Nature Medicine 11, 1205 - 1213 (2005)
Published online: 9 October 2005; | doi:10.1038/nm1301
NKCC1 transporter facilitates seizures in the developing brainVolodymyr I Dzhala1, 5, Delia M Talos2, 5, Dan A Sdrulla1, Audrey C Brumback1, Gregory C Mathews3, Timothy A Benke1, Eric Delpire4, Frances E Jensen2
& Kevin J Staley11
Departments of Neurology and Pediatrics, School of Medicine, University of Colorado Health Sciences Center, 4200 East Ninth Avenue, Denver, Colorado 80262, USA. 2
Department of Neurology, Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, Massachusetts 02115, USA. 3
Department of Anesthesiology, Vanderbilt University Medical Center, 6140 MRB III, 465 21st Avenue South, Nashville, Tennessee 37232-8552, USA. 4
Department of Neurology, Vanderbilt University Medical Center, MRB III, T-4202 MCN 2520, Nashville, Tennessee 37232-8552, USA. 5
These authors contributed equally to this work.
Correspondence should be addressed to Kevin J Staley kevin.staley@uchsc.edu During development, activation of Cl--permeable GABAA receptors (GABAA-R) excites neurons as a result of elevated intracellular Cl- levels and a depolarized Cl- equilibrium potential (ECl). GABA becomes inhibitory as net outward neuronal transport of Cl- develops in a caudal-rostral progression. In line with this caudal-rostral developmental pattern, GABAergic anticonvulsant compounds inhibit motor manifestations of neonatal seizures but not cortical seizure activity. The Na+-K+-2Cl- cotransporter (NKCC1) facilitates the accumulation of Cl- in neurons. The NKCC1 blocker bumetanide shifted ECl negative in immature neurons, suppressed epileptiform activity in hippocampal slices in vitro and attenuated electrographic seizures in neonatal rats in vivo. Bumetanide had no effect in the presence of the GABAA-R antagonist bicuculline, nor in brain slices from NKCC1-knockout mice. NKCC1 expression level versus expression of the Cl--extruding transporter (KCC2) in human and rat cortex showed that Cl- transport in perinatal human cortex is as immature as in the rat. Our results provide evidence that NKCC1 facilitates seizures in the developing brain and indicate that bumetanide should be useful in the treatment of neonatal seizures.
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