Demonstration of the presence and localization of the synthesis of a somatostatin-like substance by immunocytochemistry and hybridization in situ in the brain of Helix aspersa]

The immunocytological method has revealed the presence of somatostatin-like substance (SSI) in the brain of the snail Helix aspersa Müller. The Cerebral Green Cells (CeGC) in the mesocerebron and some neurons in parietal and visceral ganglia react positively with an antibody raised against Vertebrate somatostatin-14. The hybridization in situ with an oligonucleotide probe labelled with 35S-dATP complementary to the 3'-coding region of rat preprosomatostatin mRNA seems to show a colocalization between synthesis and stocking sites of SSI in the nervous ganglia. These results suggest for the first time that the codage of a SSI seems to be realized in the same way in Helix aspersa and Mammals.