Effect of Environmental Enrichment on Aggression in BALB/cJ and BALB/cByJ Mice Monitored by Using an Automated System.

Aggression among mice remains a common undesirable problem in laboratory settings, and animal welfare and scientific outcomes may become compromised depending on the severity of aggression. This study evaluated the effect of cage enrichment comprising a bilevel, mounted 'mezzanine' compared with a cotton square or shelter on intracage male aggression over a 6-wk period. Our first study involved home-cage behavioral challenges to male mice from a high aggression substrain (BALB/cJ) and low-aggression substrain (BALB/cByJ). Aggressive interactions and locomotor activity were scored manually and then compared with measures of activity obtained by using a continuous automated home-cagemonitoring system, the Digital Ventilated Caging (DVC) system. BALB/cJ mice exhibited similar levels of aggression acrosshousing conditions, whereas BALB/cByJ mice had lower aggression when housed with a mezzanine. In the second study,videorecordings and continuous DVC automated measures were collected over 24 h and divided into 12-h light and dark phases. BALB/cByJ mice-but not BALB/cJ-mice had increased aggressive behaviors during the dark phase. However, the DVC detected higher activity levels during the dark phase, compared with the light phase, in both substrains. Elevated activity levels recorded by the DVC correlated with fighting bouts and high levels of locomotion. These results show that a bilevel structural form of enrichment reduces aggression, depending on the BALB/c substrain, and confirms higher aggression levels in the BALB/cJ substrain. In addition, our findings provide evidence that the DVC is effective in identifying mouse cages with patterns of high activity levels, signaling possible aggression incidences, thus potentially allowing for early intervention and consequently improving animal welfare.

Alfalfa-derived HSP70 administered intranasally improves insulin sensitivity in mice.

Heat shock protein (HSP) 70 is an abundant cytosolic chaperone protein that is deficient in insulin-sensitive tissues in diabetes and unhealthy aging, and is considered a longevity target. It is also protective in neurological disease models. Using HSP70 purified from alfalfa and administered as an intranasal solution, we tested in whether the administration of Hsp70 to diet-induced diabetic mice would improve insulin sensitivity. Both the 10 and 40 µg given three times per week for 26 days significantly improved the response to insulin. The HSP70 was found to pass into the olfactory bulbs within 4-6 hours of a single dose. These results suggest that a relatively inexpensive, plentiful source of HSP70 administered in a simple, non-invasive manner, has therapeutic potential in diabetes.