Immunohistochemical localization of insulin-like growth factor I and II in the endocrine pancreas of birds, reptiles, and amphibia.
Immunoreactive insulin-like growth factors I and II (IGF-I, IGF-II) were sought in the endocrine pancreas of representative birds, reptiles, and amphibia using antisera specific for mammalian IGF-I and IGF-II and the classical islet hormones insulin ( INS), glucagon ( GLUC), somatostatin ( SOM), and pancreatic polypeptide ( PP) in double immunofluorescence. Both IGF-I and IGF-II immunoreactivities were present in the endocrine pancreas of all species. IGF-II immunoreactivity was exclusively found in INS-immunoreactive (-IR) cells, indicating evolutionary conservation of the islet IGF-II system. In contrast, IGF-I immunoreactivity was distributed differently among the species and never occurred in INS-IR cells. In the anuran Xenopus laevis, IGF-I immunoreactivity was present in islet cells showing coexistence of GLUC and PP immunoreactivities. In reptiles, the lizards (Lacerta viridis, Scincus officinalis) exhibited IGF-I immunoreactivity in PP-IR and SOM-IR cells and the snakes (Psamophis leniolatum, Coluber ravergieri) in SOM-IR and GLUC-IR cells. In birds, IGF-I immunoreactivity was located either in SOM-IR cells only (Gallus g. domesticus, Streptopelia roseogrisea) or in PP-IR and SOM-IR cells (Coturnix c. japonica). Thus, the distribution patterns of islet IGF-I immunoreactivities in birds, reptiles, and amphibia are equivalent to those in mammals and most bony fish. They differ, however, from those found in cartilaginous fish, cyclostomes, and protochordates, where a total or partial coexistence of IGF-I and INS immunoreactivities has been obtained. Therefore, the divergence of IGF-I and INS seems to have occurred early in vertebrate phylogeny. Furthermore, the existence of IGF-I immunoreactivity likely is common in the islets of all vertebrates. Finally, no phylogenetic trend to concentrate IGF-I immunoreactivity in a particular islet cell type is apparent.[1]References
- Immunohistochemical localization of insulin-like growth factor I and II in the endocrine pancreas of birds, reptiles, and amphibia. Reinecke, M., Broger, I., Brun, R., Zapf, J., Maake, C. Gen. Comp. Endocrinol. (1995) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg
