Graduate Studies Faculty
Susan Ingram Osborn, Ph.D.
Programs:Neuroscience Graduate Program
Physiology & Pharmacology
Program in Molecular & Cellular Biosciences
Research Interests:pain; drug addiction; amphetamine; dopamine; dopamine transporter; periaqueductal gray; electrophysiology, Neurobiology of Disease » PubMed Listing
Preceptor RotationsDr. Ingram Osborn has not indicated availability for preceptor rotations at this time.
Faculty MentorshipDr. Ingram Osborn has not indicated availability as a mentor at this time.
My research is focused on understanding neuronal plasticity in response to acute and long-term exposure to drugs of abuse. I am particularly interested in cellular mechanisms underlying changes in neuronal excitability following drug exposure. One area of current research is focused on the dopamine transporter (DAT) and an associated chloride current that I identified in midbrain dopamine neurons during my postdoctoral work with Dr. Susan Amara. The DAT is one of a family of transporters that are the main targets for psychostimulants, such as amphetamine and cocaine. These transporters are also targets for therapeutic drugs for disorders including depression and attention deficit disorder. Although the transporters are primarily known for regulating the extracellular concentrations of neurotransmitters through reuptake of released neurotransmitters, they have significant electrical activities as well. My recent studies of the electrical properties of the monoamine transporters have shown that these transporters have a potential role in modulating excitability of midbrain neurons. Future studies are planned to determine the relevance of transporter-associated currents in the regulation of synaptic transmission in midbrain dopamine neurons associated with reward pathways using electrophysiology and real-time imaging of a chloride biosensor that I have developed with my collaborators at the University of Pittsburgh.
Another area of current research focuses on identifying intracellular signaling mechanisms involved in morphine tolerance and dependence using in vitro brain-slice recordings. We study how mu opioid receptors (MORs) in the periaqueductal gray area (PAG) modulate neuronal excitability and synaptic transmission of PAG neurons. MORs are an integral part of the endogenous descending antinociceptive pathway that decrease pain impulses in the spinal cord. During my postdoctoral fellowship with Dr. Macdonald Christie, my colleagues and I determined the cellular pathway involved in opioid modulation of presynaptic GABA release and identified changes induced in this pathway following chronic opioid administration. I have continued these studies in my own laboratory since 2003 with a focus on changes in the PAG associated with repeated morphine administration, a paradigm that dissociates morphine tolerance from dependence. Techniques that we use in the laboratory on a daily basis include whole-cell patch-clamp electrophysiological recordings, live-cell fluorescence imaging, confocal microscopy, pharmacology and brain-slice and primary cultures of midbrain neurons. My collaboration with Dr. Michael Morgan, a behavioral neuroscientist at Washington State University Vancouver has been very successful in developing an integrative behavioral and cellular approach for studying mechanisms of opioid tolerance. Our most recent work determined that regulation of MORs (i.e. desensitization and internalization processes) is vastly different in presynaptic versus postsynaptic sites in PAG neurons. In addition, we have described compensatory signaling via ERK1/2 and changes in GABA neurotransmission following the development of antinociceptive tolerance. I recently moved my laboratory to Oregon Health & Science University to enhance the research environment for my work. I have active collaborations with Dr. Julie Saugstad (Department of Anesthesiology) and Dr. Mary Heinricher (Department of Neurological Surgery) at OHSU. These collaborations will continue to foster multi-disciplinary work from molecular mechanisms (Dr. Saugstad), electrophysiology (myself) and systems level analyses of network activation (Dr. Heinricher) in the study of descending pain and analgesia mechanisms.