Analgesia, the dampening of nociceptive responses to noxious stimuli capable of damaging tissues, is an adaptive behavioral response for organisms- allowing them to feel less pain in physiologically appropriate situations. Our parent grant uses the genetically tractable model organism Drosophila to explore the molecular/genetic bases of opiate-induced analgesic signaling. Our long-term goal in this basic research project is to identify and characterize analgesic signaling pathways in Drosophila larvae. We have found previously that the opiate compounds morphine and fentanyl are analgesic for Drosophila larvae and that a conserved G-protein coupled receptor (GPCR), AstC-R1, is required in this organism for opiate-induced thermal analgesia upon exposure to high-temperature noxious stimuli. This parent NIH grant, like most others, involves training graduate students. My lab, like the NIH and NINDS, is dedicated to training a diverse scientific workforce. In February of 2023 we took on a new graduate student, Samantha (Sam) Mota, who, due to her Latin-American descent, qualifies as a diversity supplement candidate. The aims of the parent grant are to characterize AstC-R1's requirement for thermal analgesia, to interrogate functional expression of AstC-R1 in mediating thermal analgesia, and to assess whether the putative receptor's analgesic effects extend to other sensory modalities beyond heat. Sam's graduate project is two-tiered. She is first driving the completion of our first analgesia paper- focusing on the cellular locus of action of AstC-R1 and possible analgesic actions of the AstC peptide. Her more exploratory work (subject of a planned future F31 submission) is primarily related to our original third aim where we explore deleterious biological side effects of morphine such as constipation. Sam's aims in this diversity supplement are two-fold and represent an in-scope expansion of the original project: First, she will build on prior experiments to unravel where AstC-R1 functions in analgesia- trying to pinpoint which particular nociceptive basin interneurons are required. Second, Sam will explore endogenous analgesic roles of the AstC neuropeptide ligand for AstC-R1, and, in a substantial but related expansion of the original aims- tackle possible neuronal connectivity between AstC-R1-expressing and AstC-expressing neurons. The NINDS diversity supplement we propose here will fund a highly promising graduate student who is likely to become, upon the successful completion of her graduate project(s), a powerful role model for female-scientists of Latin-American descent. As her project progresses, Sam will apply for F31 funding focused on a new research direction that allows her to build her research skills- especially as they relate to assay design and video microscopy- opiate-induced constipation. Successful completion of her project aims will enable her to achieve both her short-term and long-term career goals, which eventually include teach...