Effect of prenatal and postnatal environmental enrichment on laboratory rats' welfare

This work was designed to investigate effects of environmental enrichment during gestation on behaviour, physiology and brain histology of enriched and non-enriched offspring rats. A total of 30 female wistar rats were randomly divided into two groups; control and enriched groups. Offspring from prenatally enriched group were divided after weaning into two groups; one raised under standard condition (enriched group) and the other raised under enriched condition after weaning (E+EC group) from the day 23 to the day 35 postnatal. Observing neonates' behaviour, on the day 36 postnatal, rats subjected to behavioural tests. On the day 42 postnatal, blood samples were collected and brain samples were obtained for histopathology. Behavioural tests revealed significant (P<0.05) increased time spent in open arm, open arm entries and time in center in E+EC group and unprotected stretch attend posture (USAP) were significantly (P<0.01) increased in E+EC group. Freezing time in open field test was significantly (P<0.01) decreased in the enriched group, while grooming frequency was significantly (P<0.05) increased in prenatally and post weaning enriched rats group (E+EC). The corticosterone level was significantly (P<0.05) decreased in prenatally and post weaning enriched rats group (E+EC). The mean of tertiary processes of cytoplasmic processes in cross section of hippocampal region were significantly (P<0.05) increased in prenatally and post weaning enriched rats group (E+EC) group. In conclusion, providing experimental laboratory rats with physical enrichment tools in prenatal and postnatal life can improve their behavioural and physiological status reflecting on their welfare.