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Tinnitus and the potassium channels activity (papers by Dr Tzounopoulos)

Discussion in 'Other Health News and Research' started by pattismith, Nov 22, 2017.

  1. pattismith

    pattismith Senior Member

    (Dr. Tzounopoulos, who is associate professor of otolaryngology and neurobiology at the University of Pittsburgh)

    Noise-Induced Plasticity of KCNQ2/3 and HCN Channels

    Underlies Vulnerability and Resilience to Tinnitus
    Vulnerability to noise-induced tinnitus is associated with increased spontaneous firing rate in dorsal cochlear nucleus principal neurons, fusiform cells.

    This hyperactivity is caused, at least in part, by decreased Kv7.2/3 (KCNQ2/3) potassium currents.

    However, the biophysical mechanisms underlying resilience to tinnitus, which is observed in noise- exposed mice that do not develop tinnitus (non-tinnitus mice), remain unknown. Our results show that noise exposure induces, on average, a reduction in KCNQ2/3 channel activity in DCN fusiform cells in noise-exposed mice by 4 days after exposure. Tinnitus is developed in mice that do not compensate for this reduction within the next 3 days.
    Resilience to tinnitus is developed in mice that show a re-emergence of KCNQ2/3 channel activity and a reduction in HCN channel activity.

    Our results highlight KCNQ2/3 and HCN channels as potential targets for designing novel therapeutics that may promote resilience to tinnitus.

    Potent KCNQ2/3-Specific Channel Activator Suppresses In Vivo Epileptic Activity and Prevents the Development of Tinnitus

    Voltage-gated Kv7 (KCNQ) channels are voltage-dependent potassium channels that are activated at resting membrane potentials and therefore provide a powerful brake on neuronal excitability.

    Genetic or experience-dependent reduction of KCNQ2/3 channel activity is linked with disorders that are characterized by neuronal hyperexcitability, such as epilepsy and tinnitus.

    Retigabine, a small molecule that activates KCNQ2–5 channels by shifting their voltage-dependent opening to more negative voltages, is an US Food and Drug Administration (FDA) approved anti-epileptic drug.

    However, recently identified side effects have limited its clinical use. As a result, the development of improved KCNQ2/3 channel activators is crucial for the treatment of hyperexcitability-related disorders.
    By incorporating a fluorine substituent in the 3-position of the tri-aminophenyl ring of retigabine, we synthesized a small-molecule activator (SF0034) with novel properties.
    Heterologous expression of KCNQ2/3 channels in HEK293T cells showed that SF0034 was five times more potent than retigabine at shifting the voltage dependence of KCNQ2/3 channels to more negative voltages.
    Moreover, unlike retigabine, SF0034 did not shift the voltage dependence of either KCNQ4 or KCNQ5 homomeric channels.
    Conditional deletion of Kcnq2 from cerebral cortical pyramidal neurons showed that SF0034 requires the expression of KCNQ2/3 channels for reducing the excitability of CA1 hippocampal neurons. Behavioral studies demonstrated that SF0034 was a more potent and less toxic anticonvulsant than retigabine in rodents. Furthermore, SF0034 prevented the development of tinnitus in mice. We propose that SF0034 provides, not only a powerful tool for investigating ion channel properties, but, most importantly, it provides a clinical candidate for treating epilepsy and preventing tinnitus.

    NotThisGuy and zzz like this.
  2. ahmo

    ahmo Senior Member

    Northcoast NSW, Australia
    I had horrific tinnitus. It lessened when I quit gluten and dairy, and essentially disappeared when my adrenals were less stressed.

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