Distribution of α and β integrin subunits in the adult rat hippocampus after pilocarpine-induced neuronal cell loss, axonal reorganization and reactive astrogliosis

Abstract

Integrins are αβ−heterodimers that act as cell-extracellular matrix (ECM) and cell-cell adhesion molecules. During development, they are involved in axonal guidance, synaptogenesis, and in astrocytic maturation and migration. Here, we have examined the potential role of the integrin subunits α1–α5 and β1–β5 in axonal sprouting, synaptogenesis and reactive astrogliosis in the adult rat brain caused by pilocarpine-induced status epilepticus (SE). Strong hippocampal immunoreactivity of α1–α5, β1, β3, β4, and β5 was observed in the pia mater, in vascular endothelia, and in astrocytes at the pial surface. β2 immunoreactivity was found exclusively in vascular endothelia. Pyramidal cells and interneurons of CA3–CA1, as well as hilar neurons revealed moderate α5 labeling in their cell bodies. Mossy fibers were immunoreactive for α2, β4, and β5. After pilocarpine-induced SE, strong immunoreactivity for α1, α2, α4, α5, β1, β3, and β4 was observed in reactive astrocytes. Our results show that members of the integrin family are differently distributed in cellular and subcellular compartments of the hippocampus and undergo specific patterns of regulation, which may be important for lesion-induced reactive changes in the adult brain.