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Date of Award
5-2025
Document Type
Restricted Thesis: Campus only access
Degree Name
Bachelor of Science
Department
Biology
First Advisor
Dr. Kelly G. Lambert
Second Advisor
Dr. Colleen Carpenter-Swanson
Abstract
Although 95% of all preclinical animals in biomedical research are laboratory rodents (Hickman et al., 2016), little is known about how selectively bred laboratory Rattus norvegicus compared to their wild counterparts. Neurophysiologist Curt Richter reported hypertrophied adrenal glands in wild rats compared to laboratory rats around 76 years ago, suggesting increased stress responsivity in the wild rodents (Richter, 1949). Given elevated threats in natural environments compared to laboratories, the current study aims to compare cellular profiles in brain areas associated with vigilance and adaptive responses in wild and lab rats. To explore this question, urban-wild and rural-wild rats (Rattus norvegicus) of both sexes were trapped and compared to sex and weight-matched laboratory rats. Microglial activation was examined using immunolabeling for Iba1 in the hippocampus (CA1, CA2, CA3, and dentate gyrus/DG) to assess stress responses and immune function. Astroglia activation was also assessed using glial fibrillary acidic protein (GFAP) immunofluorescence in the same regions of the hippocampus. A significant main effect for habitat context in various hippocampus regions, including increased percentage area of microglial spread in CA2, CA3, and DG, as well as increased astrocyte activation in the CA3 and DG as revealed by two-way ANOVAs (p< 0.05 for all), with wild rats having significantly higher measures than labs. Significant main effects were also seen for habitat in number of myelin-like projections observed in GFAP stained CA1 and CA2, as revealed by a two-way ANOVA (p< 0.05), with lab rats having higher numbers of projections than lab rats. With these results, and additional forthcoming data regarding microglial morphologies and corticosterone-binding globulin, the differences in the neurobiology of wild-trapped and laboratory-raised rats appear distinct. Further research is necessary to determine the association of these neural characteristics on adaptive responses in animals living in natural, complex habitats.
Recommended Citation
Narayanan, Aditya, "Surveying the Neural Cellular Landscape in Wild and Laboratory Rats: Neuronal and Glial Profiles" (2025). Honors Theses. 1845.
https://scholarship.richmond.edu/honors-theses/1845
