title: Neonatal seizures are associated with redistribution and loss of GABAAα-subunits in the hypoxic-ischaemic pig.
abstract: Seizures are a common manifestation of hypoxic-ischaemic brain injury in the neonate. In status epilepticus models alterations to GABAAR subunit expression have been suggested to contribute to (i) abnormal development of the GABAergic system, (ii) why seizures become self-sustaining and (iii) the development of pharmacoresistance. Detailed investigation of GABAAR subunit protein expression after neonatal hypoxia-ischaemia (HI) is currently insufficient. Using our pig model of HI and subsequent spontaneous neonatal seizures, we investigated changes in protein expression of the three predominant α-subunits of the GABAAR; α1, α2and α3. Anaesthetized, ventilated newborn pigs (< 24 h old) were subjected to 30 min HI and subsequently recovered to 24 or 72 h. Amplitude-integrated electroencephalography was used to monitor brain activity and identify seizure activity. Brain tissue was collected post-mortem and GABAAR α-subunit protein expression was analysed using western blot and immunohistochemistry. GABAAR α1and α3protein expression was significantly reduced in animals that developed seizures after HI; HI animals that did not develop seizures did not exhibit the same reductions. Immunohistochemistry revealed decreased α1and α3expression, and α1redistribution from the cell membrane to the cytosol, in the hippocampus of seizure animals. Multivariate analyses, controlling for HI severity and neuronal injury, revealed that seizures were independently associated with significant GABAAR α3reduction. This is the first study to show loss and redistribution of GABAAR α-subunits in a neonatal brain experiencing seizures. Our findings are similar to those reported in models of SE and in chronic epilepsy.
authors.affiliation: The University of Queensland, Perinatal Research Centre, UQ Centre for Clinical Research, Herston, Qld, Australia. s.odriscoll@uq.edu.au.
authors.forename: Stephanie M
authors.identifier: 0000-0002-5565-2001
authors.initials: SM
authors.lastname: Miller
authors.affiliation: The University of Queensland, Perinatal Research Centre, UQ Centre for Clinical Research, Herston, Qld, Australia.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Sullivan
authors.affiliation: The University of Queensland, Perinatal Research Centre, UQ Centre for Clinical Research, Herston, Qld, Australia.
authors.forename: Zoe
authors.initials: Z
authors.lastname: Ireland
authors.affiliation: The University of Queensland, Perinatal Research Centre, UQ Centre for Clinical Research, Herston, Qld, Australia.
authors.forename: Kirat K
authors.identifier: 0000-0001-7739-2098
authors.initials: KK
authors.lastname: Chand
authors.affiliation: The University of Queensland, Perinatal Research Centre, UQ Centre for Clinical Research, Herston, Qld, Australia.
authors.forename: Paul B
authors.identifier: 0000-0002-6408-8238
authors.initials: PB
authors.lastname: Colditz
authors.affiliation: The University of Queensland, Perinatal Research Centre, UQ Centre for Clinical Research, Herston, Qld, Australia.
authors.forename: S Tracey
authors.initials: ST
authors.lastname: Bjorkman
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal; D001923:Brain Chemistry; D004569:Electroencephalography / Q000187:drug effects; D005260:Female; D006624:Hippocampus / Q000378:metabolism; D020925:Hypoxia-Ischemia, Brain / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D011963:Receptors, GABA-A / Q000378:metabolism*; D012121:Respiration, Artificial; D012640:Seizures / Q000378:metabolism* / Q000523:psychology; D013552:Swine
chemical_list: D011963:Receptors, GABA-A
keywords: GABAA receptor subunits; anticonvulsants; brain injury; hypoxia