Neurobiology of taste, smell and eating behaviors: Molecular and neuronal mechanism of sensory science and metabolism along the gut-brain-axis in animal models.

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The Sensory Science and Metabolism Unit was established in October 2017 (FY18). This fiscal year FY20, we continued to study sensory science and metabolism in animal models of obesity and metabolic dysfunction. We established animal projects focused on the overall goal of the laboratory. This should complement the clinical protocols and enable us to study biological mechanisms of sensory science and metabolism- including the underlying pathophysiology of maladaptive behaviors and assess potential interventions. To achieve this goal, we have been developing protocols that utilize techniques including optogenetics, electrophysiology, transcriptomic studies, immunohistochemistry, and behavioral studies. Two new collaborations have been established with intramural and extramural collaborators. Metabolic Dysfunction and Sensory Science: The rise in obesity is associated with an increased availability of highly palatable and energy-dense foods, rich in fat and sugar. The pleasure driven value of energy-dense foods promotes their preferential consumption which can lead to increased caloric intake and obesity. Taste, olfaction, and other chemosensory systems contribute to hedonic processing and eating behavior. Thus, there is growing interest in the role of taste in obesity, including the study of the biological mediators of fat-taste and associated olfaction as potential targets for pharmacologic and nutritional interventions. As part of this overall umbrella we began examining the effect of diet (high fat) on genes a project led by Rosario Jaime-Lara with support from Brianna Brooks and Claudia Colina-Prisco: The growing interest in the role of fat taste in obesity highlights the importance of taste and diet in eating behavior and health. Studies of taste-related genes have focused on gene expression in the mouth. However, taste-related genes are located throughout the body, including in brain regions known to regulate eating and taste. Thus, we aimed to examine genetic differences in taste and metabolic related genes in brain tissue of obese and normal-weight mice. We used qPCR to examine 64 taste and metabolic related genes in the striatum, olfactory-bulb, and striatum. We also used RNA sequencing to examine transcriptomic-level differences in these three brain regions. We found changes in metabolic gene expression of obese mice (compared to normal-weight mice). We also found increased expression of CD36, a gene associated with fat-taste. Additionally, RNA sequencing revealed genes were differentially expressed in the striatum (274 genes) and in olfactory bulb (19 genes). Lastly, we are working to characterize D1 and D2 MSNs in mice following a HFD, including their chemosensory phenotype and activity patterns. Sensory System Disturbances: Opioid use disorders, including abuse of prescription pain relievers, are a national crisis with devastating consequences, including a rapidly escalating number of opioid overdose-related deaths. The physiological mechanisms underlying pain, addiction, and their intersection are not fully understood. The purpose of this research is to study genomic changes across multiple phenotypes of pain, opioid use, and opioid use disorder. The goal is to improve understanding of relationship between disturbances in sensory systems and disease. This includes individual and addiction-induced differences in thresholds and responses to taste, olfaction, and changes in pain perception. Projects have started and preliminary findings have been obtained. No publication are available for these projects yet.