Alcohol abuse and dependence affect an estimated 8.5% of the U.S. population and are responsible for substantial health and societal costs. The large conductance calcium-activated potassium (BK) channel, together with more than 20% of the proteins known to interact with BK a subunit, have been identified by the INIA-West consortium as potential genetic determinants of ethanol preference. In the present proposal, we hypothesize that perturbation of BK channel interaction network by alcohol in relevant brain regions contributes to excessive drinking. We will focus our investigation on the neurocircuitry subtending the motivational effects of ethanol (nucleus accumbens, amygdala and prefrontal cortex). We further hypothesize that ethanol-induced reorganization of the BK channel interactome mediates changes in neurotransmission and synaptic plasticity observed in ethanol-dependent animals. To test these hypotheses, we will quantify and manipulate expression levels of key interaction partners of the BK a subunit. The first Specific Aim is to characterize the phenotype of knockout mice deficient for either of the two neuronal auxiliary subunits of the BK channel. We will use assays of ethanol intoxication, tolerance and withdrawal, as well as paradigms of voluntary drinking leading to moderate or excessive ethanol intake. The second Specific Aim is to map the expression of known BK interaction partners in the nucleus accumbens, amygdala and prefrontal cortex, and assess how excessive ethanol exposure alters their protein levels. An innovative protein assay will be exploited for the simultaneous quantification of 19 BK channel subunits and interaction partners in brain samples. We will then assess how virally-mediated local silencing of the most promising genes affects ethanol self-administration. In a third Specific Aim, a similar functional approach will be used to probe the contribution of these genes to GABAergic neurotransmission in the amygdala and synaptic plasticity in the nucleus accumbens, in collaboration with INIA-West investigators. The proposed experiments are expected to uncover the contribution of BK channel interactome to ethanol self-administration and potentially pinpoint novel molecular targets for the treatment of alcoholism.
This research project investigates the contribution of a major potassium channel of the brain to excessive alcohol drinking. We anticipate this work to provide integrated insights into the molecular mechanisms mediating the behavioral and cellular effects of alcohol. Translational implications include the identification of novel targets for the development of a more efficient treatment of alcoholism.
|Herman, Melissa A; Contet, Candice; Justice, Nicholas J et al. (2013) Novel subunit-specific tonic GABA currents and differential effects of ethanol in the central amygdala of CRF receptor-1 reporter mice. J Neurosci 33:3284-98|