EMVIRONMENTAL ENRICHMENT IN LABORATORY MICE: ITS EFFCTS UPON REPRODUCTIVE PHYSIOLOGY

PONZIO M. F.; LUQUE EM; RUIZ RD; FIOL DE CUNEO M; MARTINI AC

Congreso; 8° WORLD CONGRESS ON ALTERNATIVES Y ANIMAL USE IN THE LIFE SCIENCES; 2011

Although a growing body of evidence indicates that environmental enrichment (EE) facilitates normal development and behaviour in laboratory mice, few studies have been conducted to demonstrate its impact upon male and female reproductive physiology. In the present study we investigated the effects of PVC tubular devices and shredded paper as physical enrichment on reproductive physiology and postnatal development of laboratory mice. Animals were allocated in regular housing cages in groups of five individuals, and treated as non-enriched (control, C) or enriched from weaning to adulthood (E). In males, parameters evaluated were body, testicular and accessory glands weight, sperm quality (motility, viability, acrosome and membrane integrity), testosterone concentration, in vivo fertilization rates and litter size. In females, parameters assessed included body, uterine and ovary weight, spontaneous ovulation, estradiol concentration, pregnancy percentages and litter size. Also, at postnatal day 1 litter was reduced to 8 pups (4 males and 4 females) and their neurobiological (cliff avoidance, negative geotaxis, surface righting reflex), physical (body weight evolution, bilateral pinna detachment, low incisor eruption and eyes opening) and reproductive development (testicular descent, balano-prepucial separation and vaginal opening) was assessed. A second group of C females was enriched from day 1 of pregnancy to discriminate the mother?s ability to breed their offspring (EP). A higher number of pups were born from enriched mothers (Mean±SEM; C: 9.5±0.6, n=4; E: 10.7±0.2, n=5; EP: 12.2±0.7, n=5; p=0.03 E and EP vs. C). As well, a strong tendency was detected towards a faster physical and reproductive development of pups born from E and EP mothers, yet significant differences were only observed for testicular descent (day 19, C: 0±0%, n=16; E: 62.5±12.5%, n=17; EP: 21.6±9.7%, n=21; p=0.002). In conclusion, in this strain of mice an increased environmental complexity showed limited effects upon reproductive physiology and postnatal development.