The effects of bedding materials on learning and memory performance and texture preference in rats

Document Type : Research Articles


1 Faculty of Sciences, Shahid Bahonar University of Kerman

2 shahid bahonar university

3 Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran


The present study was designed to investigate the effect of different available bedding materials on learning and memory performance, bedding texture preference as well as intra-cage ammonia concentration in rats. The animals were housed on different bedding types for two weeks. Bedding materials were produced in the same sizes from poplar, walnut, pistachio, apricot, almond woods and alfalfa steam and live. Spatial and passive avoidance learning and memory were assessed by Morris water maze (MWM) and shuttle box tasks. A modifying six-arm radial maze was used to assess bedding texture preference by rats. For each bedding groups, average ammonia level (ppm) over a week was calculated. The data indicated that the rats that had walnut and almond chips show better learning and memory performance in both MWM and shuttle box tests than other groups. The weakest learning and memory performances were observed in rats exposed to alfalfa bedding. In texture preference test, the rats spent more time in walnut and almond arms, and less time in alfalfa. Besides, the total water and food intake as well as the number of visit to alfalfa arm were decreased as compared to other arms. Moreover, in alfalfa bedding cage, average intra-cage ammonia level was utmost. Overall, current bedding materials may contain diverse biochemically effective compounds or individual micro edges which alter learning and memory performances of rats.


