Difference in Endocrine and Behavior between Short-Term Single- And Paired-Housing Mice in Metabolic Cage

Thermoneutral Environment Improves Mouse Metabolism and Reduces Stress in Metabolic Cages

“…Despite the increased food intake, laboratory mice lose BW -supposedly due to a loss of fat -when transferred to colder environments 14 . As described before, we observed a BW loss during MC housing in all groups, although the weight loss was far below those reported by other studies [25][26][27][28][29][30] (a weight loss of up to 27% for male and 21% for female mice 30 ). This might be explained by us using younger mice with ad libitum access to food and the usage of gentle (tube) handling.…”

“…Food intake, BC, BCT, BAT markers, ketone bodies and ac)vity pa ern can be used to describe the acclima)sa)on to different environmental condi)ons and the animal's metabolic state, respec)vely. Stress hormone analyses are commonly used to detect stress in rodents 2,5,16,25,27,29 but cannot provide the same temporal resolu)on as con)nuous undisturbed monitoring of physiological parameters. Cor)costerone is a slow ac)ng parameter enabling the detec)on of chronic stress 16 .…”

“…Only few studies studied MC housing of mice showing that mice housed in MCs had an increased BP for several hours and prolonged tachycardia las)ng for two days 24 and sugges)ng that MC housing accelerates metabolism 16,[25][26][27] and oxida)ve stress 16 . While some studies showed that mice had stable urina)on rates in the MC aRer 3-4 days 28 , others stated that mice did not acclima)ze 24,25,29 , even aRer three weeks 16 . Acclima)sa)on was paralleled by an increase in food/water intake and urinary output 28,30 .…”

“…Acclima)sa)on was paralleled by an increase in food/water intake and urinary output 28,30 . An increased food intake could indicate an increased thermogenesis as detectable by an upregula)on of Ucp1 expression in the brown adipose )ssue 25 and consecu)ve loss of fat [25][26][27] or body mass 16,[25][26][27][28][29][30] . Another study showed increased urinary noradrenaline, vanillylmandelic acid and cor)costerone concentra)ons 29 and an increase of anxiety-like behaviours when mice were single housed in MC 29 .…”

“…MCs are kept at standard housing condi)ons (ambient temperature of 23°C). However, it remains widely unclear to what extent ambient temperature contributes as a major stressor 16,[24][25][26][27][28][29][30] while a recent study demonstrated a beneficial effect of thermoneutral temperature on some metabolic parameters 27 . To the best of our knowledge, only one study measured body temperatures in mice during MC housing, showing an average body surface temperature of around 30°C at an ambient cage temperature of 22.5°C 25 .…”