2018 |
Castro, Daniel Charles |
F32Activity Code Description: To provide postdoctoral research training to individuals to broaden their scientific background and extend their potential for research in specified health-related areas. |
Dissecting the Role and Mechanisms of Mu Opioid Receptors in Nucleus Accumbens
PROJECT SUMMARY: The primary goal of this training proposal is to define the functional role and mechanisms of the mu opioid receptor (MOR) system in nucleus accumbens (NAc) medial shell. During my training period, I will be trained in novel genetic, in vivo imaging, and optogenetic approaches, as well as guided on a robust, specifically tailored career development plan designed to prepare me for eventual independence. The first research aim of this training proposal seeks to determine the functional role of MORs in NAc through constitutive and conditional knockout models and reversible pharmacological manipulations. Each of these models will be tested on multiple behavioral assays to determine whether MORs are necessary for generating motivated behaviors, or selectively recruited to enhance behaviors in highly motivated states (e.g., hunger). In a related, but separate set of experiments, Aim 1B uses cell type specific knockout and knockin models to further refine and identify the mechanisms through which MORs act to mediate motivated behaviors. While Aim 1 identifies where and when MORs act, Aim 2A seeks to identify how MOR signaling alters neural activity in specific neuronal population ensembles of neurons with subsecond resolution. Finally, Aim 2B uses a temporally precise chimeric photosensitive mu opioid receptor and optogenetic methods to specifically and spatiotemporally activate MOR signaling pathways during discrete behaviors. This dual approach of observational in vivo imaging during MOR-dependent behaviors, coupled with experimenter controlled time-locked activation of MOR systems will provide important insights into the mechanisms of how MORs mediate motivated behaviors. The information gained from the studies outlined in this proposal may help provide insights into how endogenous opioid systems become highjacked during opioid addiction or other forms of drug abuse. A more refined analysis of this neuropeptide system will allow for more directed and targeted treatments for those suffering from addiction or mood/motivation disorders.
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1 |
2020 |
Castro, Daniel Charles |
K99Activity Code Description: To support the initial phase of a Career/Research Transition award program that provides 1-2 years of mentored support for highly motivated, advanced postdoctoral research scientists. |
Physiological and Molecular Mechanisms of Mu Opioid Receptors in Motivation and Affect @ University of Washington
Project Summary: The primary goal of this training proposal is to understand, with mechanistic granularity, how mu opioid receptors (MORs) modulate motivated `wanting' versus affective `liking' in nucleus accumbens (NAc). During the proposed K99 training period, I will be trained in two in vivo physiology/imaging approaches (fiber photometry and 1-photon microscopy) and on intracellular/molecular effector systems. Additionally, I will actively participate in professional/career training opportunities and have frequent meetings with my mentoring committee to prepare to apply and succeed in an independent faculty position. The first research aim of my proposal seeks to understand the temporal dynamics and effects of endogenous MOR signaling in the DRNEnk?NAc pathway. My previous postdoctoral research, using pharmacology, genetics, and optogenetics/chemogenetics, has identified the terminals of an enkephalinergic dorsal raphe nucleus projection to NAc as the site of MOR action for modulating food intake behaviors. To better understand how MOR signaling affects this pathway, I will use two in vivo imaging approaches, fiber photometry and microendoscopy, to determine how endogenous MOR signals shape neural circuit activity during motivated behaviors (Aim 1, K99). Additionally, because the roles of specific intracellular signaling cascades have not been well defined in brain reward circuits, I will manipulate G-protein and beta-arrestin signaling pathways to determine how each of them contributes to behavior (Aim 2, K99). During the K99 phase, I will also be preparing to lead my own research lab. I will actively participate in scientific society leadership positions (chairing symposia, steering committees), learn about how to direct a lab (budgeting and administrative tasks), and continue to further my scholarly knowledgebase (planned interactions with my mentor and committee members). For the R00 ?independent? phase of my proposal, I propose to build on the mentored training above to examine what mechanisms and circuits underlie MOR-mediated affective `liking' in NAc (Aim 3). These studies are of interest because growing evidence suggests that though NAc MORs can robustly modulate both motivation and affect, they likely do so via different neural mechanisms. Understanding how these biopsychological systems are dissociable, even within a specific neurochemical class, has important implications for developing novel therapeutic drugs that are efficacious without also having a propensity for abuse. I will selectively disrupt or restore MOR function using multiple genetic mouse models and viral vector interventions, as well as record endogenous neuronal responses in vivo using microendoscopic approaches. I will perform these experiments while testing mice on the affective test reactivity (TR) test, which classifies and quantifies innate orofacial reactions to taste stimuli and has been used effectively for decades to measure the affective value of taste stimuli. The knowledge gained from these studies and mentorship opportunities will greatly facilitate the development of my own research program, preparing me for the next phase of my career.
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0.99 |