Immunohistochemical study of secretory proteins in the developing human exocrine pancreas

doi:10.1111/j.1432-0436.1992.tb00680.x

Differentiation

Volume 51, Issue 1, September 1992, Pages 55-60

https://doi.org/10.1111/j.1432-0436.1992.tb00680.x Get rights and content

Abstract

We have studied, by immunohistochemical methods using specific antisera, the development of three glycoproteins of human pancreatic secretion: lipase, carboxyl ester hydrolase (CEH) and the P19 protein (precursor of the non glycosylated protein X or “pancreatic thread/stone protein”). We have compared their development to that of trypsinogens (Tgs) and chymotrypsinogen A (Ch TgA), as well as to that of FAP (feto acinar pancreatic protein), a glycoprotein associated with the differentiation of human pancreas. Our studies show the characteristic appearance and development of lipase, the immunoreactivity of which appears later (at the 21st week of pregnancy) than it does for Tgs and ChTg (at the 16th week of pregnancy). Moreover, the lipase labelling is first observed in a few acini dispersed in the pancreas and then spreads out progressively to be present in all the acini after the age of 15 days. By contrast, as soon as they appear, Tgs and ChTg are observed uniformly in all acinar cells. The intensities of the lipase, Tgs and ChTg labellings increase greatly at birth. The ontogenesis of CEH does not follow that of lipase but that of Tgs and ChTg. The ontogenesis of P19 is parallel to that of Tgs. As previously observed, FAP presents a maximal immunoreactivity at the 24th-27th weeks of pregnancy, which decreases slowly up until birth.

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However, one study by Yang et al. (1) showed PLRP 1 and 2 mRNAs are expressed from the 16th week of gestation in the human fetal pancreas whereas PTL begins to be expressed after birth. In another study, Carrère et al. (12), using an immunostaining technique, found that BSSL/CEH protein is detectable earlier than lipase protein in the human exocrine fetal pancreas. This study most likely did not discriminate between PTL and the related proteins, PLRP1 and 2, as they share a high degree of homology and the antibodies used were not necessarily specific for PTL.
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The enzymes secretory responses to pancreozymin and secretin remained almost absent until the age of two years [11]. The problem with this absence of response in the early months does not result from lack of enzymes in the acini since all of them, except amylase, are present in the pancreatic gland of foetus and neonates as well as in the gut of premature and full-term neonates [13,14], Despite histological and ultrastructural maturity of the exocrine pancreatic gland early in life [13], this observed unresponsiveness to muscarinic agents in rat neonates [15,16] and to pancreozymin and secretin in human newborns [11], could either depend on deficiency and/or maturation of the involved receptors or on defects in the intracellular post-binding events leading to exocytosis. The lack of secretory response to cholinergic and hormonal stimuli in early ages does not seem to depend on either type of muscarinic and cholecystokinin (CCK) receptors.
Studies on the control of pancreatic secretion in humans of all ages have been a difficult task over the years because of patients’ availability and ethic committee rules. Nevertheless, studies were performed and the objectives of this review are to summarize our knowledge on the development of secretory process in newborns, on the different phases of the pancreatic responses to a meal, on the pancreatic responses to the different components of the diet, on the mechanisms involved in the control of the pancreatic responses, and finally on the receptors involved in these controls.

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Immunohistochemical study of secretory proteins in the developing human exocrine pancreas

Abstract

Biochim Biophys Acta

Differentiation

Biochim Biophys Acta

Biophys Acta

Anal Biochem

J Biol Chem

Biochem Biophys Res Commun

Differentiation

Biochem Biophys Res Commun

Biochem Biophys Res Commun

Biochim Biophys Acta

J Biol Chem

Comp Biochem Physiol

Protein X, a proteolysis product of human pancreatic juice. Immunological relationship with trypsinogen 1

Biol Chem Hoppe Seyler

Assay of human pancreatie lipase in biological fluids using a non competitive enzyme immunoassay

Clin Chim Acta

Levels and molecular forms of immunoreactive trypsin and chymotrypsin in amniotic fluids from normal and cystic fibrosis fetus: Evidence for a lack of activation of proteolytic zymogens in cystic fibrosis fetus

J Pediatric Gastroenterol Nutr