental weight gain (P < 0.05), depressed NK cytotoxicity (P < 0.05), and increased tumor colonization in the presence of chronic restraint stress in adulthood (P < 0.00 l). These findings occurred independently of circulating plasma corticosterone as only adult stress exposure potentiated corticosterone responses (P < 0.05). Our findings indicate that maternal separation and chronic stress can impair NK cytotoxicity and hence tumor immunity, but these effects are not directly mediated by perturbations in HPA axis function.

Acknowledgements

We would like to thank Eleanor Huber for her assistance in maintaining animal requirements.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

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