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Unpredictable Chronic Mild Stress Suppresses the Incorporation of New Neurons at the Caudal Pole of the Chicken Hippocampal Formation

Lookup NU author(s): Dr Fabio Gualtieri, Elena Armstrong, Georgia Longmoor, Dr Timothy Boswell, Dr Tom SmuldersORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


In the mammalian brain, adult hippocampal neurogenesis (AHN) is suppressed by chronic stress, primarily at the ventral pole of the hippocampus. Based upon anatomy, we hypothesise that the caudal pole of the avian Hippocampal Formation (HF) presents a homologous subregion. We thus investigated whether AHN is preferentially suppressed in the caudal chicken HF by unpredictable chronic mild stress (UCMS). Adult hens were kept in control conditions or exposed to UCMS for 8 weeks. Hens experiencing UCMS had significantly fewer doublecortin-positive multipolar neurons (p < .001) and beaded axons (p = .021) at the caudal pole of the HF than controls. UCMS birds also had smaller spleens and lower baseline plasma corticosterone levels compared to controls. There were no differences in AHN at the rostral pole, nor were there differences in expression of genetic mediators of the HPA stress response in the pituitary or adrenal glands. Duration of tonic immobility and heterophil/lymphocyte (H/L) ratios were also not responsive to our UCMS treatment. These results support the hypothesised homology of the caudal pole of the avian HF to the ventral pole of the rodent hippocampus. Furthermore, quantifying neurogenesis in the caudal HF post-mortem may provide an objective, integrative measure of welfare in poultry, which may be more sensitive than current welfare measures.

Publication metadata

Author(s): Gualtieri F, Armstrong EA, Longmoor GK, D'Eath RB, Sandilands V, Boswell T, Smulders TV

Publication type: Article

Publication status: Published

Journal: Scientific Reports

Year: 2019

Volume: 9

Online publication date: 09/05/2019

Acceptance date: 25/04/2019

Date deposited: 25/04/2019

ISSN (electronic): 2045-2322

Publisher: Nature Publishing Group


DOI: 10.1038/s41598-019-43584-x


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