Main Subjects

1. Cui M, Yang Y, Yang J, Zhang J, Han H, Ma W, et al. Enriched environment experience overcomes the memory deficits and depressive-like behavior induced by early life stress. Neuroscience letters. 2006;404(1-2):208-12.
2. Van Praag H, Kempermann G, Gage FH. Neural consequences of enviromental enrichment. Nature Reviews Neuroscience. 2000;1(3):191.
3. Diamond MC, Ingham CA, Johnson RE, Bennett EL, Rosenzweig MR. Effects of environment on morphology of rat cerebral cortex and hippocampus. Journal of neurobiology. 1976;7(1):75-85.
4. Freymann J, Tsai P-P, Stelzer H, Hackbarth H. The impact of bedding volumes on laboratory mice. Applied Animal Behaviour Science. 2017;186:72-9.
5. Couto M. Laboratory guidelines for animal care. Vertebrate Embryogenesis: Springer; 2011. p. 579-99.
6. Council NR. Guide for the care and use of laboratory animals: National Academies Press; 2010.
7. Potgieter F, Wilke P. The dust content, dust generation, ammonia production, and absorption properties of three different rodent bedding types. Laboratory animals. 1996;30(1):79-87.
8. Vijayakumar R, Samanta R, Samanta A, Guria R, Joardar S. Influence of different types of bedding materials on immune response and serum biochemical profile of caged mice. Veterinary World. 2010;3(9):417.
9. Moehring F, O’Hara CL, Stucky CL. Bedding material affects mechanical thresholds, heat thresholds, and texture preference. The Journal of Pain. 2016;17(1):50-64.
10. Robinson I, Dowdall T, Meert TF. Development of neuropathic pain is affected by bedding texture in two models of peripheral nerve injury in rats. Neuroscience letters. 2004;368(1):107-11.
11. Natusch C, Schwarting R. Using bedding in a test environment critically affects 50-kHz ultrasonic vocalizations in laboratory rats. Pharmacology Biochemistry and Behavior. 2010;96(3):251-9.
12. Burn CC, Peters A, Day MJ, Mason GJ. Long-term effects of cage-cleaning frequency and bedding type on laboratory rat health, welfare, and handleability: a cross-laboratory study. Laboratory animals. 2006;40(4):353-70.
13. Gordon CJ. Effect of cage bedding on temperature regulation and metabolism of group-housed female mice. Comparative medicine. 2004;54(1):63-8.
14. Gaskill BN, Gordon CJ, Pajor EA, Lucas JR, Davis JK, Garner JP. Impact of nesting material on mouse body temperature and physiology. Physiology & behavior. 2013;110:87-95.
15. Buddaraju AKV, Van Dyke RW. Effect of animal bedding on rat liver endosome acidification. Comparative medicine. 2003;53(6):616-21.
16. Armstrong KR, Clark TR, Peterson AR. Use of corn-husk nesting material to reduce aggression in caged mice. Journal of the American Association for Laboratory Animal Science. 1998;37(4):64-6.
17. Landeros RV, Morisseau C, Yoo HJ, Fu SH, Hammock BD, Trainor BC. Corncob bedding alters the effects of estrogens on aggressive behavior and reduces estrogen receptor-α expression in the brain. Endocrinology. 2012;153(2):949-53.
18. Tanaka T, Ogata A, Inomata A, Nakae D. Effects of different types of bedding materials on behavioral development in laboratory CD1 mice (Mus musculus). Birth Defects Research Part B: Developmental and Reproductive Toxicology. 2014;101(5):393-401.
19. Hullinger R, O’riordan K, Burger C. Environmental enrichment improves learning and memory and long-term potentiation in young adult rats through a mechanism requiring mGluR5 signaling and sustained activation of p70s6k. Neurobiology of learning and memory. 2015;125:126-34.
20. Blom H, Van Tintelen G, Van Vorstenbosch C, Baumans V, Beynen A. Preferences of mice and rats for types of bedding material. Laboratory animals. 1996;30(3):234-44.
21. Kawakami K, Shimosaki S, Tongu M, Kobayashi Y, Nabika T, Nomura M, et al. Evaluation of bedding and nesting materials for laboratory mice by preference tests. Experimental animals. 2007;56(5):363-8.
22. Broderson JR, Lindsey JR, Crawford JE. The role of environmental ammonia in respiratory mycoplasmosis of rats. The American journal of pathology. 1976;85(1):115.
23. Shi D, Chen C, Zhao S, Ge F, Liu D, Hao S. Effects of walnut polyphenol on learning and memory functions in hypercholesterolemia mice. J Food Nutr Res. 2014;2(8):450-6.
24. Smach M, Hafsa J, Charfeddine B, Dridi H, Limem K, editors. Effects of sage extract on memory performance in mice and acetylcholinesterase activity. Annales pharmaceutiques francaises; 2015: Elsevier.
25. Bakoyiannis I, Daskalopoulou A, Pergialiotis V, Perrea D. Phytochemicals and cognitive health: Are flavonoids doing the trick? Biomedicine & Pharmacotherapy. 2019;109:1488-97.
26. Khan H, Amin S, Kamal MA, Patel S. Flavonoids as acetylcholinesterase inhibitors: Current therapeutic standing and future prospects. Biomedicine & Pharmacotherapy. 2018;101:860-70.
27. Rosenzweig MR, Bennett EL. Psychobiology of plasticity: effects of training and experience on brain and behavior. Behavioural brain research. 1996;78(1):57-65.
28. Rosenbaum MD, VandeWoude S, Johnson TE. Effects of cage-change frequency and bedding volume on mice and their microenvironment. Journal of the American Association for Laboratory Animal Science. 2009;48(6):763-73.
29. Jaasma L. A Review of the Housing Conditions for Laboratory Animals 2014.
30. Coon R, Jones R, Jenkins Jr L, Siegel J. Animal inhalation studies on ammonia, ethylene glycol, formaldehyde, dimethylamine, and ethanol. Toxicology and applied pharmacology. 1970;16(3):646-55.
31. Ferrecchia CE, Jensen K, Van Andel R. Intracage ammonia levels in static and individually ventilated cages housing C57BL/6 mice on 4 bedding substrates. Journal of the American Association for Laboratory Animal Science. 2014;53(2):146-51.
32. Bosoi CR, Rose CF. Identifying the direct effects of ammonia on the brain. Metabolic brain disease. 2009;24(1):95-102.
33. Niknahad H, Jamshidzadeh A, Heidari R, Zarei M, Ommati MM. Ammonia-induced mitochondrial dysfunction and energy metabolism disturbances in isolated brain and liver mitochondria, and the effect of taurine administration: relevance to hepatic encephalopathy treatment. Clinical and experimental hepatology. 2017;3(3):141.
34. Kilburn KH. Is inhaled ammonia neurotoxic? Environmental Management and Health. 2000;11(3):239-50.