Dopamine Neuronal Microcircuits Controlling Methamphetamine Seeking Behavior

Project Summary/Abstract This proposal is being submitted to support the transition of Dr. Dominguez-Lopez from mentored trainee to an independent investigator in the neurobiology of drug addiction, specifically studying the dopamine microcircuits controlling drug-seeking behavior. Dr. Dominguez-Lopez works under the mentorship of Dr. Michael Beckstead at the Oklahoma Medical Research Foundation (OMRF) investigating the role of dopamine neurotransmission in the ventral tegmental area (VTA) in methamphetamine (METH) self- administration behavior. Dr. Beckstead is a recognized expert in dopamine synaptic transmission in the fields of addiction. Dr. Beckstead’s laboratory combines mouse models of drug self-administration with patch-clamp electrophysiology and immunocytochemistry, providing a dynamic environment for Dr. Dominguez-Lopez to become an experienced scientist. The submitted proposal incorporates scientific training in methodologies to study mitochondrial metabolism, transcriptional analysis, bioinformatics and genetic labeling of active neuronal populations. The applicant will be receiving training in educational methods, scientific writing, grant preparation and other skills necessary to become an independent brain research scientist from an underrepresented group. The proposed program includes mentoring interactions with Dr. Holly Van Remmen, Dr. Willard Freeman, Dr. Linda Thompson, members of OMRF, and Dr. Rajeshwar Awatramani from Northwestern University in Chicago. The short-term objective of this application is to enhance Dr. Dominguez- Lopez’s knowledge of mitochondrial metabolism and single cell transcriptomics applied to dopaminergic circuits. In the long-term, this will enable Dr. Dominguez-Lopez to secure protected time for training and research activities, establish new collaborations, and pursue his novel independent research resulting in competitive grant proposals. Preliminary data obtained by Dr. Dominguez-Lopez indicates that prolonged METH self-administration in mice produces a decrease of dopamine neurons in the VTA, decreases dopamine cell excitability, increases mitochondrial oxygen consumption rate and decreases levels of glutathione. These observations are concurrent with increased drug-seeking behavior. This research proposal expands on those findings to identify metabolic and molecular characteristics in dopamine circuits that provide resistance or vulnerability to METH exposure. The central hypothesis is that a subpopulation of VTA dopamine neurons is responsible for METH-seeking behavior, forming a microcircuit that is resistant to mitochondrial oxidative stress induced by chronic METH exposure. The proposed aims are 1) Identification of VTA dopamine microcircuits encoding METH-seeking behavior, and 2) Metabolic characteristics of VTA dopamine neurons encoding METH-seeking behavior. Identification of the specific brain circuits responsible for METH addictive properties is a first step to develop therapeutic strategies to help addicts recover from METH addiction.