Insulin-like growth factor II messenger ribonucleic acids are synthesized in the choroid plexus of the rat brain

Abstract

Previous studies demonstrating the presence of immunoreactive insulin-like growth factors (IGFs) and their receptors in the brain suggest a role of the IGFs in the central nervous system. IGF-II has been implicated as the predominant IGF in brain of mature animals based on studies of immunoreactive pep-tide and of IGF-II mRNAs. To obtain information about the sites of synthesis of IGF-II in adult rat brain, a32P-labeled 31 base long synthetic oligo- deoxyribonucleotide complementary in sequence to trailer peptide coding sequences in rat IGF-II mRNA (IGF-II 31 mer) was hybridized with coronal sections of fixed rat brain. The IGF-II 31 mer showed specific hybridization with the choroid plexus throughout rat brain, whereas in other brain regions, structures or cells, hybridization was not discernibly above back-ground. These findings suggest that the choroid plexus is a primary site of synthesis of IGF-II, a probable source of IGF-II in cerebrospinal fluid, and a potential source of IGF-II for actions on target cells within the adult rat brain. © 1988 by The Endocrine Society.