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Hart DW, Sherman MA, Kim M, Pelzel R, Brown JL, Lesné SE. Standard diet and animal source influence hippocampal spatial reference learning and memory in congenic C57BL/6J mice. RESEARCH SQUARE 2024:rs.3.rs-4582616. [PMID: 39070656 PMCID: PMC11276007 DOI: 10.21203/rs.3.rs-4582616/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Background Assessing learning and memory has become critical to evaluate brain function in health, aging or neurological disease. The hippocampus is crucially involved in these processes as illustrated by H.M.'s remarkable case and by the well-established early symptoms of Alzheimer's disease. Numerous studies have reported the impact of gut microbiota on hippocampal structure and function using pro-, pre- and antibiotics, diet manipulations, germ-free conditions or fecal transfer. However, most diet manipulations have relied on Western diet paradigms (high fat, high energy, high carbohydrates). Here, we compared the impact of two standard diets, 5K52 and 2918 (6% fat, 18% protein, 3.1kcal/g), and how they influenced hippocampal learning and memory in adult 6-month-old congenic C57BL/6J mice from two sources. Results Using a hippocampal-dependent task, we found that 5K52-fed mice performed consistently better than 2918-fed animals in the Barnes circular maze. These behavioral differences were accompanied with marked changes in microbiota, which correlated with spatial memory retention performance. We next tested whether 2918-induced alterations in behavior and microbiome could be rescued by 5K52 diet for 3 months. Changing the 2918 diet to 5K52 diet mid-life improved spatial learning and memory in mice. Shotgun sequencing and principal component analyses revealed significant differences at both phylum and species levels. Multivariate analyses identified Akkermansia muciniphila or Bacteroidales bacterium M11 and Faecalibaculum rodentium as the strongest correlates to spatial memory retention in mice depending on the animal source. In both settings, the observed behavioral differences only affected hippocampal-dependent performance as mice fed with either diet did similarly well on the non-spatial variant of the Y-maze. Conclusions In summary, these findings demonstrate the diverging effects of seemingly equivalent standard diets on hippocampal memory. Based on these results, we strongly recommend the mandatory inclusion of the diet and source of animals used in rodent behavioral studies.
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Saha P, Weigle IQ, Slimmon N, Poli PB, Patel P, Zhang X, Cao Y, Michalkiewicz J, Gomm A, Zhang C, Tanzi RE, Dylla N, Al-Hendy A, Sisodia SS. Early modulation of the gut microbiome by female sex hormones alters amyloid pathology and microglial function. Sci Rep 2024; 14:1827. [PMID: 38246956 PMCID: PMC10800351 DOI: 10.1038/s41598-024-52246-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 01/16/2024] [Indexed: 01/23/2024] Open
Abstract
It is well-established that women are disproportionately affected by Alzheimer's disease. The mechanisms underlying this sex-specific disparity are not fully understood, but several factors that are often associated-including interactions of sex hormones, genetic factors, and the gut microbiome-likely contribute to the disease's etiology. Here, we have examined the role of sex hormones and the gut microbiome in mediating Aβ amyloidosis and neuroinflammation in APPPS1-21 mice. We report that postnatal gut microbiome perturbation in female APPPS1-21 mice leads to an elevation in levels of circulating estradiol. Early stage ovariectomy (OVX) leads to a reduction of plasma estradiol that is correlated with a significant alteration of gut microbiome composition and reduction in Aβ pathology. On the other hand, supplementation of OVX-treated animals with estradiol restores Aβ burden and influences gut microbiome composition. The reduction of Aβ pathology with OVX is paralleled by diminished levels of plaque-associated microglia that acquire a neurodegenerative phenotype (MGnD-type) while estradiol supplementation of OVX-treated animals leads to a restoration of activated microglia around plaques. In summary, our investigation elucidates the complex interplay between sex-specific hormonal modulations, gut microbiome dynamics, metabolic perturbations, and microglial functionality in the pathogenesis of Alzheimer's disease.
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Affiliation(s)
- Piyali Saha
- Department of Neurobiology, The University of Chicago, Chicago, IL, USA
| | - Ian Q Weigle
- Department of Neurobiology, The University of Chicago, Chicago, IL, USA
| | - Nicholas Slimmon
- School of Biomedical Sciences, UT Southwestern Medical Center, Dallas, TX, USA
| | - Pedro Blauth Poli
- Department of Neurobiology, The University of Chicago, Chicago, IL, USA
| | - Priyam Patel
- Center for Genetic Medicine, Northwestern University, Chicago, IL, USA
| | - Xiaoqiong Zhang
- Department of Neurobiology, The University of Chicago, Chicago, IL, USA
| | - Yajun Cao
- Genomic Facility, The University of Chicago, Chicago, IL, USA
| | - Julia Michalkiewicz
- Department of Physiology and Biophysics, The University of Illinois, Chicago, IL, USA
| | - Ashley Gomm
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Can Zhang
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Rudolph E Tanzi
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Nicholas Dylla
- Duchossois Family Institute, The University of Chicago, Chicago, IL, USA
| | - Ayman Al-Hendy
- Department of Obstetrics and Gynecology, The University of Chicago, Chicago, IL, USA
| | - Sangram S Sisodia
- Department of Neurobiology, The University of Chicago, Chicago, IL, USA.
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Gozalo AS, Elkins WR. A Review of the Effects of Some Extrinsic Factors on Mice Used in Research. Comp Med 2023; 73:413-431. [PMID: 38217072 PMCID: PMC10752364 DOI: 10.30802/aalas-cm-23-000028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/20/2023] [Accepted: 11/15/2023] [Indexed: 01/14/2024]
Abstract
Animals have been used in research for over 2,000 y. From very crude experiments conducted by ancient scholars, animal research, as a science, was refined over hundreds of years to what we know it as today. However, the housing conditions of animals used for research did not improve significantly until less than 100 years ago when guidelines for housing research animals were first published. In addition, it was not until relatively recently that some extrinsic factors were recognized as a research variable, even when animals were housed under recommended guidelines. For example, temperature, humidity, light, noise, vibration, diet, water, caging, bedding, etc., can all potentially affect research using mice, contributing the inability of others to reproduce published findings. Consequently, these external factors should be carefully considered in the design, planning, and execution of animal experiments. In addition, as recommended by others, the housing and husbandry conditions of the animals should be described in detail in publications resulting from animal research to improve study reproducibility. Here, we briefly review some common, and less common, external factors that affect research in one of the most popular animal models, the mouse.
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Affiliation(s)
- Alfonso S Gozalo
- Comparative Medicine Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - William R Elkins
- Comparative Medicine Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
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