In humans there are two isoforms of this membrane transport protein, nkcc1 and nkcc2, encoded by two different genes slc12a2 and slc12a1 respectively. This action depends on depolarizing gabaergic output synapses and requires chloride uptake via nkcc1. Developmental patterns in the regulation of chloride. The nakcl cotransporter nkcc is a protein that aids in the secondary active transport of sodium, potassium, and chloride into cells. Inhibition of wnk3 kinase activity, a molecule expressed highly in the developing brain, is the most potent means of concurrently inhibiting nkcc1 activity and activating kcc2 activity in vitro, and does so via changes in transporter phosphorylation at critical regulatory residues figure 4 kahle et al. Understanding the seizureinducing mechanisms of tbi is of the utmost importance, because these seizures are often resistant to traditional first and secondline antiseizure treatments. Anomalous levels of cl transporters in the hippocampal.
In the present study we show a strong increase of both. Neurodevelopment copyright 2019 tuning the regulator. Some mice remained seizurefree for several days, others had frequent seizures with as many as 1. In humans there are two isoforms of this membrane transport. He depressed synchronous bursts of action potentials by combining local field potential and wholecell recordings of epileptiform activity induced by 8. All these pathways described above enhance kcc2 protein activity and facilitate. Neonatal seizures have devastating consequences for brain development and are inadequately treated by available antiepileptics. Nkcc1 is an emerging target for developing therapeutics to treat neonatal seizures. Bumetanide enhances phenobarbital efficacy in a neonatal seizure model. Our results provide evidence that nkcc1 facilitates seizures in the developing brain and indicate that bumetanide should be useful in the treatment of. Sep 01, 2010 to determine whether the seizureinduced, nkcc1 dependent changes in gaba ar function contribute to the increased probability of subsequent seizures dzhala and staley, 2003. In general, the frequency of spontaneous seizures varied among different animals.
Microrna101 regulates multiple developmental programs to. Developing neural circuits generate burstlike spontaneous activity. Elevated nkcc1 transporter expression facilitates early post. Nkcc1 and kcc2 are two main secondary active transporters which. Although most seizures in children are benign and result in no longterm consequences, increasing experimental animal data strongly suggest that frequent or prolonged seizures in the developing brain result in longlasting sequelae. In developing, as well as in the adult brain, nkcc1 is the most important transporter mediating neuronal chloride accumulation blaesse et al. Pharmacological inhibition of cationchloride cotransporters. Dentate circuitry as a model to study epileptogenesis. Nkcc1 chloride importer antagonists attenuate many. Pharmacological inhibition of cationchloride cotransporters for neurological diseases rachel nepomuceno 1, dandan sun ph. Thermodynamic regulation of nkcc1mediated cl cotransport. A major clinical problem is that neonatal epileptic seizure activity shows only limited response to the. Nkcc1 transporter facilitates seizures in the develop ing brain. Nkcc1 transporter facilitates seizures in the developing brain volodymyr i dzhala1,5, delia m talos2,5, dan a sdrulla1, audrey c brumback1, gregory c mathews3, timothy a benke1, eric delpire4, frances e.
Structure of the human cationchloride cotransporter nkcc1. One way to gain insight into potential mechanisms is to reduce the features of epilepsy to. Comment on local impermeant anions establish the neuronal. Wnkcab39nkcc1 signaling increases the susceptibility to ischemic brain damage in hypertensive rats. It is also widely distributed in the brain including striatum. Sevofluraneinduced dysregulation of cationchloride. The immaturity of inhibitory systems, such as gaba, during normal brain development and its further dysregulation under. Brain sciences free fulltext neuronal transmembrane. Neuronal ischemia results in chloride gradient alterations which impact the excitatoryinhibitory balance, volume regulation, and neuronal survival. Nkcc1 transport was limited only by the net electrochemical driving force for na, k, and cl. He depressed synchronous bursts of action potentials by combining local field potential and wholecell recordings of. In contrast, in the developing brain, gaba depolarizes and. Thermodynamic regulation of nkcc1mediated cl cotransport underlies plasticity of gabaa signaling in neonatal neurons.
A common way to explain seizures in a normal individual is that a. Bumetanide for the treatment of seizures in newborn babies. Publication nkcc1 transporter facilitates seizures in the. Bumetanide, an inhibitor of nkcc1 nak2cl cotransporter. Influence of brain development on status epilepticus holmes. Nkcc1 facilitates seizures in the developing hippocampus during development of inhibitory synapses, the action of the neurotransmitter gaba shifts from depolarizing to hyperpolarizing 12, 14, 15. In the early stages of brain development, elevated expression level of nkcc1.
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. Finally, the nkcc1 transporter facilitates seizures in the developing brain because of its high expres. In humans there are two isoforms of this membrane transport protein, nkcc1. Neuronal transmembrane chloride transport has a time. Infants and children are at a high risk for seizures compared with adults. Nkcc1 transporter facilitates seizures in the developing brain dzhala vi, talos dm, sdrulla da, brumback ac, mathews gc, benke ta, delpire e, jensen fe, staley kj nat med. To determine whether the seizureinduced, nkcc1dependent changes in gaba ar function contribute to the increased probability of subsequent seizures dzhala and staley, 2003. However, there is increasing experimental animal data strongly suggesting that prolonged seizures in the developing brain produce long lasting sequels by intervening with developmental programs leading to inadequate construction of cortical networks rather than inducing neuronal cell loss ben.
