Influence Of Local And Circuit-Wide Modulation Of The Mesocorticolimbic Reward System On The Reinstatement Of Cocaine Seeking

Cocaine abuse poses a significant public health concern both in the United States and across the globe. A critical issue with cocaine abuse is the discouragingly high rate of relapse among addicts following detoxification and abstinence. The research presented in this doctoral dissertation examines the influence of local and circuit-wide modulation of the mesocorticolimbic reward system on cocaine reinstatement, an animal model of relapse. The data presented in the second and third chapters of this dissertation demonstrate that DBS may serve as a possible non-pharmacological therapeutic intervention in the treatment of cocaine addiction. In Chapter 2, I show that DBS of the nucleus accumbens shell attenuates the cue-induced reinstatement of cocaine seeking, expanding upon previous work demonstrating the efficacy of accumbal shell DBS in attenuating cocaine priming-induced reinstatement. In Chapter 3, I demonstrate that DBS of the medial prefrontal cortex (mPFC), but not the basolateral amygdala (BLA) or the ventral hippocampus (vHipp) selectively attenuates the reinstatement of cocaine seeking. Moreover, this effect is constrained to the infralimbic subregion of the mPFC as DBS in the prelimbic or anterior cingulate cortices has no effect on cocaine reinstatement. Further, my results also suggest that infralimbic mPFC DBS attenuates cocaine reinstatement by disrupting glutamatergic transmission to the nucleus accumbens. The data presented in Chapter 4 of this dissertation support a substantial body of evidence demonstrating that increased transmission through GluA1-containing AMPA receptors (AMPARs) in the nucleus accumbens shell promotes cocaine reinstatement. These data reveal the novel role of the protein, AKAP150, in the reinstatement of cocaine seeking. My findings indicate that AKAP150 promotes cocaine reinstatement by facilitating D1-like dopamine receptor (D1DR)-induced, PKA-mediated phosphorylation of GluA1-containing AMPARs. Collectively, these findings suggest that AKAP150 may serve as a biochemical bridge linking the dopamine and glutamate systems in the nucleus accumbens during cocaine reinstatement

Colocalization of Protein Kinase A with Adenylyl Cyclase Enhances Protein Kinase A Activity during Induction of Long-Lasting Long-Term-Potentiation

The ability of neurons to differentially respond to specific temporal and spatial input patterns underlies information storage in neural circuits. One means of achieving spatial specificity is to restrict signaling molecules to particular subcellular compartments using anchoring molecules such as A-Kinase Anchoring Proteins (AKAPs). Disruption of protein kinase A (PKA) anchoring to AKAPs impairs a PKA-dependent form of long term potentiation (LTP) in the hippocampus. To investigate the role of localized PKA signaling in LTP, we developed a stochastic reaction-diffusion model of the signaling pathways leading to PKA activation in CA1 pyramidal neurons. Simulations investigated whether the role of anchoring is to locate kinases near molecules that activate them, or near their target molecules. The results show that anchoring PKA with adenylyl cyclase (which produces cAMP that activates PKA) produces significantly greater PKA activity, and phosphorylation of both inhibitor-1 and AMPA receptor GluR1 subunit on S845, than when PKA is anchored apart from adenylyl cyclase. The spatial microdomain of cAMP was smaller than that of PKA suggesting that anchoring PKA near its source of cAMP is critical because inactivation by phosphodiesterase limits diffusion of cAMP. The prediction that the role of anchoring is to colocalize PKA near adenylyl cyclase was confirmed by experimentally rescuing the deficit in LTP produced by disruption of PKA anchoring using phosphodiesterase inhibitors. Additional experiments confirm the model prediction that disruption of anchoring impairs S845 phosphorylation produced by forskolin-induced synaptic potentiation. Collectively, these results show that locating PKA near adenylyl cyclase is a critical function of anchoring

Molecular Characterization and Evolutionary Analyses of <i>Carnivore Protoparvovirus 1</i> <i>NS1</i> Gene

Carnivore protoparvovirus 1 is the etiological agent of a severe disease of terrestrial carnivores. This unique specie encompasses canine parvovirus type 2 (CPV-2) and feline panleukopenia virus (FPLV). Studies widely analyzed the main capsid protein (VP2), but limited information is available on the nonstructural genes (NS1/NS2). This paper analyzed the NS1 gene sequence of FPLV and CPV strains collected in Italy in 2009&#8211;2017, along with worldwide related sequences. Differently from VP2, only one NS1 amino-acid residue (248) clearly and constantly distinguished FPLV from CPV-2, while five possible convergent amino-acid changes were observed that may affect the functional domains of the NS1. Some synonymous mutation in NS1 were non-synonymous in NS2 and vice versa. No evidence for recombination between the two lineages was found, and the predominance of negative selection pressure on NS1 proteins was observed, with low and no overlap between the two lineages in negatively and positively selected codons, respectively. More sites were under selection in the CPV-2 lineage. NS1 phylogenetic analysis showed divergent evolution between FPLV and CPV, and strains were clustered mostly by country and year of detection. We highlight the importance of obtaining the NS1/NS2 coding sequence in molecular epidemiology investigations