Maturation of Secretory Function in Rat Pancreas

Werlin, Steven L.; Stefaniak, John

doi:10.1203/00006450-198202000-00009

Cited by 29 publications

(12 citation statements)

References 3 publications

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“…Teleologically, the pancreas at this age does not "need" high rates of protein synthesis. A large increase in protein synthesis does occur at 48 h, at the time when we and others have shown both increased binding of CCK and responsiveness to CCK and carbachol (13)(14)(15)(16)(17)(18). DNA synthesis, in contrast, already high at birth, reaches a maximum at 72 h of age, then slowly declines exponentially to adult levels.…”

Section: Discussionmentioning

confidence: 97%

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DNA and Protein Synthesis in Developing Rat Pancreas

et al. 1987

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ABSTRACT. To define developmental patterns, we determined the rate of protein and DNA synthesis in rat pancreas at birth, 1, 2, 3, 7, 10, 14, 21, 28 days, 2 months, 3 months, and in adults. Fragments of freshly minced pancreas were incubated with [3H]-thymidine and [14Cj-leucine and the DNA and protein synthesis rates were measured. We found that 1) DNA content was lowest at birth, rose through day 3, plateaued at about 8 mg/g wet weight through day 14, then slowly decreased to the adult value of about 5 mg/g at 2 months; 2) protein content, although high at birth, decreased rapidly to a value of 80 mg/g at day 3 and slowly rose to the adult value of 160 mglg; 3) protein synthesis, low at birth, rapidly increased to about five times the adult value by day 3, and remained elevated for the 1st month; 4) DNA synthesis was 15 times the adult rate at birth, increased to 30 times at 3 days of age, then declined slowly in an exponential fashion to the adult value. We conclude that the pancreas at birth is poised biosynthetically to undergo a rapid hyperplastic and hypertrophic response, and this process reaches a maximal rate at about 3 days of age. (Pediatr Res 22: 34-38,1987) Abbreviations MEM, minimum essential medium BSA, bovine serum albumin SA, specific activity PCA, perchloric acid CCK, cholecystokinin Numerous studies have defined the structural and functional development of rodent exocrine pancreas. Similarly, a number of studies has evaluated the effects of various agents thought to be trophic for the exocrine pancreas on DNA and protein content of the developing pancreas. Previous studies, however, have evaluated total DNA and protein content, but not actual rates of synthesis of DNA and protein at various ages (1-5). Since cellular content of biomolecules reflects the opposing actions of synthesis and degradation, the true effects of any agent tested may be masked when total organ content is measured. In addition, increases in DNA synthesis in the stomach and small intestine can be observed before an increase in DNA content itself (6). A further difficulty is that technically it is extremely difficult to remove the entire pancreas from neonatal rats. Accordingly, we have evaluated DNA and protein synthesis in rat pancreas of various ages and compared synthetic rates to those found in the adult animal. Not surprisingly, the synthesis rates of both were found to be considerably higher in the immature animal than in the mature animal. MATERIALS AND METHODSSprague Dawley rats obtained from King Laboratories, Madison, WI were used for all studies and were kept under controlled light and temperature conditions. After birth, the rats were not disturbed except for the addition of food and water. Pups were sacrificed at the stated ages a 2 h for ages up to 72 h, and a 1 day for ages 1 to 4 wk. Adult animals (males only) were 4-6 months old. The date of birth was designated as day 0. Before weaning, rats were not fasted; after weaning (day 21), rats were fasted overnight before sacrifice, but allowed free access t...

