Protein Kinase C Epsilon Activity in the Nucleus Accumbens and Central Nucleus of the Amygdala Mediates Binge Alcohol Consumption

Abstract

Background Protein kinase C epsilon (PKCε) is emerging as a potential target for the development of pharmacotherapies to treat alcohol use disorders, yet little is known regarding how a history of a highly prevalent form of drinking, binge alcohol intake, influences enzyme priming or the functional relevance of kinase activity for excessive alcohol intake. Methods Immunoblotting was employed on tissue from subregions of the nucleus accumbens (NAC) and the amygdala to examine both idiopathic and binge drinking-induced changes in constitutive PKCε priming. The functional relevance of PKCε translocation for binge drinking and determination of potential upstream signaling pathways involved were investigated using neuropharmacological approaches within the context of 2 distinct binge drinking procedures, Drinking in the Dark (DID) and Scheduled High Alcohol Consumption (SHAC). Results Binge alcohol drinking elevated p(Ser729)-PKCε levels in both the NAC and the central nucleus of the amygdala (CeA). Moreover, immunoblotting studies of selectively bred and transgenic mouse lines revealed a positive correlation between the propensity to binge drink alcohol and constitutive p(Ser729)-PKCε levels in the NAC and CeA. Finally, neuropharmacological inhibition of PKCε translocation within both regions reduced binge alcohol consumption in a manner requiring intact Group1 metabotropic glutamate receptors, Homer2, phospholipase C (PLC) and/or phosphotidylinositide-3 kinase (PI3K) function. Conclusions Taken together, these data indicate that PKCε signaling in both the NAC and CeA is a major contributor to binge alcohol drinking and to the genetic propensity to consume excessive amounts of alcohol.

Adolescent Mice Are Resilient to Alcohol Withdrawal-Induced Anxiety and Changes in Indices of Glutamate Function within the Nucleus Accumbens

“…Due to the relatively brief duration of mouse adolescence (Brust et al, 2015), all animals were subjected to a 14-day drinking period. This drinking period is similar to that employed in other studies of adolescent alcohol exposure (Spear, 2000b; Brunell and Spear, 2005; O’Tousa et al, 2013) and enables the extension of prior immunoblotting work (Cozzoli et al, 2012, 2014, 2016) to a shorter history of binge-drinking in adult animals. Approximately 24 h following the final drinking period, animals underwent behavioral testing or tissue collection.…”

“…For the present study, we also included plasticity-related calcium/calmodulin-dependent protein kinase II (CAMKII) in our analysis due to its recent implication in the maintenance of alcohol consumption, as well as negative affective states (Easton et al, 2013a; Zhao et al, 2015). Prior work from our group indicates that alcohol-drinking history increases glutamate-related protein expression selectively within the AcbS (Szumlinski et al, 2008; Cozzoli et al, 2009, 2012, 2016; Goulding et al, 2011). Thus, we measured protein expression within both the Acb shell and core in the present study with the expectation that the AcbS would show a greater number and larger changes in protein levels, relative to the adjacent, but functionally distinct, AcbC.…”

“…Our proteins of interest were selected based on previous work from our lab demonstrating that binge-drinking history upregulates these protein indices of excitatory neurotransmission including mGlu1/5, NR2A/B, and the downstream effector protein kinase C epsilon (PKCε; Szumlinski et al, 2008; Cozzoli et al, 2009, 2016; Goulding et al, 2011), which are believed to promote a “pro-alcoholic” phenotype (Szumlinski et al, 2008; Kalivas et al, 2009; Cozzoli et al, 2012). For the present study, we also included plasticity-related calcium/calmodulin-dependent protein kinase II (CAMKII) in our analysis due to its recent implication in the maintenance of alcohol consumption, as well as negative affective states (Easton et al, 2013a; Zhao et al, 2015).…”

Selective chemical genetic inhibition of protein kinase C epsilon reduces ethanol consumption in mice

“…These behaviors do not result from developmental changes since inducible transgenic expression of PKCε in the amygdala and striatum restores normal sensitivity to intoxication and increases drinking in Prkce −/− mice to levels observed in wild type mice (Choi et al, 2002). Moreover, knockdown of PKCε in the amygdala by RNA interference (Lesscher et al, 2009) or inhibition by a peptide designed to block translocation of activated PKCε (Cozzoli et al, 2015) reduces ethanol consumption in adult wild type mice. PKCε may modulate ethanol intoxication and consumption through phosphorylation of at least 2 substrates: GABA A γ2 subunits at Ser-327 (Qi et al, 2007) and the N-ethylmaleimide sensitive factor at Ser-460 and Thr-461 (Chou et al, 2010).…”

Binge Drinking With Protein Kinase C Epsilon: A Role for Mammalian Target of Rapamycin Complex 2?

“…(2) investigate the role of the enzyme protein kinase C epsilon (PKCɛ) in binge-like ethanol consumption using two models: a modified drinking in the dark (DID) procedure and a modified scheduled high alcohol consumption procedure. Their findings add to a growing literature, much of it from our laboratory, that indicates an important role for PKCɛ in ethanol consumption and reward (3).…”