Abstract: In order to investigate the distribution and function ofsomatostatin 4 (sst4) gene during zebrafish (Danio rerio) development,sst4gene specifically expressed in the pancreas of zebrafish was identified during 24－96 hpf byin situhybridization (ISH). By espousing the 5 dpf zebrafish larva with different mass concentration of glucose, qPCR analysis showed thatsst4expression levels were significantly reduced with the increase of the exposed glucose concentration. These results suggested an important role ofsst4gene on pancreatic development and differentiation and glucose regulation. Further, by counted the number of α cells producing glucagon and β cells producing insulin, laser confocal scanning results showed that in thesst4mutant, β cell number was significantly increased compared to that in the wildtype fish, while α cell number was no difference between the two genotypes. Blood glucose measurement in adults (120 dpf) showed thatsst4mutants were with lower glucose levels, compared to wildtype. And glucose metabolism related genes,insa,insbandg6pca.1showed a significant decrease, whilegcgbgene showed an increase in thesst4mutant. These results indicated that thesst4gene may involve into blood glucose homeostasis though its function as an inhibitor of β cell proliferation.

Key words: somatostatin 4, pancreas, β cell proliferation, blood glucose, zebrafish