Neuropeptide Y (NPY) is a widely distributed neurotransmitter in the central and peripheral nervous system. In the normal rat pancreas, NPY is confined to neuronal elements, including fibers penetrating the islets. However, treatment of rats with the glucocorticoid dexamethasone (DEX) induces NPY expression also in islet cells. Previously performed double immunocytochemistry (ICC) and in situ hybridization (ISH) combined with ICC revealed that the majority of NPY-expressing islet cells are β-cells. The present study, using ICC, ISH, and Northern blot, addressed the question whether the islet cell expression of NPY induced by DEX is affected by concomitant insulin (60 U/kg body wt daily for 12 days) treatment. Further, the time course of NPY expression in the islet cells after DEX withdrawal was examined. Treatment with DEX (2 mg/kg body wt daily for 12 days) confirmed the induction of NPY expression in numerous cells, most of which were β-cells, dispersed within the islets. Northern blot analysis of RNA extracted from isolated islets of DEX-treated rats revealed a strong signal for NPY. Furthermore, DEX also induced NPY expression in isolated rat islets during a 5-day culture period in DEX (100 nmol/l). In vivo, the DEX-induced islet cell expression of NPY mRNA was rapidly reversed after cessation of DEX, being nondetectable 5 days post-treatment; NPY peptide was nondetectable 10 days post-treatment, indicating a slower turnover of the formed peptide. After combined treatment with DEX and insulin, the frequency of islet cells expressing NPY was markedly lower than after treatment with DEX alone. The vast majority of the NPY-expressing cells were β-cells. In conclusion, DEX-induced NPY expression in rat islet cells is dependent on continuous DEX treatment and is partly prevented by exogenous insulin. The results suggest that the DEX-induced islet NPY expression is regulated by insulin.
Skip Nav Destination
Article navigation
Original Articles|
October 01 1996
Dexamethasone-Induced Neuropeptide Y Expression in Rat Islet Endocrine Cells: Rapid Reversibility and Partial Prevention by Insulin
Ulrika Myrsén;
Ulrika Myrsén
Department of Physiology and Neuroscience, Section of Neuroendocrine Cell Biology
Lund
Search for other works by this author on:
Bo Ahrén;
Bo Ahrén
Department of Medicine, University of Lund
Malmo, Sweden
Search for other works by this author on:
Frank Sundler
Frank Sundler
Department of Physiology and Neuroscience, Section of Neuroendocrine Cell Biology
Lund
Search for other works by this author on:
Address correspondence and reprint requests to Dr. Ulrika Myrsen, Department of Physiology and Neuroscience, Section of Neuroendocrine Cell Biology, Biskopsgatan 5, 223 62 Lund, Sweden.
Diabetes 1996;45(10):1306–1316
Article history
Received:
January 02 1996
Revision Received:
May 30 1996
Accepted:
May 30 1996
Citation
Ulrika Myrsén, Bo Ahrén, Frank Sundler; Dexamethasone-Induced Neuropeptide Y Expression in Rat Islet Endocrine Cells: Rapid Reversibility and Partial Prevention by Insulin. Diabetes 1 October 1996; 45 (10): 1306–1316. https://doi.org/10.2337/diab.45.10.1306
Download citation file:
13
Views