Comparison of inflammatory cytokines changes in the hippocampal CA1 region between the young and adult gerbil after transient cerebral ischemia

Young animals appear much less vulnerable to ischemic insults. In present study, we compared neuronal damage and changes in the immunoreactivities and levels of inflammatory cytokine, interleukin (IL-) 2 as a pro-inflammatory cytokine and its receptor (IL-2Rβ), IL-4 and IL-13 as anti-inflammatory cytokines, in the hippocampal CA1 region between adult and young gerbils after 5 min of transient cerebral ischemia. Most (about 89%) of hippocampal CA1 pyramidal neurons showed neuronal damage only in the adult gerbil at 4 days post-ischemia; in the young ischemia-group, about 61% of CA1 pyramidal neurons showed neuronal damage at 7 days post-ischemia. Thereafter, the neuronal damage in the CA1 pyramidal neurons was not significantly changed in both the groups. IL-2 and IL-2Rβ immunoreactivity in the stratum pyramidale (SP) of the CA1 region was similar in both the sham groups. At 4 days post-ischemia, IL-2 and IL-2Rβ immunoreactivity in the adult SP was dramatically decreased; however, in the young SP, they were not changed, and they were decreased at 7 days post-ischemia. IL-4 and IL-13 immunoreactivity in the SP of the young sham-group were much lower than those in the adult group. Four days after ischemia-reperfusion, they were dramatically decreased in the adult ischemia-group; however, at this time, they were markedly increased in the young ischemia-group. In brief, our findings indicate that IL-2, 2Rβ, IL-4 and IL-13 immunoreactivity in young gerbils was similar or low compared to those in the adult, and they were decreased at 4 days post-ischemia in the adult; however, at this time, they were distinctively increased in the young.

► Neuronal damage in the ischemic CA1 region of the young gerbil was much more delayed than the adult.
► Interleukin (IL-) 2 and IL-2Rβ in the young were not markedly changed before neuronal death after ischemia.
► IL-4 and IL-13 in the normal young were much lower than those in the normal adult.
► IL-4 and IL-13 in the ischemic young were dramatically increased after ischemia.