NKCC1 Inhibitor Bumetanide Corrects Synaptic and Circuit Hyperexcitability in Fragile X Mouse Model

NKCC1 Inhibitor Bumetanide Corrects Synaptic and Circuit Hyperexcitability in Fragile X Mouse Model

Qionger He, PhD, and Anis Contractor, PhD

Anis Contractor, PhD
Principal Investigator

Qionger He, PhD
FRAXA Fellow

Northwestern University
Chicago, IL

2013-2017 Grant Funding: $258,000
2005-2008 Grant Funding: $127,000

Summary

With $258,000 in grants since 2013 from FRAXA Research Foundation, Dr. Anis Contractor and Dr. Qionger He at Northwestern University found that the available drug bumetanide can correct altered GABA signalling in a mouse model of Fragile X syndrome.

“We found that if we gave this drug early in development, it not only corrected the development of synapses during the early critical period, it also corrected the sensory problems we saw in adult mice,” Contractor said. “It is possible that correcting chloride or correcting neurotransmitter signaling in humans could also have the same effect.”

The Results

Results Published

Mol Psychiatry 2019 Nov;24(11):1732-1747. doi: 10.1038/s41380-018-0048-y. Epub 2018 Apr 27.
Critical period inhibition of NKCC1 rectifies synapse plasticity in the somatosensory cortex and restores adult tactile response maps in fragile X mice

The Science

In this project we will test the hypothesis that alterations in inhibitory neurotransmission in the cortex during early development cause abnormal trajectories in the development of cortical circuits.

GABA is the major inhibitory neurotransmitter in the adult brain. In contrast, during early development this neurotransmitter excites neurons. In the cortex there is a well-defined time-point when GABA switches from this immature excitatory to the mature inhibitory form, that is critical to the normal development of neurons.

In preliminary studies we have determined that the timing of this switch from GABA excitation to inhibition is delayed in the cortex of the Fragile X mouse model. This altered timing could result in altered circuit development and ultimately could be linked to an increased propensity for seizures, hyper-arousal, and hypersensitivity to sensory stimuli.

We propose a simple way to correct this altered GABA signaling using a commonly used diuretic – bumetanide – that affects the balance of intracellular ions in neurons, and will thus promote the switch to the mature form of GABA signaling. This early correction of GABA signaling in the cortex can potentially have a dramatic effect on correcting the neuronal deficits associated with the disorder. We will test this possibility by testing whether behavioral alterations that have been observed in the Fragile X mouse model are rectified by chronic treatment, during cortical critical periods, with this drug. These studies will test a novel hypothesis about the mechanism for the altered development of synapses and circuits in the cortex, and potentially provide a new direction for treatment of Fragile X syndrome.

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Global Leader in Fragile X Research

FRAXA-funded researchers around the world are leading the way towards effective treatments and ultimately a cure.

Explore Current Research Grants
Help Fund the Cure