Comparison of Glial Activation in the Hippocampal CA1 Region Between The Young and Adult Gerbils After Transient Cerebral Ischemia

Abstract

It has been reported that young animals are less vulnerable to brain ischemia. In the present study, we compared gliosis in the hippocampal CA1 region of the young gerbil with those in the adult gerbil induced by 5 min of transient cerebral ischemia by immunohistochemistry and western blot for glial cells. We used male gerbils of postnatal month 1 (PM 1) as the young and PM 6 as the adult. Neuronal death in CA1 pyramidal neurons in the adult gerbil occurred at 4 days post-ischemia; the neuronal death in the young gerbil occurred at 7 days post-ischemia. The findings of glial changes in the young gerbil after ischemic damage were distinctively different from those in the adult gerbil. Glial fibrillary acidic protein-immunoreactive astrocytes, ionized calcium-binding adapter molecule (Iba-1), and isolectin B4-immunoreactive microglia in the ischemic CA1 region were activated much later in the young gerbil than in the adult gerbil. In brief, very less gliosis occurred in the hippocampal CA1 region of the young gerbil than in the adult gerbil after transient cerebral ischemia.

CD74-immunoreactive activated M1 microglia are shown late in the gerbil hippocampal CA1 region following transient cerebral ischemia

“…Microglial reactivity in the ischemic brain is closely associated with the development of delayed neuronal cell death in vulnerable regions (4,30). An early and transient microglial reaction occurs throughout the majority of the hippocampus within 24 h of ischemia, including the hippocampal CA3 region, where no subsequent neuronal loss occurs (31).…”

Differences in TNF‑α and TNF‑R1 expression in damaged neurons and activated astrocytes of the hippocampal CA1 region between young and adult gerbils following transient forebrain ischemia

“…This result is consistent with our and other previous studies reporting that tFI-induced DND in the hippocampal CA1 in young gerbils was shown in fewer pyramidal neurons and more delayed in time than that shown in adult gerbils ( 9 , 24 , 25 ). Taken together, we suggest that the difference of DND between young and adult groups might be associated with the differences of various factors to affect DND, including glial activation, inflammatory cytokine expression and NMDA receptor expression ( 26 – 28 ).…”

YES-10, A Combination of Extracts from Clematis mandshurica RUPR. and Erigeron annuus (L.) PERS., Prevents Ischemic Brain Injury in A Gerbil Model of Transient Forebrain Ischemia

“…In the BBB, extracellular ion and water balance are controlled by various ion and water channels that are expressed in the astrocyte-endfeet [31]. In the case of microglia, they take charge as immunocytes in the CNS and secrete diverse kinds of inflammatory cytokines in specific states such as ischemic insults [32,33]. As immune cells, microglia can remove dead cells and tissue debris in the CNS under pathological conditions [34].…”