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201228 https://hdl.handle.net/2286/R.2.N.201228 http://rightsstatements.org/vocab/InC/1.0/ All Rights Reserved 2025 2027-05-01T11:16:30 97 pages Masters Thesis Academic theses en Symes, Maggie Sweazea, Karen Johnston, Carol Domer, Adi Arizona State University Partial requirement for: M.S., Arizona State University, 2025 Field of study: Nutrition Birds have been considered a promising model for studying diabetes due to their ability to maintain health despite having naturally high plasma glucose concentrations. Preliminary studies in hummingbirds show that myo-inositol may play a role in protecting from the consequences of naturally high plasma glucose by regulating fuel selection and uptake in tissues. No study has focused on the myo-inositol pathway in an insectivorous avian species. The purpose of this study was to understand how myo-inositol impacts circulating glucose and its uptake in tissues of insectivorous birds. This was accomplished by catching wild European starlings (Sturnus vulgaris) at a park near Phoenix, AZ. The birds were brought to Arizona State University in Tempe, AZ, and had ad libitum access to water and a nutritionally balanced diet. Birds were also provided enrichment items and housed under controlled temperatures, 12-hour light/dark schedules, and allowed to acclimate for two weeks. For the first experiment, whole blood glucose concentrations were measured using a veterinary glucometer with blood from fasted birds before, 30, and 60 minutes after ingesting oral glucose (2 g/kg) with or without co-administration of 5% myo-inositol. In the second experiment, birds were fed two mealworms and consumed the same treatment amount of 2 g/kg of oral glucose and 13C-labeled glucose tracer with or without 5% myo-inositol. Blood samples were collected after 10 minutes and again after 45 minutes. The birds were then euthanized, and liver, kidney, pectoralis, and gastrocnemius muscle tissues were collected for LC-MS targeted metabolomics. Results showed a significant (p<0.001) difference in the time intervals of the fed and fasted birds. However, myo-inositol did not affect the blood glucose concentrations long-term. Statistical analysis showed a significant effect of body mass on tissue glucose concentrations (p=0.016). After oral glucose administration, smaller birds had ~1.3 times higher liver glucose concentrations than larger birds (p=0.014). Additionally, heavier birds had lower glucose concentrations in the gastrocnemius muscles following oral myo-inositol compared to glucose (p=0.019). This study demonstrates that myo-inositol may influence storage of glycogen and utilization of non-glucose energy sources in postural muscles dependent on different body masses in birds. Nutrition Examining the Effects of Oral Myo-inositol on Glucose Metabolism and Regulation in Wild European Starlings (Sturnus vulgaris)