Preliminary data suggests there exists an autoregulatory feedback loop within the human islet: insulin stimulates somatostatin, and somatostatin inhibits insulin secretion. The purpose of this First Award project is to demonstrate that insulin and somatostatin are intraislet mediators of islet cell secretion. Hormonal infusions and immunoneutralization techniques with antibodies and Fab fragments of antibodies directed against insulin and somatostatin will be used in isolated perfused human and rat pancreas models. These models allow for in vitro studies of cell-to-cell communication with preservation of islet microvasculature. Insulin and somatostatin secretory responses will be measured using radio- immunoassay techniques. Somatostatin and insulin mRNA transcription will be characterized using Northern blot technique. Diffusion characteristics of FITC-antibody and FITC-Fab fragments can be examined utilizing an in vivo microscopy rat pancreas model. The experiments in this proposal have these specific aims: 1. To determine whether intraislet somatostatin is an inhibitory mediator of insulin secretion; 2. To determine whether intraislet insulin is a stimulatory mediatory of somatostatin secretion; 3. To determine whether intraislet insulin regulates the transcription of somatostatin mRNA; 4. To determine whether intraislet somatostatin regulates the transcription of insulin mRNA; 5. To determine whether the antibodies and Fab fragments of the antibodies leave the intravascular compartment and enter the interstitium of the islet. The significance of this study is in obtaining a better understanding of islet physiology. Furthermore, we anticipate that these techniques will be used to study the transplanted islet.
Showing the most recent 10 out of 16 publications
