Providing height to pullets does not influence hippocampal dendritic morphology or brain-derived neurotrophic factor at the end of the rearing period

Allison N Pullin; Victoria S Farrar; Jason W Loxterkamp; Claire T Jones; Rebecca M Calisi; Kristina Horback; Pamela J Lein; Maja M Makagon

doi:10.1016/j.psj.2022.102161

Providing height to pullets does not influence hippocampal dendritic morphology or brain-derived neurotrophic factor at the end of the rearing period

Poult Sci. 2022 Dec;101(12):102161. doi: 10.1016/j.psj.2022.102161. Epub 2022 Aug 30.

Authors

Allison N Pullin¹, Victoria S Farrar², Jason W Loxterkamp³, Claire T Jones⁴, Rebecca M Calisi², Kristina Horback⁴, Pamela J Lein³, Maja M Makagon⁴

Affiliations

¹ Center for Animal Welfare, Department of Animal Science, University of California, Davis, CA 95616, USA; Animal Behavior Graduate Group, College of Biological Sciences, University of California, Davis, CA 95616, USA. Electronic address: apullin@ncsu.edu.
² Animal Behavior Graduate Group, College of Biological Sciences, University of California, Davis, CA 95616, USA; Department of Neurobiology, Physiology and Behavior, University of California, Davis, CA 95616, USA.
³ Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA.
⁴ Center for Animal Welfare, Department of Animal Science, University of California, Davis, CA 95616, USA; Animal Behavior Graduate Group, College of Biological Sciences, University of California, Davis, CA 95616, USA.

Abstract

Pullets reared with diverse behavioral experiences are faster to learn spatial cognition tasks and acclimate more successfully to laying environments with elevated structures. However, the neural underpinnings of the improved spatial abilities are unclear. The objective of this study was to determine whether providing structural height in the rearing environment affected the development of the hippocampus and whether hippocampal neural metrics correlated with individual behavior on spatial cognition tasks. Female Dekalb White pullets were reared in a floor pen (FL), single-tiered aviary (ST), or two-tiered aviary (TT; 5 pens/treatment). Pullets completed floor-based Y-maze and elevated visual cliff tasks to evaluate depth perception at 15 and 16 wk, respectively. At 16 wk, brains were removed for Golgi-Cox staining (n = 12 for FL, 13 for ST, 13 total pullets for TT; 2 to 3 pullets/pen) and qPCR to measure gene expression of brain-derived neurotrophic factor (BDNF; n = 10 for FL, 11 for ST, and 9 pullets for TT). Rearing environment did not affect various morphometric outcomes of dendritic arborization, including Sholl profiles; mean dendritic length; sum dendritic length; number of dendrites, terminal tips, or nodes; soma size; or BDNF mRNA expression (P > 0.05). Hippocampal subregion did affect dendritic morphology, with multipolar neurons from the ventral subregion differing in several characteristics from multipolar neurons in the dorsomedial or dorsolateral subregions (P < 0.05). Neural metrics did not correlate with individual differences in behavior during the spatial cognition tasks. Overall, providing height during rearing did not affect dendritic morphology or BDNF at 16 wk of age, but other metrics in the hippocampus or other brain regions warrant further investigation. Additionally, other structural or social components or the role of animal personality are areas of future interest for how rearing environments influence pullet behavior.

Keywords: Golgi stain; brain-derived neurotrophic factor; chicken; hippocampus; rearing environment.

MeSH terms

Animals
Brain-Derived Neurotrophic Factor* / genetics
Chickens* / physiology
Female
Hippocampus

Substances

Brain-Derived Neurotrophic Factor

Grants and funding

P30 ES023513/ES/NIEHS NIH HHS/United States