Expression of Id proteins increases in astrocytes in the hippocampus of epileptic rats

Reactive gliosis is a prominent morphological feature of temporal lobe epil epsy. The molecular mechanisms underlying glial cell activation remain uncl ear, We examined expression of Id 1-3 protein, a family of helix-loop-helix proteins involved in the regulation of cell proliferation and differentiat ion, in glial cells after electrically induced status epilepticus (SE) in t he rat. In control hippocampus, Id3 was weakly expressed in astrocytes, whi le Idl-2 were below detection level. After SE, Idl-3 protein expression inc reased markedly in reactive astrocytes within 1 day and this persisted up t o 3 weeks after SE. Three months after SE when rats experience spontaneous seizures, Id expression had returned to control levels. These results suppo rt a role of the Id gene family in regulating astrocyte reactivity in epile ptic tissue. NeuroReport 12:2461-2465 (C) 2001 Lippincott Williams & Wilkin s.