Differential changes in the 5-hydroxytryptamine and insulin content of guinea-pig B-cells.
In the guinea-pig pancreas, 5-hydroxy-tryptamine (5-HT) occurs in the B-cells as well as in enterochromaffin cells scattered in the exocrine parenchyma. In the present study we examined the effects on the pancreatic 5-HT and insulin content of drugs known to affect the B-cells. For this purpose a radioimmunoassay of guinea-pig insulin was developed. Streptozotocin reduced the number of detectable B-cells and partially degranulated those that remained. It also lowered the insulin content of the pancreas and the 5-HT content of the B-cells but did not affect the 5-HT content of the enterochromaffin cells. Reserpine lowered the 5-HT content of both B-cells and enterochromaffin cells. The number and ultrastructure of the B-cells and the pancreatic insulin content was not affected. Streptozotocin + reserpine seemed to have additive effects of B-cell 5-HT. The results with these 2 drugs indicate that roughly 50% of pancreatic 5-HT is contained in the B-cells. Diazoxide markedly increased the pancreatic insulin content without affecting pancreatic 5-HT. Despite the fact that 5-HT and insulin are stored together in the cytoplasmic granules of the B-cells, 5-HT was differentially depleted from this store by reserpine. A marked disproportionality between 5-HT and insulin content was also induced by diazoxide.
D000818:Animals; D003594:Cytoplasmic Granules / Q000187:drug effects; D003981:Diazoxide / Q000494:pharmacology; D006168:Guinea Pigs; D007328:Insulin / Q000378:metabolism*; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008854:Microscopy, Electron; D011863:Radioimmunoassay / Q000379:methods; D012110:Reserpine / Q000494:pharmacology; D012701:Serotonin / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013311:Streptozocin / Q000494:pharmacology
D007328:Insulin; D012701:Serotonin; D013311:Streptozocin; D012110:Reserpine; D003981:Diazoxide