Project Summary – Genetic Targeting Core Substance use disorders (SUD) are characterized by dysregulation of brain circuitry that involves diminished activity of the brain reward circuits, increased responsiveness of the stress circuits and impaired functioning of the executive cortical circuits. Neural changes are observed in the basal ganglia, extended amygdala and prefrontal cortical regions and encompass a wide range of endogenous neurotransmitters including dopamine, opioid peptides, endocannabinoids, corticotropin releasing factor (CRF), dynorphin, glutamate and others. It implies that these maladaptations may be causally responsible for behavioral changes often observed in chronic drug users, for example habit formation and compulsive drug taking, that further worsen the neuronal and behavioral signs of SUD. Restoration of normal functioning of the brain circuits is therefore a desirable goal of SUD therapies. However, the exact influence of chronic drug use on the addiction brain circuits and how manipulation of these circuits could prevent or treat substance use disorders remains to be elucidated. As part of the Center of Excellence in Addiction Studies, the Genetic Targeting Core (GT Core) will assist users in obtaining preliminary data on neural mechanisms of addiction that will form basis for future NIDA grant applications. The GT Core will provide services to target and manipulate the addiction circuits in a cell specific and circuits specific manner using state-of-the-art genetic techniques, including optogenetics, chemogenetics and CRISPR/Cas9 gene editing. Optogenetic strategies use microbial-based light activated ion channels (opsins) that allow fast neuronal activation (channelrhodopsins) or inhibition (halorhodopsins, archaerhodopsins), while chemogenetic approaches use engineered ion channels (PSAMs) or G protein- coupled receptors (DREADDs) that can be activated pharmacologicaly. CRISPR/Cas9 gene editing allows direct in vivo manipulation of the genome in rodents. The introduction of functional transgenes, such as opsins and DREADDs or editing of native genes requires in vivo delivery and expression of genetic material in desired cells. This is accomplished with viral or nonviral vector systems. Cell and circuit specificity can be further enhanced by the use of a specific Cre-driver mouse line. The GT Core will provide three main services to its users that correspond with the three Specific Aims: 1) assist with the selection of gene targeting methods, including the choice of the transgenic mouse line, and the type of viral vector; 2) optimize and implement gene delivery using high precision stereotaxic instruments; and 3) verify the efficacy of gene targeting using fluorescent microscopy or protein and gene quantification techniques. The GT Core will coordinate work with the Administrative, Behavioral and Neuroanalytical Cores to develop effective experimental strategies that involve several Cores. The close collaboration bet...