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Section: Discussionmentioning

confidence: 97%

“…This appears due to a deficiency of both muscarinic and CCK receptors (1 6-18). The postreceptor Ca++ transducing machinery appears to be functional at birth (13)(14)(15).…”

Section: Discussionmentioning

confidence: 99%

DNA and Protein Synthesis in Developing Rat Pancreas

et al. 1987

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“…The exocrine pancreas of fetal and new born rats are unresponsive to hormonal secretagogues such as cholecystokinin, but with increasing age the pancreatic receptors de velop functional maturity [22], Hormonal un responsiveness due to receptor deficiency may also be a factor in the newborn human infant [4]. The increase in serum lipase secre tion in early life may merely reflect an in crease in the specificity of the pancreatic acini to bind and respond to cholecystokinin.…”

Section: Discussionmentioning

confidence: 99%

The Ontogeny of Serum Immunoreactive Pancreatic Lipase and Cationic Trypsinogen in the Premature Human Infant

et al. 1988

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We evaluated the development of the exocrine pancreas in 16 healthy preterm infants (29.3 ± 1.6 weeks). The infants were fed breast milk with formula supplements (n = 8) or formula alone (n = 8). Growth was monitored weekly for 12 weeks then at 3, 6, 9, 12 months. At the same intervals sera were determined for pancreatic lipase and cationic trypsinogen. In addition, cord blood samples were analysed from another 33 preterm (27.6 ± 5.2 weeks) and 75 healthy full-term infants. Serum pancreatic lipase in the cord blood of term (3.7 ± 0.4 μg/l) and preterm infants (1.8 ± 0.2 μg/l) was significantly below values reported for older children (10.5 ± 0.9 μg/l; p < 0.001). In the preterm infant, serum lipase was also significantly lower than values obtained at term (p < 0.001). At birth, serum trypsinogen for preterm (16.8 ± 1.3 μg/l) and term infants (23.3 ± 1.9 μg/l) were below those for older children (31.4 ± 3.7 μg/l; p < 0.05). Over the first 3 weeks of life, serum lipase and trypsinogen increased significantly. From 3 weeks to 12 months of age, serum trypsinogen values remained unchanged, but serum lipase increased dramatically after 10 weeks of age. Thus, at 6 and 12 months of age, the preterm infants had significantly higher serum lipase values than infants of the same age born at term. These two pancreatic enzymes appear to show independent age-related maturation in infants born before term. The rate of maturation of lipase appears to be accelerated by exposure to the extrauterine environment.

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“…The term fetal and newborn rat pan creases contain high concentrations of ex portable protein [1,2] but are insensitive to cholinergic and hormonal stimulation [3][4][5]. We have shown that not only is sensitivity to secretagogucs attained between 17 and 24 h of age, but that starvation for the first 24 h of life inhibits the maturation of secretory func tion [5].…”

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confidence: 93%

“…We have shown that not only is sensitivity to secretagogucs attained between 17 and 24 h of age, but that starvation for the first 24 h of life inhibits the maturation of secretory func tion [5]. Treatment of the enterally starved newborn rat with cholecystokinin octapep tide (CCK-8) or hydrocortisone allows nor mal development of secretory function [5], Since certain gastrointestinal hormones [6][7][8][9][10][11][12] and adrenocorticosteroids [13][14][15][16][17][18] are trophic for the pancreas, it is possible that the release of these agents secondary to feeding may be among the critical events related to the development of functional maturation. Consequently, we studied the effect of exoge nous CCK-8 and hydrocortisone on the mat uration of secretory function and on the on togeny of the neonatal rat pancreas.…”

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confidence: 99%

Effects of Cholecystokinin Octapeptide and Hydrocortisone on the Development of Fetal Rat Pancreas

Werlin¹,

Stefaniak²

1983

Neonatology

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Mechanisms and development of pancreas and pancreatic secretory function were studied in the rat. Injections of cholecystokinin octapeptide and hydrocortisone into pregnant rats altered pancreatic size, zymogen enzyme, and DNA content in the fetal newborn pancreas. These studies suggest that the developmental signals for pancreatic function may be related to endogenous release of cholecystokinin or hydrocortisone in the perinatal period.

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Maturation of Secretory Function in Rat Pancreas

Cited by 29 publications

References 3 publications

DNA and Protein Synthesis in Developing Rat Pancreas

DNA and Protein Synthesis in Developing Rat Pancreas

The Ontogeny of Serum Immunoreactive Pancreatic Lipase and Cationic Trypsinogen in the Premature Human Infant

Effects of Cholecystokinin Octapeptide and Hydrocortisone on the Development of Fetal Rat Pancreas

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