Greg M. Swain, PhD
Ph.D., 1991, University of Kansas
East Lansing Campus
Neuroanalytical Measurements in the Peripheral Vasculature and Gastrointestinal Tract
Neuroeffector transmission mechanisms differ depending on the target tissue. Abnormalities in signaling are associated with various diseases including hypertension and gastrointestinal disorders (e.g., IBS). We use diamond and carbon fiber microelectrodes along with in vitro electrochemical methods to investigate neuroeffector signaling in peripheral tissues. These measurements are useful for probing dynamic changes in concentration of an electroactive analyte in response to a stimulus. They also provide insight on the local neuropharmacology. We are using these analytical methods to better understand the dysregulation that is associated with obesity-linked (i) hypertension and (ii) gut dysmotility. Nearly 70% of American adults are either overweight or obese. Being obese puts one at a higher risk for health problems such as heart disease, stroke, high blood pressure, diabetes and more. Inexpensive conducting diamond is an enabling electrode material for these measurements because of its superior response sensitivity, reproducibility and stability in the complex tissue environment.
The targeted signaling molecules include (i) norepinephrine released from sympathetic nerves supplying arteries and veins, (ii) serotonin released from enterochromaffin cells in the intestinal mucosa and (iii) nitric oxide released from inhibitory motor neurons in the gut. Tissues from animal models as well as humans are being used in the research. Immunohistochemical and pharmacological approaches, analytical separation methods and in vitro electrochemical methods are being employed to better understand these obesity-linked disorders.
New research is involving the design, fabrication and application of (i) diamond microelectrode arrays (MEAs) that will enable the measurement of one or multiple neurotransmitters spatially across a tissue specimen and (ii) amperometric chem/biosensors for important signaling molecules like ATP and peroxynitrite (a marker of inflammation). The diamond microelectrode arrays are fabricated at the Center for Coatings and Diamond Technology at MSU. The projects are collaborative with faculty in the Departments of Pharmacology and Toxicology, Physiology and Pediatric Medicine at MSU.