Nkcc1 transporter facilitates seizures in the developing brain. Chloride transporters and gaba polarity in developmental. Thermodynamic regulation of nkcc1 mediated cl cotransport underlies plasticity of gabaa signaling in neonatal neurons. Nkcc1 expression level versus expression of the clextruding transporter kcc2 in human and rat cortex showed that cl transport in perinatal human cortex is as immature as in the rat. Nkcc1 and kcc2 prevent hyperexcitability in the mouse. Nkcc1 transporter facilitates seizures in the developing brain dzhala vi, talos dm, sdrulla da, brumback ac, mathews gc, benke ta, delpire e, jensen fe, staley kj nat med 2005. 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. Delpire e, jensen fe, staley kj 2005 nkcc1 transporter facilitates. Andang m, lendahl u 2008 ion fluxes and neurotransmitters signaling in neural development. Genetic and pharmacological modulation of giant depolarizing. The first situation in which neuronal chloride was found to be elevated was in the immature brain. The immaturity of inhibitory systems, such as gaba, during normal brain development and its further dysregulation under pathological conditions that predispose to seizures have been speculated to play a major role in facilitating seizures.
Somatostatin interneurons promote neuronal synchrony in the. The nkcc1 blocker bumetanide shifted ecl negative in immature neurons, suppressed epileptiform activity in hippocampal slices in vitro and. In neonates, gaminobutyric acid gaba is an excitatory neurotransmitter due. The dual roles of gaba in seizures and epilepsy generate more. The immature nak2cl transporter nkcc1 imports chloride into the cell, creating an insidetooutside chloride gradient.
Vitexin reduces epilepsy after hypoxic ischemia in the neonatal. It is widely distributed in cells including skeletal muscle and heart. The pharmacological assessment of gabaa receptor activation. Using fm143 to study neuropeptide granule dynamics and exocytosis. It is also widely distributed in the brain including striatum, neocortex, and hippocampus, as well as dorsal root ganglia and glia. Although the exact mechanism of epileptogenesis is not yet fully understood, epilepsy is widely believed to be associated with an excitatoryinhibitory. Neuronal chloride accumulation and excitatory gaba underlie. Nkcc1 a sodiumpotassiumchloride cotransporter, which facilitates chloride entry and kcc2. Quantitative rtpcr analyses of the mrnas extracted from the human. Nkcc1 and kcc2 prevent hyperexcitability in the mouse hippocampus. For example, epileptogenic injuries alter neuronal chloride transport, which is the principal. The developmental switch in intracellular chloride concentration has been attributed primarily to changes in function expression of two chloride transporters.
Such seizures may intervene with developmental programmes and lead to inadequate. The bumetanidesensitive nak2cl cotransporter nkcc1 as a. Although most seizures in children are benign and result in no longterm consequences, increasing experimental animal data. Jan 17, 2020 dzhala found that bumetanide contributed to more hyperpolarized e gaba. However, there is increasing experimental animal data strongly suggesting that prolonged seizures in the developing brain produce long lasting sequels by intervening with developmental programs leading to. The posttraumatic seizures caused by tbi may occur either early within 1 week of the.
Many factors have been shown to play important roles in facilitating the development of epilepsy in humans and animal disease models, including genetic mutations, environmental factors during development, and brain injury. Assessment of the level of gaba and some trace elements in. Nkcc1 upregulation contributes to early posttraumatic. Nkcc1 transporter facilitates seizures in the developing. One major clinical issue is that commonly used gabamimetic and gabamodulating antiepileptic drugs are not necessarily efficacious against earlychildhood seizures because gaba can be excitatory in the. Progressive nkcc1dependent neuronal chloride accumulation. Wnkcab39 nkcc1 signaling increases the susceptibility to ischemic brain damage in hypertensive rats. Request pdf nkcc1 transporter facilitates seizures in the developing brain during development, activation of cl permeable gaba a receptors gaba ar excites neurons as a result of. Limitations of current gaba agonists in neonatal seizures.
Decreased seizure activity in a human neonate treated with. Vitexin also significantly suppressed brain electrical activity in neonatal rats. Inhibition of wnk3 kinase activity, a molecule expressed highly in the developing brain, is the most potent means of concurrently inhibiting nkcc1 activity and activating kcc2 activity in vitro, and does so via. Epilepsy is a complex disease with diverse clinical characteristics that preclude a singular mechanism. Effects of seizures on developmental processes in the. Dzhala vi, talos dm, sdrulla da, brumback ac, et al. Request pdf nkcc1 transporter facilitates seizures in the developing brain during development, activation of clpermeable gabaa receptors gabaar excites neurons as a result of. Their findings have implications for the activitydependent refinement of developing brain circuits. Dzhala vi, talos dm, sdrulla da, brumback ac, mathews gc, benke ta, delpire e, jensen fe, staley kj 2005 nkcc1 transporter facilitates seizures in the developing brain.
Seizures in the neonatal period are serious events associated with high morbidity and mortality. Dzhala vi, talos dm, sdrulla da, brumback ac, mathews gc, benke ta, et al. The developmental switch in intracellular chloride concentration has been attributed primarily to changes in function expression of two chloride. Dzhala found that bumetanide contributed to more hyperpolarized e gaba.
Evaluation of nkcc1 and kcc2 mrna expression by realtime pcr. As the rodent brain switches from gaba excitation to gaba inhibition during. Developmental patterns in the regulation of chloride homeostasis and gabaa receptor signaling by seizures. In the present study we show a strong increase of both the expression and staining of nkcc1 in epileptic peritumoral cortex compared to normal cortex. The incidence of seizures is particularly high in the early ages of life. Elevated nkcc1 transporter expression facilitates early posttraumatic brain injury seizures.
Nkcc1 mrna underwent a sharp increase at the first day after pilocarpine. Genetic loss of kcc2 in diverse model organisms including worms, flies, fish, and. Indeed, kcc2deficient mice exhibited frequent generalized seizures and died. In the developing brain gaba promotes excitationdepolarization of neurons ben.