Effects of Varied Housing Density on a Hybrid Mouse Strain Followed for 20 Months.

To evaluate the effect of increased housing density in a hybrid mouse strain, we evaluated a panel of physiological and behavioral traits in animals that were housed in groups of 3, 5, 8, or 12, using cages that provide 78.1 in2 of floor space. Such groupings resulted in cage densities that ranged from half to almost twice the density recommended by the Guide for the Care and Use of Laboratory Animals. While previous studies have investigated physiological effects of increased housing density using inbred mouse strains, including C57BL/6J and 129S1/SvImJ, this study tested an F1 hybrid population of C57BL/6J x 129S1/SvImJ for changes resulting from either decreased or increased housing density. Mice were followed until they were 20 months old, a substantially longer duration than has been used in previous density studies. We evaluated mortality, growth, home cage behavior, blood pressure, body composition, clinical plasma chemistries, immune function, and organ weights (heart, kidney, adrenal glands, and testes) as endpoints of chronic stress that may arise from sub-optimal housing conditions. Few statistically different parameters were observed in this study, none of which describe chronic stress and all within normal physiological ranges for research mice, suggesting that this hybrid strain was not adversely affected by housing at twice the density currently recommended.

Pitfalls of animal model systems in ageing research.

Often, reports of anti-ageing research using animal models are overly optimistic and incomplete. Without having the details of the study (issues inherent with the animal models, the condition of the animal colony, the replicability of the findings, for example), even the educated public can find it difficult to interpret the reports accurately. This chapter provides background information about ageing research and animal models in general and arms readers with guidelines they can use to assist them when analyzing reports of ageing research using those models. The article also uses the guidelines to briefly evaluate three anti-ageing treatment candidates: one in the very early stages of testing (resveratrol), one that has been proven unfounded as an anti-ageing intervention by testing [dehydroepiandrosterone (DHEA)] and one that has undergone testing successfully (l-deprenyl).