title: Expression of urokinase-type plasminogen activator receptor is increased during epileptogenesis in the rat hippocampus.
abstract: Urokinase-type plasminogen activator receptor (uPAR) is functionally a pleiotropic mediator involved in cell adhesion, proliferation, differentiation and migration as well as in matrix degradation, apoptosis, and angiogenesis in cancer tissue. Comparable cellular alterations occur in the brain during post-injury tissue repair. As the first step to assess the role of uPAR in brain tissue remodeling, we tested a hypothesis that uPAR expression is altered in the hippocampus during epilepsy-related circuitry reorganization. Epileptogenesis was triggered by inducing status epilepticus (SE) with electrical stimulation of the amygdala in rats. To monitor the development of SE and the occurrence of spontaneous seizures animals were continuously video-EEG monitored until sacrificed (1, 2, 4 or 14 days after SE). The hippocampal expression of uPAR was studied with real time qPCR and immunohistochemistry. Double-immunohistochemistry and confocal microscopy were used to investigate the expression of uPAR in astrocytes, microglia and neurons. We show that in the normal hippocampus the expression of uPAR was low and confined to small population of astrocytes and interneurons. In animals undergoing SE, uPAR expression increased dramatically, peaking at 1 and 4 days after SE. According to double-immunohistochemistry, uPAR was highly expressed in parvalbumin positive interneurons in the hippocampus and dentate gyrus, and in a subgroup of somatostatin and neuropeptide Y positive hilar interneurons. Increased uPAR expression during post-injury phase supports its contribution to tissue remodeling in the brain. Surviving hilar interneurons that are known to be denervated due to loss of afferent inputs in post-SE brain provide a target for future studies to investigate the contribution of uPAR in reinnervation of these cells, and to identify the signaling cascades that mediate the effects of uPAR.
authors.affiliation: Epilepsy Research Laboratory, A.I. Virtanen Institute for Molecular Sciences, University of Kuopio, PO Box 1627, FIN-70211 Kuopio, Finland.
authors.forename: L
authors.initials: L
authors.lastname: Lahtinen
authors.forename: N
authors.initials: N
authors.lastname: Huusko
authors.forename: H
authors.initials: H
authors.lastname: Myöhänen
authors.forename: A-K
authors.initials: AK
authors.lastname: Lehtivarjo
authors.forename: R
authors.initials: R
authors.lastname: Pellinen
authors.forename: M P
authors.initials: MP
authors.lastname: Turunen
authors.forename: S
authors.initials: S
authors.lastname: Ylä-Herttuala
authors.forename: E
authors.initials: E
authors.lastname: Pirinen
authors.forename: A
authors.initials: A
authors.lastname: Pitkänen
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000378:metabolism; D002460:Cell Line; D004195:Disease Models, Animal; D004558:Electric Stimulation; D004827:Epilepsy / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D005786:Gene Expression Regulation / Q000502:physiology; D006624:Hippocampus / Q000378:metabolism* / Q000503:physiopathology; D006801:Humans; D007150:Immunohistochemistry; D007395:Interneurons / Q000378:metabolism; D007696:Kindling, Neurologic; D008297:Male; D009410:Nerve Degeneration / Q000209:etiology / Q000378:metabolism* / Q000503:physiopathology; D009478:Neuropeptide Y / Q000378:metabolism; D010320:Parvalbumins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D055293:Receptors, Urokinase Plasminogen Activator / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D013004:Somatostatin / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology
chemical_list: D009478:Neuropeptide Y; D010320:Parvalbumins; D012333:RNA, Messenger; D055293:Receptors, Urokinase Plasminogen Activator; D013004:Somatostatin