Changes in pain sensitivity with age, differ in male and female wistar rats, Rattus norvegicus (Berkenhout)

The present study is designed to examine the pain sensitivity among different age groups of wistar rats (Rattus norvegicus Berkenhout). Nociception was measured by tail flick latency (TFL) in male and female rats of 1, 4, 8, 12, 20 and 26-30 months age groups with a view to determine the age related changes in pain sensitivity. The baseline tail flick latencies (bTFL) were calculated for each rat as the mean± S.E.M. Two-way ANOVA was applied on mean values of baseline tail flick latencies. The results show high pain sensitivity at 1 month of age; while the 8 months old animals had low sensitivity to pain. The females showed significantly more sensitivity to pain from 8 to 26-30 months of age than the males of the same age. This difference in pain sensitivity between male and female was significant (P<0.05) on 8, 12, 20 and 26-30 months. The present results demonstrate gender and age associated differences in nociception sensitivity.