Expression of ornithine decarboxylase in pancreatic development

Abstract

We examined the relationship between ornithine decarboxylase (ODC) and growth and differentiation in the developing rat exocrine pancreas. The ODC activity profile showed 2 distinct stages of increases with the first occurred at 14-16 days of age, and a second at 21-23 days of age. Growth parameters evaluated as gains in tissue mass, protein and DNA content in the pancreas indicated a low growth rate soon after birth with a transition to a much more rapid growth rate around the age of 20-21 days, a time corresponded to the second rise in ODC activity. Differentiation parameters evaluated as the accumulation of trypsinogen, amylase and lipase showed different temporal changes. While the rate of accumulation of all three enzymes was relatively low following birth, a rapid rate of accumulation of trypsinogen and amylase started around 15-16 days, a time corresponding to the first rise in ODC activity. Lipase, however, did not show an increase in its accumulation until around age 20 days. These results indicate that a rise in ODC activity is closely associated with growth and differentiation in the developing rat pancreas. To further examine this issue, the steady state levels of ODC mRNA in developing rats were evaluated by Northern blots probed with an ODC cDNA. The developmental profile of ODC mRNA showed a broad peak with a pronounced shoulder occurring at 10 days of age. A higher peak was reached around 20 days of age, then dropped precipitously to a very low level at the age of 24 days. This temporal changes in the level of ODC mRNA show good relationship to the changes in ODC activity suggesting that the control of ODC expression occurs at least in part at the pre-translational level.

Neonatal Hypoxia in the Rat: Effects on Exocrine Pancreatic Development

“…This would divert the necessary energy and building blocks from the general systemic pool that would otherwise be used for normal development of tissues including the pancreas. From 14 to 21 days of age, the exocrine pancreas undergoes rapid transformation (20). The nutritional handicap created by hypoxia may cause the delay in maturation of pancreatic digestive enzymes in the hypoxic rats after return to normoxia, leading to a compromised pancreas in the 21-dayold animals (14 days after hypoxia).…”

Neonatal Hypoxia in the Rat: Effects on Exocrine Pancreatic Development

“…This would divert the necessary energy and building blocks from the general systemic pool that would otherwise be used for normal development of tissues including the pancreas. From 14 to 21 days of age, the exocrine pancreas undergoes rapid transformation (20). The nutritional handicap created by hypoxia may cause the delay in maturation of pancreatic digestive enzymes in the hypoxic rats after return to normoxia, leading to a compromised pancreas in the 21‐day‐old animals (14 days after hypoxia).…”