Substance P binding in gastrointestinal tract of nondiabetic BB rat and changes in diabetic BB rat over time

Our aim was to determine sites of substance P binding in the gut of the BB rat and examine changes in SP binding in the diabetic rat, over time. Specific binding of [¹²⁵I]substance P was localized in sections of nondiabetic gut using emulsion autoradiography and quantitated in diabetic and nondiabetic gut using film autoradiography. High levels of SP binding were located in esophageal muscularis mucosa, circular muscle of the stomach and colon, deep muscular plexus, and in the circular muscle adjacent to the plexus in the ileum. The myenteric plexus demonstrated moderate to high levels of binding. Specific binding increased in the antrum and pylorus at three weeks and in the jejunum and distal colon at four weeks of diabetes but decreased in the distal ileum at two to four weeks of diabetes. Changes persisted at four to six months. These results contribute to understanding changes in the control of intestinal motility in diabetes.