Adult (2 to 3 months old) Sprague-Dawley rats and rat pups ranging from
postnatal day 0 (P0) to P14 were used in this study.
The day of birth was accepted as
postnatal day 0. The animals were not handled until the time of weaning, and the cages were cleaned once a week to minimize disruption of the mother-pups relationship.
Births were examined daily and the day of parturition was considered as
postnatal day 0 (PD 0).
Birth was considered as
postnatal day 0 (PN 0) and animal aged at PN 1,3,6,10,15,21,30,45,60,90 and PN 180 were analyzed.